A new Stygarctus (Arthrotardigrada: Stygarctidae) from Japan, with entangled seminal receptacle ducts

Abstract

Stygarctus ayatori sp. nov. (Arthrotardigrada: Stygarctidae), is described from a sandy beach located at Okinoshima, Tat-eyama Bay, Boso Peninsula, Honshu, Japan. The most prominent characters were observed in the female genital structure, with the seminal receptacle ducts forming a three-dimensional entanglement near the exterior opening, and internal thick-ening situated peripheral to the gonopore and between the gonopore and anus. The new species is distinguished from the congeners by these characters; excluding S. abornatus McKirdy et al., 1976 for which there is no information on the gen-ital structure. However, S. ayatori sp. nov. and S. abornatus can be differentiated by the presence of dorsal spines on the former species, which are absent from the latter. Copyright © 2014 Magnolia Press.