Goto, R. & Tanaka, M. (2019). Worm-riding clam: description of Montacutona sigalionidcola sp. nov. (Bivalvia: Heterodonta: Galeommatidae) from Japan and its phylogenetic position. Zootaxa. 4652 (3): 473-486.
Worm-riding clam: description of <em>Montacutona sigalionidcola</em> sp. nov. (Bivalvia: Heterodonta: Galeommatidae) from Japan and its phylogenetic position
Zootaxa
4652 (3): 473-486
Publication
Published 9 August 2019
Available for editors
A new galeommatid bivalve, Montacutona sigalionidcola sp. nov. , is described from an intertidal flat in the southern end of the Kii Peninsula, Honshu Island, Japan. Unlike other members of the genus, this species is a commensal with the burrowing scale worm Pelogenia zeylanica (Willey) (Annelida: Sigalionidae) that lives in fine sand sediments. Specimens were always found attached to the dorsal surface of the anterior end of the host body. This species has a ligament lithodesma between diverging hinge teeth, which is characteristic of Montacutona Yamamoto & Habe. However, it is morphologically distinguished from the other members of this genus in having elongate-oval shells with small gape at the posteroventral margin and lacking an outer demibranch. Molecular phylogenetic analysis based on the four-gene combined dataset (18S + 28S + H3 + COI) indicated that this species is monophyletic with Montacutona, Nipponomontacuta Yamamoto & Habe and Koreamya Lützen, Hong & Yamashita, which are commensals with sea anemones or Lingula brachiopods. This result suggests that host shifting across different phyla occurred at least twice in this clade.