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Introduction
As a result of several specimens obtained by the South African Spelaeological Association from underground cave pools in Bat Cave, Table Mountain, South Africa, Gordon (1957, 1960) described a new malacostracan crustacean species, Spelaeogriphus lepidops. This crustacean possesses a typically peracaridan brood pouch with five pairs of oöstegites, and was thus placed within the Superorder Peracarida. While its closest affinities seem to be to the Tanaidacea, it is not sufficiently similar to any of the existing peracaridan orders for it to be placed comfortably within any of these orders. Thus, the Order Spelaeogriphacea was erected by Gordon (1957) to accommodate this new and "complicated" taxon. Little research has followed up on this initial description, with the exception of work on the respiratory mechanism and its phylogenetic significance for Spelaeogriphus lepidops by Grindley and Hessler (1971) .
While work on S. lepidops has been sparse, continuing research on other fronts has increased the number of species credited to this order to three. Pires (1987) described a second recent form, Potiicoara brasiliensis, found in a lake inside the calcareous cave Gruta do Laga Azul in the Bodoquena Mountains, Mato Grosso do Sul, Brazil. This form is distinguished from S. lepidops by its shorter carapace, biramous fifth pleopod, three-segmented mandibular palp, spinose maxillipedal endite and it‘s highly specific collection locality, considerably distant from that of S. lepidops. Pires also included a phylogenetic analysis of the peracaridan orders, considering the phylogeny of the order as a whole. Of particular note, she proposed as a result of this analysis a sister-group relationship between the Spelaeogriphacea and Mictacea.
The third spelaeogriphacean taxon, Acadiocaris novascotica, is a Lower Carboniferous form collected from the Maritime Provinces of Canada and was described initially by Copeland (1957) . It was later redescribed by Schram (1974) , who placed it into his newly-erected spelaeogriphacean family Acadiocarididae, reassigning it from the peracaridan Order Anthracocaridacea as previously proposed by Brooks (1962) . This species is described from poorly preserved material, composed of black carbonaceous pyritized films on black shale which, as Schram (1974) has observed, appears to be in the process of disintegrating as the pyrite in them oxidizes. This form appears to posses several ‘primitive‘ characters when compared to the other spelaeogriphacean taxa, such as an absence of an optic notch in the rectangular carapace, well-developed and elongate thoracopodal endopods, and five pairs of well-developed, but relatively small and simple pleopods.
A fourth species of spelaeogriphacean has now been discovered from two equivalent localities consisting of Upper Jurassic outcrops in Liaoning Province of the People‘s Republic of China (and is the third taxon of a series of new crustacean species from China to be described by the authors). The first locality represents the Jianshangou sedimentary intercalation of the Upper Jurassic Yixian Formation and is found in Chaomidianzi village, Jianshangou, Beipiao County. The second locality represents the slightly younger Dakangpu sedimentary intercalation, also from the Yixian Formation, and is located in Dakangpu village, Yixian County (Chen 1988; Chen et al. 1980) (Figure 1).
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Fig 1. Locality map of collection sites of Liaoningogriphus quadripartitus, highlighted by pointers (inset: China, with map area shown as a black rectangle (highlighted by small pointers)). |
Spelaeogriphacean research dealing with new taxa has also developed on other fronts recently. Eva E. Pinardo-Moya at the Unidad de Paleontologia, Universidad Autonoma de Madrid is currently working on the description of a new spelaeogriphacean taxon from Lower Cretaceous (Barremian) deposits of Las Hoyas, Spain (pers. com.). In addition, Gary Poore, Museum of Victoria, Australia and Bill Humphries, Western Australian Museum, are describing a newly discovered Recent spelaeogriphacean, said to closely resemble Potiicoara brasiliensis, from the Pilbara Craton of Australia (Humphries, pers. com.).
The phylogeny of this enigmatic order will be discussed in some detail later in this paper. A different approach will be used than that of Pires (1987) , however, who conducted a phylogenetic analysis of the orders composing the Superorder Peracarida. We will use the cladistic method to suggest possible relationships within the order. In addition, we will include representative members of the peracaridan orders in this analysis to determine the ordinal relationships suggested by our data.