Shigemitsu Shokita

The complete larval development of Sadayoshia edwardsii (37) (Decapoda: Anomura: Galatheidae) described from laboratory‐reared material

The complete larval development of Sadayoshia edwardsii (Miers, 1884) is described and illustrated from laboratory‐reared material. The development comprises four zoeal and one megalopal stages. Diagnostic zoeal characters of Sadayoshia are provided and these are compared with other galatheid genera for which the larval morphology is known. Zoeas of S. edwardsii are readily distinguished from those of other galatheid species by the setation of the maxillular endopod together with the basis and endopod of the first maxilliped. The megalop of S. edwardsii has a flattened, triangular‐shaped rostrum, which differs remarkably from that of the adult. Although the rostral shape resembles that of Galathea megalops, the armature of the lateral margins is different between megalops of the two genera. The present larval study suggests that Sadayoshia is more closely allied to Galathea than to Munida.

A first fossil record of the terrestrial crab, Geothelphusa tenuimanus (Miyake & Minei, 1965) (Decapoda, Brachyura, Potamidae) from Okinawa Island, Central Ryukyus, Japan

Fossils of the terrestrial crab, Geothelphusa tenuimanus , are described. These fossils were collected from clay within the e ssures that rift the limestone of the Middle Pleistocene Ryukyu Formation on Okinawa Island, Ryukyu Islands. The geological age of the fossil G. tenuimanus was estimated as Late Pleistocene, because they occurred in association with a fossil deer ( Cervus sp.), which is already extinct on Okinawa Island. This is the e rst fossil record of a true freshwater crab from the Ryukyu Islands. In both fossil and extant specimens of G. tenuimanus, the longer movable e ngers of the chelipeds usually have a stronger curvature, but the present fossil specimens contain higher numbers of strongly curved movable e ngers than found in extant specimens. This difference may be caused by the fact that no sufe ciently large extant specimens have been examined.

ON THE SPECIES OF JAPANESE ATYID SHRIMPS (DECAPODA: CARIDEA) DESCRIBED BY WILLIAM STIMPSON (1860)

Abstract The taxonomic status of the six Japanese species of Caridina described by W. Stimpson (1860) is clarified on the basis of fresh specimens from the type localities. Caridina grandirostris, which has long been synonymized under C. longirostris H. Milne Edwards, 1837, is shown to be a distinct species; C. leucosticta is redescribed; C. multidentata is the senior synonym of C. japonica De Man, 1892; C. acuminata and C. brevirostris are regarded as junior synonyms of Atyoida pilipes (Newport, 1847); and C. exilirostris is synonymized with C. typus H. Milne Edwards, 1837. Neotypes for the six species are designated to stabilize their taxonomy, all of which are redescribed and figured. The various nomenclatural problems associated with these species are discussed.

ABBREVIATED LARVAL DEVELOPMENT OF A FRESH-WATER PRAWN, MACROBRACHIUM NIPHANAE SHOKITA AND TAKEDA (DECAPODA: PALAEMONIDAE), FROM THAILAND

The abbreviated larval development of a fresh-water prawn from Thailand, Macrobrachium niphanae Shokita and Takeda, is described and illustrated in detail. Two zoeal, 1 megalopal, and 2 juvenile stages are distinguished, and their characteristics are compared with those of related species which have an abbreviated larval life.

Atyid shrimps (Crustacea : Decapoda : Caridea) of the Ryukyu Islands, southern Japan, with descriptions of two new species

The freshwater atyid shrimps of Ryukyu Islands, southern Japan, are documented and discussed. A total of 21 species of freshwater shrimps, belonging to seven genera is reported. Two new species are here described and illustrated in detail. Caridina sakishimensis Fujino and Shokita, 1975, is synonymized with Caridina prashadi Tiwari and Pillai, 1971. S.ome previous records are revised, viz. Caridina weberi De Man, 1892a is referred to C. laoagensis Blanco, 1939; Neocaridina brevirostris reported from Ishigaki Island by Kubo (1941) is most probably an undescribed species. Caridina hainanensis Liang and Yan, 1983, from China and Caridina blancoi Chace, 1997, from Philippines are also synonymized with Caridina propinqua in the present study.

LARVAL DEVELOPMENT OF THE MANGROVE SESARMID CRAB NEOSARMATIUM TRISPINOSUM (BRACHYURA: GRAPSOIDEA) DESCRIBED FROM LABORATORY-REARED MATERIAL

Abstract The larvae of the mangrove sesarmid crab Neosarmatium trispinosum Davie, 1994, were reared in the laboratory. Five zoeal stages and one megalopa are described in detail and illustrated. Morphologically, the zoea larvae of N. trispinosum are similar to those of other species of Neosarmatium in that they share most of the following characters: no lateral carapace spines; 1+5, 5, and 0+1+6 setae on the endopods of the maxillule, the maxilla, and the second maxilliped, respectively; uniform setal formula on the basis of the first (2,2,3,3) and the second (1,1,1,1) maxilliped. The differences between the zoeae and the megalopae of N. trispinosum and those of its congeners are discussed briefly.

A revision of the Geothelphusa levicervix species group (Crustacea: Decapoda: Brachyura: Potamidae), with descriptions of three new species

The taxonomy of the Geothelphusa levicervix species‐group of freshwater crabs (Potamidae), members of which are distributed on five islands in the Ryukyus, Japan, is revised. The present study recognizes five species in the group, three of which are here described as new, and each of which is restricted to its own island. They can be easily distinguished by both carapace and male gonopod characters. On the basis of recent collections, the precise type locality of G. levicervix is here determined to be Tokashiki Island. The five species are diagnosed and a key to the species of the species‐group is provided.

Neocaridina iriomotensis, a new species of land-locked freshwater shrimp (Crustacea: Decapoda: Atyidae) from Iriomote Island, southern Ryukyus, Japan

ABSTRACT Neocaridina iriomotensis is described from Iriomote Island, southern Ryukyus, Japan. This species apparently belongs to the N. palmata species group and is morphologically closest to N. anhuiensis (Liang, Zhu & Wei, 1984) and N. ishigakiensis (Fujino & Shokita, 1975). It can be differentiated from the former by the longer rostrum and the presence of a pterygostomian spine, and from the latter by the armature of the rostrum.

Larval Development of the Swimming Crab Thalamita pelsarti Montgomery, 1931 (Crustacea: Brachyura: Portunidae) Reared in the Laboratory

The larval development of the swimming crab Thalamita pelsarti Montgomery was studied from the first zoea to megalopa under laboratory conditions. Five zoeal stages and one megalopa are identified, and detailed descriptions and illustrations are provided for each stage. At an average salinity and temperature of 34 ± 1‰ and 24 ± 1°C, the megalopa was attained 17 days after hatching. Morphologically, the first zoea of T. pelsarti is similar to those of other species of Thalamita in having a lateral spines on the carapace, one plus six setae on the endopod of the maxillule, two plus four setae on the endopod of the maxilla, and three pairs of serrate setae on the posterior margin of the telson furca. The differences between the first zoea and megalopa of T. pelsarti and those of its congeners are discussed briefly.