A trichonotid sanddiver, Trichonotus blochii Castelnau, 1875, known only from its short original description, is redescribed on the basis of the holotype and 11 additional specimens from northern Australia. This species differs from its congeners by displaying the following combination of characters: dorsal fin soft rays 43-46; anal fin soft rays 39-41; lateral line scales 57-60; gill rakers 4-6+17-21; vertebrae 55; infraorbital and supraorbital canals separated anterior to eye; elongated dorsal fin spines 4-6 in males; caudal fin with 2 black stripes in males.
A new species of crangonid shrimp, Philocheras coralliophilus, is described on the basis of material from shallow coral reefs of southern Japan, the Philippines, Vanuatu, and New Caledonia. Several presumably apomorphic characters, including the strongly broadened rostrum with a truncate or broadly concave anterior margin, the lack of appendices internae on every pleopod, and the lack of an appendix masculina on the male second pleopod, suggest that the new species is closely related to P.sabsechota (Kemp, 1911) and P.breviflagella Komai, 2001. The shape of the rostrum and the development of the carapacial carinae distinguish P.coralliophilus from its two close congeners.
First-instar juveniles of six caprellid amphipods of the genus Caprella are described based on specimens collected from the Pacific coast of southern Hokkaido, Japan: Caprella acanthogaster Mayer, 1890, C.alaskana Mayer, 1903, C.bispinosa Mayer, 1890, C.cristibrachium Mayer, 1903, C.mixta Mayer, 1903, and C.mutica Schurin, 1935. Morphological characters of the juveniles are compared with those of the previously described juveniles of six other species distributed along the northern coasts of Japan. We newly identified traits of the flagellum of antenna 1 and the seta at the base of the gill as diagnostic characters for species discrimination among the 12 species. This study makes it possible to identify first-instar juveniles of the 12 species of Caprella occurring in northern Japan.
A new species of the cyclopoid copepod genus Hemicyclops, H.xiamenensis, is described from plankton sampled at the mouth of the Jiulong River, southern China. This is the second species of the genus occurring in Chinese waters. The new species is readily distinguishable from its congeners by a combination of features of the fourth pediger, female genital double-somite, caudal ramus, and appendages. Because adults of Hemicyclops are ordinarily associated with benthic animals, the planktonic occurrence of the new species may be interpreted as either, 1) a new mode of life involving diel migration, 2) host switching between day and night, or 3) accidental occurrence.