Oxinasphaera brucei, 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 : 1262-1265

Oxinasphaera brucei sp. nov.

( Figures 29 , 30 )

Material examined

Holotype: ZMUC, one male (5.1 mm), IIOE sta 371-G, off Mozambique, 24 ° 299S, 35 ° 139E, 73 m, 18 August 1964 . Paratype: USNM 280352 , one male 5.6 mm , IIOE sta 403-E, off Mozambique, 19 ° 099S, 36 ° 559E, 88 m, 9 August 1964 .

Description

Male. Body length excluding uropods slightly more than twice maximum width; lateral margins subparallel, widest at pereonite 4. Cephalon pitted, with short, sparse setae; anterior margin with five to six tiny tubercles on either side of rostrum; rostral spike broad with slightly crenulate margin. Pereonite 1 smooth. Pereonites 2–4 each with two transverse rows of short rounded spikes, occasional intermediate nodules and granules between rows; pereonites 5–7 each with two rows of somewhat longer, more acute spikes. Pleon very granulose with posterior boss bearing two prominent posteriorly directed projections extending beyond mid-length of pleotelson. Pleotelson very granulose, sparsely setose with two submedian anteriorly directed obtuse spikes beneath pleonal projections; lateral, transverse concavities at two-thirds of pleotelson extending inward to median one-third of width; posterior margin with two submedian indentations on either side of narrowly pointed median lobe. Ventral view as figured; ventral median lobe on posterior margin with short projection anterior to apex.

Antennule peduncle article 1 with four large, regular anterior spikes, single large proximoventral spike and posterior blade; several setae on articles 1 and 2; flagellum of nine articles, distal five each with single aesthetasc. Antennae articles 3–5 with long setae; flagellum with seven articles. Epistome with thick, transverse blade anteriorly; lateral lobes very granulose. Mandibles and maxilliped typical of genus.

Pereopod 1, five to six strong, fringed setae on posterior margin of propodus; carpus having two fringed setae on posterior margin; merus with single such seta on anterodistal margin. Pereopod 2, several simple setae on distal margins of propodus; carpus with four fringed spine-like setae on posterior margin of carpus. Pereopod 7 longest, with several very robust, complex tridentate setae on distal margin of carpus; merus with two long, fringed and several simple setae on posterodistal margin. Penes elongate, tapering to narrow apex, length more than 12 times width; very short stiff setules proximally at lateral margins; fewer setules on distal one-sixth of length.

Pleopod 1 peduncle with three coupling hooks, setose on outer margin; exopod with strong stiff seta proximolaterally; endopod having groove on medial margin. Pleopod 2, appendix masculina extending somewhat beyond apex of endopod, narrowing distally before inflating to bulbous tip; tiny setules medially. Uropods rough, very granulose with several setae; exopod about one-third length of endopod and deeply bifid apically; endopod with two or more medium spikes distoventrally; apex with two prominent spikes, one directed dorsally, one ventrally.

Female. Unknown.

Remarks

As noted by Bruce (1997) in his monograph of the genus Oxinasphaera , all the western Indian Ocean species, all of which except O. kensleyi are described as new in the present paper, possess elongate pleonal processes. The four new species of Oxinasphaera described in this paper, all from the western Indian Ocean, appear to be related to the O. tripartita – O. kensleyi clade proposed by Bruce, having in common a posterior antennular blade and a pleotelsonic lobe overriding the apical sinus. O. brucei is distinguished by the chisel-like blade on the epistome, the formula of spikes on the antennular peduncle, and morphology of the appendix masculina. In the same monograph, Bruce discusses the characters which separate this genus from its probable sister group, Cymodoce .

Etymology

The species is named for Dr Niel L. Bruce, respected friend, colleague and authority on numerous isopod taxa.

Figures

Figure 29. Oxinasphaera brucei sp. nov. (A) Male, dorsal view; (B) male in lateral view; (C) antennular bases and frontal lamina; (D) antennule; (E) antenna; (F) cephalon in anterior view; (G) male pleotelson, ventral view; (H) maxilliped; (I) penes; (J) pereopod 1.

Figure 30. Oxinasphaera brucei sp. nov. (A) Pereopod 2; (B) pereopod 7; (C) male pleopod 2; (D) pleopod 1; (E) carpal seta of pereopod 7, enlarged; (F) uropod.