The genus Anacaena Thomson from the Ryukyu Archipelago of Japan (Coleoptera, Hydrophilidae)

By

Minoshima, Yûsuke
Kamite, Yuuki
Fikáček, Martin

Type

Article

Date of Publication

2023

Original Publication

Deutsche entomologische Zeitschrift

Volume

70

Series / Issue

Issue: 1

Pages

143--157

Subjects

Amami Islands , Anacaenini , Aquatic beetles , Chaetarthriinae , new species , Okinawa Islands , water scavenger beetles

Contributed by

Pensoft Publishers

Language

English

Published by

Berlin Nicolai'sche Verlags-Buchandlung 1881-

Identifiers

DOI: https://doi.org/10.3897/dez.70.96994

 

Abstract

We review the genus Anacaena Thomson, 1859 from the Ryukyu Archipelago, southern Japan. Three aquatic species are recognised: A. torikaii sp. nov. from Amami-ôshima Island, A. okinawana sp. nov. from Okinawa-jima Island and Kerama Islands, and A. kumejimana sp. nov. from Kumejima Island. All three species are very similar, with the morphology of the aedeagus being essential for a reliable identification. Dorsal colouration is also useful as a diagnostic character, despite some variation within species. We observe a possible geography-based variation between A. okinawana from Okinawa-jima I. and the neighbouring Kerama Is., but we treat both populations as conspecific based on genital morphology. Anacaena kumejimana and A. okinawana share many morphological characters possibly indicating their close relationship. We compare the endemism of aquatic Hydrophilidae in the Ryukyu Archipelago to that in other groups of aquatic beetles: the proportion of endemic species is higher in aquatic Hydrophilidae than in Dytiscidae, but much lower than in stream-inhabiting Hydraenidae and Elmidae. A list of Japanese species of Anacaena and a key to the Japanese species of the genus are provided.