Reproductive morphology and redescriptions of some Neanthes Kinberg, 1865 (Annelida: Nereididae) species from the southeastern Asian seas, with comparative synoptic tables of accepted species

Abstract

Neanthes Kinberg, 1865 is a speciose nereidid genus with some species exhibiting epitoky during the timing of reproduction. The epitokal morphology of males and females has long been agreed to be diagnostic to distinguish species. In the present study, we provide redescriptions of the type material and reassess the current taxonomic status of four Neanthes species originally described based on the reproductive forms of specimens collected from Southeast Asia: Neanthes augeneri (Gravier & Dantan, 1934), N. gisserana (Horst, 1924), N. trifasciata (Grube, 1878) and N. trifasciata vandersandei (Horst, 1924). The non-metamorphosed and epitokous diagnostic features, including new characters found in this study, were used to redescribe and distinguish these species from other congeners. The four species are here recognised in Neanthes, whereby N. vandersandei is elevated to species level. Neanthes gisserana is considered as distinct from its previous senior synonym N. rubicunda (Ehlers, 1868). Morphology of both N. trifasciata and N. vandersandei, originally described based on mixed species, is restricted. Additionally, some remarks on the status of N. thysanota (Ehlers, 1908) are given. Distributional and reproductive data of the reviewed species are provided. An updated checklist of 80 valid species in Neanthes and synoptic tables of diagnostic features including the atokous and epitokous morphology are also presented.