Prior to the present study, the genus Trizopagurus Forest, 1952, included ten species, mostly from the Indo-West Pacific, but two of them from the Eastern Atlantic and one from the Eastern Pacific. Following the examination of about 350 specimens, this genus has now been revised and two new genera established, Ciliopagurus gen. nov. and Strigopagurus gen. nov. In addition 24 species are assigned to the three genera, 14 of these being described as new. After an introduction that discusses the examined material and the methods used in the taxonomic study, a chapter is devoted to the characters that led to the partition of genus Trizopagurus, namely the shape of the cephalothoracic shield, ornamentation of thoracic appendages, organization of the pleopods, and the stridulatory structures. These structures, described and compared in the following chapter, are of particular interest since they can be used to define the three genera. Their homologies indicate an evolutionary trend from Trizopagurus via Ciliopagurus to Strigopagurus and the three genera are studied following the order of this dine. The systematic section first gives an account on the current status of the Diogenidae, recently enriched with four genera. The characters of each genus are tabulated and their comparison used to define some groupings. In most cases, the genera brought together in a same group show marked differentiations and are not closely related. However, the three genera presently studied form a coherent unit, especially on account of the stridulatory structures, which are peculiar and unique, not only within the family, but in all decapods. An identification key is provided for all known genera of Diogenidae. The systematic treatment of the three studied genera comprises references, diagnosis and definitions, together with remarks on the affinities of the included species. Keys for species identification are provided. For each species are given references, a full synonymy, a list of examined material, informations on type specimens, a description and an account of variations, when enough specimens are available. In the remarks, the main distinctive morphological features are pointed out and compared with those of related species. Are also mentioned the size distribution by sex, the identified inhabited shells, and the distribution. Trizopagurus Forest, 1952, is characterized by the relatively weak development of the stridulatory elements, which are fewer, less differenciated and grouped in less distinct patches than in the other two genera. The ornamentation of the chelipeds consists of slightly projecting and rounded teeth or tubercles, in front of which short setae (ciliae) are located in semicircular rows. In both sexes, there are four biramous pleopods on the left side of the abdomen, the last one smaller and never oviferous in the female. The three species inhabit shallow water, usually in the tidal zone. T. magnificus (Bouvier, 1898) belongs to the tropical fauna of the eastern Pacific. T.melitai (Chevreux & Bouvier, 1892) and T. rubrocinctus Forest & Raso, 1990, are both from the tropical northeastern Atlantic. In Ciliopagurus gen. nov., the stridulatory structures are looking like fine, corneous, parallel rods, grouped in several neatly separated patches, which are homologous in the different species. The first three thoracic legs are ornamented by transverse ciliated striae, with much longer setae in some species. There are four unpaired biramous pleopods in both sexes, the last one equal to the others and always oviferous in the female. The species can be separated into two groups, according to whether the ridges on the carpus and propodus of chelipeds, along the transverse striae, are smooth or tuberculated-denticulated. The first group includes eight species ; C. strigalus (Herbst, 1804), C. tricolor sp. nov., C. krempfi (Forest, 1952), C. caparti (Forest, 1952), C. albatrossi sp. nov., C. shebae (Lewinsohn, 1969), C. macrolepis sp. nov. et C. liui sp. nov. The second group comprises also eight species : C tenebrarum (Alcock, 1905), C. haigae sp. nov., C. hawaiiensis (McLaughlin & Bailey-Brock, 1975), C. pacificus, C. plessisi, C. major, C. alcocki and C. babai spp. nov. The genus Ciliopagurus, which is widely distributed, includes one species, C. caparti, from the tropical eastern Atlantic. All others are from the tropical Indo-West Pacific, from the Red Sea and southeastern Africa to Japan and the Hawaiian and Marquesas Islands. The bathymétrie range is highly variable. In the first group two species are restricted to very shallow water, mostly from the tidal zone. The other ones are distributed from 50 to 120 m, except for the eurybathic C. krempfi, which has been collected between 10 and 300 m. The second group is mostly present from 120 to 480 m, one species reaching probably a greater depth. The genus Ciliopagurus gen. nov. also includes a fossil pagurid from the Middle Miocene, previously known as Dardanus substriatiformis (Lorenthey) and related to the species of the second group. The genus Strigopagurus gen. nov. is provided with the most differentiated and accomplished stridulatory structures. They consist of relatively thick corneous rods, arranged in strongly individualized patches, the larger of which appearing as distinctly channelled plates. The carpus and manus of the chelipeds are covered dorsally with strong teeth that end in a thin corneous spine. Thinner corneous teeth are also present on the two following appendages. As usual within the Diogenidae, except Paguristes and Paguropsis, there are no appendages on the first abdominal segment. In the female, the four pleopods are unpaired and biramous, the last one being only partially oviferous. But the second abdominal segment of the male is usually supplied with a pair of pleopods, which, according to the species, are modified or not as gonopods ; the following three appendages are unpaired and biramous. The five species can be separated into two groups. The first comprises two species without a differentiation of the paired male pleopods, i. e. S. strigimanus (White, 1847) and S. elongatus sp. nov. The three species with differentiated gonopods, S. bilineatus, S. boreonotus and S. poupini spp. nov. form the second group. Strigopagurus gen. nov. is not as extensively distributed as Ciliopagurus gen. nov., being found only from the eastern Indian Ocean to Japan and Polynesia. The genus is not strictly tropical, since the two species with undifferenciated pleopods inhabit the southern Australia. One of the other three species is known only from Queensland and another from Polynesia. The last one, present in eastern Indonesia, New Caledonia, the Philippines and Japan, is the only species of the genus spreading north of the Equator. The species of the first group inhabit relatively shallow water, usually from a few to about a hundred meters. The other species are all present at about 250 m, but one of them, the most widely distributed, is still relatively common to 500 m. Finally, a general account of the geographic and bathymétrie distribution of genera and species is given and illustrated with maps and a table. |
