Neanthes caudata (Delle Chiaje, 1827)

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 : 806-807

Neanthes caudata (Delle Chiaje, 1827)

Material

One anterior fragment, Fang Tsang Chau (Conic Island) Cave station A.

This anterior fragment of 40 chaetigers has yellow pigment on the prostomium, the tentaculophores and the right palp. There are grey dots on the tentacles, antennae, parapodia and dorsolaterally on the anterior body, which is otherwise unpigmented. Long thin nephridial papillae are present. The anterior pair of eyes are far apart and near the posterior margin of the prostomium.

Paragnaths are present on both maxillary rings: I5an axially aligned group of 16; II5about 22; III 5an axially aligned group of about 30; IV529–30; V –VIII5a wide continuous band of paragnaths of all sizes.

The notopodial chaetae on this anterior fragment are homogomph spinigers. The neuropodial chaetae are one homogomph spiniger and one heterogomph falciger above the acicula and one heterogomph falciger and one homogomph spiniger below the acicula on each neuropodium.

According to the identification key of Fauchald (1977), this specimen is either in Nereis or Neanthes , but cannot be identified further as it is not known what chaetae were present posteriorly. Neanthes and Nereis are both large genera (50 and 134 species respectively, according to Fauchald [1977], but more species have been described since) which have not been revised, and there is no key to all the species. None of the 33 relevant taxa in Huang (2001) recorded from Chinese waters has as many paragnaths in areas I and III as this fragment displays. Paxton and Chou (2000) collate polychaete names from literature concerning all the countries surrounding the South China Sea, including four species of Neanthes not listed by Huang (2001). Of these, Neanthes arenaceodentata (Moore, 1903) , previously reported by Gallardo (1967) from off Vietnam, has a similar paragnath complement to the present specimen.

Nereis arenaceodentata Moore, 1903 , was described in detail as Nereis (Neanthes) arenaceodentata by Pettibone (1963), who did not mention the yellow pigment and grey dots seen on this fragment, and depicted the eyes as forming a near-rectangle on the head (rather than the anterior pair being wide apart and quite posteriorly positioned). Nereis (Neanthes) arenaceodentata has since been synonymised with Neanthes caudata by Imajima (1972) and Sun and Yang (2004), and the present fragment resembles Imajima’s description. The species Neanthes caudata is now, therefore, reported from both sides of the temperate North Atlantic, the Mediterranean, southern California, Mexico, Japan, Korea, China, Hong Kong, Vietnam, the Philippines, Australia, New Zealand, India and South Africa. This is a rather wide distribution and the species is probably in need of revision. Imajima (1972) also suggests that the name may have to be replaced by Neanthes acuminata (Ehlers, 1868) .