Oxinasphaera furcata, 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 : 1265-1267

Oxinasphaera furcata sp. nov.

( Figures 31 , 32 )

Material examined

Holotype: USNM 280353 , one male (5.7 mm), IIOE sta 463, off Somalia, 11 ° 249N, 51 ° 359E, 75–175 m, 17 December 1964 . Paratypes: USNM 280354 , two immature males, one ovigerous female, two females, three juveniles, same data as holotype . USNM 280355 , one male , IIOE sta 445, off Somalia, 9 ° 419N, 51 ° 039E, 60–70 m, 16 December 1964 . USNM 280356 , two males , IIOE sta 447, off Somalia, 10 ° 009N, 51 ° 159E, 9–61 m, 16 December 1964 .

Description

Male. Body length slightly less than twice as long as wide. Cephalon faintly tuberculate on anterior margin with prominent bifurcate spike on rostrum. Pereonite 1 unornamented. Pereonites 2 and 3 each with two rows of very low, indistinct tubercles. Pereonites 4–6 each with two rows of low rounded spikes, spikes in anterior rows larger. Pereonite 7 with anterior row of larger, conical spikes and many fewer, smaller tubercles in posterior row. Pleon very granulose with scattered setae, having two relatively short projections on posterior margin, not reaching mid-length of pleotelson; posterolateral margin of pleon produced into spike. Pleotelson very granulose with scattered setae, having pair of short protuberances ventral to each pleonal projection, posterior protuberance larger; posterior margin with produced, rounded medial lobe overlying telsonic excision, equal in length to lobes on either side.

Antennule peduncle article 1 with five regular anterior spikes, single proximoventral spike, and posterior blade; flagellum of seven to eight articles, single asethetasc each on distal five articles. Antennal peduncle articles 3–5 with long setae; flagellum of about 11 articles. Epistome bearing triangular, chisel-like blade with medial notch on posterior margin. Maxilliped as figured; other mouthparts also typical of genus.

Pereopod 1 with several stiff, fringed setae on posterior margin of propodus and two on carpus. Pereopod 2 with single fringed and three simple setae at distal margin of carpus. Pereopod 7 with long stiff setae on posterior margin of propodus, carpus and merus; several long setae and two complex tridentate setae on distal margin of carpus.

Penes length about 12 times width, tapering to acute apex; spinulose on distal onefourth.

Pleopod 1 with three coupling hooks; medial margin of endopod with groove. Pleopod 2, appendix masculina bulging somewhat at mid-length before tapering to narrowly rounded apex extending by one-sixth of length beyond posterior margin of endopod. Uropodal exopod about one-third length of endopod; endopodal apex with single, strong dorsally curved spine and three ventral tubercles, distalmost largest.

Ovigerous female. Dorsum smooth, unornamented, with broadly rounded pleotelsonic apex; not distinguishable from other females in genus. Brood pouch typical of genus.

Color. Chromatophores apparently lacking.

Remarks

The forked epistomal blade and pattern of antennular spikes (five regular anterior and one proximoventral) separate the new species from all other western Indian Ocean species. See comments under ‘‘Remarks’’ for O. brucei .

Etymology

The specific name furcata , from the Latin for ‘‘forked’’, refers to the shape of the epistome, a diagnostic characteristic of the species.

Figures

Figure 31. Oxinasphaera furcata sp. nov. (A) Male, dorsal view; (B) male, lateral view; (C) antennular bases, rostrum and frontal lamina in ventral view; (D) antennular bases and frontal lamina, anterior view; (E) antenna; (F) antennule; (G) female pleon; (H) immature male pleon; (I) male pleotelsonic apex, ventral view; (J) maxilliped; (K) pleopod 1; (L) penes; (M) uropod.

Figure 32. Oxinasphaera furcata sp. nov. (A) Male pleopod 2; (B) pereopod 2; (C) fringed seta from carpus, pereopod 2; (D) pereopod 1; (E) pereopod 7; (F) seta from carpus, pereopod 7.