Zenobianopsis cidaris, Poore, 2012

Poore, Gary C. B., 2012, Four new valviferan isopods from diverse tropical Australian habitats (Crustacea: Isopoda: Holognathidae and Idoteidae), Memoirs of Museum Victoria 69, pp. 327-340 : 328-329

Zenobianopsis cidaris sp. nov.

Figures 3 , 4

Material examined. Holotype. Coral Sea, 17°34.58'S, 146°53.21'E, 458–500 m, M. Pichon et al., 15 May 1986, sledge (CIDARIS I stn 43.2), MTQ W34049 (ovigerous female, 14.2 mm).

Description. Ovigerous female. Body 5.6 times as long as greatest width at pereonite 3, pereonites 5–7 noticeably narrower than 1–4, dorsal surface smooth, with fur of fine setae on pleotelson. Head 1.1 times as wide as long, front with broad obtuse pseudorostrum as long as lateral margins; lateral margin with horizontal groove at base of antenna 2. Pleotelson 0.25 total length, 1.8 times as long as greatest width; pleonites 1 and 2 freely articulating; pleonite 3 indicated by lateral suture barely visibly in dorsal view; pleonite 4 very short, with short suture; remaining pleotelson parallel-sided, with semicircular apex, dorsally evenly domed curving posteriorly to oblique profile in lateral view, posterodistal margin not elevated.

Antenna 1 reaching to distal margin of second article of antenna 2; flagellum of major article plus 2 minute articles. Antenna 2 0.25 body length; flagellum broken.

Mandible (right) molar truncate, with acute toothed accessory blade, with 20 molar setae; spine row of 9 spines, lacinia mobilis bifid; incisor with 3 blunt teeth.

Coxa 2 subrectangular; coxa 3 tapering posteriorly, 0.9 pereonite dorsal length; coxa 4 smaller than 3; coxae 5–7 overlapping, ventrally concave, projecting acutely posteroventrally; coxa 7 reaching back to mid-pleonite 2. Pereopod 1 ischium with prominent proximal facial robust seta; merus with 2 robust setae on flexor margin, complex seta distally on extensor margin; propodus 2.5 times as long as greatest depth, palm with 5 strong setae and comb of fine short setae, mesial face with 10 pectinate setae; dactylus almost linear except for curved unguis, reaching back to mid-carpus. Pereopod 2 1.3 times as long as pereopod 1; propodus 4.6 times as long as wide; dactylus as long as propodus. Pereopod 3 1.1 times as long as pereopod 2; propodus 6.4 times as long as wide; dactylus almost as long as propodus. Pereopods 4, 5 missing. Pereopod 6 0.4 times length of pereopod 3; propodus extensor margin projected beyond articulation with merus; merus–dactylus 1.5 times length of propodus; dactylus twisted, compact. Pereopod 7 as long as pereopod 6; propodus extensor margin scarcely projected beyond articulation with merus; merus–dactylus 3.7 times length of propodus; dactylus twisted, damaged.

Uropod 2.5 times as long as greatest width; endopod about 0.4 length of total uropod, triangular with rounded apex, suture at 75° to long axis; with 1 seta.

Etymology. Cidaris , from the name of the cruise during which the specimen was taken; noun in apposition.

Distribution. Australia, Coral Sea, eastern continental slope of Queensland, c. 17°S; 458–500 m depth.

Remarks. The single specimen has been partially dissected by a previous investigator and most mouthparts, all pereopods of the left side and pereopods 4 and 5 of the right are missing. Nevertheless, the species is undoubtedly of this genus. The new species differs from the two others in the absence of a median carina on the anterior part of the pleotelson, absence of upcurved lateral pleotelson margins and more elongate anterior pereopods. Zenobianopsis cidaris has a more rounded uropodal endopod than Z. rotundicauda . In Z. caeca , the pleotelson is decidedly truncate.

Figures

Figure 3. Zenobianopsis cidaris sp. nov. Right limbs from holotype. Scale bars = 1 mm (habitus only) and 0.2 mm (pereopods, uropod).

Figure 4. Zenobianopsis cidaris sp. nov. Right limbs from holotype; detail of p6 untwisted.