Ampharetidae (Annelida: Polychaeta) from Japan. Part III: the genus Amphicteis Grube, 1850 and closely related genera

Abstract

In the third paper about Ampharetidae from Japan, we describe six species that belong to the ‘Amphicteis genus complex’. We divide this complex into the genera Amphicteis Grube, 1850, Paramphicteis Caullery, 1944, Phyllamphicteis Augener, 1918 and Watatsumi gen. nov. Paramphicteis is considered senior synonym of Pseudoamphicteis Hutchings, 1977 and is characterized by pinnate buccal tentacles. Watatsumi gen. nov. with its type species Watatsumi grubei sp. nov. is characterized by the lack of prostomial glandular ridges, the presence of pinnate buccal tentacles, and inconspicuous nuchal ridges. Two of the Amphicteis species are new to science, including A. spinosa sp. nov. and A. taurus sp. nov. Paramphicteis weberi (Caullery, 1944) comb. nov. was transferred from Amphicteis because we found pinnate buccal tentacles in addition to four pairs of foliose branchiae. Paramphicteis foliata (Haswell, 1883) comb. nov. was transferred from Phyllamphicteis because it has pinnate buccal tentacles. Amphicteis uncopalea Chamberlin, 1919 and Paramphicteis angustifolia (Grube, 1878) are newly recorded from Japanese waters. Amphicteis orphnius Chamberlin, 1919 is considered senior synonym of A. obscurior Chamberlin, 1919. A comprehensive table with diagnostic characters of all species of the Amphicteis complex with pinnate buccal tentacles is provided.