A giant new species of Enchiridium (Polycladida, Prosthiostomidae) from southwestern Japan

By

Tsuyuki, Aoi
Kajihara, Hiroshi

Type

Article

Date of Publication

2020

Original Publication

ZooKeys

Volume

918

Pages

15--28

Subjects

Cotylea , marine flatworm , Phylogeny , Platyhelminthes , taxonomy

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers

Identifiers

DOI: https://doi.org/10.3897/zookeys.918.47061

 

Abstract

We describe a new species of polyclad flatworm, Enchiridium daidaisp. nov., from the rocky subtidal zone in the East China Sea along the coasts of the Kyushu and Okinawa Islands, Japan. Enchiridium daidaisp. nov. is characterized by i) the entire periphery of the dorsal surface narrowly fringed with orange, ii) a marginal-eyespot band extending to the position of the mouth (about anterior one-eighth of body), and iii) two prostatic vesicles covered by a common muscle sheath, which is penetrated by the ejaculatory duct. We performed a molecular phylogenetic analysis based on 945-bp 28S rDNA sequences of 16 species of Prosthiostomidae currently available in public databases in addition to those of E. daidaisp. nov. and Prosthiostomum torquatumTsuyuki et al., 2019. In the resulting tree, our new species was nested in a clade composed of Enchiridium species. The tree topology was in favor of a taxonomic view that Enchiridium should be defined by having i) a common muscle sheath that encloses two prostatic vesicles and ii) marginal eyespots that may or may not surround the periphery of the dorsal surface.