Cymadusa cavimana (Sivaprakasam) Appadoo & Myers, 2004

Appadoo, C & Myers, A. A., 2004, Corophiidea (Crustacea: Amphipoda) from Mauritius, Records of the Australian Museum 56 (3), pp. 331-362 : 343

Cymadusa cavimana (Sivaprakasam) n.comb.

Ampithoe cavimana Sivaprakasam 1970b: 65 , fig. 1.— Ledoyer 1982: 116, fig. 37.—Appadoo & Steele, 1998: 639.

Material examined. 13, 5♀♀, 2 juv., AM P60625, 733, 10♀♀, 16 juv., AM P60626, from Turbinaria ornata , Pocockiella variegata, Balaclava (20°3.7'S 57°30.7'E), 10 September 1998; 333, 5♀♀, 12 juv., AM P60627, from Halodule uninervis , Dictyota divaricata , coral rubble, Albion (20°13'S 57°23.7'E), 22 October 1998; 233, 2♀♀, 14 juv., AM P60628, from Padina sp. , Dictyota divaricata, Gelidium sp., Klondike (20°15.7'S 57°22'E), 9 November 1998; 433, 12♀♀, 4 juv., AM P60629, from Amansia glomerata , Padina sp. and Sargassum sp. , Souillac, 8 April 1999; 13, 2♀♀, AM P60630, from Padina sp. , Ulva lactuca , Amphiroa sp. , Tamarin (20°19.5'S 57°22'E), 2 August 1999; 433, 6♀♀, 5 juv., AM P60631, from Digenia simplex and Padina sp. , Roches Noires (20°6.2'S 57°44.5'E), 15 October 1999.

Diagnosis. Eyes medium in size with well-developed ommatidia.Antenna 1 accessory flagellum absent. Antenna 2 poorly setiferous, article 5, 0.8× article 4. Gnathopod 1 coxa 1.4× as broad as deep, anterodistal margin strongly produced and rounded; carpus elongate, 2.8× as long as broad weakly setiferous; propodus 0.75× length of carpus, palm oblique, with a deep, triangular excavation, posterodistal corner with 1 robust seta; dactylus overlapping palm, inner margin toothed. Gnathopod 2 coxa 1.5× as long as broad with a patch of slender setae at posterodistal corner; carpus subtriangular, as long as broad; propodus 1.7× as long as broad, palmar margin with a deep round-bottomed excavation, palmar margin with a few short slender setae; dactylus short, robust, inner margin with a rounded serrated lobe terminating in a tooth-like process. Epimera 2–3 with a small tooth at posterodistal corner. Uropod 1 peduncle distal margin with a well-developed acute interramal process. Uropod 3 peduncle with robust setae on distal margin. Telson subtriangular, distally truncate.

Female, Gnathopod 1 coxa 1.2× as long as broad, anterodistal margin moderately produced; carpus 1.9× as long as broad; propodus palm oblique. Gnathopod 2 propodus palm oblique evenly rounded; dactylus slightly overlapping palm.

Type locality. Gulf of Mannar , India .

Distribution. Madagascar, Mauritius, India.

Habitat. This species was collected at depths of less than 1 m. It occurred mostly on brown algae such as Padina sp. and Pocockiella variegata , together with coral rubble. It was abundant at sites such as Flic-en-Flac, Balaclava, Roches Noires, La Prairie, sites where coral rubble and brown algae are abundant.

Remarks. This species is here transferred from the genus Ampithoe Leach to the genus Cymadusa Savigny on the basis of the presence of a large acute distoventral interramal process on uropod 1 (see Poore & Lowry, 1997) and its large size.

Cymadusa cavimana from Mauritius agrees well with the description given by Sivaprakasam (1970b). This species is often confused with Cymadusa brevidactyla , but differs from that species in having an excavation in the male gnathopod 1 palm (smoothly convex in C. brevidactyla ) and in lacking an accessory flagellum. The presence of only one patch of slender setae at the posterodistal margin of coxae 1–4 help to distinguish this species from C. filosa which has setae all along the distal margin of these coxae. The short dactylus on the male gnathopod 2 distinguishes males of this species from Cymadusa microphthalma (Chevreux) .