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Systematics
Of course, one can diagnose any taxon without benefit of a rigorous cladistic phylogenetic analysis. However, ideally, the taxonomy of a group should reflect the phylogeny. In consequence, now having performed for the first time a cladistic analysis of the entire suborder Ingolfiellidea, we can go back and present taxonomic diagnoses that emerge naturally from the phylogeny. We provide the supra-specific taxa of the suborder below with such diagnoses (diagnostic apomorphies). For a world catalogue and bibliography of the Ingolfiellidea we refer the reader to www.uba.uva.nl/ctz
Taxonomic diagnoses derived from cladistic analysis
next sectionSuborder Ingolfiellidea Hansen, 1903
Diagnosis. – Mandible palp rudimentary or absent, molar process vestigial peg or spine; maxilla 1 outer lobe outer setae generally dentate; maxilliped with only proximal part of basis fused; pereional segments subrectangular to elongate (not deeper than long); gnathopods carpo-subchelate; gnathopod 2 palmar angle setae variable (seldom simple), dactyl tip elongate (usually thinner than thick); uropod 2 generally larger than uropod 1 or subequal.
Remarks. – Of these characters, the features concerning the mandible and the carpo-subchelate nature of the gnathopods are robust, with consistency indexes of 1. Hansen (1903) utilized two of these features to erect his superorder, and we can now see from our analysis that in fact these are robust features. However, these exclude the plesiomorphic features one could use. Thus, we have some additional arguments to supply towards justifying Ingolfiellidea as a natural taxon, e.g., vis-a-vis the arguments of Lowry & Poore (1989) and Dahl (1977). The state of the maxilla 1 outer lobe outer setae and the dactyl tip of the second gnathopod are also useful in diagnosing this suborder (ci’s = 0.4 or higher). However, the other features, while helping to define the clade on in our analysis, nevertheless, are rather homoplastic characters. For instance, the palmar angle setae of the second gnathopod is quite variable displaying elongate, pedicillate, angulate forms and these are diagnostic only in so far as they are seldom simple (see character discussion). The relative sizes of the uropod 1 to uropod 2 are even more homoplastic.
Family Metaingolfiellidae Ruffo, 1969
Metaingolfiella Ruffo, 1969
Type species. – Metaingolfiella mirabilis (by monotypy)
Diagnosis. – Ocular lobes developed; maxilla 1 with single inner lobe seta, 4 or more palp setae; maxilliped lateral propodal setae present; second thoracic segment partially fused to cephalon; gnathopod 2 carpal saw as setose brush; uropod 1 rami fused to peduncle; uropod 3 fused peduncles.
Remarks. – The most effective characters (ci = 1) towards defining this monotypic family are the partial fusion of the second thoracic segment to the head and the two features involving the uropods. In contrast, the other characters mentioned here display some degree of homoplasy.
Family Ingolfiellidae Hansen, 1903
Diagnosis. – Antennule flagellum moderate in size, i.e., more than half the length of the basal peducular segment, accessory flagellum typically of 3 segments; maxilla 1 outer lobe spines generally 6 in number, palp most often subequal to outer lobe; maxilliped medial palp setation with only 1 or 2 setae per segment; pleopods more often than not as short fins; telson short and fleshy; uropod 1 typically with outer ramus less than half the inner ramus.
Remarks. – Of these features, only one, that of the medial palp setation, is robust (ci = 1). In addition, the size of the antennular flagellum and the number of outer lobe spines on the maxilla 1 have an acceptable consistency index (ci > 0.5). All the other features mentioned above are rather homoplastic (ci < 0.5).
Genus Stygobarnardia Ruffo, 1985
Type species. – Stygobarnardia caprellinoides Ruffo, 1985 (by monotypy)
Diagnosis. – Mandible palp vestigial; maxilla 1 outer lobe outer setae typically bifid; gnathopod 2 carpal saw typically serrate; dactyl ends on pereiopods 3 to 7 produced as a seta; uropod 1 and uropod 2 subequal.
Remarks. – Of these features, only the state of the mandibular palp is a unique feature for this genus. The other features noted above also appear amongst various species of the genus Ingolfiella.
Genus Trogloleleupia Ruffo, 1974
Type species. – Ingolfiella leleupi Ruffo, 1951.
Diagnosis. – Maxilla 1 palp with 4 or more setae; lenticular organs at least incipiently developed; gnathopod 1 dactyl serrate; telson medium in size and fleshy.
Remarks. – Of these features, the state of the lenticular organs is critical. In Trogloleleupia eggerti and T. leleupi they are only incipiently developed, but in T. dracospiritus they are well developed. This is the most important diagnostic feature of the characters above, although well-developed organs also occur in Paraleleupia gobabis. It is noteworthy to mention that in T. dracospiritus we also see the unique appearance of a short and bifurcate telson, although in our analysis (Fig. 8) T. dracospiritus is more closely related to T. leleupi than to T. eggerti. A former definition of the genus Trogloleleupia by Ruffo (1964) was based on T. leleupi and T. eggerti and mentions their large body length, presence of lenticular organs on thoracic segments 3-10, long pereiopods and uropods, peducle of the second uropod with numerous rows of setae, and dimorphic first pleopods.
Proleleupia new genus
Type species. – Trogloleleupia nudicarpus Griffiths, 1991.
Diagnosis. – Maxilla 1 inner lobe setae 3 in number, palp larger than the outer lobe; gnathopod 1 dactyl with inner margin spines blade-like; gnathopod 2 carpal saw absent.
Remarks. – A separate genus, Proleleupia, for what was known as Trogloleleupia nudicarpus Griffiths, 1991 is required by our cladistic analysis, wherein the formerly large-bodied genus Trogloleleupia Ruffo, 1974 emerged as a paraphyletic taxon. The core species of the trogloleleupian group, containing the type species for Trogloleleupia, T. leleupi (Ruffo, 1951), is part of a fairly distinct clade, but two of the five species formerly placed in the genus Trogloleleupia in fact sort separately from this core species group. In addition, Proleleupia nudicarpus is the only trogloleleupian that lacks lenticular organs, a negative feature to be sure, but nonetheless one that separates it from all the other large-bodied trogloleleupians.
Paraleleupia new genus
Type species. – Trogloleleupia gobabis Griffiths, 1989
Diagnosis. – Pereional segments sub-rectangular; lenticular organs well developed; gnathopod 2 dactyl teeth developed as 4 blades, dactyl tip simple; pleopods as long fins; uropod 1 and uropod 2 subequal.
Remarks. – A separate genus, Paraleleupia, for what was known as Trogloleleupia gobabis Griffiths, 1989 is required by our cladistic analysis, wherein, as mentioned earlier the large-bodied genus Trogloleleupia Ruffo, 1963 emerged as a paraphyletic taxon. Its well-developed lenticular organs clearly characterize Paraleleupia gobabis, a feature shared only by T. dracospritus. In addition, the simple dactyl tip on the second gnathopod is a feature seen also in T. eggerti but no place else amongst all the ingolfiellideans. By erecting separate genera for Proleleupia nudicarpus and Paraleleupia gobabis we effectively set up an hypothesis of taxonomic relationships in this part of the tree. We can test this hypothesis either with discovery of future ‘trogloleleupians’, or accumulation of sequence data, or further insight into gross features of morphology.
Ingolfiella Hansen, 1903.
Type species. – Ingolfiella abyssi Hansen, 1903.
Diagnosis. – Gnathopod 1 dactyl either as a simple spine or serrate, gnathopod 2 palmar angle seta not pedicillate, carpal saw typically serrate; dactyl ends on pereiopods 3 through 7 typically produced as a spur; uropods 1 and 2 short.
Remarks. – The nature of the short uropods and the lack of a pedicillate palmar angle seta on gnathopod 2 stand out as very diagnostic for the species within the ingolfiellideans. These characters are quite stable throughout the genus: no alternate states concerning the uropods are encountered, and diverse variants of the palmar angle seta can be seen except the pedicillate form. In addition, species of Ingolfiella generally have a serrate carpal saw on gnathopod 2, exceptions being I. cottarellii, in which it is uniquely finely serrate, and I. beatricis, I. macedonica, I. xarifae, I. fuscina, and I. grandispina, in which it is absent.
The genus Ingolfiella is retained here as a single, undivided taxon, even though it is world wide in distribution and can be found in localities ranging from fresh groundwater, through diverse brackish, to deep-water ocean habitats. Given this wide distribution and variety of habitats it is instructive to examine several points on the cladogram for Ingolfiella with further comment as to character state changes.
A coastal Mediterranean clade (Fig. 8, Node D) is separated on the basis of loss of one seta on the outer lobe of the maxilla 2. These setae are reduced relative to what is common in gammaridean amphipods. Reverting from 4 setae to 3 setae would seem to reduce the ability of this limb to handle food particles. This may appear as a “subtle” feature, nevertheless the members of this clade exhibit a relatively high degree of geographic proximity.
The change over point from freshwater to brackish habitats (Fig. 8, Node E) is also defined by a single character state transition: the size of gnathopod 2 shifts from being smaller than the length of pereiopod 3 to being subequal to the latter. It again is difficult to conceive of any purported selective advantage of such a feature. Nevertheless, this node marks a distinct habitat shift within the genus. Another critical habitat shift occurs into pure marine waters (Fig. 8, Node F) and corresponds with changes in aspects of the second gnathopod. At this point we note an alteration of ornament on the dactylar margin of gnathopod 2, going from 3 blade-like processes to 3-4 teeth. Furthermore, we also note increasing variability on the distal propodus of gnathopod 2. Most freshwater Ingolfiella display blade-like distal propodi. Within brackish habitats we also see a finger-like form appearing. In the marine realm, an unmodified propodus reappears, a structural form characteristic of taxa typically outside the genus.
What surprises us about the above points is that while the habitat or geographic shifts are rather striking, the anatomical changes at these points are subtle in the extreme.
Past authors (S. Karaman 1959, Stock 1976b, Ruffo 1970, and Ruffo & Vigna Taglianti 1989), have made arguments to subdivide the genus Ingolfiella into either more genera, or at least subgenera (see bibliography). As can be seen in Fig. 8, these subgenera have little value in light of the cladistic analysis here. Nevertheless, we do see clades appearing within the genus. We have already noted the Mediterranean clade of the I. beatricis species group, characterized by a single feature. Another such clade is the I. macedonica species group (Fig. 8, Node G). This clade is characterized by two good features: 1) the claws of pereiopods 3 to 4 are simple in form, and 2) pereiopods 3 to 7 dactyls lack any decoration such as spurs or setae. These are good features at that point in the tree. If characters nicely delineating discrete clades would justify the erection of subgenera in a cladistic context, one might be tempted to look upon the so-called I. macedonica species group as a good one. We might even be tempted to say this species group is even more robust than that of I. beatricis species group discussed above, which only has a single, rather subtle diagnostic feature. However, the I. beatricis group is geographically continuous, while the members of the so-called I. macedonica species group are hardly so: I. macedonica is found in northwestern Greece, I. manni was collected from northern Chile and I. uspallatae comes from the high Andean passes of western Argentina. How do we bridge the gap from the Balkans to South America?
Thus, at this time we see no justification for establishing subgenera, or breaking up Ingolfiella into separate genera. The shifting morphological changes noted amongst the optimized characters on the cladogram are too subtle and homoplastic, and discrete clades are too few and far between. We remain confident, however, that as more taxa are added to the genus the cladogram will acquire some additional structure. Then at that time, the issue of what to do with such a wide ranging, both geographically and ecologically, genus as Ingolfiella currently represents can be revisited.
Additional descriptions
Re-examination of type and other material in light of the cladistic analysis allows additions and revisions to be made to existing species descriptions.
Metaingolfiella mirabilis Ruffo, 1969
Material examined. – collection of the Natural History Museum Verona.
Additional redescription: cephalon fused over about half the lateral lower side with the first pereionite.
Trogloleleupia eggerti (Ruffo, 1964)
Material examined . – collection of the Natural History Museum Verona.
The allotype (female) designated by Ruffo was restudied and some more sexual dimorphism is reported. Not only is the form of the first pleopod different – elongate in males and triangular in females – as mentioned by Ruffo, but also the female lacks a hooked spine on the base of the peduncle of the first uropod and the claviform process on the peduncle of the second uropod. Another noteworthy difference is the lack of the palmar corner process in the second gnathopod, but this occurs in other ingolfiellids too.
Additional description:
Maxilla 1, (Fig 6a) palp two-segmented with 4 setae on distal segment. Outer lobe with 6 serrated and combed robust setae. Inner lobe with 5 setae almost evenly distributed along its margin.
Maxilla 2 (Fig 6b), with both lobes having 5 setae, some plumed.
Mandible (Fig 6c, d). Left side with pointed pars molaris and 3 hooked and serrate spines at the base of the masticatory teeth. Right side with two such curved hooks.
Maxilliped (Fig. 5e). Palp with 3 spines apically and 1 spinule on a small pedestal submarginally on the propodal segment.
Pleopod 1 (Fig. 5f). Triangular fin with a slightly serrated hind corner margin and 3 tiny spinules on the lower margin
Trogloleleupia leleupi Ruffo, 1951
Material examined. – British Museum, Lusaka Boreholes, Zimbabwe, 9 specimen; Zoological Institute and Museum, University of Hamburg, 15 specimens, Kivu, Distric de Kindu, Territoire de Kasongo, Grotte de Mwana-Kussu, Congo, 24-X-1954
In the descriptions of Ruffo (1951) and Ingle (1961) no special emphasis was placed on the form of the first pleopod. These pleopods have in most ingolfiellids a different form in males and females. However, in the many specimens of Trogloleleupia (44 + from Belgian Congo and 9 from Lusaka, Zimbabwe), no distinction could be made between the sexes. We checked the pleopods for such differences. Indeed, some of the smaller specimens carry the digitiform first pleopods with two setules on the apex typical of males, while the larger specimens have the more spatulate crenelated type as in pleopod 2 and 3.
Additional description:
Antenna 1 (Fig. 5k) with a 4-segmented flagellum, bearing an aesthetasc on each segment. Accessory flagellum 3-segmented.
Gnathopod 2 (Fig. 5g, h) differs in aspect with increasing size. the 8 mm male (6e) has a hyaline lobe aligning the margin right under the palmar process but this is not seen in a 12 mm specimen (Fig. 5h), with a sculptured palmar process. The crenelations are more numerous on the palmar margin.
Pleopod 1 (Fig. 5i, j) is long and slender in the male, having two setae on the apex. the female form is somewhat triangular and lightly serrate on the hind margin.
Uropod 3 (Fig. 5l) in one instance quite long, with five slender setae on its apex.
Ingolfiella littoralis Hansen 1903
Material examined. – Holotype specimen, Zoological Museum of Copenhagen (ZMUC-CRU-7088)
Additional description:
Gnathopod 1 (Fig. 6a), margin of palm smooth, without structures or serrations
Gnathopod 2 (Fig. 6b), margin of palm serrated.
Pereiopod 3, 4 (Fig. 6c, d), claws tapering to a forked end
Pereiopod 5 (Fig. 6e), claw thick, undifferentiated.
Uropod 2 (Fig. 3g), with three oblique rows of setules on the inner side of the peduncle and a small group of setules on the inner side of the inner ramus.
Ingolfiella tabularis Stock 1977
Material examined. – Zoological Museum of Amsterdam, paratypes, cat. nr. 106.107
Additional description:
Mandible (Fig. 6g, h, I), with cup shaped spine on left mandible.
Maxilla 1 (Fig. 6j), with 6 combed and serrate setae of irregular length on outer lobe. Inner lobe with 1 seta, palp with 3 setae on apex.
Maxilla 2 (Fig. 6k), fitted with sparse setae on both lobes.
Ingolfiella margaritae Stock 1979
Material examined. – Zoological Museum of Amsterdam, holotype cat. nr. 106.443 – 444
Additional description:
Mandible (Fig. 6n), with apparently broken off molar process. Left or right side could not be discerned. Three curved spines just below pars incisiva.
Ingolfiella quadridentata Stock 1979
Material examined. – Zoological Museum of Amsterdam, paratypes cat. nr. 106.445 – 446
Additional description:
Mandible (Fig. 6l) with pointed molar process. Three very small spinules below the pars incisiva
Maxilla 1(Fig. 6m) has an outer lobe with 6 robust spines, bifid or serrate. Inner lobe with 1 seta, palp with 3 on apex.
Ingolfiella abyssi Hansen 1903
Material examined. – Museum of Copenhagen ZMUC-CRU-5030
Additional description:
Antenna 1 (Fig. 7c), with 4-segmented flagellum, bearing aesthetascs on the second and fourth segment. Accessory flagellum 3-segmented.
Gnathopod 1 and 2 (Fig. 7a, b), with 4 incisions on the inner margin of the dactylus, forming 4 blades. Gnathopod 2 claw with a clear articulation between dactylus and unguis.
Pereiopods 3–7 (Fig. 7d-g), with bifid claws in p3 and p4 (8d) and straight in p5-7 (8e, f, g).
Pleopods 1–3 (Fig. 7h-j), with more or less triangular form.
Uropod 1 (Fig. 7k), with 3 spiniform processes (instead of 4 in the original description) on inner ramus. Outer ramus with a breach on two-thirds of its length, dividing the ramus in two articles.