Tanaoa kuka sp. nov.

(Figs. 4 F, 13, 15A–E)

Material examined. Holotype: male (33.0 mm) (MNHN-IU-2013-7963), stn CP3984, Bismarck Sea, northwest Long I., 05°12'S 146°59'E, 500 m, 6.12.2012. Paratypes: 3 males (32.4 mm, 33.8 mm, 32.5 mm) (MNHN-IU- 2013-17899), 1 male (33.1 mm) (ZRC 2015.271), same data as holotype; 1 immature male (18.9 mm) (MNHN-IU- 2013-8886), stn CP3979, north Bagabag Is, 04°44'S 146°11'E, 540–580 m, Bismarck Sea, 5.12.2012.

Comparative material. Tanaoa distinctus (Rathbun, 1894): 1 male (37.5 mm), 1 female (ZRC 2000.535), station 34, TC33, Hawaiian Islands, coll. Townsend Cromwell. Tanaoa serenei (Richer de Forges, 1983): 1 male (33.2 mm) (ZRC 2000.565), Tumon Bay, Guam, 400 m, in fishtrap, coll. S. Annesbury, 10.1999.

Description. Carapace rounded, slightly longer than wide, globose; cardiac, intestinal regions laterally demarcated by grooves (Fig. 13 A). Dorsal surface covered densely by rounded granules of various sizes, granules somewhat larger, conical, on branchial regions; 4 pairs of pits along branchiocardiac line (Fig. 13 A, B). Intestinal region swollen, medially marked with granular tubercle, directed posteriorly (Fig. 13 A). Front narrow, slightly produced, upturned, closely set with granules, divided into 2 subtriangular lobes by minutely setose gap (Fig. 13 A– C). Eyes small, retractable within orbit, setose eyestalk exposed. Outer orbital margin with 3 sutures. V-shaped gap proximally on ventral margin. Antennular fossae below frontal lobes oblique, antennules obliquely folded, basal antennular operculiform, sealing lower half of antennular aperture when retracted. Antennae small, slender, basal antennal article inserted in orbital hiatus. Postorbital region concave. Anterior margin of efferent branchial channel convex, produced, bilobed, separated by narrow groove from lower orbital margin. Outer surface of third maxillipeds granular, granules more closely set, larger anteriorly, forming granular ridge mesially on ischium (Fig. 13 B, C).

Subhepatic region produced, angular, furnished with subconical granules, medially with granular tubercle (Fig. 13 B, C). Epibranchial margin with 3 equidistant granular tubercles (Fig. 13 A). Posterolateral margins rounded. Posterior margin of carapace narrow, laterally with 2 prominently granular tubercles (Fig. 13 A).

Chelipeds slender, subequal, covered with small granules on all articles, including fingers (Fig. 13 A, F). Cheliped merus, subcylindrical, 1.2 as long as carapace; palm subcylindrical, 0.6 as long as merus, fingers 0.6 as long as dorsal margin of palm, inner margins obsoletely denticulate. Ambulatory legs slender; decreasing in size posteriorly; merus, carpus, propodus granular, granules more prominent dorsally; dorsal surface of dactylus setose, dactylar tips corneous (Fig. 13 G).

Thoracic sternites (Fig. 13 D) closely set with flattened granules. Male abdominal cavity deep, nearly reaching buccal cavity, anterior margin ogive, slightly raised (Fig. 13 C, D). Male abdomen triangular, elongated; abdominal somites 1, 2 transversely narrow; somite 1 yoke-like, somite 2 medially convex as it fits into cavity of somite 1; somites 3–6 fused, proximo-lateral regions inflated, granular, distal margin with triangular denticle; telson slender, 1/3 as long as fused somites, not reaching tip of abdominal cavity (Fig. 13 D). G1 elongated, slightly sinuous, attenuate, with small but distinct preapical bifurcated snout-like process perpendicular to tip, opening facing dorsally (Fig. 15A–D); G2 short, distally scoop-like (Fig. 15E).

Colour in life. Dorsal surface of carapace and chelipeds bright orange-red. Ambulatory legs pale, meri banded in red (Fig. 4 F).

Etymology. Kuka for “crab” in Tok Pisin, the Pidgin language spoken in Papua New Guinea. The name is used as a noun in apposition.

Remarks. See discussion for T. retpela sp. nov.

Geographical distribution. This species is known only from the type location, Papua New Guinea.