Apanthuroides aldabrae, 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 : 2065-2068

Apanthuroides aldabrae sp. nov.

( Figures 5, 6)

Type material. HOLOTYPE: USNM 253108 , non-ovigerous m 3.2 mm, sta F-7-87, patch reef in Aldabra lagoon, 2 m, 6 April 1987 . PARATYPES: USNM 253109 , two non-ovigerous m 2.5 mm, 4.0 mm, same data as holotype .

Other material examined. USNM 253110 , l 3.2 mm, sta K-AL-24, coral rubble, oOE Ile Picard, Aldabra, 11 m, 6 April 1983 . USNM 253111 , l3.0 mm, sta K-AL-89, coral rubble, Passe du Bois, Aldabra, 10 m, 13 March 1086 . USNM 253112 , l 3.5 mm, sta F-8-87, coral rubble in Passe Hoareau, Ile Malabar, Aldabra, 0.3 m, 11 April 1987 . USNM 253113 , pre- l 2.2 mm, coral rubble, reef crest, Ile Picard, Aldabra, intertidal, 23 March 1985 .

Diagnosis. Female: Body eight to nine times longer than wide; dorsum irregularly and indistinctly pitted. Cephalon with low rounded rostrum, eyes lateral, well pigmented. Pereonite 7 less than half length of pereonite 6, lacking pereopods. Pleon subequal in length to telson, latter with faint rounded middorsal longitudinal ridge, posterior margin broadly rounded. Antennule with basal article longer and wider than two distal peduncle articles together; ¯agellum of ®ve articles, article 2 with three aesthetascs, articles 3, 4 and 5 each with single aesthetasc. Antennal ¯agellum of three setose articles. Mandibular palp of three articles, middle article longest, terminal article with three setae; incisor with three cusps; lamina dentata with seven teeth; molar curved, spike-like on one side, much shorter on other. Maxilla with strong distal spine and ®ve more slender subterminal spines. Maxillipedal palp of four articles, basal article very short, terminal article semicircular, with four distal setae. Pereopod 1, carpus triangular; propodus barely ināted, with strong posterodistal robust seta, few setae near posterior margin. Pereopod 2 similar to pereopod 1. Pereopod 6, carpus with free anterior margin shorter than posterior margin; bearing short posterodistal robust seta; propodus with serrate posterodistal seta. Pereopod 7 lacking. Pleopod 1, protopod with three retinaculae on mesial margin; both rami contributing to opercular function; endopod about half width of exopod; latter with FIG. 6. Apanthuroide s aldabrae sp. nov.: (A) lpereopod 1; (B) m pereopod 1; (C) m pereopod 2; (D) m pereopod 6; (E) left mandible; (F) right mandible; (G) antenna; (H) l

antennule; (I) lpleopod 2.

numerous elongate distal and lateral setae. Uropodal protopod with seven elongate plumose setae on outer margin, single plumose seta on inner distal angle; exopod ovate, about twice as long as wide; endopod roughly ovate, 1.5 times longer than wide.

Male: Antennular ¯agellum of eight articles each bearing row of aesthetascs. Antennal ¯agellum of six setose articles. Pereopod 1, propodus with two stout and two slender setae at or near posterior margin, plus posterodistal robust seta. Pereopod 7 lacking. Pleopod 2, endopod with copulatory stylet articulating in proximal half of mesial margin, bearing four distal plumose setae; endopod with incomplete transverse suture, nine distal plumose setae.

Remarks. All the available specimens of this species lack pereopod 7. As there are apparently mature males in the samples, it is possible that this species retains the manca condition into adulthood. In addition to this six-legged condition, Apanthuroides aldabrae diOEers from A. calculosus described below in having the rami of pleopod 1 more setose in the female; in having greater molar development of the mandible in the female; while the ischium of pereopod 1 of the male has a broad transparent ¯ange on anterior margin not seen in A. calculosus .

Etymology. The speci®c name derives from the type locality, Aldabra Atoll.