Tanaoa retpela Galil & Ng, 2015, sp. nov.
Creators: name: Galil, Bella S.
name: Ng, Peter K. L.
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Leucosiidae
Tanaoa
Tanaoa retpela

description: Tanaoa retpela sp. nov.
(Figs. 5 A, 14, 15F–K)
Material examined. Holotype: male (36.5 mm) (MNHN-IU-2013-7961), stn CP3984, Bismarck Sea, northwest Long I., 05°12'S 146°59'E, 500 m, 6.12.2012. Paratypes: 1 male (39.0 mm) (ZRC 2015.272), stn CP3978, Bismarck Sea, north Bagabag Is., 04°45'S 146°12'E, 456–582m, 5.12.2012. Additional material: BIOPAPUA – 1 female (29.5 mm) (MNHN-IU-2011-3835), stn CP3653, west of New Hanover, 02°13’S 150°23’E, 680–700 m, 28.08.2010; 2 males (38.4 mm, 29.8 mm) (MNHN-IU-2011-914), stn CP3655, west of New Hanover, 02°15’S 150°16’E, 402–440 m, 28.08.2010; 1 male (39.1 mm) (MNHN-IU- 2011-2098), stn CP3669, north of Rabaul, 04°08’S 151°56’E, 382–389 m, 24.09.2010; 1 female (28.7 mm) (MNHN-IU- 2011-2481), stn CP3681, Vitu I., 04°38’S 149°27’E, 564–712 m, 27.09.2010; 1 male (28.6 mm) (MNHN-IU- 2011-2478), stn CP3682, Vitu I., 04°38’S 149°28’E, 515–812 m, 27.09.2010; 3 juveniles (11.7–12.5 mm) (MNHN-IU- 2011-2563), stn DW3748, seamounts near Bougainville, 05°37’S 154°01’W, 398–399 m, 12.10.2010; 1 male (21.4 mm) (MNHN-IU- 2011- 2710), stn CP3695, Feni Is., 02°10’S 147°15’W, 198 m, 14.10.2010; 3 females (19.5–21.0 mm) (MNHN-IU- 2011- 2299), stn CP3760, Is., 03°58’S 153°43’W, 613–660 m, 14.10.2010.
Description. Carapace rounded, slightly wider than long, globose; gastric, cardiac, intestinal regions laterally demarcated by deep grooves (Fig. 14 A). Dorsal surface covered densely by rounded, pearliform granules of various sizes; 4 pairs of pits along branchiocardiac line, additional pair on mesogastric region (Fig. 14 A). Intestinal region swollen, anteriorly with rounded median carina, posteriorly with granular tubercle (Fig. 14 A). Front narrow, slightly produced, upturned, closely set with granules, divided into 2 rounded lobes (Fig. 14 A–C). Eyes small, retractable within orbit, minutely granulose eyestalk exposed (Fig. 14 B). Outer orbital margin with 3 sutures. Vshaped 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 (Fig. 14 B, C).
Outer surface of third maxillipeds granular, granules more prominent anteriorly, forming granular ridge mesially on endopod (Fig. 14 C).
Hepatic margin medially with granular tubercle (Fig. 14 B, C). Subhepatic region produced, inflated, with horizontal line medially free of granules (Fig. 14 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. 14 A).
Chelipeds slender, subequal, covered with small granules on all articles, including fingers (Fig. 14 A, F). Cheliped merus, subcylindrical, not nearly as long as carapace; palm subcylindrical, 0.6 as long as merus; fingers longer than dorsal margin of palm, granules arraigned in longitudinal lines, cutting edges denticulate (Fig. 14 A, F). Ambulatory legs slender; decreasing in size posteriorly; merus, carpus, propodus granular, granules more prominent dorsally; dorsal surface of dactylus setose, dactylar tips corneous (Fig. 14 A, G).
Thoracic sternites set with granules of various sizes; sternite 4 anteriorly inflated (Fig. 14 D). Male abdominal cavity deep, nearly reaching buccal cavity, anterior margin of cavity ogive, slightly raised (Fig. 14 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 greatly inflated, granular; subterminally with horizontal ridge, anterior margin with quadrate denticle; telson slender, 1/3 as long as fused somites, not reaching tip of abdominal cavity (Fig. 14 D, E). G1 elongated, slightly sinuous, attenuate, with preapical digitate process perpendicular to tip, opening facing dorsally (Fig. 15 F–J); G2 short, distally scoop-like (Fig. 15 K).
Colour in life. Carapace bright orange-red mottled bone-white. Cheliped merus pale orange, distal part bright orange; palm, fingers mottled pale orange. Ambulatory legs pale (Fig. 5 A).
Etymology. From retpela for “red” or “orange” in Tok Pisin, the Pidgin language spoken in Papua New Guinea. The name is used as a noun in apposition.
Remarks. Tanaoa distincta, T. serenei, T. kuka sp. nov. and T. retepela sp. nov. are all superficially similar in external appearance. Adults, however, are easy to separate using several reliable characters. Ng & Richer de Forges (2007) appraised the taxonomy of T. distincta and T. serenei, noting that the granulation degree and pattern on the carapace was reliable as a character, and their G1 differ. Among the four species, the granules on the carapace are finest in T. kuka sp. nov. (Fig. 13 A, B), T. distincta slightly coarser (Fig. 11 A, B). In T. serenei, the granules are large and densely packed (Fig. 12A, B), while in T. retepela sp. nov. the granules are spaced further apart (Fig. 14 A, B). Tanaoa kuka sp. nov. is distinguished from the named species by its proportionately elongated chela and palm (Figs. 13 A, F, 11A, F, 12A, F, 14A, F). With regards to the ambulatory legs, the meri of T. serenei and T. kuka sp. nov. are proportionately the most slender and longest; but whereas in T. serenei, the meri bear sharp granules (Fig. 12A, G) in T. kuka sp. nov. the meri are smoother (Fig. 13 A, G). The ambulatory meri of T. distincta and T. retepela sp. nov. are proportionately shorter (Figs. 11 A, G, 14A, G). The G1 of T. distincta is distinct in that the distal part has broad folds or is only subtruncate, lacking subdistal processes (Ng & Richer de Forges 2007: fig. 4A–D). The G1 of T. kuka sp. nov. bears a subdistal bifurcate process (Fig. 15C, D). The G1 of T. serenei and T. retepela sp. nov. are superficially similar (Fig. 15 F–J; Ng & Richer de Forges 2007: fig. 4E, F) in that there is a long subdistal process which tapers to a sharp tip. The overall gonopod structure of T. retepela sp. nov. is nevertheless relatively stouter and the subdistal process relatively shorter (Fig. 15 F–J) compared to the more slender one of T. serenei which has a relatively longer subdistal process (Ng & Richer de Forges 2007: fig. 4E, F).
Geographical Distribution. This species is known only from the type locality, Papua New Guinea.
description: Published as part of Galil, Bella S. & Ng, Peter K. L., 2015, Leucosiid crabs from Papua New Guinea, with descriptions of eight new species (Crustacea: Decapoda: Brachyura), pp. 451-486 in Zootaxa 4027 (4) on pages 463-475, DOI: 10.11646/zootaxa.4027.4.1, http://zenodo.org/record/234517