A new Species of Labiosthenolepis (Sigalionidae: Polychaeta)

Abstract

Labiosthenolepis andamanensis sp. nov. is described from the Andaman Sea, southwestern Thailand, and from Tanabe Bay, Japan. The bulk of the samples were collected from the Andaman Sea during the 'Effects of Offshore Tin Mining Project' in 1980-1982. Labiosthenolepis andamanensis differs from L. laevis (McIntosh, 1885) by having oval, thin, flattened labial lobes and stylodes on the dorsal sides of segment 1, whereas in the latter species the labial lobes are thick, fleshy, lobulate, without stylodes on the dorsal sides of segment 1. The new species also differs from L. sibogae (Horst, 1917) by having dorsal tubercles on segment 3, which are absent in the latter species. Of the total 789 specimens from the Andaman Sea, there were about 26 species representing 14 genera (Aungtonya, unpublished data). The most abundant was Labiosthenolepis. The genus is characterized by having compound neurochaetae spinigers, ceratophore of median antenna with lateral auricles, long style of median antenna, inner tentacular lobes and dorsal tentacular crests, lateral lips of mouth with labial lobes, and elytra with smooth surface and outer lateral margin without papillae. Two species of Labiosthenolepis have been recognized (Imajima, 2005, 2006; Pettibone, 1992). Labiosthenolepis laevis (McIntosh, 1885) was described based on specimens from the Pacific region. Labiosthenolepis sibogae (Horst, 1917) was described based on specimens from the Indo-Pacific region.