Corophiidea (Crustacea: Amphipoda) from Mauritius Author Appadoo, C Author Myers, A. A. text Records of the Australian Museum 2004 56 3 331 362 journal article 2201-4349 Exampithoe (Melanesius) latibasis n.sp. Figs. 13–15 Perampithoe falsa .—Appadoo & Steele, 1998: 639; non K.H. Barnard, 1932 . Type material . HOLOTYPE 3, 3.3 mm , AM P65850, from Padina gymnospora and coral rubble, La Prairie ( 20°29'S 57°20.5'E ), at depth less than 1 m , C. Appadoo, 14 October 1999 . PARATYPES , 1♀ , 3.3 mm , AM P64452, same data as holotype ; 13, 3.3 mm , AM P64453, from Sargassum sp. , Roches Noires ( 20°6.2'S 57°44.5'E ), 20 January 1999 ; 13, AM P60640, 333 and 2♀♀ , AM P60641, from Sargassum sp. , Gelidiella acerosa and Ulva reticulata , Souillac ( 20°31'S 57°30.7'E ), 14 December 1999 ; 233, AM P60642, from Amansia glomerata and Padina sp. ; 13, 9♀♀ , 1 juv. , AM P60643, from Sargassum sp. , Souillac ( 20°31'S 57°30.7'E ), 8 April 1999 ; 333, 6♀♀ , AM P60644, from Sargassum sp. , La Cuvette ( 20°00'S 57°34.2'E ), 12 October 1999 ; 1♀ , AM P60645, from Sargassum densifolium , Amansia glomerata , Jania adherens , Souillac , 14 October 1999 . Description . Male, 3.3 mm . Head longer than deep, distoventral corner excavate; eyes small, round, pink (in alcohol). Antenna 1 article 2, 0.7× article 1; article 3, 0.25× article 1; accessory flagellum absent; primary flagellum 32- articulate and bearing aesthetacs. Antenna 2 peduncle article 5, 0.9× article 4, flagellum poorly setiferous and 21-articulate. Mandible palp absent. Lower lip outer lobe wide, mandibular lobe rounded. Maxilla 1 inner plate small and triangular, with one seta. Maxilla 2 inner and outer plates narrow with long slender terminal setae. Maxilliped palp article 2 broad, unguis minutely serrate; article 4 small. Gnathopod 1 slightly larger than gnathopod 2; coxa 1.2× as logs as broad, anterodistal margin rounded, unproduced; basis 2.5× as long as broad, anterodistal lobe well developed, with one seta; carpus 1.5× as long as broad; propodus 2.1×as long as broad, palm small and transverse with one robust setae at base, followed by an excavation and a large robust seta; dactylus strongly overlapping palm, 1.6× the length of palm, inner margin smooth with few short fine setae. Gnathopod 2 coxa subquadrate, posterodistal margin with a few slender setae; basis 3× as long as broad, anterodistal lobe moderately developed; carpus slender, 2.2× as long as broad; propodus subrectangular, 2.5× as long as broad, palm transverse with one robust seta at its base; dactylus strongly overlapping palm, inner margin smooth. Pereopods 3–4 coxa subquadrate, with few slender setae on posterodistal margin; basis strongly expanded, 2× as long as broad; merus 1.5× as long as broad, anterior margin strongly expanded; carpus 1.7× as long as broad; propodus 1.2× as long as carpus. Pereopod 5 basis weakly expanded, 1.7× as long as broad; carpus 0.8× merus, subrectangular, 1.7× as long as broad; propodus slightly expanded distally, 4× as long as broad, with three robust setae on palm, one of which is curved. Pereopods 6–7, basis weakly expanded, 1.7× as long as broad; carpus subrectangular, 0.8× merus, 2.3× as long as broad; propodus slightly expanded distally, 3.5× as long as broad, with three Fig. 13. Exampithoe (Melanesius) latibasis Appadoo & Myers , n.sp. , 3, 3.3 mm (whole animal), AM P65850, ♀, 3.3 mm (G1–2), AM P64452, La Prairie, 3, 3.3 mm (P7), AM P64453, Roches Noires. Scales: a = 0.4 mm (whole animal), b = 0.2 mm (P7, ♀G1–2), c = 0.05 mm (enlargements of ♀G1–2). Fig. 14. Exampithoe (Melanesius) latibasis Appadoo & Myers , n.sp. , 3 (G1–2, P3–4), 3.3 mm, AM P65850, La Prairie, 3, 3.3 mm (P5, D5), AM P64453, Roches Noires. Scales: a = 0.2 mm (G1–2, P3–4; P5), b = 0.05 mm (enlargements of G1–2, D5). Fig. 15. Exampithoe (Melanesius) latibasis Appadoo & Myers , n.sp. , 3, 3.3 mm, AM P65850, La Prairie. Scales: a = 0.2 mm (A1–2, Mxp), b = 0.1 mm (U1–2, Md, L), c = 0.05 mm (Mx2, enlargements of outer plate of Mx1 and inner plate of Mxp, U3, T). Female: 3.3 mm (ovigerous). Gnathopod 1 similar in size to gnathopod 2; coxa subquadrate; basis 3× as long as broad, with weakly developed anterodistal lobe; carpus 2.4× as long as wide; propodus subrectangular, 2.3× as long as wide, palmar margin small and transverse, dactylus strongly overlapping palm. Gnathopod 2 coxa subquadrate; basis 3× as long as broad; carpus 2.4× as long as broad; propodus subrectangular, 2.5× as long as broad, palm small; dactylus overlapping palm, 1.6× its length, inner margin smooth. Distribution . Mauritius . Habitat . This species lives mostly amongst the brown alga Sargassum sp. It was collected at depths of less than 1 m from four sites, Souillac, La Prairie, La Cuvette and Roches Noires. Remarks . Exampithoe (Melanesius) latibasis n.sp. differs from E. (M.) cooki Ledoyer (1984) in having the male gnathopod 1 with a slender propodus with a short palm, followed by an excavation on the posterodistal margin. In E. cooki , the propodus is subovate and the posterodistal margin almost straight. The shape of the male gnathopod 1 propodus also distinguishes it from E. (M.) kutti Poore & Lowry (1997) , where the palmar margin is convex in both males and females. Etymology . From the Latin latus meaning wide and referring to the expanded flattened bases of pereopods 3–4. Material examined . 13, 1♀ , 1 juv. , AM P60646, from Digenia simplex , Albion ( 20°13'S 57°23.7'E ), 22 October 1998 ; 233, 5♀♀ , 4 juv. , AM P60647, from Pocockiella variegata , Padina sp. and coral rubble, Flic-en-Flac ( 20°16.5'S 57°21.7'E ), 5 April 1999 ; 333, 4♀♀ , 4 juv. , AM P60648, from Turbinaria ornata and Pocockiella variegata , Flic-en-Flac, 27 January 2000 . Diagnosis . Antenna 1 accessory flagellum 6-articulate. Coxae 1–4 with one patch of setae on distal margin. Gnathopod 1 larger and more robust than gnathopod 2; propodus 1.3× as long as broad, palmar margin with a deep excavation. Gnathopod 2, propodus 1.9× as long as broad, palm oblique. Uropod 1 with large acute disto-ventral spur. Uropod 3 outer ramus with one straight and one weakly curved seta at distal end. Telson distally truncate, with welldeveloped patches of slender setae. Type locality . Seychelles . Distribution . Madagascar , Mauritius , Seychelles . Habitat . This species lives mostly amongst red and brown algae and was collected at depths of less than 1 m . It was collected mostly from sites on the west and northwest coasts such as Flic-en-Flac, Albion, and Balaclava. Remarks . The fact that Paragrubia vorax is readily distinguished from other ampithoids by the strongly enlarged gnathopod 1 in males has led to the species being recorded from many parts of the Indo-Pacific. It is probable that more than one species exists in the Paragrubia vorax complex. The material from Mauritius agrees with the description given by Chevreux (1901) from Seychelles ( type locality) and also with that of Ledoyer (1982) in having a strongly excavate palm on the male gnathopod 1 propodus. Material described by J.L. Barnard (1970) from Hawaii and by Myers (1985a) from Fiji has a weakly excavate palm on the male gnathopod 1 and should probably be raised to the status of a new species.