One new species of Stegocephalus Krøyer, 1842 (Amphipoda, Stegocephalidae) described from a seamount of the Caroline Plate, NW Pacific.

A new species of the subfamily Stegocephalinae, Stegocephaluscarolussp. nov., is described from a seamount in the Caroline Plate. Two related species, S.cascadiensis (Moore, 1992) and S.longicornis (Gurjanova, 1962), were previously reported in the North Pacific. Important morphological characters which differentiate S.carolussp. nov. from S.cascadiensis are found in antenna 1, the mouthparts, pereopod 7 and the length of rami of uropods 2 and 3. The new species differs from S.longicornis by characters of antenna 1, the mouthparts and the shape of epimeral plate 3. Additionally, the morphological differences between the new species and the remaining seven species of Stegocephalus are also presented.

A new species of Orchomenella (Amphipoda, Tryphosidae) described from hydrothermal vent in the Okinawa Trough, Northwest Pacific.

A new species of the family Tryphosidae, Orchomenellacompressasp. nov., is described from hydrothermal vents in the Okinawa Trough. This is the first known Orchomenella species found in vent fields. Important morphological characters that differentiate O.compressasp. nov. from its congeners are the absence of eyes, the compressed distal three articles of gnathopod 2, the shape of the posterior margin of epimerons 2 and 3, and the number of dorsal spines on the telson. The genetic divergence of the analyzed COI gene clearly supports this new taxon.

Epimeria liui sp. nov., a new calcified amphipod (Amphipoda, Amphilochidea, Epimeriidae) from a seamount of the Caroline Plate, NW Pacific.

A calcified individual of Epimeria Costa, 1851 collected from an unnamed seamount of the Caroline Plate, NW Pacific, is recognized as new to science herein. This increases the number of known Epimeria species of the North Pacific to nine. Epimeria liui sp. nov. differs from its similar congeners by having a rostrum hardly reaching to the end margin of first peduncular article of antenna 1, the presence of large pyriform eyes, the size-increasing mid-dorsal teeth starting from pereonite 6 to pleonite 2, the projection on coxa 5 not extending to epimeral plate 1, and by having a nearly quadrate telson notched medially. To facilitate identification the new species is included in a key to Pacific species of Epimeria.

Description of Seba longimera sp. nov. from hydrothermal vents in the Okinawa Trough, Northwest Pacific (Amphipoda, Amphilochoidea, Sebidae).

Seba longimera sp. nov., of the family Sebidae Walker, 1908, is described from hydrothermal vents in Okinawa Trough. Other two congenic species, S. bathybia Larsen, 2007 and S. profundus Shaw, 1989, are also reported from these hydrothermal vents, but the new species can be readily distinguished from them in having the merus of pereopods 5 and 6 extending beyond distal margin of carpus, coxa 4 smaller than coxae 2 and 3, and coxa 5 with the posterior lobe larger than the anterior one, rather than equilobate.

Probathylepadidae, a new family of Scalpelliformes (Thoracica: Cirripedia: Crustacea), for Probathylepas faxian gen. nov., sp. nov., from a hydrothermal vent in the Okinawa Trough.

A new pedunculate barnacle, Probathylepas faxian gen. and sp. nov., is described from a hydrothermal vent in the Okinawa Trough. A new scalpelliform family, Probathylepadidae, is also proposed for the new genus and species. Probathylepadidae differs from all other five families of the order Scalpelliformes by the capitulum bearing eight primal plates and two whorls of imbricating supplementary plates, and the peduncle being without scales. The relationships between the species of the new family and sessile barnacles are also discussed.

A new species of Sinocorophium from the Yangtze estuary (Crustacea: Amphipoda: Corophiidae: Corophiinae: Corophiini), China.

Amphipods collected from the Yangtze estuary, Shanghai, China are described as a new species, Sinocorophium dongtanense. It is closely allied to Sinocorophium homoceratum Yu, 1938 but differs markedly in the inner lateral side of peduncular article 4 of male antenna 2 having two rows of teeth.

Two new species and one newly recorded species of the genus Kamaka (Crustacea: Amphipoda) from the Hainan Province, South China Sea.

A total of 5 species of the genus Kamaka (Crustacea: Amphipoda) are identified from Hainan Province, South China Sea. In those, one species, Kamaka excavata Ariyama, 2007, is recorded for the first time in Chinese waters. Two new species, Kamaka corophina sp. n. and Kamaka foliacea sp. n., are described. A key to the Chinese species is provided. They were collected from littoral zone, mud flat in seaweed of mangrove side, brackish water and seawater, sifted out with sieve.