Ampharetidae (Annelida: Polychaeta) from Japan. Part II: Genera with elevated and modified notopodia.

The second paper of the series about Ampharetidae from Japan includes twelve species of four genera with elevated and modified notopodia, Anobothrus Levinsen, 1884, Sosane Malmgren, 1866 (including species of the synonymized genera Muggoides Hartman, 1965, Sosanopsis Hessle, 1917, and Genus A sensu Uebelacker 1984), Tanseimaruana gen. nov., and Zatsepinia Jirkov, 1986. Tanseimaruana gen. nov. is related to Amphicteis Grube, 1850, but lacks prostomial glandular ridges and has a velum-like dermal outgrowth with two pairs of lobes across the dorsum of the first abdominal unciniger. The new genus comprises Tanseimaruana vestis comb. nov. (Hartman, 1965) (formerly Amphicteis vestis) and T. boninensis sp. nov. Seven additional new species, Anobothrus dayi sp. nov., A. fimbriatus sp. nov., A. flabelligerulus sp. nov., Sosane brevibranchiata sp. nov., Sosane trigintaduo sp. nov., S. uebelackerae sp. nov. (formerly Genus A sensu Uebelacker), and Zatsepinia jirkovi sp. nov., are described. Sosane cf. cinctus (Hartman, 1965), Sosane wireni (Hessle, 1917), and Zatsepinia rittichae Jirkov, 1986, all species previously known from the North Atlantic, are recorded from the North Pacific for the first time. A phylogenetic analysis of Sosane (including the synonymized genera Mugga Eliason, 1955, Muggoides, Sosanopsis, and Genus A sensu Uebelacker) suggests monophyly of the genus with Lysippe Malmgren, 1866 as sister taxon, and a monophyletic clade [Sosane cinctus, Sosane uebelackerae sp. nov., Mugga spp.] within Sosane. The monotypic genus Melinnata Hartman, 1965 has been found indeterminable.

External morphology of the posterior end, the "opisthosoma", of the beard worm Oligobrachia mashikoi (Pogonophora).

The entire length of the beard worm, Oligobrachia mashikoi (Pogonophora), including the posterior end, the "opisthosoma" was collected successfully. This species is exclusive to Tsukumo Bay in Ishikawa Prefecture, Japan. Although the portion preceding the opisthosoma was similar to a fine filament, it abruptly assumed a shape similar to a shovel and appeared to be composed of many segmental structures. The number of segments exceeded 50. The dorsal side of the opisthosoma differed from that of the ventral side in morphology. The opisthosoma was equipped with 4 lines of setae arranged longitudinally and a sucker on the tip. When considering the fact that the Family Oligobrachiidae is the most primitive group of pogonophores, the external morphology of the opisthosoma is interesting as it may be reminiscent of the ancestral condition. This is the first report of the opisthosoma in Oligobrachiidae.