The family Homolodromiidae Alcock, 1900, which makes up the superfamily Homolodromioidea, is a group of primitive crabs that consists of only two genera, Dicranodromia A. Milne Edwards, 1880, and Homolodromia A. Milne Edwards, 1880. It comprised until now nine species, all of which are bathyal : six in the genus Dicranodromia, and three in the genus Homolodromia. Due to the infrequent capture of these small crabs, which have a fragile decalicified exoskeleton and are easily damaged, the family was one of the least known among the brachyurans. The revision of the Homolodromiidae of the world has been undertaken as a result of the ORSTOM collections in Madagascar and, especially, those of the French collections that were obtained from the cooperation of ORSTOM and the Muséum national d'Histoire naturelle, Paris (especially different MUSORSTOM expeditions and also KARUBAR, BATHUS expeditions, etc.), in the upper bathyal zone in the Indo-west Pacific : the Philippines, Indonesia, New Caledonia, Vanuatu, submarine mounts of the Norfolk and Loyalty ridges. Chesterfield Islands, Wallis and Futuna Islands. We were able also to examine carcinological material collected by other various expeditions from among the least explored regions (coast of east Africa, eastern Australian coast, southwestern coast of South America, etc.). The examination of almost all Homolodromiidae deposited in the most important museums of the world, reference collections or unidentified material, prompted us to examine other faunas, especially Japanese, South African and American. The type specimens of almost all species were studied and practically all specimens mentioned in the literature were verified. Practically all references have been checked. At the end of our study, the family Homolodromiidae retains its original two genera. H. kai Guinot, 1993, previously described in a preliminary way, is here described in full, bringing the number of species in the genus Homolodromia to four. The type species of the genus, H. paradoxa A. Milne Edwards, 1880, sensu restr., is restricted to the holotype from the Lesser Antilles (Nevis) and to part of the material named as such in the literature. The genus Dicranodromia acquires four Indo-west Pacific species : D. martini sp. nov. ; D. spinulata sp. nov. ; D. crosnieri sp. nov. ; and D. nagaii sp. nov., in addition to the two species D. karubar Guinot, 1993, and D. foersteri Guinot, 1993, described in a preliminary manner. The only Dicranodromia from the eastern Atlantic is split in two : D. mahieuxii A. Milne Edwards, 1883, sensu restr., restricted to the holotype specimen from the Bay of Biscay ; D. pequegnati sp. nov. is established to include material from West Africa. The type species of genus D. ovata A. Milne Edwards, 1880, sensu restr., from the western Atlantic, is restricted to the lectotype from Barbados. In addition to D. spinosa Martin, 1994, three new species of Dicranodromia from the western Atlantic are described here : D. chacei sp. nov., D. simpUcia Guinot & Martin sp. nov. and D. alphonsei Martin & Guinot sp. nov. The total number of species that comprises the genus Dicranodromia is therefore increased to 16 species. The family Homolodromiidae now consists of 20 recent species but the true number of living species is certainly much higher, particulariy in Japan and the Caribbean region. After a short survey of the history of the family, which serves as an introduction, information is given about the ontogeny and paleontology of the group. A review is then made of the main structures and principal arrangements of the Homolodromiidae, in order to make rigorous comparisons and to examine the homologies of the morphological criteria that were utilized in the analysis of relationships. Some particular arrangements, such as the thin membraneous branchiostegite, the retention of vestigial pleopods on the third to fifth abdominal segments of the male and the presence of abdominal pleurae (sometimes very extended), are analyzed (plesiomorphy). A detailed analysis of numerous females and their spermathecae allowed us to propose the possible introduction of the long stylet of the second male pleopod into the opening of the spermatheca during fertilisation. The position of the Homolodromioidea in the subsection Dromiacea is discussed. As a consequence, a new key to the three families of the Dromiacea (Dromiidae, Dynomenidae, Homolodromiidae) is given. The uniqueness of the Homolodromioidea in relation to its sister group, the superfamily Dromioidea, is discussed. A simple analysis of the affinities of the two genera Homolodromia and Dicranodromia is also given. The primitive nature of the Homolodromiidae is demonstrated and the place of the group at the bottom of the Podotremata is supported. In the systematics section, a diagnosis is given for each of the genera that are redefined. All species have been examined for each genus with respect to its type species and a key is provided. Most species are described using diagnostic characters. For the mainly pooriy known species a summary of characters differentiating them from the nearest taxa is presented. Each species is generally represented by drawings and by several photographs. The revision is concluded by a brief review of some representative fossils related to the Homolodromiidae. The numerous ancestral homolodromiids constitute the family Prosopidae von Meyer, 1860, known from the Middle Jurassic. Three fossil forms are attributed to the family Homolodromiidae, and to the two recent genera. The most ancient, Homolodromia novaezelandica Feldmann, 1993, goes back to the Mesozoic (Cretaceous), from New Zealand. H. chaneyi Feldmann & Wilson, 1988, from Antarctica, is the most recent (Eocene). Dicranodromia sp. (Miocene from central Japan) presents the most striking analogies with recent Dicranodromia. Antarctidromia inflata Förster, Gazdzicki & Wrona, 1985, is also a relatively recent Homolodromiidae (Lower Miocene), from western Antarctica. A genus even more ancient than the known Prosopidae is added to the Homolodromiidae : Eoprosopon Förster, 1986, with E. klugi Forster, 1986, from the Liassic in Germany (late Lower Pliensbachian). The geographic and bathymétrie distribution of genera and species is briefly discussed based on the new material. |
