Three Siphonostomatoid Copepods (Dirivultidae) from a Deep-sea Hydrothermal Vent Field in the Central Indian Ridge

Abstract

Three species of copepods belonging to the family Dirivultidae (Siphonostomatoida) are collected from a deep sea hydrothermal vent field on the Central Indian Ridge in the Indian Ocean during the conduct the deep sea research cruse (July 28 &#8211 August 16 2017) by R/V ISABU of Korea Institute of Ocean Science and Technology (KIOST), and reported. They consist of Aphotopontius limulatus Humes previously known from vent fields in the East Pacific and two new species, as follows: Aphotopontius n. sp. and Stygiopontius n. sp. Aphotopontius n. sp. is characterized by the presence of the inner coxal seta in the first to third legs, not in the fourth leg, 2.86 times as long as wide of the caudal ramus in the female, and the lateral margin with an angular apex in the genital double-somite. Stygiopontius n. sp. is easily distinguishable from the congeners by the possessing the only three setae on the inner lobe in the maxillule, and a large tubercle on the first endopodal segment and two spinules-tipped distal spines on the second endopodal segment in the antenna. This is the first record on copepods living in vent fields of the Indian Ocean. &#8211 August 16 2017) by R/V ISABU of Korea Institute of Ocean Science and Technology (KIOST), and reported. They consist of Aphotopontius limulatus Humes previously known from vent fields in the East Pacific and two new species, as follows: Aphotopontius n. sp. and Stygiopontius n. sp. Aphotopontius n. sp. is characterized by the presence of the inner coxal seta in the first to third legs, not in the fourth leg, 2.86 times as long as wide of the caudal ramus in the female, and the lateral margin with an angular apex in the genital double-somite. Stygiopontius n. sp. is easily distinguishable from the congeners by the possessing the only three setae on the inner lobe in the maxillule, and a large tubercle on the first endopodal segment and two spinules-tipped distal spines on the second endopodal segment in the antenna. This is the first record on copepods living in vent fields of the Indian Ocean.