Halechiniscidae (Heterotardigrada, Arthrotardigrada) of Oura Bay, Okinawajima, Ryukyu Islands, with descriptions of three new species.

Shinta Fujimoto

doi:10.3897/zookeys.483.8936

Abstract

Marine tardigrades of the family Halechiniscidae (Heterotardigrada: Arthrotardigrada) are reported from Oura Bay, Okinawajima, one of the Ryukyu Islands, Japan, including Dipodarctus sp., Florarctus wunai sp. n., Halechiniscus churakaagii sp. n., Halechiniscus yanakaagii sp. n. and Styraconyx sp. The attributes distinguishing Florarctus wunai sp. n. from its congeners is a combination of two characters, the smooth dorsal cuticle and two small projections of the caudal alae caestus. Halechiniscus churakaagii sp. n. is differentiated from its congeners by the combination of two characters, the robust cephalic cirrophores and the scapular processes with flat oval tips, while Halechiniscus yanakaagii sp. n. can be identified by the laterally protruded arched double processes with acute tips situated dorsally at the level of leg I. A list of marine tardigrades reported from the Ryukyu Islands is provided.

Highlights

Halechiniscidae (Heterotardigrada: Arthrotardigrada) is a group of unarmoured marine tardigrades possessing cephalic appendages, including the median cirrus, and legs with four digits terminating in distal claws
Specimens were found in five sediment samples collected from Oura Bay, Okinawajima, one of the Ryukyu Islands, Japan by SCUBA diving
With the addition of the three new species and two unidentified species reported in this study, two orders, five families, 15 named and two unidentified genera, named and unidentified species of marine heterotardigrades are known from the Ryukyu Islands (Table 3)

Summary

Introduction

Halechiniscidae (Heterotardigrada: Arthrotardigrada) is a group of unarmoured marine tardigrades possessing cephalic appendages, including the median cirrus, and legs with four digits terminating in distal claws. More than half of the described marine species are assigned to this family, which comprises 29 genera in seven subfamilies. In January 2014, the first Umisawa-kai (Field Workshop for Young Marine Biologists) was held to survey the invertebrate fauna of Oura Bay, Okinawajima, one of the Ryukyu Islands, Japan. During this survey, the following five species of Halechiniscidae were encountered: Dipodarctus sp., Florarctus wunai sp. The following five species of Halechiniscidae were encountered: Dipodarctus sp., Florarctus wunai sp. n., Halechiniscus churakaagii sp. n., Halechiniscus yanakaagii sp. n. and Styraconyx sp

Materials and methods

Discussion