Eisothistos corallina, Kensley & Schotte, 2000

Kensley, B. & Schotte, M., 2000, New species and records of anthuridean isopod crustaceans from the Indian Ocean, Journal of Natural History 34, pp. 2057-2121 : 2072-2076

Eisothistos corallina sp. nov.

(Figures 11, 12)

Type material. HOLOTYPE: USNM 253127 , non-ovigerous m 2.8 mm, sta

K-AL-99, intertidal coralline algal turf, lagoon near Passe Du Bois, Aldabra,

16 March 1986. PARATYPES: USNM 253128 , one l 2.3 mm, six non-ovigerous m 2.0±3.0 mm, sta K-AL-99, same data as holotype .

Diagnosis. Female: Integument of pereon moderately sclerotized, tailfan strongly so. Telson with median longitudinal row of six to eight spines, widening posteriorly, with dentate posterior margin broadly rounded/truncate. Eyes large, anterolateral. Antennule with three peduncular articles increasing in length distally; ¯agellum of seven articles, with antepenultimate and penultimate articles each bearing single aesthetasc. Mandible with broadly rounded, sclerotized incisor. Maxilla with two broad and six slender distal spines. Maxilliped slender, shorter than mandible and maxilla, of four articles. Pereopod 1, carpus triangular, with almost no free anterior margin; propodus not expanded, with stout posterodistal serrate seta. Pereopod 2, ischium, merus and carpus bearing short rounded tubercles on posterior margin; propodus with row of distal short setae, stout posterodistal serrate seta. Pereopod 7, carpus with anterior and posterior margins subequal in length, carpus with row of short setae and posterodistal seta; propodus about four times longer than wide, posterior margin bearing low setae, stout posterodistal serrate seta present. Pleopod 1, rami fused except for distal slit, exopod with four distal plumose setae, endopod with six. Uropodal exopod ovate, with spike-like extension on dentate lateral margin; endopod tapering distally, margins dentate; protopod with margins ®nely serrate.

FIG. 11. Eisothistos corallina sp. nov. (A) lcephalon and antennae; (B) m antenna; (C) m antenna; (D) mandible; (E) maxilla; (F) mandibular palp; (G) pleopod 1; (H) telson and uropod.

Male: eyes enlarged, occupying most of lateral margins of cephalon. Antennule with articles 1±3 broad, latter with dense whorl of aesthetascs, distal ¯agellar articles also bearing aesthetascs. Pereopod 1, carpus triangular, with row of four short setae on posterior margin; propodus about ®ve times longer than wide, submarginal posterior row of setae, stout serrate posterodistal seta. Pereopod 2 similar to pereopod 1. Pereopod 7, carpus with anterior margin subequal in length to posterior, with serrate posterodistal seta; propodus slightly more than ®ve times longer than wide, bearing row of short posterior setae, stout serrate posterodistal seta.

Colour. Symmetrical thin red pigment lines on antennules, antennae and on dorsum of cephalon, pereonites, pleon, uropods and telson.

FIG. 12. Eisothistos corallina sp. nov.: (A) m pereopod 1; (B) m pereopod 2; (C) m pereopod 7; (D) lpereopod 1; (E) lpereopod 2; (F) lpereopod 7.

Remarks. The present species bears little resemblance to any of the nine known Indian Ocean species, but to some degree resembles E. besar MuÈller, 1992a , from Malaysia, in possessing mediodorsal spines on the telson. These spines are fewer in number, however (four against six in E. corallina ), while a characteristic recurved hook-like spine on the mesial surface of the uropodal exopod of E. besar , serves easily to separate these species.

Etymology. The speci®c name refers to the coralline algae from which the specimens were taken.