Sphaeromopsis sulcifera, 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 : 1275-1278

Sphaeromopsis sulcifera , sp. nov.

( Figures 37 , 38 )

Material examined

Holotype: USNM 280362 , one male (2.0 mm), sta K-SEY-6, intertidal mud flat with green algae at Harbour View Guest House , Mahe´, Seychelles, 30 April 1984 . Paratypes: USNM 280363 , 59 ovigerous females 2.1 mm, 33 females, same data as holotype .

Description

Male. Body length about twice greatest width, strongly conglobate. Cephalon smooth, or very faintly granular, wider than long, moderately convex with pointed rostrum barely visible in dorsal view; epistome narrowly rounded at apex, as broad as long, with ‘‘arms’’ extending to mid-length of labrum. Pereonites 1–6 smooth, without sculpturing or setae except few at margins. Pereonite 7 with submarginal transverse ridge underlapping margin of pereonite 6 in conglobation. Pleotelson wider than long, apex narrowly rounded, bearing in anterior half a faint medial furrow flanked by obscure ridges; with few scattered, short setae and faint tubercles over surface clearly detectable only in stained specimens.

Antennule basal article subequal in length to articles 2 and 3 together; flagellum of five articles, articles 4 and 5 each bearing single aesthetasc. Antenna with articles 1–3 short, subequal; article 4 twice length of article 3; article 5 subequal in length to 3 and 4 together; flagellum of eight setose articles. Mandible with incisor of three sclerotized cusps, spine row with five spines, two of which fringed, molar with many teeth. Maxilla 1, inner ramus with four fringed setae; outer ramus with five blunt, robust setae and four more slender stiff setae, two or three fringed. Maxilla 2, inner ramus with seven setae on distal margin; both lobes of outer ramus with four fringed stiff setae each. Maxillipedal endite broad, with single coupling hook on mesial margin, distal margin bearing three blunt and several fringed setae; palp of five setae-bearing articles, articles 2–4 each with low rounded distomesial lobe. Pereopod 1, propodus with single fringed, single dentate and several simple setae on posterodistal margin; carpus with single stout, fringed seta on posterodistal margin; merus with strong, simple anterodistal and posterodistal setae; merus and ischium with several short setae along posterior margin. Pereopod 2, single plumose seta at anterodistal margin of propodus and carpus; merus with single stiff, fringed seta at anterodistal margin. Pereopod 7, one simple and one plumose seta at anterodistal margin of propodus; four stout fringed setae at distal margin of carpus; carpus and merus with many fine setae along posterior margins, merus with single strong stiff seta at anterodistal margin and several simple setae along posterior margin. Penes long, slender, fused at base, six times longer than basal width, tapering to rounded apices; patch of tiny setules near and on margin in anterior half. Pleopod 1, basis with three distomesial coupling hooks, endopod narrower and slightly shorter than exopod, latter with single stiff seta proximally. Pleopod 2, stout appendix masculina tapering slightly, extending somewhat beyond endopod, apex blunt. Pleopod 3, basis with three coupling hooks, fringe of setae on distomesial margin of endopod. Pleopod 4, both rami with transverse folds, tapering to rounded apices.

Pleopod 5, exopod longer than endopod, with incomplete transverse suture distally, bearing two spinulose bosses. Uropodal rami subequal in length, endopod narrower, both rami extending slightly beyond pleotelsonic apex and bearing simple marginal setae.

Ovigerous female. Cephalon and pereon smooth; pleotelson with very faint medial furrow and scattered setae; pereonite 7 as in male. Mouthparts and brood pouch typical of genus.

Remarks

At present six species of Sphaeromopsis are known and can be distinguished from the new species and each other by the characters of the pleotelson. S. heardi Kensley and Schotte, 1994 from the Caribbean has obvious sculpturing on the pleotelson whereas the species from Brazil, S. mourei Loyola e Silva, 1960 , is completely smooth. That of S. serriguberna Holdich and Harrison, 1981 , from Australia has a mid-dorsal raised area. In the three known Indian Ocean species the pleotelson varies from broadly truncate in S. amathis Holdich and Jones, 1973 ( Kenya) , and reticulate with sinuous margins in S. reticulata Stebbing, 1910b (Red Sea) to smooth and broadly rounded in the Pakistan species S. minutus Javed and Yousuf, 1995 . The faint longitudinal, medial furrow in S. sulcifera is unique.

Etymology

The specific name is derived from the Latin sulcus, a furrow, plus - fera, bearing, and refers to the faint sulcus on the pleotelson.

Figures

Figure 37. Sphaeromopsis sulcifera sp. nov. (A) Male, dorsal view; (B) female, dorsal view; (C) antennule; (D) antenna; (E) male, lateral view; (F) maxilla 1; (G) frons; (H) maxilla 2; (I) uropod; (J) mandible; (K) maxilliped.

Figure 38. Sphaeromopsis sulcifera, sp. nov. (A) Pleopod 1; (B) male pleopod 2; (C) pleopod 3; (D) pleopod 4; (E) pleopod 5; (F) pereopod 2; (G) pereopod 7; (H) pereopod 1; (I) penes.