On abyssal isopods (Crustacea: Isopoda: Asellota) from the Angola Basin: Eurycope tumidicarpus n. sp. and redescription of Acanthocope galathea Wolff, 1962

Abstract

Rich samples of benthic Peracarida collected from abyssal plains of the Angola Basin (South Atlantic) contained several new and rare asellote isopods. In this contribution, Eurycope tumidicarpus n. sp. is described from well-preserved specimens. This species is remarkable because the second pereopod has an enlarged carpus, and pereopod 4 is shaped like the posterior swimming legs. New specimens of Acanthocope galathea Wolff, 1962 (Fig. 1a) are used for a redescription, hitherto unknown characters of the male are shown. Diagnosis of Eurycope tumidicarpus n. sp. (Fig. 1b–g): Species with the diagnostic characters of Eurycope Sars, 1864 (see Wilson & Hessler 1981, Wägele 1989, Wilson 1989). Rostrum present but short, rounded, with two setae; width of cephalothorax about 0.7 of maximal body width; pereonite 5 about as long as pereonite 6 and with roughly parallel lateral margins, with rounded posterior edges; pereonite 7 more than twice length of pereonite 6; pleotelson wider than long, about as long as pereonite 7, without lateral or terminal projections, tip bent downward. Broad antennular article 1 three times wider than second article, with medial lobe bearing apically 4 spines, second article as long as first article. Carpus of pereopod 2 widened, broadly oval. Ischium, carpus, and propodus of pereopod 4 somewhat expanded and furnished with swimming setae, merus with a single swimming seta. Male pleopod 1 medially with 5 hemiplumose setae on ventral surface, distal tip of inner apical lobes rounded. Pleopod 2 with 7 proximolateral hemiplumose setae, protopod apically with small distal projection (vermiform appendage) bearing 2 short, hemiplumose terminal setae. Uropodal protopod with rounded medial projection, exopod smaller than half length of endopod. Types and locality: Holotype male (Zoological Museum Berlin Nr. 27400), 3.59 mm, collected from station St.350 on cruise M48/1 with RV “Meteor” (16°13.3′S 05°26.8′E – 16°14.9′S 05°26.7′ E, depth 5389 m). Paratype male (Zoological Museum Berlin Nr. 27400), 3.9 mm, from St.348 (16°17.1′S 05°27.3′E – 16°19.3′S 05°27.2′E, 5389-5387 m).