A New Copepod Species of Smacigastes (Harpacticoida, Tegastidae) from the Hydrothermal Vent in the Indian Ocean

Abstract

The genus Smacigastes Ivanenko & Defaye, 2004 is the most primitive group in the family Tegastidae Sars, 1904 occurred from the deep-sea chemosynthetic environments such as hydrothermal vents, cold seep and wood-falls site. Our exploration on the Onnuri Vent Field (OVF) where is the sixth active hydrothermal vent site located in the Central Indian Ridge resulted in a discovery of a new species of Smaα강astes. A detail morphological analysis of S. pumila sp. nov. reveals that it mostly resembles S. barti Gollner, Ivanenko & Martinez Arbizu, 2008 described from the hydrothermal vent in the East Pacific Risce, but both species can be distinguished by the segmentation and setation of cehpalothomal appendages, the setation of the exopod on the first leg, and the structure of the fifth leg in the both sexes. Previous Smacigastes species were known to occur from the tubeworm assemblages-related habitats, but the new species was found from the Bathymodiolin mussel assemblages. This is the first record of Smacigastes in the Indian Ocean.