Yukio Hanamura

A new species of Thetispelecaris (Crustacea: Peracarida) from submarine cave on Grand Cayman Island.

Abstract A new species of the peracaridan order Bochusacea, Thetispelecaris yurikago, is described from a submarine cave on Grand Cayman Island, the Caribbean Sea. The new species is the fourth species of the order and family, and the second of the genus. Recent studies have strongly suggested a close phylogenetic affinity between cave-dwelling and deep-sea taxa in the Bochusacea as recognized in other cavernicolous/deep-sea crustaceans such as amphipods and copepods. The morphology of the gut and female reproductive system is observed for the first time in the Bochusacea: the stomach is complex with structures such as ridges, processes, spinules, and hairs in the lumen; paired gonopores are located near the base of the fifth pereiopods on the sternite.

Seasonality and infestation pattern of epibiosis in the beach mysid Archaeomysis articulata

Seasonal variation and the infestation pattern of epibiosis in the beach mysid Archaeomysis articulata Hanamura, 1997, were studied based on intertidal samples over 1 year on a sandy beach in Ishikari Bay, northern Japan. The mysid-peritrich ciliate association was a year-round phenomenon in Ishikari Bay and the prevalence of infestation varied from 49 to 100% (average: 92%) during the investigation; no significant seasonal trend was noted. Incidence of infestation in smaller mysids (<5 mm) was significantly lower than in larger mysids (>5 mm). The number of ciliates carried by adult, mostly ovigerous, females was greater than that by adult males. Last stage embryonic larvae were occasionally infested by ciliates, but early stage larvae were absolutely free from epibionts. Dense infestation of epibionts was not correlated with the abundance of mysids, hence the impact of ciliates on natural populations of mysids is assumed to be insignificant.

Reassessment of the taxonomy of Mesopodopsis orientalis (Tattersall, 1908) (Crustacea, Mysida) and proposal of a new species for the genus with an appendix on M. zeylanica Nouvel, 1954

The Indo‐Australasian mysid Mesopodopsis orientalis (Tattersall, 1908) has been recorded throughout the southwestern coast of India and the Philippines. As a result of its abundance, this mysid is regarded as one of the most important species of the shallow‐water crustacean community. Recent ecological studies of this conventionally identified species have revealed significant differences in certain life history features among populations, in particular between coastal and estuarine populations, which seemed to be associated with some differences in morphology. Following the examination of the syntypes and topotypes, the identity of M. orientalis was redefined, and a new species, M. tenuipes, was subsequently proposed on the basis of the further assessment of morphological and DNA analyses. At several sites, these two species coexist, although M. tenuipes usually inhabits inner estuaries or less haline waters compared with M. orientalis. Our analyses also suggest a possibly higher allopatric diversification within each lineage along their geographical transitions. In addition, earlier records of M. orientalis from India need to be reanalysed to rectify confusion with M. zeylanica Nouvel, 1954.

A New Species of Archaeomysis From Coastal Waters of Japan (Mysidacea, Gastrosaccinae)

A large number of Japanese specimens previously identified as Archaeomysis grebnitzkii were examined and compared with specimens from the Bering Sea and Pacific coast of North America. This study demonstrates that the Japanese population of Archaeomysis grebnitzkii sensu Ii (1964) differs consistently from those of the latter locations, particularly in the shape of the telson and the male 3rd pleopod, so as to constitute a new species, described here as A. japonica n. sp. A short note is included at the end of this paper reporting some observations on the biology of the species noted during this study.

Versatile mysids exploit multiple basal resources: implication of the bentho-pelagic habit in estuarine food webs

Mysid feeding ecology was studied in a tropical mangrove estuary and adjacent coastal mudflat, using stomach content and stable isotope analyses. We tested the hypothesis that estuarine mysids are able to exploit the various basal food resources, while their bentho-pelagic habit related to nocturnal feeding explicates their important role as trophic intermediaries in estuarine food webs. Diet composition differed among species, between habitats and between day and night. Acanthomysis thailandica, Notacanthomysis hodgarti, Mesopodopsis orientalis, and Rhopalophthalmus hastatus were generally omnivorous, while R. orientalis tended to carnivory. Although both examined species, A. thailandica and N. hodgati, showed no diel feeding rhythm, heavy feeding on surface copepods occurred at night. The largely mudflat species (A. thailandica, N. hodgarti, M. orientalis, and R. orientalis) showed significantly enriched mean δ13C values compared to the upper estuarine species, R. hastatus. The δ13C values suggest that coastal species utilized carbon sources from phytoplankton and benthic diatoms, while estuarine species utilized more mangrove carbon. Since mysid shrimps can derive nutrition from all basal sources, they form an important link in the flow of trophic energy from source to the higher consumers of tropical estuarine ecosystems.

Establishment of a New Genus Bathystylodactylus (Crustacea: Decapoda: Stylodactylidae), with Description of a New Species from Northwestern Pacific

Abstract A unique specimen of the family Stylodactyiidae (Crustacea: Decapoda) collected from a great depth, 3436-3452 m off the east coast of Taiwan, northwestern Pacific, is described as representative of a new species close to Stylodactylus bathyalis Cleva, 1994 from the Coral Sea. These two species are characterized by several specialized features which warrant the establishment of a new genus Bathystylodactylus. The new species named B. inflatus differs from B. bathyalis in having the carapace markedly swollen at the posterodorsal part, a greater number of rostral spines, and the rounded third abdominal pleuron.

A new species of Anisomysis Hansen, 1910 (Mysida, Mysidae) from inshore waters of a small island in the Andaman Sea

A new species of Anisomysis Hansen, 1910 (Mysida, Mysidae) collected from inshore waters of Racha Yai Island in the Andaman Sea, eastern Indian Ocean, is reported upon. The new species, Anisomysis (Paranisomysis) takedai, shows a close affinity to A. (P.) minicoyensis Biju et al., 2006. The new species can be distinguished from A. (P.) minicoyensis by having a short rostrum barely reaching the base of the antennular peduncle, a comparatively broader antennal scale, a proportionately longer second article of the male fourth pleopodal exopod, and a larger number of setae on the telson.

Thirty-two polymorphic microsatellite loci of the mysid crustacean Mesopodopsis tenuipes

Thirty-two polymorphic microsatellite loci were indentified and characterized from the mysid Crustacea Mesopodopsis tenuipes Hanamura et al., 2008. The number of observed alleles per locus in 32 individuals collected from its type locality in Malaysia ranged from 2 to 22. The observed heterozygosity ranged from 0.031 to 0.906, while the expected heterozygosity varied from 0.031 to 0.943. All loci conformed to Hardy–Weinberg equilibrium, no linkage disequilibrium was observed between pairs of loci and no loci showed evidence of null alleles. These 32 microsatellite loci could be used in future population genetics study of M. tenuipes.

Heteromysoides (Crustacea: Mysidacea: Heteromysini) from a submarine cave on Grand Cayman, the Caribbean Sea: descriptions of a new and a rare species

During a recent biological investigation of submarine caves of Grand Cayman, the Caribbean Sea, two species of Heteromysoides were collected. One species, referred to Heteromysoides spongicola Băcescu, 1968, is known only by the type specimens; therefore, this discovery marks the second record of occurrence and a new habitat record for the species. The other species is considered new and is described as H. stenoura, a 10th species of the genus. The new species closely resembles H. simplex Hanamura and Kase, 2001, known from the submarine caves of Okinawa, north-western Pacific, in the possession of a spiniform process on the eyes and a simple termination to the third thoracic endopod. However, the new species can be readily distinguished from the Pacific congener by a distally narrow telson and a more developed cornea in the eyes.

A New Species of the Rock Shrimp Genus Sicyonia (Decapoda, Sicyoniidae) From South-Eastern Australia, With a Key To the Indo-West Pacific Species

A new species of the rock shrimp genus Sicyonia, S. australiensis sp. nov. (Decapoda, Sicyoniidae) is described and illustrated based on specimens collected from south-eastern Australia. The new species has the first two abdominal somites with an anteriorly directed dorsomedian spine; consequently it resembles closely the following four species: S. laevis Bate, 1888, S. nebulosa (Kubo, 1949), S. truncata (Kubo, 1949) and S. nasica Burukovsky, 1990. However, S. australiensis can be distinguished from its congeners by a combination of features, having the pleuron of the fifth abdominal somites with a posteroventral spine and the rostrum moderately high throughout the entire length, with the distal end posteriorly inclined to ventrad. The genital structures also distinguish the Australian specimens from the related species.