Hidden diversity of Freyastera (Asteroidea, Brisingida, Freyellidae) at great depth: Description of new species and remarks on species boundaries

By

Zhang, Ruiyan
Zhou, Yadong
Mao, Jingwen
Wang, Chunsheng
Zhang, Dongsheng

Type

Article

Date of Publication

2025-4-10

Original Publication

Zoosystematics and evolution

Volume

101

Series / Issue

Issue: 2

Pages

735--760

Subjects

deep-sea , Phylogeny , species delimitation , taxonomy

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia Pensoft

Identifiers

DOI: https://doi.org/10.3897/zse.101.144918

 

Abstract

Freyastera represents the most derived form in the deep-sea starfish order Brisingida, known only at below 2500 m to over 6000 m depth, adapting to the great depth by small body size, reduced number of arms, and simplified body form. Long being remote and rarely investigated, newly collected specimens from the last decade revealed high species diversity of the genus. In this study, a new species, Freyastera jiaolongisp. nov., is described from the southern part of the Kyushu-Palau Ridge. Freyastera giardicomb. nov. and Freyastera loricatacomb. nov., formerly belonging to genus Freyella, are reassigned to Freyastera. The genus is hence revised to include ten species. Key characters of nine Freyastera species as well as Freyella benthophila (formerly Freyastera benthophila) are described and discussed based on an examination of type specimens and new specimens, and a key to Freyastera species is provided, aiding in the future identification of Freyastera. Phylogenetic analysis using four DNA barcoding genes retrieves a monophyletic Freyastera, providing solid support for interspecific phylogeny except at three nodes. Species delimitation analysis results in 11 species units within Freyastera, including seven unnamed species pending description. A high diversity of Freyastera revealed in the present study suggests a successful adaptation and radiation of the genus at great depth.