Michitaka Shimomura

In-situ Observations of Symbionts on Medusae Occurring in Japan, Thailand, Indonesia and Malaysia

During an ecological investigation on symbionts of medusae in Eastern and Southeastern Asian waters, seven species of hydro- and scypho-medusae were found to harbor a wide variety of invertebrates and fi shes: the isopod Idotea metallica and the nudibranch Fiona pinnata on the chondrophoran Vellela vellela; the actiniarian Peachia quinquecapitata on the leptomedusa Aequorea coerulescens; the butterfi sh Psenopsis anomala and the hyperiid amphipod Hyperia galba associated with the semaestome Chrysaora melanaster; H. galba on the semaestome Aurelia limbata; metacercariae of three species found in the mesogloea of a semaestome, Aurelia sp.; the ophiuroid Ophiocnemis marmorata, the caridean shrimp Latreutes spp., and the shrimp scad Alepes djedaba on the rhizostome Rhopilema hispidum; the swimming crab Charybdis feriata and A. djedaba on the rhizostome Versuriga anadyomene. Juveniles of benthic organisms such as crabs and ophiuroids seem to become hitchhikers for dispersal, while juvenile fi sh utilize medusae as refugia against predation. Since the previous and present studies have shown that edible rhizostomes are associated with many kinds of symbionts, fi sheries for these jellyfi shes possibly hinder the recruitment of symbionts such as decapods, ophiuroids and fi sh.

Prodajus curviabdominalis n. sp. (Isopoda: Epicaridea: Dajidae), an ectoparasite of mysids, with notes on morphological changes, behaviour and life-cycle

Adults and larvae of a new ectoparasitic isopod, Prodajus curviabdominalis n. sp., are described from the mysid Siriella okadai Ii collected from the Seto Inland Sea, western Japan. The adult female is found within the host marsupium with the cephalon directed posteriorly, whereas the dwarf adult male attaches to the ventral surface of the female pleon. The cryptoniscid larva usually attaches to the second or third abdominal somite of the host, using an oral sucker. Mature adults of the new species are distinguished from all other congeners by: pleon of ovigerous female strongly curved dorsally, with large swellings on ventral side; pereon of ovigerous female narrow; exopods on male uropods present; male pleon short and thick. This is the third record of a member of the Dajidae from Japan. The behaviour of the cryptoniscid larvae of the new species on the host mysid was also observed using a video camera. Larvae moved from the first attachment site, usually the second or third abdominal somite of the host mysid, into the marsupium. When host oostegites were not fully developed, larvae entered beneath the host carapace until her marsupium was fully formed. The host infected by a female P. curviabdominalis moved the oostegites rhythmically, an action which may aid the respiration of the parasite.

Landscape versus local factors shaping butterfly communities in fragmented landscapes: Does host plant diversity matter?

Conversion of terrestrial land for the purposes of agriculture and urban development continues to result in loss and fragmentation of natural habitats. In this study, we focus on butterflies and investigate the relative importance of landscape-level habitat amount (the proportion of woodland area within a landscape), habitat fragmentation (length of woodland edges within a landscape), urbanization (the proportion of urban area within a landscape), and local host plant diversity for butterfly communities in a fragmented landscape in Hokkaido, northern Japan. Butterfly species observed in the field were grouped into woodland and open-land species. The results showed that both landscape and local factors shape the butterfly community. At a landscape-scale, woodland butterflies positively responded to woodland area and negatively to edge density, whereas open-land butterflies showed opposite responses. At a local-scale, positive influences of local host plant diversity on woodland butterflies were evident, but not for open-land species. These results suggest that negative influences of anthropogenic land-use changes on biodiversity could be mitigated by strategies aimed at stopping the spread of woodland edges and providing a wide variety of different host plant species in the landscape. Unfortunately, this study implies that further increases in habitat loss and fragmentation and decline in host plant diversity lead to a homogenization of local biological communities and functions.

Description of a New Species of Cephalocarida, Sandersiella kikuchii, and Redescription of S. acuminata Shiino Based Upon the Type Material

Abstract A new species of cephalocarid, Sandersiella kikuchii, is described from central Japan, 300 m depth. It differs from congeners primarily based on the following points: 5-9 hooks on each ventrolateral side of cephalon; exopod proximal segment of thoracopod 6 with long finger-like lateral process (with narrow base) on the dorsal margin; exopodal distal segment of thoracopod 6 pointed distally, not divided into 2 lobes; exopodal proximal segment and pseudopipod of thoracopod 8 furnished with 2 and 2-3 setae respectively. Sandersiella acuminata Shiino, 1965 is redescribed and illustrated based on the holotype.

INGOLFIELLA INERMIS N. SR, A NEW INTERSTITIAL INGOLFIELLID AMPHIPOD FROM OKINAWA, SOUTHERN JAPAN (PERACARIDA, AMPHIPODA)

A new ingolfiellid amphipod, Ingolfiella inermis n. sp. is described from a coral sandy beach of Okinawa, southern Japan. The new species differs from its congeners in the following characters: head, pereionites, pleonites, and urosomites without dorsal setae; fleshy and moderately long telson; broad carpus of gnathopod 2 with some minute teeth and long palmar angle spine; dactyli of gnathopods 1 and 2 each with 4 teeth; pereiopod 7 longer than the other pereiopods; uropod 1 longer than uropod 2; outer ramus of uropod 1 longer than 1/2 inner ramus.

A new species of Enterognathus (Copepoda, Cyclopoida, Enterognathidae) collected from the Seto Inland Sea, western Japan

Abstract A new species of the endoparasitic copepod Enterognathus (Cyclopoida, Enterognathidae) is described from a crinoid host in the Seto Inland Sea, western Japan. This is a third species of the genus and its first occurrence in the Pacific Ocean. The new species is distinguished from two previously known congeners by the morphology of the body somites, caudal rami, antennae and legs. Crinoid parasites belonging to Enterognathus and the closely related genus Parenterognathus have a broad distribution from the northeastern Atlantic through the Red Sea to the West Pacific.

New record of a euphausiid ectoparasitic isopod, Heterophryxus appendiculatus G. O. Sars, 1885 (Crustacea: Dajidae) from Japan

ABSTRACT The euphausiid ectoparasitic isopod, Heterophryxus appendiculatus G. O. Sars, 1885, is recorded for the first time from the Pacific Ocean, based on specimens collected from off the Nansei Islands, Japan. This species is distinguished from other congeners by the nearly straight frontal margin of the cephalon. This study provides additional information on this species, including a new host, description, coloration, and scanning electron micrographs.

A new species of Aspidophryxus (Isopoda, Dajidae), ectoparasitic on Mysidella hoshinoi (Mysidae) in Japan

Abstract A new dajid, Aspidophryxus izuensis sp. n., is described from seven females and six males found infesting the dorsal carapaces of specimens of Mysidella hoshinoi Shimomura, 2016 (Mysidae: Mysidellinae) associated with an unidentified species of sea anemone (Haloclavidae) from Izu-Oshima Island, Sagami Sea, central Japan. Aspidophryxus izuensis sp. n. differs from its congeners in having a body length about as long as wide, widest at the anterior part in females; an elongate frontal part of the cephalon, half as long as wide in females; the frontal margin of the cephalon exceeding the anterior margins of lateral lamellae in females; an unsegmented, vermiform, elongate pleon in females; and a uropod composed of a protopod and an inner and outer ramus in males. A key to worldwide species in the genus is provided.

Epimeria abyssalis sp. n. from the Kuril-Kamchatka Trench (Crustacea, Amphipoda, Epimeriidae)

Abstract A new deep-sea epimeriid, Epimeria abyssalis is described from the Kuril-Kamchatka Trench, in the northwestern Pacific. This species differs from its congeners in having a short rostrum and a telson with deep and narrow Y-shaped excavation. Epimeria abyssalis is the deepest recorded Epimeria species. A key to the north Pacific species of Epimeria is provided.

Two new species of Asellota (Crustacea, Isopoda) from coral reefs on Iriomote Island, Okinawa, Japan

Abstract Pleurocope iriomotensis sp. n. and Prethura tuberculata sp. n. are described from Iriomote Island, Ryukyu Archipelago, southern Japan. These are the first records of Pleurocope from the Pacific and of Prethura from the Asian Pacific coast. Pleurocope iriomotensis differs from its congeners in having lateral spine-like processes on pereonite 4 and coxal plates of pereonite 7. Prethura tuberculata can be distinguished from its single congener in having a lateral short projection of protopod of pleopod 2.