Revision of Ostracotheres H. Milne Edwards, 1853 (Crustacea: Brachyura: Pinnotheridae)

Digital Gems > Biodiversity Library of Southeast Asia

Language

English

Creator

Ahyong, S. T.

Source Title

The Raffles Bulletin of Zoology

Publication date

2018/09/21

Publisher

Dept. of Zoology, National University of Singapore, Singapore

Page

538–571

Content Type

Journal Article

Object Type

Text

Terms of Use

Open Access

Access Status

Open

Repository

NUS Libraries

Start File Page

538

End File Page

571

Volume

66

Issue

2

Call Number

QL319 NMB

Subject

Crabs -- Identification

Keyword

Decapoda
Pinnotheridae
pea crab
Indo-West Pacific

Abstract

The Indo-West Pacific pinnotherid crab genus, Ostracotheres H. Milne Edwards, 1853, was recognised for species with a simple, unadorned carapace without marginal lamellae, and a spatulate maxilliped 3 propodus with a rounded or subtruncate apex. Prior to the present study, the genus included: O. tridacnae (Red Sea; type species), O. affinis (Mauritius, Djibouti), O. cynthiae Nobili, 1906a (Red Sea); O. spondyli Nobili, 1905 (Persian Gulf); O. subglobosus (Baker, 1907) (southern Australia); O. holothuriensis Baker, 1907 (southern Australia); O. subquadratus Sakai, 1939 (Japan); and O. tomentipes Takeda & Konishi, 1994 (Japan). Reconsideration of species assigned to Ostracotheres shows they differ considerably in other aspects such as carapace physiognomy, pereopod article proportions, and gonopod structure (where known), suggesting the genus is not monophyletic. Thus, Ostracotheres is revised based on type and other material. Ostracotheres sensu stricto is restricted to O. tridacnae and O. cynthiae. Ostracotheres tridacnae is confirmed as a senior synonym of O. savignyi H. Milne Edwards, 1853, and appears to be restricted to the Red Sea as a commensal of tridacnine clams; records of O. tridacnae from southeast Africa are referred to Afropinnotheres dofleini (Lenz in Lenz & Strunck, 1914). Similarly, O. cynthiae appears to be restricted to the Red Sea as a commensal of ascidians; the single record of O. cynthiae from Indonesia requires confirmation but its published account is not consistent with O. cynthiae sensu stricto. A new genus, Austrotheres, is proposed for O. holothuriensis and a new species from eastern Australia. Ostracotheres subglobosus and O. subquadratus, considered by some to be conspecific, are shown to be separate valid species, with the identity of the latter fixed by a neotype selection; both are transferred to a new genus, Discorsotheres, together with O. spondyli and a new species from the tropical western Pacific. Ostracotheres affinis and O. tomentipes are referred to a new genus Latatheres, with the identity of the former fixed by a neotype selection. Keys to the species of the genera studied herein and to pinnotherid genera with a 2-segmented maxilliped 3 palp are provided.

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