A New Family for a New Genus and New Species of Hermit Crab of the Superfamily Paguroidea (decapoda: Anomura) and Its Phylogenetic Implications

A new family, Pylojacquesidae. is proposed for Pylojacquesia colemani. new genus and species. Although (he new family, with its monoiypic genus, exhibits characicrs of both supcrfamilles of the Section Paguridea, it is tentatively assigned to the Paguroideu until additional material becomes available that would permit a more detailed study. The new family Pylojacquesidae is diagnosed, and its type genus and species arc de.scribed and illustrated. The possible phylogenetic relationships of the new genus are discussed. A key to all the families of hermit crabs is presented. Prior to the classic study of MucDonald et al. (1957), all hermit crabs were included in a single superfamily, the Paguroidea, with pagurids and diogenids ranked as subfamilies within the family Paguridae. However, MacDonald et al. found what they believed to be sufficient evidence among the larvae to separate hermit crabs into two distinct superfamilies, the Paguroidea, including the family Lithodidae and the subfamily Pagurinae, and the Coenobitoidea, including the families Pylochelidae, Coenobitidae, Lomidae (as Lomisidae), and the subfamily Diogeninae. Both the Pagurinae and Diogeninae were raised by MacDonald et al. to familial rank. However, McLaughlin (198.3a) regarded the Lomidae as distinct from all hermits, and subsequently she (McLaughlin. 1983b) argued against MacDonald's et al. implied polyphyly in hermits. In the classification proposed by McLaughlin (1983a, b), the family Lomidae was elevated to superfamily rank, the superfamily Coenobitoidea was suppressed, and the remaining families were reunited within the single superfamily Paguroidea. Although Forest (1987) supported McLaughlin's (1983b) view of monophyly among hermit crab families, he felt strongly that the difference between coenobitoids and paguroids was sufficient to justify the reinstatement of the Coenobitoidea and, with the Paguroidea, return to the use of the hierarchical Section Paguridea (cf. Holthuis, 1959). The new. albeit monotypic, taxon described herein is sufficiently distinct from all other hermit crab families to justify the establishment of a new family. Despite the fact that Pylojacquesidae shares characters of both the Coenobitoidea and Paguroidea, a third superfamily has not been deemed appropriate. Initially, we were prompted to propose the suppression of the superfamily Coenobitoidea once again, and reunite the existing families, i.e., Coenobitidae, Diogenidae, Lithodidae, Paguridae. Parapaguridae. and Pylochelidae, under the superfamily Paguroidea and add the new family Pylojacquesidae for Pylojacquesia, new genus. This action was strongly opposed by Professor Jacques Forest, who stressed (Forest, 1987, personal communication) that the thoracic endophragmal systems of the two superfamilies were so different that suppression of the Coenobitoidea was entirely unjustified. Information concerning the endophragmal systetTis remains, at present, still unpublished; however, the salient differences have been pointed out to us. Given the paucity of material upon which Pylojacquesidae is established, we have not been able to determine the characteristics of this system in the new family. Consequently, at least for the present, we are assigning Pylojacquesidae to the superfamily Paguroidea. Nonetheless, it is equally possible that further study will show by the characters of the endophragmal system that Pylojacquesidae could be con-