Ampithoe longicarpus, Appadoo & Myers, 2004

Appadoo, C & Myers, A. A., 2004, Corophiidea (Crustacea: Amphipoda) from Mauritius, Records of the Australian Museum 56 (3), pp. 331-362 : 338-340

Ampithoe longicarpus n.sp.

Figs. 7–9

Type material. HOLOTYPE 3, 3.5 mm, AM P65844 from mixture of Sargassum sp. , Ulva reticulata and Gelidiella acerosa, Souillac (20°31'S 57°30.7'E), at depth less than 1 m, C. Appadoo, 14 December 1999. PARATYPES, 13, 3.3 mm, AM P65845, 1♀, 3 mm, AM P65847, same data as holotype; 13, 2.8 mm, AM P65846, from Amansia glomerata and Padina sp. , Souillac, 8 April 1999; 13, AM P60593, 333 and 2♀♀, AM P60594, from mixture of

Antenna 1 missing in all specimens.Antenna 2 (description from male, 2.8 mm), peduncle article 5, 0.9× article 4, flagellum longer than article 5, 13-articulate. Mandible palp slender, article 3, 0.9× article 2, with two terminal slender setae. Lower lip outer plate narrow, deeply notched, with well-developed robust seta; mandibular lobes produced and rounded distally. Maxilla 1 inner plate subovate with 1 slender sub-distal seta. Maxilla 2 inner plate much narrower than outer plate. Maxilliped (from female, 3 mm), palp 4- articulate, article 3, 1.6× as long as broad, article 4 triangular with terminal nail. Gnathopod 1 coxa 1.as long as broad, anterodistally produced, rounded, distal margin with minute setae; basis 2.9× as long as broad, anterodistal lobe well developed with 3 stout setae, posterior margin with few slender setae; ischium long, 1.5× as long as broad; carpus elongate, subtriangular, 1.8× as long as broad; propodus 1.1×carpus, 2× as long as broad, palm oblique and poorly defined with a robust seta on posterodistal corner; dactylus long, 0.7× length of propodus, inner margin toothed. Gnathopod 2 coxa subquadrate, as long as broad, distal margin with minute setae; basis 3× as long as broad, anterodistal lobe well developed bearing stout setae; ischium elongate, 1.7× as long as broad; merus with posterodistal process; carpus elongate, subtriangular, 2.3× as long as broad; propodus and carpus subequal in length; propodus 1.8× as long as broad, anterior margin with numerous groups of long slender setae, palm sinuous with a weak excavation and with slender setae; dactylus over-reaching palm, inner margin toothed. Pereopods 3–4 coxa 1.4× as long as broad, distal margin with minute seta; basis weakly expanded, 2.4× as long as broad; merus 1.7× as long as broad; carpus subrectangular, 1.3× as long as broad; propodus 2.6× as long as broad. Pereopod 5 missing on described specimen (description from 3.3 mm male); basis strongly expanded, subequal in length and breadth; carpus 0.8× merus; propodus 1.6× carpus, slightly expanded distally with 4 striate robust setae at posterodistal corner. Pereopod 6 (from male, 3.3 mm), basis pyriform, 1.3× as long as broad, posterior margin broadly sinuous and scalloped, with a few slender setae; carpus 0.8× merus; propodus 1.3× carpus, slightly expanded distally, with 4 striate robust setae at anterodistal margin. Pereopod 7 similar to pereopod 6 but basis 1.4× as long as broad, anteriorly expanded, distally tapered. Epimera 1–3 posterodistal margin broadly rounded. Uropod 1 peduncle 3.7× as long as broad, outer margin with evenly spaced slender setae, inner margin with a few robust setae, distal margin with a short, rounded interramal process; outer ramus 0.9× inner ramus. Uropod 2 peduncle 2.8× as long as broad, outer ramus 0.9× inner ramus, rami with numerous robust setae. Uropod 3 peduncle 2.2× as long as broad, with one group of medial and one group of distal slender setae, distal margin with robust setae; inner ramus subovate with 1 robust and several slender distal setae; outer ramus with two large recurved robust setae at apex and small conical teeth on outer margin. Telson subtriangular with dorsolateral setae and two groups of slender medial setae; telsonic cusps small.

Female, 3 mm (ovigerous). Gnathopod 1 coxa 1.3× as long as broad, anterodistal margin produced, distal margin with minute setae; basis 3.1×s long as broad, anterodistal lobe moderately well developed; carpus 1.6× as long as broad; propodus elongate, 1.3× length of carpus, 2.6× as long as broad, palm oblique, poorly defined, with robust seta at posterodistal corner; dactylus 0.6× length of propodus, inner margin toothed. Gnathopod 2 coxa 1.4× as long as broad, distal margin with short setae; basis 3.3× as long as broad, anterodistal margin with robust setae; carpus subtriangular, 1.2× as long as broad; propodus 1.5× length of carpus, 1.8× as long as broad, palmar margin weakly sinuous with robust seta at posterodistal corner; dactylus slightly overlapping palm. Uropod 1 lacking an interramal process.

Distribution. Mauritius.

Habitat. This species was collected mostly from red algae at depths of less than 1 m. It was common among algae in rock pools at Souillac, in the south coast of the island.

Remarks. This species has prehensile pereopods 5 to 7 with large striate robust setae and a slender mandibular palp. It resembles Ampithoe kaneohe kaneohe J.L. Barnard (1970: 44 , figs. 14–16, 24 l) and Pleonexes kaneohe navosa from Fiji ( Myers, 1985a: 36, figs. 27–28). It differs from this species by being smaller in size and having a long slender carpus on the male gnathopod 2 (2.2× as long as broad as compared to being subequal in length and breadth in material described from Hawaii and 1.4× as long as broad in material from Fiji). It also differs from the A. kaneohe kaneohe from Hawaii, in the shape of the propodus, which is more subquadrate with an excavation in the present species, as compared to a subovate propodus and a strongly oblique palm with poorly defined palmar margin in A. kaneohe . Moreover, in A. kaneohe kaneohe , there are dense patches of setae on the posterior margins of propodus of male gnathopod 2. Another character of A. longicarpus n.sp. is the weakly scalloped posterior margin of the basis of pereopods 6 and 7, which appears smooth in A. kaneohe kaneohe (J.L. Barnard, 1970: 47, fig. 14).

Etymology. From the Latin longus, long, and carpus, referring to the long carpus of the male gnathopod 2.