New Benthopelagic Calanoids (Copepoda: Clausocalanoidea) of the deep Japan Sea

Abstract

Two new species of benthopelagic calanoid copepod Bradfordian genera Pseudophaenna japonica sp. nov. and Xantharus dubius sp. nov. are described from collections of the Russian-German deep-sea expedition (SoJaBio) to the Sea of Japan onboard of the R/V Akademik Lavrentyev, 51st cruise taken close to the sea bed. The rare calanoid copepod genera Pseudophaenna Sars, 1902 and Xantharus Andronov, 1981 and a rare aetideid species Bradyidius rakuma (Zvereva, 1977) are recorded for the first time from the Japan Sea; the male of B. rakuma is described for the first time. Pseudophaenna japonica sp. nov. is the second species described for the genus Pseudophaenna and is distinguished by biramous rostrum, antennule ancestral segment XXII without seta, details of oral parts setation in females and in P5 structure in dimorphic males. Xantharus dubius sp. nov. is described from males and is distinguished from congeners in the antennule ancestral segments XXII and XXIII not comparatively small relative to the segment XXI and in the large and robust uniramous P5. In the collections of the expedition SoJaBio in 2010 from the Japan Sea the near-bottom benthopelgic fauna of Calanoida have been represented by these species only and they all belong to the calanoid superfamily Clausocalanoidea.