Two New Species of Spiochaetopterus (Polychaeta: Chaetopteridae) from Okinawa, Japan, with Notes on Pacific Spiochaetopterus

Abstract

Two new species of Spiochaetopterus are described from recently collected material from sandy substrates at Bise Beach and Sesoko Island in northern Okinawa, southern Japan. These two new species, Spiochaetopterus okinawaensis and S. sesokoensis, are similar in body size but differ with respect to presence or absence of eyes, bilobed or unilobed Bl neuropodia, and morphology of the specialized modified A4 chaeta. In S. okinawaensis there are oculate spots on the lateral side of the prostomium, neuropodia of segment B1 are unilobed but those on the other segments are bilobed, and the tube lacks periodic rings. There are no oculate spots in S. sesokoensis; all the neuropodia of the B segments are bilobed, including Bl; and the ventral gland in the anterior A region lacks a pale white crescent.