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Systematic paleontology: superfamilies and families recognized herein
General.Our diagnoses for each taxon include features of the carapace and other morphologic characters that are not necessarily synapomorphic for the superfamily but that do in fact characterize them. These features are essential to produce an overall diagnosis for the taxon at hand, whether it be a family or superfamily. As has been pointed out in earlier manuscripts (Schweitzer, 2003a, b), it is necessary to use a suite of characters to refer fossil, and often extant, specimens to taxa within the Xanthoidea sensu lato, because of the high degree of homoplasy and convergent evolution within the group. This is especially true for fossil specimens in which gonopods, pleopods, antennae, and other morphological parts with a poor fossilization potential are rarely accessible and in which dorsal carapace characters, termed proxy characters (Schweitzer and Feldmann, 2000a) because they track the diagnostic soft part anatomy typically used by biologists, are especially necessary. They are usually all that is preserved.
Genera discussed below that have been reassigned at the family level are compiled in Table 5.
Notations used. Taxa listed in 'Included families' headings are extant only unless marked otherwise. Genera listed in 'Included fossil genera' headings are extinct unless otherwise noted. Characters synapomorphic and/or diagnostic for the family or superfamily are italicized in the diagnoses; often characters must be used in combination with one another, especially to diagnose fossil specimens.
Infraorder Brachyura Latreille, 1802
Section Heterotremata Guinot, 1977
Superfamily Carpilioidea Ortmann, 1893
Included families. Carpiliidae Ortmann, 1893 (extinct and extant); Palaeoxanthopsidae Schweitzer, 2003a (extinct); Tumidocarcinidae Schweitzer, 2005a (extinct); Zanthopsidae Vía, 1959 (extinct).
Diagnosis. Carapace wider than long, maximum carapace length 70-80 percent maximum carapace width, ovate or hexagonal in shape, position of maximum width between half and three-quarters the distance posteriorly on carapace; dorsal surface generally not densely ornamented but may have large spherical swellings, regions range from well defined to very poorly defined; anterolateral margins entire or with spines or lobes; front with a medial sulcus, bi- or quadrilobed, frontal width between one-quarter to two-thirds maximum carapace width; antenna situated outside the supraorbital angle; orbits entire or rarely with clearly defined upper orbital fissures, fronto-orbital width between half and two-thirds maximum carapace width; medial sulcus on male thoracic sternite 4, male sternum may exhibit distinctive Y-shaped groove pattern (Palaeoxanthopsidae, Tumidocarcinidae, Zanthopsidae; see Schweitzer, 2005a, for illustrations), sternal sutures 4/5 and 5/6 of both sexes complete or incomplete and sometimes parallel, sutures 6/7 and 7/8 complete; male abdomen entirely occupying space between coxae of fifth pereiopods; sternite 8 not visible in ventral view; male abdominal somites free or 3-5 fused with suture between somites 4/5 sometimes visible; chelipeds at least weakly heterochelous, sometimes markedly so in males; occlusal surface of dactylus of major chela with a basal molar tooth; absence of corneous tips of pereiopods 2-4; cylindrical propodi of pereiopods 2-5.
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Table 5: Genera that have been moved herein to a different family. |
Occurrence. Cretaceous - Recent.
Discussion. Work on the families referred to the Carpilioidea has largely been conducted in recent years (Vega, Cosma et al., 2001; Schweitzer, 2003a, b; Schweitzer et al., 2004; Schweitzer, 2005a; Schweitzer et al., 2005). The four families referred here to the superfamily each exhibit an excellent fossil record; three are extinct. In spite of some being known only from fossils, a surprisingly detailed diagnosis can be made for these taxa, including features of the sternum and male abdomen which traditionally have been considered to be important for brachyuran classification.
The phylogenetic analysis presented here shows the superfamily to be well supported by six synapomorphies. Further, the excellent fossil record for each family, extending well back into the Paleogene or even the Cretaceous, suggests that this is indeed a closely related lineage. The earliest occurrences of all but one of these families (Carpiliidae (Eocene), Palaeoxanthopsidae [Cretaceous], Zanthopsidae [Paleocene]) is Tethyan, suggesting a possible single area of origin for the superfamily and subsequent radiation to other areas. The families with known paleoecological preferences inhabited somewhat different habitats. The Carpiliidae, in the Eocene and Miocene, as now, are known from tropical warm climates, in at least photic zone depths (Müller, 1984; Feldmann et al., 1998). The Zanthopsidae, on the other hand, preferred off-shore, clear, shelf environments below fair-weather wave base (Schweitzer et al., 2005). The Eocene to Miocene Tumidocarcinidae are typically found in deeper, quiet water, siliciclastic habitats (Glaessner, 1960; Feldmann, 1998; Casadío et al., 2004). Thus, there may have been early differentiation within the superfamily for different environments.
Family Carpiliidae Ortmann, 1893
Included fossil genera. Carpilius Leach in Desmarest, 1823 (also extant); Eocarpilius Blow and Manning, 1996; Holcocarcinus Withers, 1924; Ocalina Rathbun, 1929; Palaeocarpilius A. Milne-Edwards, 1862; Proxicarpilius Collins and Morris, 1978.
Occurrence. Eocene - Recent.
Diagnosis. Carapace wider than long, length about 70-80 percent maximum carapace width, widest about two-thirds to three-quarters the distance posteriorly on carapace; may be ornamented with large, flat swellings; regions moderately to poorly defined; grooves not developed except branchiocardiac groove in some cases. Front usually with bilobed medial projection and blunt inner orbital spines, thus appearing quadrilobed, but may be produced into downturned, blunt triangle; notch between frontal margin and supraorbital angle indistinct, frontal width averaging 36 percent maximum carapace width. Orbits circular, entire, rimmed or beaded, directed forward, fronto-orbital width about half to two-thirds maximum carapace width. Anterolateral margin may be entire or with blunt lobes or spines; last spine may be extended onto dorsal carapace as short, low ridge; anterolateral margin long, much longer than posterolateral margin, terminating two-thirds to three-quarters the distance posteriorly, concave, tightly curved posteriorly, often very convex posteriorly. Posterolateral margin straight or weakly convex, short, at a very low angle to posterior margin, around 25-30 degrees; posterior margin nearly straight, narrow, averaging about 30 percent maximum carapace width.
Carapace regions may be weakly inflated or not defined. Branchiocardiac groove often defining lateral margins of urogastric region. Buccal frame usually tapering anteriorly. Thoracic sternum narrow, rectangular, with subparallel margins; sternite 3 without medial groove; articulation condyle of pereiopods on sternum; sutures 4/5-7/8 complete, parallel; sternite 8 not visible in ventral view. Male abdominal somites 3-5 fused, abdomen filling entire space between coxae of fifth pereiopods. Chelae large, subequal or heterochelous; outer, upper and lower surfaces generally smooth, upper surface may have blunt nodes; chelipeds much larger than other walking legs; merus fused to basis-ischium; merus and coxa articulating directly. Pereiopods 2-5 narrow, smooth, tubular. Male gonopod 1 weakly curved, stout, with simple apex. Male gonopod 2 long with long, filamentous flagellum (after Schweitzer, 2003a: 1110).
Family Palaeoxanthopsidae Schweitzer, 2003a
Included fossil genera. Jakobsenius Schweitzer, 2005a; Lobulata Schweitzer, Feldmann, and Gingerich, 2004; Palaeoxanthopsis Beurlen, 1958; Para-verrucoides Schweitzer, 2003a; Remia Schweitzer, 2003a; Rocacarcinus Schweitzer, 2005a; Verrucoides Vega et al., 2001.
Occurrence. Cretaceous - Eocene.
Diagnosis. Carapace wider than long, maximum carapace length about 75 percent maximum carapace width, position of maximum width about half to two-thirds the distance posteriorly; regions defined by grooves; moderately or deeply incised, V-shaped groove separating gastric regions from hepatic and branchial regions; regions may be moderately or weakly inflated, often with large, spherical swellings. Frontal width about 20 percent maximum carapace width, quadrilobed, medial two lobes may project well beyond orbits. Orbits with two fissures or sutures, rectangular, sometimes rimmed, outer-orbital angle a projected spine, fronto-orbital width about half maximum carapace width. Anterolateral margin with a straight segment followed by three to five spines not including outer-orbital spine; spines well-separated by notches or fissures; last spine longest, directed laterally or posterolaterally. Posterior margin narrow, concave, about one-quarter maximum carapace width. Branchial regions often with linear, transverse swellings.
Male sternum with no evidence of suture between sternites 2 and 3; may exhibit distinctive Y-shaped groove pattern on sternites 3 and 4; sternal suture 3/4 oriented at steep angle; sternite 4 with large episternal projection; sternite 4 with very clear, longitudinal grooves near lateral margins, which appear to be episternal projections from sternite 3 fused with and prominent on sternite 4; male abdominal somites free.
Female sternum with deep suture between sternite 2/3; groove from sterno-abdominal cavity extending anteriorly onto sternite 4; abdomen reaching level of base of coxae of pereiopods 1.
Discussion. Schweitzer (2003a) erected the Palaeoxanthopsidae and referred four genera to it. Subsequently, more genera were named and added, resulting in a slight broadening of the diagnosis and addition of details of the sternum of males and females (Schweitzer et al., 2004; Schweitzer, 2005a). The above diagnosis embraces all of the referred genera to date.
Family Tumidocarcinidae Schweitzer, 2005a
Included genera (all fossil). Baricarcinus Casadío et al., 2004; Paratumidocarcinus Martins-Neto, 2001; Pulalius Schweitzer et al., 2000; Tumidocarcinus Glaessner, 1960; Xanthilites Bell, 1858.
Occurrence. Eocene - Miocene.
Diagnosis. Carapace wider than long, L/W about 0.80, widest at position of last or penultimate anterolateral spine, about half the distance posteriorly on carapace; carapace markedly vaulted longitudinally, especially in anterior third; front four-lobed including inner-orbital spines, frontal width about one-quarter maximum carapace width; fronto-orbital width a little less than half maximum carapace width; orbits rimmed, sometimes with very faint, completely fused fissure, circular, directed forward; antenna situated outside supraorbital angle; carapace regions well defined to poorly defined; anterolateral margins with three or four small, blunt spines excluding outer orbital spine or entire and granular; epibranchial regions usually arcuate.
Male sternites 1 and 2 fused with no evidence of suture; very clear, deep, continuous suture between sternites 2 and 3; sternites 3 and 4 with notch in lateral margins where suture intersects it, suture becoming increasingly shallow, becoming a shallow groove at midlength, completely interrupted axially; left and right sternal sutures between sternites 3 and 4 merge with deep groove extending anteriorly from sterno-abdominal cavity, forming prominent, Y-shaped groove pattern; suture between sternites 3 and 4 oriented at high angle; sternite 4 with very clear, longitudinal grooves near lateral margins, which appear to be episternal projections from sternite 3 fused with and prominent on sternite 4; sternal sutures not parallel;sternite 8 not visible in ventral view.
Male abdomen barely reaching or not quite reaching posterior margin of coxae of first pereiopods; all male abdominal somites free; male abdomen completely occupying space between coxae of fifth pereiopods.
Chelae subequal to very unequal; mani stout; fingers with black tips; coxae of first pereiopods articulating with basis-ischium, basis-ischium not fused to merus; other pereiopods slender (after Schweitzer 2005a: 282).
Family Zanthopsidae Vía, 1959
Included genera (all fossil). Fredericia Collins and Jakobsen, 2003; Harpactocarcinus A. Milne-Edwards, 1862; Harpactoxanthopsis Vía, 1959; Martinetta Blow and Manning, 1997; Neozanthopsis Schweitzer, 2003a; Zanthopsis McCoy, 1849.
Occurrence. Paleocene - Miocene.
Emended Diagnosis. Carapace wider than long, maximum carapace length about 80 percent maximum carapace width, widest about one-half to two-thirds the distance posteriorly on carapace; ovate or circular in shape; may be ornamented with large swellings, sometimes arranged on ridges; regions poorly or moderately defined; branchiocardiac groove well-developed; front with four blunt spines including inner orbital spines, frontal width about one-quarter maximum carapace width; orbits circular or rectangular, entire, rimmed, fronto-orbital width about half maximum carapace width; anterolateral margin convex, entire, with three to five blunt spines, or with numerous small spines; last anterolateral spine may extend onto carapace as long, low ridge; anterolateral margin often tightly arched posteriorly; anterolateral margin about as long or slightly longer than posterolateral margin; posterolateral margin sinuous or weakly concave; posterior margin nearly straight, 30-40 percent maximum carapace width.
Sternum narrow, ovate, broadest anteriorly at position of fourth sternite, narrowing posteriorly; sternal suture 4/5 incomplete; sutures 5/6-7/8 complete; sutures 4/5 and 5/6 not parallel; sternite 4 in males and females with swelling just anterior to episternal projection of sternite 4; sternite 4 with clear longitudinal grooves near lateral margins that appear to be episternal projections of sternite 3 fused with sternite 4; sternite 8 not visible in ventral view. Male abdomen with somites 3-5 fused, suture between 4/5 visible; somite 3 with lateral extensions often ornamented with spherical swellings; telson longer than somite 6; male abdomen reaching base or middle of coxa of pereiopod 1; male abdomen covering entire space between coxae of pereiopods 5. Chelae large, subequal or weakly heterochelous, outer surface smooth or with large swellings, upper and lower margins with numerous small spines; chelipeds much longer than walking legs; ischium of major cheliped articulating with coxa, merus not fused completely to ischium.
Discussion. The emended diagnosis is based upon material examined in the Museu Geològic del Seminari de Barcelona ( Harpactocarcinus punctulatus (Desmarest, 1823), MGSB 10815, 6404, 9935) during the summer of 2004 (CS) and Harpactoxanthopsis lutugini (Likharev, 1917) and Zanthopsis bispinosa Bell, 1858, deposited in the Mizunami Fossil Museum (HK). These specimens have extremely well preserved sterna and abdomina; thus, new observations were made and are herein recorded.
Fredericia Collins and Jakobsen, 2003, is added to the family based upon the carapace shape; projected front with four spines; entire orbits; fronto-orbital width about half the maximum carapace width; weak Y-shaped groove on sternum; sternite 4 with clear longitudinal grooves near lateral margins which appear to be episternal projections of sternite 3 fused with sternite 4; sternite 8 not visible in ventral view; fused male abdominal somites 3-5; and male somite 3 with lateral projections. All of these characters are diagnostic for the family and make placement of Fredericia within the Zanthopsidae quite certain.
Superfamily Pilumnoidoidea Guinot and Macpherson, 1987
Included family. Pilumnoididae Guinot and Macpherson, 1987
Occurrence. Recent.
Diagnosis. As for Pilumnoididae.
Family Pilumnoididae Guinot and Macpherson, 1987
Included genus. Pilumnoides Lucas in H. Milne Edwards and Lucas, 1843.
Occurrence. Recent.
Diagnosis. Carapace ovate or subhexagonal, wider than long, maximum carapace length about 80 percent maximum carapace width, widest about 60 percent the distance posteriorly; regions usually well-defined, usually granular but may be smooth ( Pilumnoides inglei Guinot and Macpherson, 1987); front with axial notch, may have weak projection just to orbit, frontal width about one-third maximum carapace width; orbits may have two closed fissures, fronto-orbital width about half to two-thirds maximum carapace width; anterolateral margins with four or five spines or lobes excluding outer-orbital spine or with numerous granules or spinelets. Endostomial crests complete. Sternum narrow, long, sutures 4/5, 5/6, 6/7 and 7/8 uninterrupted and subparallel, sternite 8 not visible in ventral view. All male abdominal somites free, male abdomen completely covering space between coxae of fifth pereiopods. Male gonopod 1 long, straight, slightly incurved, with a terminal opening, ornamented with tubercles, rarely with setae; male gonopod 2 medium in length, straight, with a well-developed peduncle, flagellum short. Chelipeds weakly heterochelous, often with rows of tubercles on outer surface of manus; chelipeds much more robust than pereiopods 2-5; merus fused to basis-ischium. (After Guinot and Macpherson, 1987).
Discussion. Guinot and Macpherson (1987) created the subfamily Pilumnoidinae to embrace the unusual genus Pilumnoides , which they considered to be a plesiomorphic genus within the Xanthoidea sensu Guinot, 1977. They considered it to be an evolutionary grade similar to the Carpiliidae (Guinot and Macpherson, 1987: 218), which is interestingly where it appears in our analysis. Guinot and Macpherson (1987) compared their monotypic subfamily to several other families and subfamilies within the Xanthoidea sensu Guinot, 1977, but the unusual suite of characters could not be accommodated by any of them. Other authors have maintained the Pilumnoidinae within the Goneplacidae sensu lato (Davie, 2002). However, Karasawa and Kato (2003b) excluded the Pilumnoidinae within the Goneplacidae based upon cladistic analysis and showed that the subfamily was the sister to the Carpiliidae. All Goneplacoidea as herein defined have all sternal sutures interrupted and indistinct and relatively unornamented regions, which cannot accommodate the Pilumnoidinae. We herein raise the subfamily to family status and create a new superfamily for it.
Superfamily Xanthoidea MacLeay, 1838 sensu stricto
Included families.Pilumnidae Samouelle, 1819; Domeciidae Ortmann, 1893; Trapeziidae Miers, 1886; Panopeidae Ortmann, 1893; Pseudorhombilidae, Alcock, 1900; Xanthidae MacLeay, 1838 sensu stricto.
Occurrence. Cretaceous - Recent.
Diagnosis. Carapace hexagonal, ovate, rectangular, or circular, usually wider than long, maximum length from 66 - 100 percent maximum carapace width, usually between 75 - 85 percent, usually widest about 40 - 50 percent the distance posteriorly but two-thirds to three-quarters the distance in most Xanthidae; carapace regions poorly defined to very well defined; front usually bilobed but may be entire or multi-lobed, frontal width about one-quarter to half maximum carapace width; orbits may have two fissures or notches, fronto-orbital width ranging from half to 90+ percent maximum carapace width; anterolateral margin entire or with between two and six spines or lobes excluding outer-orbital spines, anterolateral and posterolateral margins usually distinct from one another, posterolateral margin straight or concave.
Male gonopod 1 slender. Male gonopod 2 short. Sternum narrow, sternal sutures 4/5 and 5/6 interrupted, sternal sutures 6/7 and 7/8 complete. Male abdominal somites free or somites 3-5 fused, sutures may be visible. Chelipeds subequal or heterochelous, fingers often with black tips.
Family Domeciidae Ortmann, 1893
Included fossil genera. Jonesius Sankarankutty, 1962 (also extant); Palmyria Galil and Takeda, 1986 (also extant).
Occurrence. Oligocene - Recent.
Diagnosis. Carapace hexagonal or ovate, wider than long, maximum carapace length averaging about 80 percent maximum carapace width, position of maximum width about 40 percent the distance posteriorly on carapace; regions poorly defined; front bilobed, sometimes granular or spinose, about half maximum carapace width; orbits shallow, semi-circular, directed forward, fronto-orbital width averaging about 80 percent maximum carapace width; anterolateral margin extending obliquely and distally from outer-orbital corner, often spinose. Basal article of antenna not reaching front. Merus of third maxilliped short, much wider than long; "second maxilliped with endopod having propodus and dactylus fused into a very large endite" (Davie, 2002: 152). Male gonopod 1 stout, sinuous, with blunt tip; male gonopod 2 about half the length of gonopod one, thick proximally. Male abdomen with somites 3-5 fused, sutures may be visible, third somite in some taxa much wider than other somites. Chelipeds equal or unequal, usually strongly granular or spinose, merus short; pereiopods 2-5 "with dactylo-propodal articulation formed by rounded prolongation of propodal lateral margin sliding against and beneath a projecting button situated proximally on lateral margin of dactylus" (Davie, 2002: 152). (After Davie, 2002; Castro et al., 2004; Schweitzer, 2005b: 625).
Family Panopeidae Ortmann, 1893
Included fossil genera. Balcacarcinus new substitute name for Bittneria Schweitzer and Karasawa, 2004 (see below); Carinocarcinus Lörenthey, 1898; Eurypanopeus A. Milne-Edwards, 1880 (also extant); Eurytium Stimpson, 1859 (also extant); Glyphithyreus Reuss, 1859; Hexapanopeus Rathbun, 1898 (also extant); Laevicarcinus Lo´´renthey in Lörenthey and Beurlen, 1929; Lophopanopeus Rathbun, 1898 (also extant); Micropanope Stimpson, 1871 (also extant); Neopanope A. Milne-Edwards, 1880 (also extant); Pakicarcinus Schweitzer et al., 2004; Palaeograpsus Bittner, 1875; Panopeus H. Milne Edwards, 1834 (also extant); Sereneopeus Collins, 2002.
Occurrence. Paleocene - Recent.
Diagnosis. Carapace hexagonal, transversely ovate, or sometimes circular, wider than long, L/W ranging from 0.70-0.95, point of maximum width about 40-50 percent the distance posteriorly on carapace; carapace flattened, regions moderately well-marked to weakly defined; front bilobed, ranging from 30 to 43 percent maximum carapace width; orbits with two fissures or notches, fronto-orbital width about 60-80 percent maximum carapace width; anterolateral margin entire or with 2 - 4 spines excluding outer-orbital spine; anterolateral margins usually distinct from posterolateral margins. Sternum narrow or wide, triangular in shape, sometimes comparatively large portion of sternite 8 visible in ventral view; male abdominal somites 1, 2, and 3 usually covering entire space between fifth pereiopods; male abdominal somites 3-5 fused, sutures may be evident. Male genital openings coxal or coxo-sternal but penis often lies in a more or less elongate sternal (coxo-sternal) position. Male gonopod 1 slender, curved or straight, sometimes with spines or setae, with several, sometimes complex, apical extensions. Gonopod 2 short, less than 25 percent length of gonopod 1, curved. Chelipeds subequal or heterochelous; with pointed fingers or with spoon-shaped tips, tips may be black; pereiopods 2-5 long, without dactylo-propodal articulation. Diagnosis after Rathbun (1918), Davie (2002), and Schweitzer and Karasawa (2004).
Genus Balcacarcinus new substitute name
Bittneria Schweitzer and Karasawa, 2004: 80, fig. 1.6 (non Bittneria Broili, 1904, p. 168).
Type species. Palaeograpsus attenuatus Bittner, 1875, by monotypy.
Description. See Schweitzer and Karasawa (2004).
Etymology. The genus name is derived from the Anglo-Saxon word balca, meaning ridge, and the Greek word karkinos , meaning crab and a common ending for brachyuran generic names, in reference to the numerous ridges on the dorsal carapace in this taxon.
Discussion. Schweitzer and Karasawa (2004) erected the genus Bittneria to accommodate Palaeograpsus attenuatus in their revision of Palaeograpsus . However, the name Bittneria is preoccupied by a genus of mollusc (Broili, 1904); thus, we herein provide the substitute name, Balcacarcinus , to replace Bittneria Schweitzer and Karasawa, 2004, as per Article 60.3 of the International Code of Zoological Nomenclature (1999).
Family Pilumnidae Samouelle, 1819
Included fossil genera. Actumnus Dana, 1851a (also extant); Arges De Haan, 1835; Budapanopeus Müller and Collins, 1991; Eohalimede Blow and Manning, 1996; Eopilumnus Beschin et al., 2002; Eumorphactaea Bittner, 1875; Galene De Haan, 1835 (also extant); Galenopsis A. Milne-Edwards, 1865; Glabropilumnus Balss, 1932 (also extant); Gollincarcinus Beschin and De Angeli, 2004; Halimede De Haan, 1833 (also extant); Lessinioplax Beschin and De Angeli, 2004; Lobogalenopsis Müller and Collins, 1991; Lobonotus A. Milne-Edwards, 1864; Maingrapsus Tessier et al., 1999; Paracorallicarcinus Tessier et al., 1999; Pilumnus Leach, 1815 (also extant); Pilumnopeus A. Milne-Edwards, 1863 (also extant); Titanocarcinus A. Milne-Edwards, 1864; Typhlocarcinus Stimpson, 1858 (also extant); Viacarcinus Blow and Manning, 1996. The presence of Heteropanope Stimpson, 1858 (also extant) in the fossil record must be evaluated by examination of type material of Heteropanope? wylliei Glaessner, 1933, to confirm its placement in the genus.
Occurrence. Cretaceous - Recent. The Cretaceous occurrence is based upon Titanocarcinus serratifrons A. Milne-Edwards, 1864, reported from southern Belgium in rocks of late Maastrichtian age (J. Jagt, personal commun.). Although we have been unable to locate the type of T. serratifrons , the species is well described and illustrated and appears at this time to be referrable to the Pilumnidae. Numerous Eocene occurrences of the family are known (A. Milne-Edwards, 1864, 1865; Müller and Collins, 1991; Blow and Manning, 1996; Beschin and De Angeli, 2004).
Diagnosis. Carapace hexagonal (Galeninae A. Milne-Edwards, 1862; Halimedinae Alcock, 1898; Pilumninae Samouelle, 1819), transversely rectangular (Rhizopinae Stimpson, 1858), ovate (Calmaniinae Števčić, 1991), or bizarrely projected (Eumedoninae Dana, 1853), wider than long, maximum carapace length usually about 70 - 80 percent maximum carapace width but may be much higher (90 + percent in Calmaniinae, Eumedoninae, and Halimedinae), position of maximum width variable among and within subfamilies; dorsal surface convex, often markedly so in anterior one-third; regions smooth or granular and setose, sometimes with transverse swellings (Rhizopinae); frontal margin entire, bilobate, with many lobes, or greatly anteriorly projected (Eumedoninae), front usually ranges from one-third to half maximum carapace width but may be much lower (about 20 percent in Galeninae, some Rhizopinae); orbits usually with two orbital notches or fissures, fronto-orbital width two-thirds to three-quarters (Calmaniinae, Eumedoninae, Halimedinae, Pilumninae) or 40 - 60 percent (Galeninae, Rhizopinae) maximum carapace width; anterolateral margins usually with spines, often 1 - 4 (Galeninae, Halimedinae, Pilumninae, some Rhizopinae), but can be entire or indistinctly lobate (Calmaniinae, Eumedoninae, some Rhizopinae); gastric regions often long; usually anterolateral and posterolateral margins distinct from one another. Endostome with crests defining efferent branchial channels at least moderately developed and continuing to anterior margin of buccal cavity (Davie, 2002: 392). Sternal sutures 4/5 and 5/6 interrupted medially; posterolateral prolongation of sternite 7 well marked; sternite 8 not visible ventrally. All male abdominal somites free, narrow, covering most of sternite 4 , abdominal locking mechanism ('bouton-presson') present; male genital openings coxal or coxo-sternal. Male gonopod 1 slender or stout, sinuous, tip usually simple and recurved; gonopod 2 very short and sigmoid. Chelae subequal or heterochelous, fingers may have black tips; pereiopods short or moderately long. Subfamilies as defined by Davie (2002) and Poore (2004).
Discussion. The Pilumnidae as currently defined is a diverse group that is acknowledged to be in need of revision at the species, generic, and subfamily levels (Davie, 2002). Števčić (2005) separated the Pilumnidae into numerous subfamilies and tribes. Evaluation of these many subdivisions is beyond the scope of this paper.We follow primarily Davie (2002) in the definition of the family, and have previously discussed the problems attendant with such taxa as Galene and the Galeninae (Schweitzer, 2005a). Schweitzer (2005a) also discussed the fact that the subfamilies are so different from one another that at least in discussions of fossil taxa, it may be necessary to make comparisons to each included subfamily rather than the family as a whole. Davie (2002) and Poore (2004) each provided good subfamily diagnoses which need not be repeated here.
Beschin and De Angeli (2004) described Gollin-carcinus and Lessinioplax , both from the Eocene of Italy. They placed those two genera within the Go-neplacidae, and noted similarities with Magyarcar-cinus Schweitzer and Karasawa, 2004, and Palaeograpsus Bittner, 1875, for the former, and Georgeoplax Türkay, 1983, for the latter. There are in fact similarities among the four genera, but those similarities appear to be superficial. We place Gollincarcinus and Lessinioplax within the Pilumnidae, because they are similar morphologically to Georgeoplax . The family placement of Georgeoplax itself has been the subject of much debate, which was recently summarized (Karasawa and Kato, 2003b), and the genus was placed within the Pilumnidae in that same work. We concur. Gollincarcinus and Lessinioplax are placed within the Pilumnidae based upon their possession of a smooth carapace; entire frontal, supraorbital, and anterolateral margins; a highly vaulted carapace, especially anteriorly; broad fronto-orbital width; and hexagonal carapace. Magyarcarcinus and allied members of the Goneplacidae admittedly also exhibit many of these features, but they are ovate and are not as highly vaulted. Description of the sternum and abdomen of Gollincarcinus and Lessinioplax would help to confirm their family placement.
Family Pseudorhombilidae Alcock, 1898
Included fossil genera. Nanoplax Guinot, 1967a (also extant); Pseudorhombila H. Milne Edwards, 1837 (also extant).
Occurrence. Miocene - Recent.
Diagnosis. Carapace hexagonal, wider than long, L/W ranging from 0.72-0.76, position of maximum width about 40-55 percent the distance posteriorly on carapace; carapace flattened, regions moderately well-marked to weakly defined; front bilobed, ranging from 26-32 percent maximum carapace width; orbits with two fissures or notches, orbital rim sinuous, convex between fissures, marked protuberance on inner orbital rim; fronto-orbital width about 53-59 percent maximum carapace width; anterolateral margin with 3-5 spines including outer-orbital spine; sternum wide, tiny portion of sternite 8 visible adjacent to articulation condyle of coxa of fifth pereiopod, visible in posterior or dorsal view; male abdominal somites 1 and 2 not covering entire space between fifth pereiopods, somite 3 usually touching coxa of fifth pereiopod; male abdominal somites 3-5 fused, often weakly, sutures may be quite obvious. Diagnosis based in part on descriptions and observations from Rathbun (1918), Guinot (1969), Hendrickx (1998) and Schweitzer and Karasawa (2004: 81).
Family Trapeziidae Miers, 1886
Included fossil genera. Archaeotetra Schweitzer, 2005b; Eomaldivia Müller and Collins, 1991; Tetralia Dana, 1851c (also extant); Trapezia Latreille, 1828 (also extant).
Occurrence. Eocene - Recent.
Diagnosis. Carapace cordate, not much wider than long, length averaging about 86 percent maximum carapace width, position of maximum width about half the distance posteriorly on carapace; carapace regions not defined; front weakly bilobed, four-lobed, serrate, or nearly straight, without median notch, about half maximum carapace width; orbits deeply excavated, positioned at corners of frontal margin of carapace, directed anterolaterally, fronto-orbital width about 90 percent or more maximum carapace width; anterolateral margins short, usually oriented nearly perpendicular to frontal margin of carapace or oriented at very high angle to frontal margin, entire or with one or two spines. Basal antennal article slender; efferent channels defined by well-developed endostomial crests; merus of third maxilliped shorter than ischium, about as wide as long; endopod of second maxilliped composed of four separate segments. Sternites 1 and 2 fused into triangle, sternal suture 2/3 present or absent. Male abdomen with somites 3-5 fused with visible sutures or with all somites free. Male gonopod 1 slender or stout, sinuous or straight, with pointed or rounded tip; male gonopod 2 stout or slender, curved, tip spoon-shaped. Chelae unequal, smooth or weakly granular, merus of cheliped extending beyond carapace margins when folded; pereiopods 2-5 "with dactylo-propodal articulation formed by rounded prolongation of propodal lateral margin sliding against and beneath a projecting button situated proximally on lateral margin of dactylus" (Davie, 2002: 493) (After Schweitzer, 2005b: 627).
Family Xanthidae MacLeay, 1838 sensu stricto
Included fossil genera. Actaea De Haan, 1833 (also extant); Actaeops Portell and Collins, 2004; Atergatis De Haan, 1833 (also extant); Banareia A. Milne-Edwards, 1869 (also extant); Chlorodiella Rathbun, 1897 (also extant); Cyclodius Dana, 1851a (also extant) (= Phymodius A. Milne-Edwards, 1863); Cycloxanthops Rathbun, 1897 (also extant); Cymo De Haan, 1833 (also extant); Demania Laurie, 1906 (also extant); Etisus H. Milne Edwards, 1834 (also extant); Forestia Guinot, 1976 (also extant); Glyptoxanthus A. Milne-Edwards, 1879 (also extant); Haydnella Müller, 1984; Heteractaea Lockington, 1877 (also extant); Hypocolpus Rathbun, 1897 (also extant); Lachnopodus Stimpson, 1858 (also extant); Leptodius A. Milne-Edwards, 1863 (also extant); Liagore De Haan, 1833 (also extant); Liomera Dana, 1851a (also extant); Lipaesthesius Rathbun, 1898 (also extant); Lybia H. Milne Edwards, 1834 (also extant); Macromedaeus Ward, 1942 (also extant); Medaeops Guinot, 1967a (also extant); Medaeus Dana, 1851a (also extant); Megamia Karasawa, 1993; Metopoxantho De Man, 1904; Monodaeus Guinot, 1967a (also extant); Neoliomera Odhner, 1925 (also extant) (= Neomeria Hu and Tao, 1996); Palaeotrichia Guinot, 1976; Palaeoxanthops Karasawa, 1993; Paraxanthias Odhner, 1925 (also extant); Paraxanthodes Guinot, 1967b (also extant); Phlyctenodes A. Milne-Edwards, 1862; Pilodius Dana, 1852 (also extant); Sculptoplax Müller and Collins, 1991; Xanthias Rathbun, 1897 (also extant); Xantho Leach, 1814 (also extant); Xanthodius Stimpson, 1859 (also extant); Zalasius Rathbun, 1897 (also extant); Zosimus Leach in Desmarest, 1823 (also extant).
Occurrence. Eocene - Recent.
Diagnosis. Carapace hexagonal or transversely ovate; carapace length/width falling into two groups, length either about two-thirds to three quarters or 90-100 percent maximum carapace width, widest two-thirds to three quarters the distance posteriorly except in some Xanthinae and Polydectinae in which position of maximum width is before the midlength; regions usually well-defined but dorsal carapace can be smooth; frontal margin bilobed, with axial notch, ranging from one-quarter to about 40 percent maximum carapace width; fronto-orbital width generally about half to two-thirds maximum carapace width; anterolateral margins with between 2 and 6 lobes or spines; anterolateral margin well-differentiated from posterolateral margin, anterolateral margin often tightly convex; posterolateral margin often concave. Epistome with ridges that define efferent branchial canals absent or only on posterior portion of buccal cavity, not intercepting anterior part of buccal frame. Sternum narrow, sternite 8 not visible ventrally. Male abdomen with somites 3-5 fused, sutures may be visible. Male genital openings coxal. Male gonopod 1 slender, curved or sinuous, simple apex without complex lobes or folds, with long setae distally or subdistally; gonopod 2 short, less than 25 percent length of gonopod 1. Cheliped fingers typically black; chelae subequal or heterochelous, may have spoon-shaped tips. Chelipeds much stouter than pereiopods 2-5. Modified after Davie (2002).
Discussion. Števčić (2005) separated the Xanthidae sensu stricto into numerous subfamilies and tribes. Evaluation of the validity and composition of these is beyond the scope of this paper; we have considered them simply as members of the family.
Rathbun (1945) referred a species to Carpilodes Dana, 1851a, which has subsequently been made a junior synonym of Atergatis ; thus, Carpilodes sublensis Rathbun, 1945, is now referred to Atergatis . Interestingly, the notes of one of us (CES) suggest that the holotype of that species (USNM 498416) possibly could be a damaged specimen of Atergatis laddi Rathbun, 1945, (holotype USNM 498415), named in the same paper.
Neomeria Hu and Tao, 1996, is herein considered as a junior synonym of Liomera based upon its carapace shape and groove pattern.
Superfamily Xanthoidea MacLeay, 1838, incertae sedis
Included fossil genera. Actaeites Müller and Collins, 1991; Actaeopsis Carter, 1898; Caprocancer Müller and Collins, 1991; Carpiliopsis Fischer-Benzon, 1866; Colpocaris Von Meyer, 1863; Creticarcinus Withers, 1928; Cretichlorodius Fraaye, 1996; Cyclo-corystes Bell, 1858; Eoplax Müller and Collins, 1991; Eoxanthias Hu and Tao, 1996; Gemmacarcinus Müller and Collins, 1991; Martinocarcinus Böhm, 1922; Megaxantho Vega, Feldmann et al., 2001; Paraxanthosia Müller and Collins, 1991; Pilumnomimus Müller and Collins, 1991; Pregeryona Hu and Tao, 1996; Prochlorodius Müller and Collins, 1991; Santeella Blow and Manning, 1996; Styrioplax Glaessner, 1969; Syphax A. Milne-Edwards, 1864; Thelecarcinus Böhm, 1891; Thelphusograpsus Lörenthey, 1902; Wanga Hu and Tao, 1996.
Discussion. The description of Actaeopsis contains similarities to members of the Tumidocarcinidae or the Palaeoxanthopsidae; however, examination of type material will be necessary to confirm its identity. The various taxa described by Müller and Collins (1991) are poorly preserved but retain features characteristic of the Xanthoidea sensu stricto. Actaeites appears to be most similar to Titanocarcinus , and Pilumnomimus and Prochlorodius may be most similar to Glabropilumus sensu lato (see Galil and Takeda, 1988). However, both of the latter fossil genera also have similarities with members of the Panopeidae and Euryplacidae. Thus, examination of more complete specimens will be necessary to confirm their family-level placement. The dorsal carapace of Martinocarcinus is quite damaged although the sternum is preserved; examination of type material will be necessary to confirm its identity. Megaxantho was originally placed within the Xanthidae; it was later suggested that it more closely resembled the Cancridae based upon the conformation of the anterolateral spines (D. Guinot, personal commun.). Most recently, Števčić (2005) erected a new family Megaxanthidae of the Goneplacoidea incertae sedis for it. Better preserved material would help clarify the familial placement of Megaxantho . Placement of Styrioplax , Syphax , Thelphusograpsus , and the genera erected by Hu and Tao (1996) must await examination of type material.
Thelecarcinus may well be referrable to the Hepatidae, based on the shape of the carapace, ornamentation, and the conformation of the anterolateral margins (Böhm, 1891, pl. 1, fig. 3); however, formal placement must await examination of type material. Creticarcinus and Carpiliopsis may be junior synonyms of Caloxanthus , referred below to the Etyidae Guinot and Tavares, 2001; however, Creticarcinus has better defined and more tumid dorsal carapace regions (Withers, 1928, pl. XIII, fig. 4), and Carpiliopsis lacks a distinct cervical furrow and granular ornamentation (Fischer-Benzon, 1866, pl. II, fig. 1) as seen in Caloxanthus . Type material needs to be examined to formally place these two genera within a family.
Superfamily Eriphioidea MacLeay, 1838
Included families. Platyxanthidae Guinot, 1977; Hypothalassiidae Karasawa and Schweitzer new family; Pseudoziidae Alcock, 1898; Eriphiidae MacLeay, 1838; Oziidae Dana, 1851a (= Menippidae Ortmann, 1893; see Schweitzer, 2003a, for discussion of synonymy).
Occurrence. Eocene - Recent.
Diagnosis. Carapace hexagonal or ovate, wider than long, maximum carapace length 60-75 percent maximum carapace width, widest about half to two-thirds the distance posteriorly on carapace; dorsal carapace regions moderately or weakly defined; frontal margin bilobed or quadrilobed excluding inner-orbital spines, frontal margin about 20-30 percent maximum carapace width except in Eriphiidae (50 percent) and Dacryopilumninae of Oziidae (70 percent); fronto-orbital width about one-third to half maximum carapace width except in Eriphiidae (70 percent) and Dacryopilumninae of Oziidae (90 percent); anterolateral margins with four spines or lobes, or entire, or with a variable number of spines; anterolateral margin distinct from posterolateral margin. Buccal frame anteriorly tapered, trapezoidal. Sternum narrow; sternal sutures 4/5 and 5/6 interrupted but uninterrupted in female of Menippinae; sternal sutures 6/7 and 7/8 complete; all male abdominal somites free, movable; male abdomen fills space between coxae of fifth pereiopods. Male gonopod 1 stout, straight or weakly curved or long and slender; gonopod 2 as long as or longer than gonopod 1, with a short, developed, long, or very long flagellum. Chelipeds at least weakly heterochelous, sometimes markedly so. (In part modified after Ng and Wang, 1994; Davie, 2002).
Discussion. Rice (1981, 1983) suggested that the platyxanthid Homalaspis and two eriphiids, Eriphia and Ozius , had the most primitive zoeal features within the xanthoids and that the other xanthoids, the cancroids, and the portunoids may have evolved from them. Števčić (1998) considered that the Eriphiidae had the most primitive characters in terms of adult morphology within the Xanthoidea. However, in the present analysis, the Eriphiidae is a rather derived group within the Xanthoidea.
The Platyxanthidae is the sister to the remainder of the clade. The Eriphiidae sensu lato is polyphyletic. The polyphyly of the Eriphiidae sensu lato was previously suggested by Coelho and Coelho Filho (1993), and they included the Menippinae with Menippe within the Xanthidae and placed Eriphia in its own family Eriphiidae. More recently, Ng et al. (2001) recognized four eriphiid subfamilies, Eriphiinae including only Eriphia ; Oziinae including Ozius , Epixanthus, Epixanthoides Balss, 1935, Lydia Gistel, 1848, Baptozius Alcock, 1898, Bountiana Davie and Ng, 2000, and Eupilumnus Kossmann, 1877 = Globopilumnus Balss, 1933; Menippinae including Hypothalassia , Menippe , Myomenippe , Sphaerozius, and Pseudocarcinus H. Milne Edwards, 1834; and Dacryopilumninae including only Dacryopilumnus , based upon characters of the carapace, antennae, orbits, and gonopod 2. Davie (2002) added Ruppellioides A. Milne-Edwards, 1867, to the Menippinae. Sakai (2004) synonymized the Menippinae with the Oziinae and placed Eupilumnus and Hypothalassia under the Eriphiinae. Poore (2004) considered Eupilumnus as a member of the Oziinae and placed Hypothalassia within the Menippinae. Števčić (2005) recognized three subfamilies, Eriphiinae, Platyxanthinae, and Dacryopilumninae within the Eriphiidae. Thus, the classification of the Eriphiidae sensu lato has been problematic. We follow Ng et al. (2001) in the arrangement of genera within subfamilies and families, with the exception that Hypothalassia is herein placed within a monotypic family.
Family Platyxanthidae Guinot, 1977
Included fossil genera. Pelaeus Eydoux and Souleyet, 1842 (fossil and extant); Platyxanthus A. Milne Edwards, 1863 (fossil and extant).
Occurrence. Eocene - Recent.
Diagnosis. Carapace hexagonal, wider than long, length about two-thirds maximum carapace width, ranging from 0.63 to 0.70; front with four spines excluding inner-orbital projection or nearly straight with central notch, frontal width about 0.2 maximum carapace width, ranging from 0.13 to 0.24; orbits with fissures, usually two, fronto-orbital width about 0.36 maximum carapace width, ranging from 0.33 to 0.38. Anterolateral margins moderately convex; many possible configurations, either with numerous blunt spines, or with broad, bluntly spinose lobes separated by fissures, or with broad, entire lobes separated by fissures; last anterolateral spine extending posteriorly and axially onto dorsal carapace; angle of posterolateral to posterior margin about 38 degrees; posterior width about 0.38 maximum carapace width, ranging from 0.36 to 0.41. Carapace regions poorly defined, protogastric and hepatic regions weakly inflated. Endostomial ridges absent. Chelae stout, smooth, coxa of first pereiopod articulating with merus, merus not fused to basis-ischium. Sternum relatively straight and narrow or rather wide, sternal sutures 4/5 and 5/6 not continuous, 6/7 and 7/8 continuous; suture between sternites 2 and 3 complete; suture between sternites 3 and 4 deep, well developed laterally but becoming a shallow groove axially, merging with long groove extending anteriorly from sterno-abdominal cavity to form deep, Y-shaped groove pattern; sternite 8 not visible in ventral view. All male abdominal somites free, male abdomen barely reaching or not reaching level of posterior margin of coxae of first pereiopods, covering entire space between coxae of fifth pereiopods. Male gonopod 1 stout; male gonopod 2 long, with an elongated proximal article and a developed flagellum (after Schweitzer, 2005a: 287).
Family Hypothalassiidae new family
Type and sole included genus. Hypothalassia Gistel, 1848.
Occurrence. Recent.
Diagnosis. Carapace hexagonal, wider than long, maximum carapace length about 85 percent maximum carapace width; front bilobed, medially notched, projecting anteriorly, with numerous supplementary spines; orbit not closed; inner-orbital spine well developed; frontal width about one-quarter maximum carapace width; orbits spinose, with two fissures; fronto-orbital width about half maximum carapace width. Basal article of antenna not reaching to front. Endostomial ridges present. Anterolateral margins moderately convex, spinose. Posterolateral margin nearly straight, tuberculate. Posterior margin about half maximum carapace width. Carapace regions well defined, ornamented with spines anteriorly and posterolaterally. Chelipeds heterochelous, spinose, fingers black. Pereiopods 2-5 spinose, with corneous dactyl tips. Thoracic sternum moderate in width; sternal sutures 4/5 and 5/6 not continuous; sternite 8 not visible in ventral view. Male abdomen reaching to posterior end of coxa of pereiopod 1; all male abdominal somites free, movable, filling entire space between coxae of fifth pereiopods. Male gonopod 1 stout, gently curved; male gonopod 2 longer than 1, with long flagellum.
Discussion. Hypothalassia previously had been placed in the subfamily Menippinae (Ng et al., 2001; Davie, 2002), the Eriphiinae (Sakai, 2004), or simply within the Eriphiidae sensu lato (Koh and Ng, 2000). Our analysis shows that Hypothalassia belongs to an independent lineage within the Eriphioidea. The Hypothalassiidae lack a weakly protruded front (5-1) and the absence of upper orbital fissures (7-1), which are diagnostic characters of the Pseudoziidae, Eriphiidae, and Oziidae. The Pseudoziidae have a short male gonopod 2 with a short flagellum, while the Hypothalassiidae have a long gonopod 2 with a long flagellum. The Hypothalassiidae, Eriphiidae, Oziidae, and Platyxanthidae have a long male gonopod 2 with a long flagellum. However, the Oziidae are characterized by having a filamentous flagellum. In the Eriphiidae, the fronto-orbital width is about 70% of the maximum carapace width and the orbit is completely closed, but in the Hypothalassiidae, the fronto-orbital width is about 50% of the maximum carapace width and the orbit is open. The Hypothalassiidae differ from the Platyxanthidae because in the Hypothalassiidae, the carapace and all pereiopods are ornamented with spines and tubercles, the carapace regions are well defined, a Y-shaped sternal groove pattern is absent, the suture between the thoracic sternites 3 and 4 is shallow and indistinct, and episternal markings on thoracic sternite 4 are absent. Thus, at this time the Hypothalassiidae is an independent, monotypic lineage for which there is no recognized fossil record; however, ongoing investigation of Titanocarcinus aculeatus Busulini et al., 1984, may result in its placement within the family.
Family Pseudoziidae Alcock, 1898
Included fossil genera. Archaeozius Schweitzer, 2003a; Euryozius Miers, 1886 (also extant); Priabonocarcinus Müller and Collins, 1991; Santeexanthus Blow and Manning, 1996.
Occurrence. Eocene - Recent.
Diagnosis. Carapace usually ovate, wider than long, flattened, maximum carapace length about 65-75 percent maximum carapace width; regions moderately, poorly or not defined, grooves defining cardiac and other gastric regions weakly developed, epigastric regions may be weakly developed but often indistinct. Front nearly straight, bilobed, or weakly quadri-lobed, axially notched, can be markedly deflexed, all lobes extending the same distance anteriorly, front about 30 percent maximum carapace width in most taxa but 60 percent in Planopilumnus Balss, 1933; orbits shallow, ovoid, weakly rimmed; fronto-orbital width about half maximum carapace width in most taxa but up to 80 percent in Planopilumnus . Anterolateral margin entire, with small spines at anterolateral corner, or lobed with shallow notches or fissures separating lobes; extending to about mid-length or just anterior to it. Posterolateral margin sinuous or nearly straight, angle of posterolateral to posterior margin 40-45 degrees. Posterior margins 30 percent to half maximum carapace width except much wider in Planopilumnus . All male abdominal somites free; male abdomen sometimes not entirely occupying space between coxae of fifth pereiopods; sternite 8 sometimes visible ventrally. Fusion of the basis-ischium with merus of major cheliped sometimes present, incomplete, remnants of suture visible; coxa appearing to articulate directly with merus; fingers of chelae black (modified from Crosnier and Guinot, 1969; Schweitzer, 2003a: 1112). Sternites 1/2 fused, suture not visible; sternal suture 2/3 relatively deep; sternal suture 3/4 medially interrupted; sternal sutures 4/5 and 5/6 incomplete, 6/7 and 7/8 complete. Antenna not lodged in orbital hiatus, instead, second and third segments placed in rounded cleft formed by front and supraorbital spine. Male gonopod 1 long, slender or moderately stout, with numerous short spines; male gonopod 2 short, straight, about 30 to 50 percent the length of gonopod 1, flagellum short to very short. (After Ng and Wang, 1994; Davie, 2002; Ng and Liao, 2002).
Family Eriphiidae MacLeay, 1838
Included genus. Eriphia Latreille, 1817 (also extant).
Occurrence. Oligocene - Recent.
Diagnosis. Carapace hexagonal, wider than long; regions distinct, with ridges and granules especially on anterior regions; front axially notched, bordered on either side of notch by straight segment, notch just proximal to each orbit, front about half maximum carapace width; orbits closed, strongly rimmed, directed anterolaterally, fronto-orbital margin about 70 percent maximum carapace width; antennae placed at some distance from orbits and antennules; anterolateral margin with variable number of spines. Sternum narrow; sternal sutures 4/5 and 5/6 incomplete, 6/7 and 7/8 complete; male sternite 8 not visible (USNM 48565) or barely visible (RO 3976, specimen figured in Glaessner, 1969, fig. 326.7); male abdomen covers space between coxae of fifth pereiopods. Chelipeds heterochelous, fingers of chelipeds black. Male gonopod 1 stout; male gonopod 2 long with long flagellum. (In part after Davie, 2002).
Family Oziidae Dana, 1851a
Included subfamilies. Dacryopilumninae Serène, 1984; Menippinae Ortmann, 1893; Oziinae Dana, 1851a. The latter two have a known fossil record.
Included fossil genera. Menippe De Haan, 1833 (also extant) (Menippinae); Ozius H. Milne Edwards, 1834 (also extant) (Oziinae); Pseudocarcinus H. Milne Edwards, 1834 (also extant) (Menippinae).
Diagnosis. Carapace hexagonal or ovate, wider than long, maximum length 60-75 percent maximum carapace width, widest about half to two-thirds the distance posteriorly on carapace; dorsal carapace regions moderately or weakly defined; frontal margin bilobed or quadri-lobed excluding inner-orbital spines, frontal margin about 20-30 percent maximum carapace width except in Dacryopilumninae (70 percent); orbits opened medially or incompletely closed (Menippinae and Oziinae) or completely closed (Dacryopilumninae); fronto-orbital width about one-third to half maximum carapace width except in Dacryopilumninae (90 percent); anterolateral margins with four or five spines or lobes, or entire, or with a variable number of spines; anterolateral margin distinct from posterolateral margin.
Antennae positioned close to antennules and orbits (Menippinae and Oziinae) or at a great distance from them (Dacryopilumninae). Buccal frame anteriorly tapered, trapezoidal; sternum narrow; female sternal sutures 4/5 and 5/6 interrupted medially (Oziinae) or complete and nearly parallel (Dacryopilumninae and Menippinae); all male abdominal somites free, movable; male abdomen fills space between coxae of fifth pereiopods. Male gonopod 1 stout, straight or weakly curved; male gonopod 2 as long as or longer than 1, with long, filamentous flagellum. Chelipeds usually heterochelous; large molariform tooth on fixed finger of major cheliped (Menippinae and Oziinae). (In part modified after Davie, 2002; Ng and Wang, 1994).
Superfamily Progeryonoidea Števčić, 2005
Included family. Progeryonidae Števčić, 2005.
Diagnosis. As for the family.
Family Progeryonidae Števčić, 2005
Type and sole included genus. Progeryon Bouvier, 1922.
Occurrence. Recent.
Diagnosis. Carapace subquadrate, about as long as wide or slightly wider than long, widest about two-thirds the distance posteriorly on carapace, flattened transversely and longitudinally; dorsal carapace regions moderately defined. Front nearly straight or bilobed, medially notched, about 25-35 percent maximum carapace width; fronto-orbital width about half maximum carapace width; upper orbital margin rimmed, sometimes with weak fissure. Anterolateral margin arcuate, entire or lobate, with short lateral spine; posterolateral margin straight or weakly sinuous, much longer than anterolateral margin; posterior margin about half maximum carapace width, medially concave.
Endostomial ridges present, strong. Thoracic ster-num wide. Anterior end of the sterno-abdominal cavity not reaching to anterior of thoracic sternite 4; sternite 1 and 2 completely fused; suture between 2 and 3 complete; suture between 3 and 4 deep, complete; anterior of sternite 4 with median sulcus, together with suture 3/4 forming Y-shaped groove pattern on sternum; sutures 4/5, 5/6, and 6/7 medially interrupted; suture between 7/8 complete; sternite 8 not visible in ventral or posterior view; all male abdominal somites free; male abdomen filling entire space between coxae of pereiopods 5.
Chelipeds heterochelous, with dark-colored fingers; major cheliped with large, molar basal tooth on occlusal surface of dactylus; pereiopods 2-5 long; dactylus with corneous tips. Male gonopod 1 stout, nearly straight, with a simple apex; gonopod 2 longer than 1 with long flagellum.
Discussion.Števčić (2005) erected a new tribe Progeryonini for Progeryon and placed it within the Geryonidae. In the present analysis, Progeryon cannot be accommodated in any known families of the Goneplacoidea and Portunoidea; thus, the Progeryonini is treated as a separate family which belongs within a monophyletic group together with the known families of the Goneplacoidea and Portunoidea. However, the sister-group relationships among the Progeryonidae, Goneplacoidea, and Portunoidea cannot be resolved. Therefore, the Progeryonidae is here given superfamily status.
The Progeryonidae differs from the families of the Goneplacoidea, as defined here, by the possession of a Y-shaped groove pattern on the male thoracic sternum, the male sterno-abdominal cavity not reaching to the anterior of thoracic sternite 4 in males, absence of a posterolateral prolongation of male episternite 7, and the possession of a complete sternal suture 7/8. The Progeryonidae is readily distinguished from the families of the Portunoidea because the Progeryonidae possess a Y-shaped groove pattern on the male thoracic sternum, all male abdominal somites are free, and the male gonopod 1 is nearly straight.
Manning and Holthuis (1989) suggested that Progeryon and Paragalene , previously assigned to the Geryonidae, might well belong to a new family. However, Paragalene differs from Progeryon because Paragalene has a carapace that is much wider than long and has frontal spines and well separated anterolateral lobes, and the male gonopod 1 is rather slender and is curved. Therefore, Paragalene might be assigned to the Mathildellidae, but the known members of the Mathildellidae lack frontal spines as seen in Paragalene . Detailed examination of the thoracic sternal characters of Paragalene will be necessary to confirm its familial placement.
Superfamily Goneplacoidea MacLeay, 1838
Included families. Carinocarcinoididae Karasawa and Kato, 2003a; Chasmocarcinidae Serène, 1964; Euryplacidae Stimpson, 1871; Goneplacidae MacLeay, 1838; Hexapodidae Miers, 1886; Trogloplacidae Guinot, 1986.
Diagnosis. Carapace transversely rectangular, ovate, or trapezoidal; generally flattened transversely and longitudinally; dorsal carapace regions weakly defined or indistinct; front weakly protruded, straight, sometimes with median notch or projection; upper orbital margin with or without fissures, fronto-orbital width often very broad; buccal frame quadrangular; anterolateral margin may be entire or spined, sometimes merging with and indistinct from posterolateral margin.
Anterior end of the sterno-abdominal cavity reaching to the anterior of thoracic sternite 4; sternite 4 without medial sulcus; all thoracic sutures interrupted; well-developed posterolateral prolongation of male episternite 7, sternite 8 visible in ventral or posterior view; male abdominal somites free or 3-5 fused and immovable; male abdomen may or may not fill entire space between coxae of fifth pereiopods; fifth pereiopod and sternite 8 may be much reduced so as to be absent in ventral view (Hexapodidae).
Chelipeds usually heterochelous, usually without dark-colored fingers; absence of corneous tips on pereiopods 2-5, pereiopods 2-5 generally much less robust than cheliped. Male gonopod 1 stout, sinuous, or curved, usually with a simple apex; gonopod 2 long or short (after Karasawa and Kato, 2003a).
Occurrence. Cretaceous - Recent.
Discussion. The Goneplacoidea as herein constituted is a heterogeneous group, composed of mostly flattened crabs with weakly protruded fronts and ovate sterna. Within the group, however, there is considerable variation and there is a history of treatment of the various subfamilies as family-level taxa. Guinot (1977) first treated the Hexapodinae, previously placed under the Goneplacidae Balss (1957), as a distinct family and assigned the family to its own superfamily Hexapodoidea within the section Thoracotremata. Manning and Holthuis (1981) treated the Hexapodidae as a family closely related to the Goneplacidae. Following the work of Bowman and Abele (1982), most workers placed the Hexapodidae within the Xanthoidea sensu lato. Guinot and Richer de Forges (1997) supported the placement of the Hexapodidae within the Heterotremata based upon the larval evidence of Pereyra Lago (1988).
D’Udekem d’Acoz (1999) raised the Euryplacinae and Carcinoplacinae to full family status and included both families in the superfamily Goneplacoidea. Števcˇic´ (in Martin and Davis, 2001) suggested that the Euryplacinae be elevated to family status, and Glaessner and Secretan (1987) and Guinot et al. (2002) gave the Carcinoplacinae full family status. Davie (2002) elevated the Trogloplacinae to full family status, although Davie and Guinot (1996) and Karasawa and Kato (2003a, b) pointed out that the Trogloplacinae has close affinities with the Chasmocarcininae. Thus, our recognition of these subfamilies as families has clear precedent.
Števčić (2005) erected two new families and one new subfamily for extinct genera within the Goneplacoidea sensuŠtevčić (2005). The Amydrocarcinidae Števčić, 2005, embraces Amydrocarcinus Schweitzer et al., 2002, which we herein consider to be a member of the Goneplacidae within the Goneplacoidae. The Megaxanthidae Števčić, 2005, was erected to embrace the poorly preserved Megaxantho Vega et al., 2001. The sole specimen of the genus is too poorly preserved to form the basis of a new family, and we regard it herein as Xanthoidea incertae sedis until better preserved, more complete material can be collected. Števčić (2005) also erected a separate subfamily to embrace Icriocarcinus Bishop, 1988, the Icriocarcininae Števčić, 2005. We regard that genus as a member of the Goneplacidae based upon its well-preserved sternal, abdominal, and dorsal carapace features.
Family Carinocarcinoididae Karasawa and Kato, 2003a
Included fossil genera. Bicarinocarcinus Glaessner and Secretan, 1987; Carinocarcinoides Karasawa and Fudouji, 2000.
Occurrence. Eocene - Miocene.
Diagnosis. Carapace wider than long, length ranging from 70 to 90 percent maximum carapace width, widest at position of last anterolateral spine or just anterior to it, 40-50 percent the distance posteriorly on carapace; dorsal carapace with more or less defined dorsal regions, epibranchial regions and sometimes other regions transversely inflated to form carinae; front straight, without median notch, between one-quarter and one-third maximum carapace width; notch between frontal margin and supraorbital angle indistinct; upper orbital margin without fissures, fronto-orbital width between two-thirds and three-quarters maximum carapace width; anterolateral margin with two spines excluding outer-orbital spine; merus of maxilliped 3 subquadrate, much longer than ischium; male abdomen filling entire space between coxae of pereiopods 5, with somites 3-5 fused; thoracic sternum wide; sternal sutures 4/5, 5/6, and 6/7 apparently interrupted; sternite 7 with posterolateral prolongation; sternite 8 visible in ventral view, overlying posterior portion of sternite 7; sterno-abdominal cavity reaching anterior of sternite 4; fingers of chelipeds long, elongate, not dark in color (after Glaessner and Secretan, 1987: 7; Karasawa and Kato, 2003a: 142).
Family Chasmocarcinidae Serène, 1964
Included fossil genera. Chasmocarcinus Rathbun, 1898 (also extant); Collinsius Karasawa, 1993; Falco-noplax Van Straelen, 1933; Gillcarcinus Collins and Morris, 1978; Mioplax Bittner, 1884; Orthakrolophos Schweitzer and Feldmann, 2001.
Occurrence. Eocene - Recent.
Diagnosis. Carapace rectangular or trapezoidal, wider than long, length about 70-85 percent maximum carapace width; carapace regions poorly defined but may have swellings or ridges; front straight or weakly flared, with medial notch, about 40 percent maximum carapace width, notch between frontal margin and supraorbital margin indistinct; orbits usually small, orbital margins entire, fronto-orbital width about half maximum carapace width, eyestalk short; anterolateral margin entire or spined. Basal antennular segment very swollen, completely filling antennular fossa, excluding flagellum which thus cannot be folded and is unprotected (Davie, 2002: 196, 503). Buccal frame narrowing anteriorly; third maxillipeds not closing the buccal cavity; merus of third maxilliped suboval, about as long as ischium, palp more or less distal. Sternum wide, all sutures interrupted; sterno-abdominal cavity reaching anterior of sternite 4; sternite 8 visible in ventral view, overlying posterior part of sternite 7; open groove between sternites 7 and 8 may be covered with supplementary plate. Male abdomen not entirely filling space between coxae of fifth pereiopods; male abdominal somites 3-5 fused. Male gonopod 1 stout, sinuous, with simple apex; gonopod 2 noticeably shorter than gonopod 1, flagellum much shorter than peduncle. Dactyli of pereiopods 2-5 sickle-shaped with setae (after Schweitzer and Feldmann, 2001; Davie, 2002: 196, 503; Karasawa and Kato, 2003a).
Family Euryplacidae Stimpson, 1871
Included fossil genera. Chirinocarcinus Karasawa and Schweitzer, 2004; Chlinocephalus Ristori, 1886; Corallicarcinus Müller and Collins, 1991; Eucrate De Haan, 1835 (also extant); Euryplax Stimpson, 1859 (also extant); Orbitoplax Tucker and Feldmann, 1990; Paleopsopheticus Hu and Tao, 1996; Simonellia Vinassa de Regny, 1897; Stoaplax Vega, Cosma et al., 2001; Viaplax Karasawa and Kato, 2003a.
Occurrence. Paleocene - Recent.
Diagnosis. Carapace subquadrilateral, rectangular, or trapezoidal, wider than long, length usually about 80 percent maximum width; regions moderately to poorly defined; front generally straight with axial notch, from one-quarter to one half maximum carapace width but usually about one-third; orbits generally large, with orbital fissures, orbits open or closed due to a variety of possible morphologies (Davie, 2002: 198); fronto-orbital margin at least two-thirds maximum carapace width, usually about 80 percent but can be as much as 100 percent; eye-stalk can be short or long, apparently well-calcified as it can be fossilized; basal article of antenna reaching front; merus of third maxilliped subquadrate, much longer than ischium; anterolateral margin with three or so spines, not well-differentiated from posterolateral margin; posterolateral reentrant well-developed.
Sternum wide; sterno-abdominal cavity reaching anterior of sternite 4; all sternal sutures interrupted, sternite 8 barely visible in ventral view or quite obvious. Male abdomen with all somites free and movable, somites 4-6 much narrower than somite 3, telson usually longer than wide, male abdomen filling entire space between coxae of fifth pereiopods. Male gonopod 1 long and thin, narrow apically, ornamented with small tubercles; gonopod 2 very short. Chelipeds isochelous or weakly heterochelous; dactyli of pereiopods 2-5 usually styliform, with or without setae. (In part after Davie, 2002, and Karasawa and Kato, 2003a).
Discussion. Simonellia was described as being very similar to Chlinocephalus , differing from it only in minor aspects of the carapace shape and ornamentation. Simonellia differs from some other members of the family in having a front that is not produced. However, we ally it with Chlinocephalus in the Euryplacidae until type material can be examined. Karasawa and Kato (2003a) synonymised Paleopsopheticus with Psopheticus . However, herein Paleopsopheticus is a distinct genus and is placed within the Euryplacidae based upon its broad, straight front with small medial notch; broad orbits; broad fronto-orbital width, and anterolateral margins with few spines.
Family Goneplacidae MacLeay, 1838 (= Carcinoplacinae H. Milne Edwards, 1852; see Karasawa and Kato, 2003a)
Included fossil genera. Amydrocarcinus Schweitzer et al., 2002; Carcinoplax H. Milne Edwards, 1852 (also extant); Goneplax Leach, 1814 (also extant); Icriocarcinus Bishop, 1988; Magyarcarcinus Schweitzer and Karasawa, 2004; Ommatocarcinus White, 1852 (also extant); Psopheticus Wood-Mason, 1892 (also extant).
Occurrence. Late Cretaceous - Recent.
Diagnosis. Carapace hexagonal, transversely ovate, or subquadrate; wider than long, sometimes markedly so, position of maximum width well in advance of midlength; front straight, without median notch, sometimes with medial projection; upper orbital margins entire; notch between frontal margin and orbits indistinct; fronto-orbital width variable, ranging from two-thirds to 100 percent maximum carapace width; anterolateral margin with one to three spines excluding outer-orbital spines or entire. Eyestalks short or long, sometimes extremely long; merus of third maxilliped subquadrate, longer than ischium. Male abdomen filling entire space between coxae of fifth pereiopods; all male abdominal somites free. Sternum broad, ovate; sternite 8 not visible in ventral view; sterno-abdominal cavity reaching anterior of sternite 4. Chelipeds robust compared to other pereiopods, without black tips on fingers, usually with lateral spine on carpus; dactyli of pereiopods 2-4 styliform or spatulate, with or without setae. Male gonopod 1 stout, sinuous, usually with truncated apex; male gonopod 2 long, usually with long flagellum (after Karasawa and Kato, 2003a).
Family Hexapodidae Miers, 1886
Included fossil genera. Goniocypoda Woodward, 1867; Hexapinus Manning and Holthuis, 1981 (also extant); Hexapus De Haan, 1833 (also extant); Palaeopinnixa Vía, 1966; Stevea Manning and Holthuis, 1981 (also extant).
Occurrence. Late Cretaceous - Recent.
Diagnosis. Carapace rectangular or rarely trapezoidal; wider than long, length averages about 70 percent maximum carapace width; anterolateral and posterolateral margins confluent, often with ridge paralleling anterolateral portion, posterolateral reentrant well-defined; regions poorly or not defined; lateral margins steep. Front narrow and widest distally, axially sulcate, usually extending at least weakly beyond orbits, not deflexed; orbits usually rimmed, upper margin sinuous, entire; straight anterior margin of carapace only partially occupied by orbits except in Goniocypoda ; fronto-orbital width about half maximum carapace width but ranges from about 30 - 60 percent; fronto-orbital width to posterior width ratio averages 60 percent, ranging from 30 to 80 percent; posterior width 70-90 percent maximum carapace width; antennules folded transversely, antennae small; eyes small, usually movable but can be fixed. Third maxilliped ranging from broad to slender; propodus slender or widened distally; exopod either with or without flagellum. Sternite 4 with rounded anterior projections; sternite 8 reduced, obscured, all sternal sutures interrupted. Male abdominal somites fused, usually 3-5 but may be other combination of somites. Chelipeds well-developed; pereiopod 5 absent. (After Schweitzer and Feldmann, 2001).
Family Trogloplacidae Guinot, 1986
Type genus. Trogloplax Guinot, 1986.
Included fossil genera. None; known only from freshwater environments from which the fossil record of Brachyura is poor.
Diagnosis. Carapace rounded, regions poorly defined; front straight with shallow medial notch, notch between front and supraorbital angle not apparent; upper orbital margin entire; anterolateral margin cristate, entire, or with spines; eyestalks short, eyes small; antennules folded completely into fosset; antenna placed in orbital hiatus. Buccal frame quadrate, merus of third maxilliped suboval, about as long as ischium.
Sternum very wide, all sternal sutures interrupted, sternite 8 clearly visible in ventral view; supplementary plate between sternites 7 and 8 covering penis; sterno-abdominal cavity deep; male abdominal somites 3-5 fused. Vulvae of females large, on extremity of sternal suture 5/6. Male gonopod 1 stout, sinuous, with simple apex; male gonopod 2 as long as or longer than gonopod 1, flagellum half as long as or slightly more than half its length. Fingers of chelae sometimes elongate and deflexed; dactyls of pereiopods 2-5 styliform with setae. (After Davie, 2002; Karasawa and Kato, 2003a).
Superfamily Goneplacoidea MacLeay, 1838, Incertae Sedis
Included fossil genus. Speocarcinus Stimpson, 1859 (also extant).
Discussion. The systematic position of Speocarcinus is uncertain. The genus was placed within the 'goneplacid' Pseudorhombilinae (Balss, 1957; Williams, 1984), whereas Hendrickx (1998) excluded it from his Pseudorhombilidae, maintained as a family by Martin and Davis (2001) and Schweitzer and Karasawa (2004). Števčić (2005) placed it within its own family Speocarcinidae Števcˇic´, 2005. We are unable herein to resolve its placement but note that its fossil record extends into the Miocene (Tucker et al., 1994).
Superfamily Portunoidea Rafinesque, 1815
Included families. Carcineretidae Beurlen, 1930 (extinct); Geryonidae Colosi, 1923; Mathildellidae Karasawa and Kato, 2003a; Portunidae Rafinesque, 1815.
Occurrence. Cretaceous - Recent.
Diagnosis. Carapace hexagonal, subhexagonal, rectangular, or transversely ovate; carapace usually wider than long, usually widest at position of last anterolateral spine; flattened or weakly vaulted; regions poorly or moderately defined; anterolateral margins entire or with up to nine spines including outer orbital spine; front entire or spined; lobe on endopod of first maxilliped ('portunid lobe') sometimes present; chelipeds usually robust; last pair of pereiopods may have ovate dactyls; sternal sutures 4/5, 5/6, 6/7, and 7/8 usually incomplete; sternite 8 usually visible in ventral view, with penial groove (Portunidae); male abdominal somites all free or 3-5 fused, if 3-5 fused, sutures may be visible; gonopod 1 strongly curved, with inflated, strongly hooked base.
Discussion. Glaessner (1969) and Guinot (1978) placed the Geryonidae within the Xanthoidea sensu lato. Since Manning and Holthuis (1981) suggested a Geryonidae and Portunidae relationship, several authors, Bowman and Abele (1982); Schweitzer and Feldmann (2000b); Martin and Davis (2001), have included the family within the Portunoidea. Števcˇic´ (in Martin and Davis, 2001) felt that the Geryonidae was closely related to the Goneplacidae sensu stricto and later placed both families within the Goneplacoidea (Števčić, 2005). Recently, Sakai (2004) placed the Geryonidae into the Xanthoidea sensu lato. Our analysis strongly supports the position of the Geryonidae within the Portunoidea.
The Portunoidea is traditionally arranged as less derived than the Xanthoidea sensu lato (Guinot, 1978; Williams, 1984; Martin and Davis, 2001). In some previous phylogenetic works, the Portunoidea were shown to be early-derived heterotremes, more so than the Xanthoidea sensu lato (Jamieson, 1991, 1993; Von Sternberg et al., 1999; Brösing, 2002; Wetzer et al., 2003), whereas Rice (1981, 1983), Števčić (1998), and Von Sternberg and Cumberlidge (2001) considered that the Portunoidea was a more advanced group than the Xanthoidea sensu lato. The present analysis suggests that the Portunidae together with Progeryon and Goneplacoidea is a more derived group than at least some of the xanthoid families. The fossil record supports this view with regard to the Portunidae and the Geryonidae, but it must be remembered that the Portunoidea as currently defined also embraces the extinct, Cretaceous Carcineretidae Beurlen, 1930. The Carcineretidae were not included in this analysis because they are known only from Cretaceous, Central and North American occurrences that are not sufficiently preserved to permit them to be useful within this analysis. The earliest known portunids are Danian in age (Schweitzer and Feldmann, 2000b), but their record does not become robust until the Eocene and later. The earliest known mathildellid is also Paleocene (Stenzel, 1944). The earliest record of the Geryonidae is from the Oligocene of Argentina or Europe (Glaessner, 1969; Schweitzer and Feldmann, 2000b). Thus, the Portunoidea in general is a lineage with later occurrences than the Xanthoidea sensu lato.
Family Carcineretidae Beurlen, 1930
Included fossil genera. Branchiocarcinus Vega et al., 1995; Carcineretes Withers, 1922; Longusorbis Richards, 1975; Mascaranada Vega and Feldmann, 1991; Ophthalmoplax Rathbun, 1935; Woodbinax Stenzel, 1952; questionably Cancrixantho Van Straelen, 1934, and Lithophylax A. Milne-Edwards and Brocchi, 1879.
Occurrence. Lower - Upper Cretaceous (Maastrichtian).
Diagnosis. Carapace quadrate or ovate, wider than long, with one or more transverse ridges; transverse ridges located on protogastric, hepatic, or branchial regions; front narrow, may be entire or with blunt spines; supraorbital margin long, with spines and notches; fronto-orbital width nearly equal to maximum carapace width; posterior margin narrow; epibranchial region inflated, arcuate. Male sternum ovate, sternites 1-2 fused with no evidence of suture; sternal suture 2/3 a deep groove; sternal suture 3/4 incomplete; sternite 8 not visible in ventral view. Male abdomen narrow, somites apparently all free, entirely filling space between coxae of fifth pereiopods, reaching to about middle of somite 4. Chelipeds more robust than pereiopods 2-5, manus may have keels on outer surface; propodi and dactyli of fourth and/or fifth pereiopods flattened into paddle-like shape (after Vega et al., 1997, fig. 4; Feldmann and Villamil, 2002; Schweitzer et al., 2003, fig. 15).
Discussion. The Carcineretidae traditionally has been placed within the Portunoidea based upon its possession of paddle-like dactyls on the fifth and sometimes fourth pereiopods. Members of the family also possess arcuate epibranchial regions and long orbits which are typical of many portunoids. However, many aspects of the Carcineretidae are quite abberrant as compared to other portunoids, such as the overall carapace shape, the extremely narrow front, and the ornate orbital margins. It is possible that the possession of paddle-like appendages, broad orbits, and arcuate epibranchial regions are examples of convergent evolution and that the Carcineretidae warrant their own superfamily. For example, members of the Matutidae De Haan, 1841, also possess paddle-like dactyls of the fifth pereiopods and are not portunoids, and some of the goneplacids have extremely broad orbits and are not portunoids. Testing this hypothesis, however, is beyond the scope of this paper and currently in preparation.
Family Geryonidae Colosi, 1923
Included fossil genera. Archaeogeryon Colosi, 1923; Archaeoplax Stimpson, 1863 (non Archaeoplax Alcock and Anderson 1894); Chaceon Manning and Holthuis, 1989 (also extant); questionably Coeloma A. Milne-Edwards, 1865 sensu lato.
Occurrence. Oligocene - Recent
Diagnosis. Carapace hexagonal, smooth or granular, wider than long, length about 80-85 percent maximum width; front spined, about 20 percent maximum carapace width; orbits directed forward, with or without orbital fissures, orbital hiatus completely closed, fronto-orbital width about half maximum carapace width in adults, may be considerably higher in juveniles; anterolateral margins with three to five spines; branchial regions with arcuate swelling anteriorly. Sternal sutures 4/5, 5/6, and 6/7 medially interrupted, 7/8 continuous or nearly so. Male abdominal somites 3-5 fused and immovable but with obvious sutures. Chelipeds heterochelous, much more robust than pereiopods 2-5; pereiopods 2-5 with long, pointed dactyli. Male gonopod 1 stout, curved, inflated basally, with simple apex; gonopod 2 long with long flagellum. (After Guinot, 1978; Schweitzer and Feldmann, 2000b; Davie, 2002).
Discussion. Geryon latifrons Van Straelen, 1936, is the only fossil species to have been referred to Geryon . Examination of a specimen of that species, R03977, by one of us (CES) in the Muséum National d’Histoire Naturelle in Paris suggests that it is probably the figured holotype (Van Straelen, 1936, pl. XXXIII, fig. 4), based upon the published description and measurements. However, the label did not designate the specimen as the type, and Van Straelen was often remiss about mentioning the repository of type material in his papers. In the introduction of the 1936 paper in which G. latifrons was described, he did mention the Muséum National d’Histoire Naturelle in Paris; thus, we believe that R03977 probably is the holotype.
Geryon latifrons is not a member of the Geryonidae based upon its extremely broad front (one-third maximum carapace width); broad fronto-orbital width (three-quarters maximum carapace width); and front and anterolateral margins with no or few spines, respectively. The species is similar is many respects to species of Chlinocephalus Ristori, 1886, including possession of a straight front with median notch; wide frontal width; fronto-orbital width about three-quarters maximum carapace width; anterolateral margin with two spines; arcuate epibranchial region; and depressed intestinal and posterior-most branchial regions. Geryon latifrons lacks the arcuate ridges on the dorsal carapace evident on Chlinocephalus (Garassino et al., 2004, fig. 16). Thus, we place G. latifrons in Chlinocephalus provisionally until type material can be reexamined to confirm placement.
Coeloma as currently defined embraces a broad range of dorsal carapace morphologies. Investigation of the genus is underway, which will resolve its status.
Family Mathildellidae Karasawa and Kato, 2003a
Included fossil genera. Branchioplax Rathbun, 1916; Tehuacana Stenzel, 1944.
Occurrence. Paleocene - Recent.
Diagnosis. Carapace wider than long, maximum carapace length about 80 percent maximum carapace width, widest about 45 percent the distance posteriorly, flattened, regions weakly defined; front straight with axial notch, frontal width about one-third maximum carapace width; supraorbital angle separated from frontal margin; orbit relatively small, with upper orbital fissures, fronto-orbital width about 60 percent maximum carapace width; anterolateral margins short, with five spines or lobes; posterolateral margins longer than anterolateral margins. Eyestalks short, antennular fossae broad laterally; merus of third maxilliped subquadrate, much longer than ischium. Sternum wide, usually with interrupted sutures except 7/8 which is continuous; sternite 7 without posterolateral prolongation, sternite 8 not visible in ventral view. Male abdominal somites usually all free, abdomen entirely filling space between coxae of fifth pereiopods. Chelipeds with dark fingers; dactyli of pereiopods 2-5 with corneous tips; dactyli of fifth pereiopods spatulate and with setae. Male gonopod 1 stout, curved, inflated basally, with simple apex; gonopod 2 long with long flagellum. (After Karasawa and Kato, 2003a).
Discussion. Števčić (2005) considered the Mathildellidae to be a tribe within the Geryonidae. Whereas our results show that the family is indeed related to the Geryonidae, and in fact, the Portunoidea, we retain it as a separate family due to the many distinctive differences between its members and the other portunoid families.
Family Portunidae Rafinesque, 1815
Included fossil genera. Acanthoportunus Schweitzer and Feldmann, 2002; Boschettia Busulini et al., 2003; Callinectes Stimpson, 1860 (also extant); Carcinus Leach, 1814 (also extant); Carupa Dana, 1851a (also extant); Charybdis De Haan, 1833 (also extant); Cicarnus Karasawa and Fudouji, 2000; Colneptunus Lörentheyin Lörenthey and Beurlen, 1929; Enoplo-notus A. Milne-Edwards, 1860; Eocharybdis Beschin et al., 2002; Euphylax Stimpson, 1860 (also extant); Falsiportunites Collins and Jakobsen, 2003; Liocarcinus Stimpson, 1871 (also extant); Libystes A. Milne-Edwards, 1867; Lissocarcinus Adams and White, 1848 (also extant); Lupocyclus Adams and White, 1848 (also extant); Macropipus Prestandrea, 1833 (also extant); Maeandricampus Schweitzer and Feldmann, 2002; Megokkos Schweitzer and Feldmann, 2000b; Minohellenus Karasawa, 1990; Miopipus Müller, 1984; Mioxaiva Müller, 1979; Necronectes A. Milne-Edwards, 1881; Neptocarcinus Lörenthey, 1898; Nogarolia Beschin et al., 1994; Ovalipes Rathbun, 1898 (also extant); Parathranites Miers, 1886 (also extant); Pleolobites Remy, 1960; Podophthalmus Lamarck, 1801 (also extant); Pororaria Glaessner, 1980; Portufuria Collins et al., 2005; Portumnus Leach, 1814 (also extant); Portunites Bell, 1858; Portunus Weber, 1795 (also extant); Proterocarcinus Feldmann et al., 1995; Psammocarcinus A. Milne-Edwards, 1860; Psygmophthalmus Schweitzer et al., 2006; Rakosia Müller, 1984; Rhachiosoma Woodward, 1871; Scylla De Haan, 1833 (also extant); Sandomingia Rathbun, 1919; Saratunus Collins, Lee and Noad, 2003; Thalamita Latreille, 1829 (also extant).
Occurrence. Paleocene - Recent.
Diagnosis. Carapace hexagonal, transversely ovate, or subrectangular, usually wider than long; dorso-ventrally flattened; regions usually poorly defined, epibranchial region arcuate, arching anteriorly (except Caphyrinae Paul’son, 1875 and Carupinae Paul’son, 1875); front straight and without spines (Carupinae) or lobate (Caphyrinae) or T-shaped (Podophthalminae Dana, 1851a) or with spines (Carcininae MacLeay, 1838; Polybiinae Ortmann, 1893; Portuninae Rafinesque, 1815; Psammocarcininae Beurlen, 1930; Thalamitinae Paul’son, 1875); orbits very wide (Podophthalminae) or small to moderate-sized (all other subfamilies), usually with fissures; anterolateral margin usually spined, with as many as nine spines, or entire (some Carupinae). Lobe on endopod of first maxilliped (so-called portunid lobe) usually present; chelipeds usually large, chelae often with keels and spines; fifth pereiopod usually with paddle-like dactylus (Caphyrinae; Polybiinae; Portuninae; Podophthalminae; Psammocarcininae; Thalamitinae) but may be styliform (Carcininae; Carupinae). Sternum broad, ovate; male thoracic sternite 8 visible ventrally; episternite 7 with well-developed posterolateral prolongation, penial groove present on male thoracic sternite 8; all sternal sutures incomplete except in some Carcininae. Male abdominal somites 3-5 usually fused.
Discussion. No attempt has been made to place the fossil genera within appropriate subfamilies; the Carcininae and the Polybiinae, for example, have been suggested to be polyphyletic (Von Sternberg and Cumberlidge, 2001; Schubart and Reuschel, 2005), and evaluation and revision of the Portunidae is beyond the scope of this paper.
The fossil record and diversity of the Xanthoidea sensu lato
At least 172 genera known in the fossil record within the Xanthoidea sensu lato are now assigned to the four superfamilies Carpilioidea, Xanthoidea sensu stricto, Eriphioidea, and Goneplacoidea. The familial arrangement of these genera is shown in Fig. 3 based upon the present new classification of the Xanthoidea sensu lato. Twenty-two extinct genera which were originally assigned to the Xanthidae sensu lato cannot be placed within any family.
The geologic ranges of the Palaeoxanthopsidae, Pilumnidae, Goneplacidae, and Hexapodidae all extend into the Late Cretaceous (Schweitzer et al., 2002; Schweitzer, 2003a, b; 2005a) (Figs. 3 and 4). The occurrences of these families suggest that the Carpilioidea (Clade A), Pilumnoidoidea (Clade B), Xanthoidea (Clade C), Eriphioidea (Clade D), Progeryonoidea (Clade E), Goneplacoidea (Clade F), and Portunoidea had diverged by the Late Cretaceous, although some of the other families have ghost ranges. The Pilumnoidoidea (Clade B), Progeryonoidea (Clade E), and the Trogloplacidae, lack fossil records and thus have very long ghost ranges.
|
Fig. 4. Inferred cladogram, arranged to reflect occurrences of the families in the fossil record. Stratigraphic ranges are based on the oldest confirmed occurrence in each family. Ghost ranges are indicated as gray lines. |
Within the Carpilioidea (Clade A), the earliest-known family Palaeoxanthopsidae was well-established during the late Cretaceous and became extinct during the Eocene (Schweitzer, 2003a). The Tumidocarcinidae and Zanthopsidae each have rich Eocene fossil records, and both have last records during the Miocene (Schweitzer, 2003a; 2005a). The Carpiliidae was well established by Eocene time. Eocarpilius and Palaeocarpilius , both extinct genera, occurred in the Eocene and survived into the Miocene, and the only extant genus of the Carpiliidae Carpilius, appeared by the Miocene (Schweitzer, 2003a; 2005a).
Within the Xanthoidea (Clade C), the extant Pilumnidae and Panopeidae had first occurrences in the Cretaceous and Paleocene respectively and were well established by the Eocene, and both families are represented by numerous extinct genera at that time (Schweitzer, 2000; Schweitzer and Karasawa, 2004). The Trapeziidae and Xanthidae sensu stricto had appeared by the Eocene, the Domeciidae first appeared during the Oligocene, and the Pseudorhombilidae has its first record during the Miocene (Schweitzer, 2005b; Schweitzer and Karasawa, 2004). Most extinct genera within the Pilumnidae, Trapeziidae, Panopeidae, and Xanthidae did not survive beyond the Oligocene, but two pilumnids, Titanocarcinus and Lobonotus, and a panopeid, Laevicarcinus, survived into the Miocene (Schweitzer et al., 2002). A few extant genera, including the two panopeids Panopeus and Lophopanopeus and the trapeziid Tetralia , appeared during the Eocene. However, most extant genera of each family appeared during the Miocene, a pattern observed by Schweitzer (2001). The Xanthidae sensu stricto, with very few pre-Miocene records, has rich Miocene-Pleistocene fossil records, composed mostly of extant genera (Müller, 1984; Karasawa, 1993, 2000; Donovan et al., 2003); the family seems to have diversified during the Miocene (Fig. 3).
Within the Eriphioidea (Clade D), the Platyxanthidae, Pseudoziidae, and Oziidae each have Eocene fossil records. The Pseudoziidae embraces Eocene extinct genera, and the Platyxanthidae and Oziidae are represented in the Eocene by extant genera (Schweitzer, 2003a; 2005a). Eriphia , the sole genus of the Eriphiidae, makes its first occurrence in Oligocene rocks and is extant. The Hypothalassiidae contains only one extant genus, Hypothalassia , and has no fossil record; however, Titanocarcinus aculeatus Busulini et al., 1983, from the Eocene of Italy is quite similar to Hypothalassia and may represent a new monotypic genus within the family.
The Goneplacoidea first appeared during the Late Cretaceous, with representatives of the Hexapodidae and the Goneplacidae sensu stricto; both families are extant (Schweitzer and Feldmann, 2001; Schweitzer et al., 2002). The fossil record of both of these families became quite robust in the Eocene and remained so until the Recent (Schweitzer and Feldmann, 2001; Karasawa and Kato, 2003a). The Chasmocarcinidae made its first known appearance in the Eocene and is extant (Feldmann and Zinsmeister, 1984; Schweitzer and Feldmann, 2001). The Euryplacidae has had a robust fossil record since the Eocene and is extant; however, the Carinocarcinoididae, with only Eocene to Miocene records, has never been a robust family (Karasawa and Kato, 2003a). The Trogloplacidae has no fossil record; it is possible that the invasion of freshwater habitats in this lineage was an evolutionarily late event.
Guinot and Tavares (2001) restricted the genus Xanthosia Bell, 1863, and placed it and Etyus Leach in Mantell (1822), which had previously been assigned to the Xanthidae sensu lato by Schweitzer-Hopkins et al. (1999), in a new podotreme family Etyidae Guinot and Tavares, 2001. However, they did not indicate the generic status of the remainder of the species that have been assigned to Xanthosia sensu lato. Caloxanthus A. Milne-Edwards, 1864, from the late Albian to Danian of U.S.A. and the North Atlantic traditionally has been placed within the Xanthidae sensu lato (Glaessner, 1969; Schweitzer et al., 2002). Wright and Collins (1972) and Jakobsen and Collins (1997) considered it as a member of the Carpiliidae; however, Guinot (1978) excluded Caloxanthus from that family. Sterna and abdomina preserved on specimens of C. americanus Rathbun, 1935, from the Cretaceous of Texas, housed in the collections at Kent State University, indicate that Caloxanthus should be referred to the Etyidae. Caloxanthus possesses the small size; hexagonal carapace; granular ornamentation; well-developed, complete orbits; narrow sternum that is completely covered by the female abdomen and nearly completely covered by the male abdomen; and free male and female abdominal somites that are diagnostic for the family. In addition, the abdominal somites of male and female Caloxanthus exhibit the distinctive feature of bearing marginal outlines so as to 'fit in' like puzzle pieces with the coxae of the pereiopods as seen in taxa of the Etyidae.
Bishop (1988) erected Xandaros to embrace Zanthopsis sternbergi Rathbun, 1926, and the genus has since been placed within the Xanthidae sensu lato. Xandaros is best placed within the Dromiidae De Haan, 1833, based upon its possession of a sulcate, triangular, bifid, front; orbits directed anterolaterally and with a swelling on the inner-orbital margin; and deep cervical and moderately defined branchio-cardiac grooves (Schweitzer et al., 2003).
Palaeoplax A. Milne-Edwards and Brocchi, 1879, from sub-Recent deposits of the Indo-Pacific, was referred to the Goneplacidae by Glaessner (1929) and later to Brachyura of uncertain systematic position (Glaessner, 1969). Examination of the illustration of the sole specimen (Desmarest, 1822, pl. XIII, fig. 9), strongly suggests that it is an eroded specimen of Macrophthalmus Latreille in Desmarest (1822). Pleistocene and Sub-Recent occurrences of Macrophthalmus are common in the Indo-Pacific and Pacific Ocean (Kesling, 1958; Idris, 1989; Karasawa and Mutsuoka, 1991; Morris and Collins, 1991; Karasawa et al., 1995; Schweitzer, Scott-Smith, and Ng, 2002); thus, synonymy of Palaeoplax with Macrophthalmus expands neither the geologic nor geographic range of the genus.
The extinct genera which are herein assigned to the Xanthoidea and Goneplacoidea incertae sedis, together with the remaining species of Xanthosia sensu lato, need to be evaluated in terms of family-level placement based upon proxy characters of the carapace and examination of newly obtained material. Then, the ghost ranges of each family might become better resolved as will the timing of appearance of each lineage.