Alox naispela, 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 : 453

Alox naispela sp. nov.

( Figs. 2 A, B, 6A–E, 8A)

Material examined. Holotype: 1 ovigerous female (8.3 mm) (MNHN-IU-2013-1352), stn PD31, Alexishafen, 05°05.3'S 145°48.1'E, 1–6 m, 17.12.2012. Paratypes: 1 immature female (6.3 mm) (MNHN-IU-2013-1193), stn PD66, south Yabob I., 05°15.5'S 145°47.3'E, 2–6 m, 3.12.2012; 1 immature female (6.6 mm) ( ZRC 2015.269), stn PD73, Madang, 6.12.2013.

Description. Carapace ( Fig. 6A–D ) laterally expanded, 1.5 times as wide as long, irregularly rimmed, dorsal surface prominently sculpted, pitted, irregularly covered with coalesced flattened granules, resembling eroded coral rubble. Front narrow, produced, upcurved, bilobed, medially deeply pitted. Anterior margin of carapace vertical. Antennule well developed, basal antennular article operculiform, rugose, entirely sealing subovate antennular fossa. Antennae folded in orbital hiatus without gap. Orbits small, rounded, visible in dorsal view; ocular peduncle nearly seals orbit when retracted. Third maxillipeds concealing buccal cavity, closely set with flattened granules ( Fig. 8A ); merus with pointed apex, outer margin convex, surface with median shallow depression; ischium twice as long as merus along inner margin.

Anterior, lateral margins of carapace upturned to form granular rim; posteriorly, margin forms granular ridge merging with branchial protuberances. Anterolateral margin with 2 closed fissures, subhepatic margin with angular, granular, facet medially, visible in dorsal view. Posterolateral margin with prominently granular angular facet submedially. Posterior margin produced, narrow, bilobate. Postfrontal median longitudinal ridge narrow, distinct, merging into cardiac region; on either side of ridge slightly anterior to branchial regions a granular protuberance, pitted anteriorly. Bottom of depression between anterolateral rim, swollen branchial regions lined with flattened granules. Branchial regions swollen, with irregular cluster of granules. Granule-lined grooves separate cardiac, intestinal regions from branchial regions. Intestinal region swollen. Branchiostegal region covered with obsolete granules, medially demarcated by faint longitudinal suture.

Chelipeds ( Fig. 6E ) subequal, robust, covered with flattened granules. Cheliped palm inflated, minutely granular; fingers 1.5 as long as palm; dactylus with longitudinal rows of closely spaced granules on outer surface; pollex, wider than dactylus, with carinate ventral margin; cutting edges with minute teeth. Ambulatory legs stout, short, closely granular, diminishing in size posteriorly; meri with single granular row dorsally, 2 rows ventrally; propodi with row of conic granules ventrally; dactyli slender, longer than propodi, studded with conic granules, terminating in incurved cornute claw.

Thoracic sternum closely granular. Female abdominal cavity deep, reaching buccal cavity. Abdomen closely covered with flattened granules; abdominal somites 1, 2 narrow, horizontal; somites 3–6 fused shield-like, divided by 2 submedian furrows; telson laciniate. Vulvar sternal cover oval, large kidney-shaped opening directed interiorly.

Colour in life. Carapace bone-coloured, carapacial pits and grooves brown, female abdomen with 2 pairs of brown dots; dorsal margin of cheliped merus medially with 3 dark red granules, fingers spotted dark red; dorsal margins of ambulatory legs with dark red blotches ( Fig. 2 A, B).

Remarks. Alox naispela sp. nov. closely resembles A. patella (Alcock, 1896) (type locality: Andaman Is.) in the general appearance of the carapace, with its distinct rim formed by the upturned margins. It is distinguished from the latter, however, by its proportionately longer fingers (1.5 as compared to 1.2 as long as palm in A. patella, Tan & Ng 1995 : fig. 11A), dorsal surface of carapace with coalesced flattened granules rather than large mushroom-like granules, groove parallel to anterior margin of carapace nearly obsolete rather than distinct; and branchiostegal region covered with obsolete granules rather than large mushroom-like granules ( Tan & Ng 1995: pl. 6A–C).

Etymology. From naispela for “beautiful” in Tok Pisin, the Pidgin language spoken in Papua New Guinea. Used as a noun in apposition.

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

Figures

FIGURE 2. Colours in life. A, Alox naispela sp. nov., holotype ovigerous female (8.3 mm) (MNHN-IU- 2013 - 1352), stn PD 31; B, Alox naispela sp. nov., paratype female (6.3 mm) (MNHN-IU- 2013 - 1193), stn PD 66; C, Alox rugosum, male (7.3 mm) (MNHN-IU- 2013 - 8854), stn PR 69; D, Alox rugosum, female (5.9 mm) (ZRC 2015.268), stn PD 19; E, Alox liklik sp. nov., holotype ovigerous female (8.3 mm) (MNHN-IU- 2013.8855), stn PR 152.

FIGURE 6. A – E, Alox naispela sp. nov., holotype ovigerous female (8.3 mm) (MNHN-IU- 2013.1352), stn PD 31; F – J, Alox liklik sp. nov., holotype female (8.3 mm) (MNHN-IU- 2013.8855), stn PR 152. A, F, overall habitus; C, H, frontal view of cephalothorax; D, I, right lateral view of cephalothorax; E, J, outer view of right chela; F, G, ventral surfaces, thoracic sternum and abdomen.

FIGURE 8. A, Alox naispela sp. nov., paratype female (6.6 mm) (ZRC 2015.269), stn PD 73; B, D, E – H, Alox rugosum, male (5.8 mm) (ZRC 2015.267), stn PB 12; C, Alox liklik sp. nov., holotype ovigerous female (8.3 mm) (MNHN-IU- 2013 - 8855), stn PR 152; I, J, K, Alox rugosum, male (7.3 mm) (MNHN-IU- 2013 - 8854), stn PR 69. A – C, left third maxilliped; D, right last ambulatory leg; E, male abdomen; F, G, I, J, left G 1; H, K, right G 2. Scales: A – E = 1.0 mm; F – K = 0.5 mm.