A New Species of the Genus Spinianirella Menzies (crustacea: Isopoda: Janiridae) from the Western Atlantic

-Spinianirella serrata is described from 350 m off Puerto Rico. This new species differs from S. walfishensis Menzies (from the south-eastern Atlantic) in the more spinose nature of the cephalic and pereonal processes, and in the pleonal and uropodal structure of the male. Menzies (1962) described the genus Spinianirella to accommodate a single female specimen taken in 1816 m in the Walvis Basin ofthe south-eastern Atlantic. Kensley (1984) recorded 14 specimens ofthe same species from off the east coast of South Africa, in depths of 150-850 m. To date, these two records constitute the entire record for the genus. The occurrence of a second species of the genus, S. serrata, from the western Atlantic off Puerto Rico, forms a significant extension to both the distribution and diagnosis of the genus. Family Janiridae Spinianirella Menzies Spinianirella Menzies, 1962: 171, fig. 55. Wolff, 1962:34, 262, 271, 274, 275.Kensley, 1984:283, fig. 37. Type-species. -Spinianirella walfishensis Menzies, 1962, by original designation. Revised diagnosis. -Janiridae with lateral margins of cephalon and pereon produced into spinous processes. Pleon consisting of single broad segment. Eyes absent. Mandibular palp of 3 articles. Pereopod 1 shorter than following pereopods, prehensile, with dactylus and propodus together folding against carpus. Pereopods 2-7 slender, ambulatory. Uropod uniramous, of 2 articles. Spinianirella serrata, new species Figs. 1, 2 Material. -HOLOTYPE, USNM 211360, 2, TL 3.2 mm, PARATYPE, USNM 211361,5, TL 5.0 mm, 17°49.9'N, 66°34.1'W, 350 m, Mar 1984, bottom substrate a mixture of sand, silt, and clay. Description. -Body slightly more than 3 times longer than wide (excluding lateral spinous processes); widest at pereonite 3. Integument dorsally sclerotized, somewhat rugose, bearing scattered tubercles and setules. Anterior cephalic margin concave between antennal bases. Anterolateral elongate process of cephal on apically acute, bearing spine-like tubercles; lateral margin of cephalon convex posterior to spinose processes. Pereonites 1-3 increasing in length and width posteriorly, pereonites 4-7 decreasing in width and length posteriorly. Pereonite 1 with single lateral spinose process; spines on posterior margin and on lateral pereonite Fig. I. Spinianirella serrata: A, Holotype <3, dorsal view, TL 3.2 mm; B, Mandibular palp; C, Right mandible, palp not shown; D, Incisor and spine row of left mandible; E, First maxilla; F, Second maxilla; G, Maxilliped and epipod. Scale = 0.1 mm. margin behind process becoming elongate. Pereonites 2-4 each with 2 lateral spinose processes. Pereonite 5 with single lateral process. Pereonites 6 and 7 lacking processes, with convex spinulose lateral margin. Pleon consisting of single segment, but with shallow anterodorsal transverse groove perhaps indicating single fused pleonite. Pleonal lateral and posterior margins gently convex. Pleon 1.3 times longer than wide, dorsally with raised and rounded central longitudinal area. Anterolateral margins spinose.