Mesanthura quadrata, 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 : 2080-2083

Mesanthura quadrata sp. nov.

( Figures 17, 18)

Type material. HOLOTYPE: USNM 253163 , ovigerous m 8.0 mm, sta J-SEY-2, red coralline algae from reef ¯at, 1±1.5 m, Mahe Beach , MaheÂ, Seychelles, 30 April 1984 . PARATYPES: USNM 253164 , two non-ovigerou s m 5.2 mm, 7.0 mm, ten juveniles, sta K-SEY-22, algal turf on granite boulders, 1 m, Anse Marie Louise , MaheÂ, Seychelles, 25 April 1989 . USNM 253165 , four non-ovigerous m 4.6±6.3 mm, two juveniles, sta K-SEY-23, algal turf from reef crest, 0.5 m, Anse Marie Louise , MaheÂ, Seychelles, 25 February 1989 . USNM 253166 , one non-ovigerous m 7.9 mm, sta J-SEY-6, coral rubble between brown algae, 1 m, Anse aÁ la Mouche, MaheÂ, Seychelles, 1 May 1984 .

Other material examined. USNM 253167 , one non-ovigerous m, two juveniles, sta K-SEY-15, coral rubble, 2.5±5 m, Anse aÁ la Mouche, MaheÂ, Seychelles, 1 May 1984 . USNM 253168 , two non-ovigerous m, one juvenile, sta K-SEY-21, coralline alga on reef ¯at, 1 m, Anse Marie Louise, MaheÂ, Seychelles, 25 February 1989 . USNM 253169 , two juveniles, sta K-SEY-24, coral rubble, 1±1.5 m, Anse aÁ la Mouche, MaheÂ, Seychelles, 26 February 1989 .

Diagnosis. Female: Telson fused dorsally with pleonite 6. Telson length about 2.7 times basal width, posterior margin evenly convex, apex with cluster of six pairs of setae of varying lengths. Antennular ¯agellum of four articles, two distal articles each bearing two aesthetascs. Antennal ¯agellum of four articles. Mandibular palp, short terminal article bearing seven fringed setae; lamina dentata of ®ve serrations. Distal article of maxillipedal palp subcircular, with four setae mesially. Pereopod 1, carpus triangular, distally truncate, ridged; propodal palm with low rounded tooth at midlength, bearing six setae. Pereopods 2 and 3, propodus rectangular, with single stout dentate seta posterodistally. Pereopod 7, carpus with anterior margin much shorter than posterior, with short squat seta posterodistally; propodus rectangular, posterior margin bearing numerous fringed scales, stout sensory seta posterodistally. Pleopod 1, endopod slightly shorter than, and about 0.4 times width of exopod, bearing ten distal plumose marginal setae. Uropodal exopod ovate, lateral FIG. 18. Mesanthura quadrata sp. nov.: (A) lcephalon; (B) lpleopod 2; (C) lpereopod 1.

margin distally very slightly emarginate, apically rounded; endopod distally broadly rounded, slightly longer than basal width.

Colour. Fairly solid rectangles of red±brown pigment dorsally on cephalon, all pereonites, pleon and telson; blobs of pigment on uropodal exopod and endopod/ protopod.

Remarks. The present species, with its solid rectangles of pigment, bears some resemblance to those species referred to as M.`maculata ’, described by various authors (see Poore and Lew Ton, 1986b: 88). The latter, however, point out the confusion with both the name `maculata ’ and the fact that several species undoubtedl y masquerade under this name. As Haliophasma maculata Haswell, 1881 , is a species of Accalathura , this name is to be avoided, hence the present species is given a new name. M. quadrata bears some resemblance to M. dianella Poore and Lew Ton, 1986b , from New South Wales, but has a more strongly notched uropodal exopod and pleonite 6 not visibly fused dorsally with the telson.

Etymology. The speci®c name refers to the quadrate pigment patches on the dorsum of the animal.