A new freshwater species of Gnorimosphaeroma (Crustacea, Isopoda, Sphaeromatidae) from Chichi-jima Island, Ogasawara Islands, Japan

By

Tomikawa, Ko
Yoshii, Junpei
Noda, Akari
Lee, Chi-Woo
Sasaki, Tetsuro
Kimura, Naoya
Nunomura, Noboru

Type

Article

Date of Publication

2023

Original Publication

Zoosystematics and evolution

Volume

99

Pages

545--556

Subjects

freshwater , inland water , Isopod , molecular phylogeny , oceanic island , stream , taxonomy

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia Pensoft

Identifiers

DOI: https://doi.org/10.3897/zse.99.108032

 

Abstract

This study describes Gnorimosphaeroma rivulare sp. nov. from a stream on Chichi-jima Island, Ogasawara Islands, Japan. This is the second freshwater species of Gnorimosphaeroma and the third Sphaeromatidae from oceanic islands. Gnorimosphaeroma rivulare sp. nov. is morphologically similar to G. boninense Nunomura, 2006, G. naktongense Kwon & Kim, 1987 and G. saijoense Nunomura, 2013. However, G. rivulare sp. nov. differs from these species in various morphological features, such as the shape of pleotelson and pereopod 2, relative length of antennule peduncular articles and pleopod 3 rami, number of setae on maxillula and maxilliped, and setation on pereopod 3. Phylogenetic analyses revealed that G. akanense is sister to G. saijoense, and together they are sister to G. hokurikuense. This three taxa clade is sister to G. rivulare sp. nov. with G. iriei basal to them all. Our analysis concludes that G. boninense from Haha-jima Island, Ogasawara Islands is only distantly related to G. rivulare and may represent an independent colonization event.