Quadrimaera micheli, Appadoo & Myers & Fagoonee, 2002

Appadoo, Chandani, Myers, Alan A. & Fagoonee, Indur, 2002, The genera Quadrimaera and Maera (Amphipoda: Gammaridea: Melitidae) from Mauritius, Journal of Natural History 36 (6), pp. 641-673 : 643-646

Quadrimaera micheli sp. nov.

(®gures 1, 2)

Type material. HOLOTYPE: 1, 2.9 mm (microscope slides), AM P60084; PARA- TYPES: 1 (slides, carcass), AM P60085, one juv., AM P60086, from Sargassum sp. , La Cuvette (20ss00¾S 57ss 34.2 E), 12 October 1999.

Description

Male. Length, 2.9 mm. Head without subocular notch; eyes subovate. Antenna 1 peduncle article 1 with stout robust setae on ventral margin; peduncle article 2 a little longer than article 1; article 3 one-third length of article 2; primary ¯agellum eight-articulate, accessory ¯agellum four-articulate. Antenna 2 peduncle article 4 longer than 5; ¯agellum a little shorter than peduncular article 5, moderately setose and ®ve-articulate. Mandible palp article 2 and 3 subequal, article 3 parallel-sided with four terminal setae and two medial setae. Maxilla 1 inner plate with two terminal setae. Maxilla 2 outer plate distinctively wider than inner plate. Maxilliped palp article 3 with setae on distal and part of lateral margin. Gnathopod 1 coxa 1 antero-ventrally rounded and bearing a small patch of setae at the antero-distal margin; basis three times as long as broad; carpus anterior margin with subdistal excavation; propodus 1.8 times as long as wide, palmar margin convex and bearing numerous robust setae; dactylus ®tting palm. Gnathopod 2 basis more than twice as long as broad, antero-distal margin lobate; merus postero-distal margin produced, acute; carpus short, cup-shaped; propodus subquadrat e with transverse palm, palmar margin with stout robust setae and with a deep U-shaped medial excavation and a shallow distal excavation; dactylus posterior margin medially expanded, with several setae on posterior margin. Pereopod 3±4 basis three times as long as broad, with robust setae on the anterior and posterior margins; merus slightly produced anterodistally; dactylus with a well-de®ned bi®d tip. Pereopod 5 basis subovate, 1.3 times as long as broad and with few robust setae on the anterior and posterior margins. Pereopods 6±7 missing. Epimeron 3 postero-distal margin smooth, sub-acute, with a single robust seta inserted at the antero-ventra l margin. Uropod 1 peduncle scarcely longer than rami; rami subequal. Uropod 2 peduncle subequal with inner ramus which is 1.3 times length of outer ramus. Uropod 3 peduncle a little shorter than inner ramus, outer ramus 1.5 times length of inner ramus bearing six distal robust setae; inner ramus with two distal robust setae. Telson cleft to about three-quarter its length; lobes notched, each bearing a strong robust seta at the notch and a strong robust seta on the outer margin.

Female. Length, 3 mm (oostegites well-developed). Gnathopod 2 propodus, palmar margin with one deep medial excavation and a very shallow distal excavation.

Remarks

Q. micheli is distinguished from Q. serrata by having a smooth postero-distal margin to epimeron 3. In Q. micheli the gnathopod 2 propodus is rectangular, the telson is incised and carries apical robust setae which are longer than 50% the length of the telson. In these characters it is similar to Q. ariel from Bermuda (RuOEo et al., 2000) and Q. vigota from California ( Barnard, 1969). It diOEers from these two species by more than one of the robust setae distally on each telson lobe being longer than half the telson length. The presence on the telson of one apical robust seta in the incision and one robust seta outside the incision, groups Q. micheli with Q. inaequipes from Mediterranean ( Karaman, 1982) and Q. kaiulani ( Barnard, 1970) from Hawaii. Q. micheli diOEers from Q.kaiulani by having a rectangular propodus and a medially expanded posterior margin of the dactylus in the gnathopod 2. In Q. kaiulani ( Barnard, 1970: 148, ®gure 90) gnathopod 2, the posterior margin of the dactylus is not expanded and the propodus is slightly convex with a weakly scalloped margin. Q. micheli resembles more closely Q. inaequipes ( Costa, 1857) from the Mediterranean ( Karaman, 1982: 314 ±317, ®gure 3; Krapp et al., 1996: 41 ±45, ®gure 9). It diOEers from it by showing little sexual dimorphism in gnathopod 2. In Q. inaequipes , the propodus palm of that appendage is unexcavate in the female but with a strong U-shaped excavation in the male. The palm of the male gnathopod 2 also has numerous stout robust setae in Q. micheli , but these are poorly represented in Q. inaequipes ( Karaman, 1982: 316, ®gure 213). Q. massauensi s ( Kossman, 1880) from the Red Sea is close to but probably distinct from Q. inaequipes ( Krapp et al., 1996) . It is too poorly known to allocate to any described species or to Q. micheli .

Present material may be conspeci®c with the material described by Ledoyer (1982: 527 ±529, ®gure 198) from Madagascar under the name Q. inaequipes . It diOEers, however, from that material in the shorter accessory ¯agellum (four-articulat e in present material, eight-articulate in Madagascar material) and in its smaller (but mature) size (3 mm in present material, 5 mm in Madagascar material).

This species was quite rare in the present study. It diOEers from Q. serrata by its smooth epimeron 3 and from Q. paci W ca by the very deep medial excavation on gnathopod 2 palm and the notched telson lobes with short robust setae. The notched telson also distinguishes it from Q. mirandella which has a truncate telson.

The authorship of this new species lies with Appadoo and Myers.

Type locality. La Cuvette, Mauritius .

Distribution. Mauritius and? Madagascar.

Etymology. Named after Michel Ledoyer in recognition of his study on the amphipods of Mauritius.