Ryocalanus spinifrons, a new species of Ryocalanidae (Copepoda : Calanoida), from the southwestern part of Sagami Bay, Japan

A new Ryocalanoid copepod, Ryocalanus spinifrons, collected by the MTD net system at a depth of 1400 m from the southwestern part of Sagami Bay, Japan , is described. The new species is morphologically very close to R. infelix Tanaka, 1956 (female unknown) from the Izu region of Sagami Bay. It is dis tinguished from other species by the presence of 12 long spinules on the ve ntral inner side of the fifth pedigerous somite, nine setae on the coxal ep ipodite of the maxillule and nine large robust spinules on the coxal segmen t of the fourth leg. The row of five robust spines on the paragnath disting uishes R. spinifrons.