Pertsovius serratus Andronov & Kosobokova, 2011, gen. nov.

Pertsovius serratus gen. nov. et sp. nov.

(Figures 7–8)

Material examined. Holotype: adult female, dissected, total body length 0.65 mm. ZIN accession number 91100. Collected during the USCGC “ Healy ” Ocean Exploration-05/2 cruise, station 6, Canada Basin (at 74° 07’N, 153° 37’W), 8 July 2005, bottom depth 3850 m, depth of collection 500– 300 m.

Species description. Prosome ovoid in dorsal view (Fig. 7: 1), nearly 2.5 times as long as urosome and 2.2 times as long as wide. The first pediger fused to cephalosome, pedigers fourth and fifth fused (Fig. 7: 2).

Genital double somite slightly asymmetrical, with appreciable convexity on each side; curvature on right side more pronounced (Fig. 7: 5). Spermathecae visible in ventral view but difficult to see in lateral view. Anterior part of genital complex protruding strongly ventrally, forming thick wide fold, covering middle part of double somite (Fig. 7: 4).

Antennule of 24 free segments and extending to proximal border of caudal rami (Fig. 7: 2). Mouthparts as in P. tridentatus, with first lobe of maxilliped syncoxa with one seta (Fig. 7: 7); no substantial differences from similar appendages of other species.

Р1-Р4 (Fig. 8: 1–5) of typical structure for genus: endopods one-segmented, exopods three-segmented. Outer distal spine on first segment of P1 exopod extending almost to base of outer proximal spine of third segment. Outer spine of first exopodal segment of Р2 reaching beyond base of spine of second segment; both spines of identical length. Lateral borders of P2 third exopod segment on left and right bearing two spines, proximal part of left segment ornamented with three small denticles (Fig. 8: 2).

Differential diagnosis. The presence of denticles on the outer edge of the third exopodal segment of the left Р2 and the appearance of the genital fields separate this species from other species of the genus. Etymology. The specific name reflects the presence of denticles at the external edge of the distal segment of the left P2 exopod.