Anobothrus sp.

Muir, Alexander I. & Bamber, Roger N., 2008, New polychaete (Annelida) records and a new species from Hong Kong: the families Polynoidae, Sigalionidae, Chrysopetalidae, Pilargiidae, Nereididae, Opheliidae, Ampharetidae and Terebellidae, Journal of Natural History 42 (9 - 12), pp. 797-814 : 810

Anobothrus sp. indet.

Material

One specimen, control station Z, Long Kei Wan, 13.7 m, in clean sand.

The tentacles of this specimen (partially withdrawn into mouth) are not papillate but their surface is covered in mounds rather than smooth. Large forwardly-directed paleae are present; there are 14 pairs of notopodia (the first smaller than the rest) bearing narrowly bilimbate capillary chaetae. Four pairs of branchiae are present, marked to a varying degree with dark brown hoops or larger blobs. Six branchiae form a continuous row across the dorsum, with the fourth pair immediately behind and touching this row. The eleventh pair of notopodia is not raised above the level of the others, and bears the same chaetae, but the two are obviously linked by a raised ridge crossing the dorsum between them.

This small ampharetid is clearly a member of the genus Anobothrus because of the raised ridge across the dorsum linking the notopodia of the eleventh pair. Holthe (1986a) lists three genera of the Ampharetidae with dorsal ridges – Melinnampharete and Neosamytha have the ridge in the anterior part of the thorax (and Holthe, loc. cit., puts them together in his tribe Melinnampharetini ) while Anobothrus has the ridge in the posterior part of the thorax (and is placed in the tribe Sosanini ).

Of the species of Anobothrus listed by Holthe (1986a, updated in Holthe [2002]), only Anobothrus cf. gracilis Malmgren, 1866 has been reported from Hong Kong (by Ong Che et al., [1999]). Ushakov (1965) cites an occurrence of this species in the Sea of Japan (in a depth of 44–2900 m). The type locality is, however, Bohuslän, Sweden ( Holthe 1986b). The present specimen is not this species, which has 15 pairs of notopodia, the eleventh pair elevated and bearing chaetae with denticulate tips. A. mancus Fauchald, 1972 (from the Gulf of California and the Central American Trench) is also similar to the Hong Kong specimen, but here the tenth chaetiger has a ridge linking notopodia bearing chaetae with pilose tips ( Fauchald 1972). This Hong Kong specimen probably represents a species new to science, but it is not considered appropriate to describe a new species from a single specimen.