Three New Polychaete Species of Platynereis (Annelida, Polychaeta, Nereididae) from Taiwan

The present study describes three new species of Platynereis Kinberg, 1865 from Taiwan to provide a better understanding of the diversity of Platynereis in the tropical Western Pacific. Platynereis hemeiensis sp. nov. is similar to P. abnormis (Horst, 1924), P. australis (Schmarda, 1861), P. hutchingsae de Leon-Gonzalez, Solis-Weiss and Valadez Rocha, 2001, and P. sinica Sun, Shen and Wu, 1978 in terms of having no notopodial homogomph falcigers in adults. However, P. hemeiensis sp. nov. differs from P. australis by having: 1) fewer transverse rows or diagonal lines in Areas III, IV, VI and VII-VIII (2-3, 6-8, 2 and 2 versus 5, 10, 4 and 4, respectively); 2) tapered dorsal cirri on anterior-most chaetigers (versus stout dorsal cirri); and 3) dorsal cirri always shorter than dorsal ligule in posterior chaetigers (versus always longer than dorsal ligule). Platynereis hemeiensis sp. nov. can be distinguished from P. abnormis and P. sinica by having transverse rows of pectinate paragnaths in Area Ill (versus no pectinate paragnaths). Platynereis hemeiensis sp. nov. can be readily differentiated from P. hutchingsae by having long-bladed heterogomph spinigers in neuropodia (versus short-bladed heterogomph spinigers). Both P. jihueiensis sp. nov. and P. shihmenensis sp. nov. are somewhat similar to P. bicanaliculata (Baird, 1863), because all have bifid tip of notopodial anchylosed falcigers. However, the two species differ from P. bicanaliculata by having either no pectinate paragnaths or rows of pectinate paragnaths in Area Ill (versus a broad, oval patch of pectinate paragnaths). Platynereis jihueiensis sp. nov. differs from P. shihmenensis sp. nov. by having: 1) three groups of pectinate paragnaths in Area III (versus no pectinate paragnaths); 2) six to seven transverse rows of pectinate paragnaths in Area IV (versus four transverse rows); 3) three parallel transverse rows of pectinate paragnaths in Area VI (versus three to four non-parallel rows); 4) seven groups of transverse rows of pectinate paragnaths in Areas VII-VIII, middle groups each with three rows and two outer most groups each with one and two paragnaths (versus five groups of transverse rows of pectinate paragnaths, middle groups each with 1-2 rows and two outer most groups each with one paragnath); and 5) each parapodium of chaetigers in anterior, mid-body and posterior regions with three, two and one notopodial homogomph falcigers, respectively (versus each parapodium with one notopodial homogomph falciger in all body regions). A key for identifying Platynereis species from East Asia is provided.

Automated summary

This study describes three new species of Platynereis from Taiwan, increasing our understanding of the diversity of these worms in the tropical Western Pacific. The new species Platynereis hemeiensis is similar to other species in terms of lacking certain features in adults, but differs in various morphological characteristics. Platynereis jihueiensis and Platynereis shihmenensis are similar to Platynereis bicanaliculata but differ in the presence or absence of pectinate paragnaths in specific areas. A key for identifying Platynereis species from East Asia is provided.