Paracilicaea stauros, 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 : 1272-1275

Paracilicaea stauros sp. nov.

( Figures 35 , 36 )

Material examined

Holotype: USNM 280360 , one male (4.0 mm), sta K-SEY-16, coral reef at Anse á la Mouche, Mahe´, Seychelles, 2.5–5 m, 1 May 1984 . Paratypes: USNM 280361 , one male, one ovigerous female, two females, three juveniles, same data as holotype .

Description

Male. Pereon smooth with scattered setae, single and in pairs on dorsum, especially abundant at posterolateral margins; four tufts of setae along posterior margin of pereonite 7. Brown chromatophores spread evenly, sparsely over all segments. Pleotelson short, broad; anterior fused pleonites with two submedial projections and four bundles of setae along posterior margin; fifth pleonite bearing two large bosses on either side of midline, each with fringes of long, prominent setae; long setae numerous on lateral margins of segment; deep median notch bearing a cruciform projection, apically truncate, with many setae anteriorly and extending from apex.

Antennule flagellum with 10 articles, single aesthetasc on articles 5–8 and 10, two on penultimate article. Antenna flagellum with 10 articles. Frontal lamina broad with rounded apex, transverse ledge projecting ventrally. Maxilliped as figured. Pereopod 1 with three stout, complex setae each on propodus, carpus and merus; dense setal patches near anterior margins of carpus and merus. Pereopod 2, setal patches on anterior margins of carpus and merus, proximal area of propodus and anterodistal margin of ishium. Pereopod 7 with many long, robust, fringed setae as figured on carpus; merus with three stiff, robust setae at posterolateral angle. Penes, length five times width at base. Pleopod 1 with three coupling hooks on basis, plumose setae where figured. Pleopod 2, four hooks on basis; appendix masculina extending one-fourth length beyond apex of endopod, dilating slightly near tip then constricting to narrowly rounded apex. Pleopod 3 with four hooks on basis, complete transverse suture on exopod, plumose marginal setae indicated in figure. Pleopod 4 with sparse simple setae on external margins of both rami; single strong apical seta on each ramus; subterminal indentation on endopod. Pleopod 5 exopod with four distinct patches of dentate spinules, one patch anterior to articulation; sparse setae on internal margin. Uropod with endopod short, extending to length of pleotelsonic apex, with rounded median extension; exopod tuberculate, setose and twice length of endopod, inner margin convex anteriorly; exopod and endopod ventrally tuberculate.

Ovigerous female. Pleotelson with boss on either side of midline, few setae, apex truncate with marginal setae. Uropodal rami of equal length, both shorter than pleotelsonic apex; endopod broadly rounded apically and wider than exopod. Brood pouch with anterior pair of oostegites meeting at midline, posterior three pairs overlapping.

Remarks

Paracilicaea stauros is distinguishable from all other members of this genus by the nature of the tripartate apex of the pleotelson, including the unique cross-shaped median projection. Paracilicaea setosa Müller, 1995 from Kenya possesses a robust medial pleotelsonic projection but of differing shape and lacks the lateral projections on either side of this process, which are present in the new species.

Etymology

The specific name is from the Greek, meaning ‘‘cross’’, suggested by the cruciform shape of the medial projection of the pleotelsonic notch.

Figures

Figure 35. Paracilicaea stauros sp. nov. (A) Male, dorsal view; (B) frons; (C) antenna; (D) antennule; (E) male, lateral view; (F) female, pleon in lateral view; (G) male pleotelson, posterior view; (H) male pleotelson in ventral view; (I) female pleon in dorsal view; (J) pereopod 7; (K) pereopod 2; (L) pereopod 1; (M, N, O) carpal setae from pereopod 1, enlarged.

Figure 36. Paracilicaea stauros sp. nov. (A) Maxilliped; (B) pleopod 1; (C) male pleopod 2; (D) right mandible; (E) pleopod 3; (F) pleopod 5; (G) left mandible; (H) pleopod 4; (I) penes.