Seulocia gagulae, Galil, Bella S. & Ng, Peter K. L., 2015

Galil, Bella S. & Ng, Peter K. L., 2015, Leucosiid crabs from Papua New Guinea, with descriptions of eight new species (Crustacea: Decapoda: Brachyura), Zootaxa 4027 (4), pp. 451-486 : 476-479

Seulocia gagulae sp. nov.

( Figs. 16–18 )

Material examined. Holotype: 1 male (12.6 mm) (MNHN-IU-2013-12758), stn PD73, Yomba I., 05°14.7'S 145°47.3'E, 20–25 m, 6.12.2012. Paratypes: 1 male (12.4 mm) ( ZRC 2015.273), 1 male (10.5 mm), 1 female (13.2 mm) (MNHN-IU-2013-12756), stn PD73, Yomba I., 05°14.7'S 145°47.3'E, 20–25 m, 6.12.2012; 1 male (11.6 mm), 2 females (11.8, 11.5 mm) (MNHN-IU-2013-12755), stn PD63, north Banap Damon Point, 05°09.9'S 145°48.3'E, 0–15 m, 1.12.2012.

Description. Carapace subpentagonal, glabrous; regions of carpace indistinct; dorsal surface smooth, finely punctate ( Figs. 16 A, 17A). Frontal region constricted, produced, laterally concave; frontal margin mucronate. Antennular fossae continuous with orbit, sealed by basal antennular article; antennules fold obliquely within fossa. Antennae short, inserted between antennular fossa, orbit. Eyes retractable. Orbits small, rounded, outer orbital margin entire, anterior margin of efferent branchial channel forms part of lower orbital margin. Third maxillipeds concealing trapezoid buccal cavity; endopod merus triangulate, as long as ischium, planar ( Fig. 16 C); in female, endopod with setose fringe lengthwise, ischium medially keeled ( Fig. 17 B).

Anterolateral margins of carapace oblique, margin minutely beaded ( Fig. 16 B). Lateral angle of carapace prominent, overhanging tomentose thoracic sinus, margin sinuous, distinctly milled. Thoracic sinus shallow, anteriorly defined by straight, smooth margin of pterygostomian region ( Fig. 16 C, D); ventral margin of sinus, above base of cheliped, with row of granules continuous with epimeral ridge. Posterolateral margins of carapace devoid of granulation. Epimeral margin visible in dorsal view, slightly notched medially, shallow gutter-like anteriorly, narrowing posteriorly, continuous with posterior margin ( Figs. 16 A, 17A). Posterior margin nearly horizontal in male, rounded in female ( Figs. 16 A, 17A), slightly deflexed, surface granular ( Fig. 16 H, I).

Chelipeds subequal, robust, slightly longer in adult male than in female ( Figs. 16 A, 17A). Cheliped merus trigonal in cross-section, with pearliform granules on anterior, posterior margins; patch of spongy pubescence proximally on dorsal surface, bordered basally by coalesced cluster of granules ( Fig. 16 A, E), 3 pearliform granules anteriorly; ventral surface pitted proximally, nearly smooth ( Fig. 16 F). Carpus rounded, cluster of granules on inner margin. Propodus somewhat inflated, dorsal margin obscurely beaded, ventral surface with prominently granular rows at inner, outer margins, continuing onto pollex. Fingers as long as dorsal margin of palm ( Fig. 16 E). Ambulatory legs slender, short. Meri of first and second legs with 2 minutely beaded lines on dorsal margin, posterior line short; 2 beaded lines on ventral margin. Meri of third and fourth legs with single beaded line dorsally; 2 beaded lines ventrally ( Fig. 16 G), P5 merus proximally constricted in female, posterior margin prominently crested. Dorsal margin of carpi of ambulatory legs prominently carinate, propodi dorsally, ventrally carinate. Dactyli longer than propodi, dorsoventrally flattened, lanceolate ( Fig. 16 G).

Male abdominal cavity deep, elongated, nearly reaching buccal cavity ( Fig. 16 C). Male abdomen with somite 2 minute; somites 3–6 fused, tapering distally, with a non-articulating suture, constriction at commissure of somites 5, 6, opposite ridge on lateral wall of abdominal cavity, triangular denticle fronted by an indentation, halfway lengthwise; telson triangular ( Fig. 16 D). Female abdomen with somites 3–6 fused, greatly enlarged, shield-like, telson triangular ( Fig. 17 B, C). G1 elongated, shaft straight, twisted once on its axis, distally club-like ( Fig. 18 A– D). G2 short, curved, apex scoop-like ( Fig. 18 E). Vulvae prominent, ovoid; anterolaterally hooded by calcified peaked semi-dome; opening, directed posteriorly, kidney-shaped ( Fig. 17 D).

Colour (alcohol preserved specimens). Dorsal surface of carapace and chelipeds grayish-taupe peppered with fine dark grey dots, paler posteriorly; pearliform granules on cheliped merus yellowish ivory, fingers proximally barred pale yellow. Ambulatory legs whitish, meri tinted yellow distally.

Remarks. The new species is superficially similar to the three Seulocia species with a granular deflexed surface of the posterior carapace margin: S. cristata Galil, 2005 , S. rhomboidalis (De Haan, 1841) and S. vittata (Stimpson, 1858) . Yet, it is easily distinguished from these congeners. The front of S. cristata is strongly deflexed and medially cristate, whereas the front of the new species is neither deflexed nor cristate, but mucronate. The carapace of S. rhomboidalis is only slightly longer than wide, its palms are lenticular, and it bears five red spots on each side of the median line of the carapace, arranged in arcuated diverging lines, whereas the carapace of the new species is 1.3 as long as wide, its palm distinctly longer than wide, and it lacks the red spots. Seulocia vittata has the thoracic sinus anteriorly defined by the granular, overhanging, margin of the pterygostomian region and smooth dorsal margin of the palm, whereas the pterygostomian margin in the new species is smooth, and the dorsal margin of the palm indistinctly beaded.

Etymology. This new species is named after Janet Gagul, Project Officer of the Papua Niugini Expedition in Port Moresby in 2012–2013. Janet was instrumental in facilitating permits and logistics for the expedition, skillfully and efficiently liaising with PNG authorities, administrations, service providers, and scientists.

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

Figures

FIGURE 16. Seulocia gagulae sp. nov. A – G, holotype male (12.6 mm) (MNHN-IU- 2013 - 12758), stn PD 73; H, I, paratype male (12.4 mm) (ZRC 2015.273), stn PD 73. A, overall habitus; B, right lateral view of cephalothorax showing thoracic sinus; C, third maxillipeds, anterior thoracic sternum and abdomen; D, thoracic sternum and abdomen; E, dorsal view of left chela and merus; F, ventral view of left chela and merus; G, right last ambulatory leg; H, I, different views of posterior margin of carapace.

FIGURE 17. Seulocia gagulae sp. nov., paratype female (13.2 mm) (MNHN-IU- 2013 - 12756), stn PD 73. A, overall habitus; B, third maxillipeds, anterior thoracic sternum and abdomen; C, thoracic sternum and abdomen; D, thoracic sternum and vulvae.

FIGURE 18. Seulocia gagulae sp. nov., holotype male (12.6 mm) (MNHN-IU- 2013 - 12758), stn PD 73. A, left G 1 (ventral view); B, left G 1 (dorsal view, denuded); C, distal part of left G 1 (ventral view, denuded); distal part of left G 1 (dorsal view, denuded); E, left G 2. Scales: A, B, E = 1.0 mm; C, D = 0.5 mm.