A New Record of Dirivultus spinigulatus (Copepoda: Dirivultidae) from Japan Associated with a Siboglinid Tubeworm

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The siphonostomatoid copepod Dirivultus spinigulatus Humes, 1999 (Dirivultidae) was originally described as an associate of the siboglinid tubeworm Paraescarpia echinospica Southward, Schulze, and Tunnicliffe, 2002 from the Edison Seamount hydrothermal vent in Papua New Guinea. Here, we report a new record and range extension of this copepod from the Off Toi cold seep in Suruga Bay, Japan where it was also found on P. echinospica. A detailed redescription of D. spinigulatus based on newly collected material from Japan along with some of its paratypes is provided. This copepod is characterised by a combination of the following characters: the rostral area with three pairs of spines in female and one pair in male; the antennule with a large posterior process on second segment in both sexes; the oral cone with two pairs of dentiform processes directed posteriorly and a pair of lateral processes; and the maxillule with a stout conical process on the basal part (the protopod). Our finding increases the diversity of dirivultids in Japan to four species, two in Dirivultus Humes and Dojiri, 1981 and two in Stygiopontius Humes, 1987.