Dynamenella remex, Schotte & Kensley, 2005

Schotte, Marilyn & Kensley, Brian, 2005, New species and records of Flabellifera from the Indian Ocean (Crustacea: Peracarida: Isopoda), Journal of Natural History 39 (16), pp. 1211-1282 : 1255-1258

Dynamenella remex sp. nov.

( Figures 25 , 26 )

Material examined

Holotype: USNM 280298 , one male (3.9 mm), sta JR-38 , Port Fievre , Nosy-Be´, Madagascar, intertidal mud and rock, 20 January 1964 . Paratypes: USNM 280299 , three females, four ovigerous females, four juveniles, same data as holotype .

Description

Male. Dorsum smooth, few lateral setae, pereonites 4 and 5 granular, 3 much less so, posterior edge of pereonite 6 with coarsely irregular, brittle ridge. Scattered chromatophores, densest on pleotelson. Pleotelson: granular, two large submedian tubercles on anterior fused segments; posterior pleonite with two diverging, longitudinal rows of four tubercles each on either side of midline, anterior pair largest; numerous smaller tubercles and tiny granulations scattered on surface; margins of pleotelsonic slit meet in midline, opening into circular, rimmed, dorsally directed foramen.

Antenna flagellum of nine articles; antennular flagellum bearing 11. Mandible as figured. Pereopods 1 and 2 with simple setae only; carpus of each with two stiff setae at posterolateral angle. Pereopod 7, single plumose and two simple setae at anterodistal margin. Pleopods typical of genus. Appendix masculina evenly wide, narrowly rounded at apex, extending slightly beyond endopod. Penes fused at base, length about seven times greatest width, expanded at proximal one-third of length and tapering to blunt apices. Uropodal endopod sparsely granular on dorsal surface, extending beyond apex of pleotelson by one-sixth of length, marginally dentate; exopod exceeding length of endopod, dorsally smooth, ventrally thickened submarginally, with three or more rows of teeth.

Ovigerous female. Dorsum very similar to male, tubercles and granulation less obvious; uropods much shorter and narrower, extending only slightly beyond pleotelsonic apex. Internal pouches absent.

Remarks

The new species resembles most closely its Indian Ocean congener D. savignyi (H. Milne Edwards, 1840) . It is a larger species with straighter pleotelsonic margins, broader uropodal rami and a relatively shorter appendix masculina which does not taper to an acute apex. It is also closely allied with D. bullejiensis Javed and Ahmed, 1988 from the Arabian Sea. The primary differences lie in the shape and length of the appendix masculina, the size of the uropods (longer and broader in D. remex ), the lack of pubescence and oblique tubercles on the pleotelson, and straight versus sinuous pleotelsonic margins in the new species.

Etymology

The specific name, from the Latin meaning ‘‘oarsman’’, refers to the paddle-like uropods.

Figures

Figure 25. Dynamenella remex sp. nov. (A) Male, dorsal view; (B) male pleon, dorsal view; (C) male, pleotelsonic foramen; (D) male, lateral view; (E) antennule; (F) antenna; (G) pleopod 1; (H) male pleopod 2; (I) pleopod 3; (J) left mandible; (K) pleopod 4; (L) pleopod 5.

Figure 26. Dynamenella remex sp. nov. (A) Pereopod 1; (B) pereopod 2; (C) pereopod 7; (D) penes; (E) uropodal exopod.