Description of the supergiant isopod Bathynomus raksasa sp. nov. (Crustacea, Isopoda, Cirolanidae) from southern Java, the first record of the genus from Indonesia.

Conni M Sidabalok,Helen P.-S Wong,Peter K L Ng

doi:10.3897/zookeys.947.53906

Abstract

The giant isopod genus Bathynomus A. Milne-Edwards, 1879, is recorded for the first time in Indonesian waters, from deep waters off southern Java in the Indian Ocean. Bathynomus raksasasp. nov. is described and notes on juvenile specimens of an unidentified species found in the same locality are also provided. Bathynomus raksasasp. nov. is characterized by the large size (averaging at 330 mm), narrowly rounded clypeus apex, prominent longitudinal carina on the clypeus, convex lateral margins of the uropodal exopod and endopod, produced distolateral corners of the uropodal exopod and endopod which have acute ends, an uropodal exopod with a setal fringe of medium length (69%), a pleotelson 1.6 times wider than long with the posterior margin medially concave, and the large number (11–13) of spines on the pleotelson.

Highlights

Two other “supergiant” species are known from the western Atlantic: B. giganteus A
The material was collected by the 2018 South Java Deep Sea Survey (SJADES 2018), a joint project between NUS and LIPI, with localities mostly in southern Sumatra and Java (Fig. 1)
Uropod (Figs 2D, 3D, E) not extending beyond pleotelson; peduncle with 3 robust setae; exopod and endopod with smooth lateral and distal margins; exopodal lateral margin convex with robust setae along margin, setal fringe medium to continuous in length (69%), medial margin straight, distomedial corner rounded, distal margin convex with 5 robust setae, distolateral corner slightly produced, acute; endopodal lateral margin convex, distally sinuate, with 4 robust setae; medial margin straight; distomedial corner rounded; distal margin straight with robust setae; distolateral corner produced, acute

Summary

Introduction

Keywords Bathynomus, Cirolanidae, Indian Ocean, Indonesia, new species, South Java, taxonomy Milne-Edwards, 1879 inhabits the deep sea in the Atlantic, Pacific and Indian Oceans, with some species reaching large sizes in excess of 30 cm length (Lowry and Dempsey 2006).

Results

Conclusion