Cymadusa ledoyeri, Peart, 2004

Peart, R. A., 2004, A revision of the Cymadusa filosa complex (Crustacea: Amphipoda: Corophioidea: Ampithoidae), Journal of Natural History 38 (3), pp. 301-336 : 310-313

Cymadusa ledoyeri n. sp.

(figures 5–7)

Cymadusa filosa: Ledoyer, 1982: 130–135 , figures 44–46 (form B).

Type material. HOLOTYPE: male, 13 mm length, MNHN-AM3297 (Paris), Tuléar, Madagascar, 23°12∞S, 43°24.6∞E, collected by Caye-Thomassin. PARATYPES: female (one specimen), unknown length, MNHN-AM3300 (Paris), collection data as for holotype; males (two specimens), MNHN-AM3298 and AM3299 (Paris), collection data as for holotype .

Type locality. Tulear , Madagascar .

Diagnosis. Antenna 1 with a two-articulate accessory flagellum. Antenna 2 not documented. Gnathopod 1 with poorly setose margins; merus slightly produced to form a small, subacute anteroventral lobe; carpus subtriangular. Adult male gnathopod 2 with poorly setose margins; propodal palm defined by large, rounded posterodistal tooth, mid-palmar tooth absent; dactylus longer than the palm.

Description

Based on the holotype, male, 13 mm length.

Head. Antenna 1 peduncular article 1 subequal to article 2, article 2 longer than article 3, article 3 shorter than article 1; primary flagellum with 50 articles; accessory flagellum with two articles. Antenna 2 not documented. Lower lip outer plate, outer lobe longer than inner lobe. Mandible molar setal row with 10 robust setae; palp article 1 shorter than article 2, article 2 shorter than article 3, article 3 longer than article 1, setae on posterior margin and apex. Maxilla 1 inner plate with four slender setae. Maxilla 2 outer lobe broader than inner lobe. Maxilliped setose.

Pereon. Gnathopod 1 smaller than gnathopod 2; poorly setose; coxa produced forward, anterior margin straight, ventral margin with a tuft of a few simple setae on posterior corner; basis subequal in length to the coxa, without long plumose setal fringe, distal lobe present; merus produced to form a small, subacute anteroventral lobe; carpus longer than merus, longer than propodus, margins divergent at distal end, carpal lobe truncated with rounded corners; propodus ovoid; palm entire, straight, defining posterodistal tooth absent, mid-palmar tooth absent; dactylus subequal to palm length. Gnathopod 2 with sparse setae; coxa ventral margin with a tuft of simple setae on posterior corner; basis longer than coxa, without setae on anterior margin, distal lobe present; merus produced to form a small, subacute anteroventral lobe; carpus subequal to merus, shorter than propodus; propodus ovoid; palm entire, straight, posterodistal tooth rounded and large, mid-palmar tooth absent; dactylus longer than palm, tapering evenly.

Pereopods 3 and 4 similar in shape; coxae with a row of small setules along the ventral margin and a tuft of longer setae on the posterior corner. Pereopod 5 coxae with a row of small setules along the ventral margin, but absent from the medial surface. Pereopod 6 basis with sparse medial setae. Pereopod 7 basis ovoid. Pereopods 6 and 7 much longer than pereopods 3–5; distal articles with setae.

Pleon. Epimeron 3 subquadrate. Uropod 1 peduncle with nine robust setae; outer ramus longer than inner ramus. Uropod 2 outer ramus longer than inner ramus. Uropod 3 with eight distal peduncular robust setae; outer ramus shorter than inner ramus, both hooks strongly recurved, setal fringe present on dorso-lateral margin; inner ramus with both apical robust and slender setae. Telson truncated, apical and lateral slender setae in oblique rows, apical cusps present.

Female. Based on paratype, unknown length, sexually dimorphic characters.

Pereon. Gnathopod 1 coxa anterior margin concave; basis shorter than the coxa; carpus subequal to propodus, margins divergent at distal end, carpal lobe rounded; propodal palm entire, convex; dactylus subequal to or slightly longer than palm. Gnathopod 2 weakly setose; basis shorter than coxa; propodus subquadrate; propodal palm defining posterodistal tooth subacute and small; dactylus subequal to palm.

Remarks

Ledoyer (1982) notes that this form is very close to the species Grubia microphthalma Chevreux, 1901 . However, C. microphthalma has only been recorded as females (illustrations and specimens), making it difficult to identify. Cymadusa ledoyeri n. sp. differs from Cymadusa filosa by having poorly setose antenna 2, gnathopods 1 and 2 ( C. filosa has densely setae antenna 2, gnathopods 1 and 2); gnathopod 2 palm is defined by a large rounded posterodistal tooth (gnathopod 2 palm defined by a small, subacute posterodistal tooth) and uropod 3 has fewer robust setae.

Etymology. This species is named for Michel Ledoyer who contributed so much to the systematics of this group of species.

Habitat. These specimens were collected from seagrasses.

Distribution. Tuléar, Madagascar, Indian Ocean ( Map 1 ).

Figures

MAP 1. Global distribution of Cymadusa filosa Savigny, 1816 (*), Cymadusa ledoyeri n. sp. (•), Cymadusa tattersalli n. sp. (*), Cymadusa imbroglio Rabindranath, 1972 (Δ), Cymadusa setosa (Haswell, 1879) (v), Cymadusa vadosa Imbach, 1967 (&).