New genera and new species of Hexapodidae (Crustacea, Brachyura) from the Indo-West Pacific and east Atlantic Author Rahayu, Dwi Listyo Author Ng, Peter K. L. text Raffles Bulletin of Zoology 2014 2014-07-04 62 396 483 journal article 10.5281/zenodo.5353945 2345-7600 5353945 4CF42744-861A-4635-9703-E6639CEBFAA9 Hexapinus latus , new species ( Figs. 16 , 17 ) Material examined. Holotype : female (8.1 × 5.0 mm) ( MZB Cru 3918), Kecinan, Lombok, Indonesia , coll. 15 May 2007 . Paratype : Indonesia : 1 female (6.5 × 4.0 mm) ( ZRC 2013.1691 ), Sira , northern Lombok , Indonesia , coll. 21 July 2009 . Diagnosis. Carapace subquadrate, about 1.6 times as broad as long, dorsal surface very smooth, region indistinct, median H-shaped depression shallow; some small granules present on dorsolateral margins, only scattered tiny granules on posterior margin ( Fig. 16A ). Anterolateral margin arcuate, posterolateral margin sinuous with 1 protuberance; posterolateral corner with angled prominence over base of posterior pereopods; lateral margin of carapace wall produced medially. Front deflexed ( Fig. 16C ). Orbit distinct, eye small, slightly movable, cornea pigmented ( Fig. 16C ). Pterygostomial region with row of oblique striae. Third maxillipeds relatively broad ( Figs. 16B , 17B ); ischium 1.1 times as broad as long, longer than merus, strongly expanded distomesially, with rounded mesial margin; combined length of dactylus, propodus and carpus shorter than that of merus and ischium; exopod narrow, about 0.3 times width of ischium, flagellum well developed. Chelipeds stout, unequal ( Fig. 16C ); major chela gaping when fingers closed; palm slightly wider than long, outer surface smooth, tubercles on upper margin; minor chela with narrower gap between closed fingers ( Fig. 16C ). P2–P4 ( Fig. 16A ) short, stout, P3 longest; merus of P4 about 2 times as long as broad; dactylus longer than propodus; dactylus of P4 slightly upcurved. Female thoracic sternum broad ( Figs. 16B ), sternites 1 and 2 fused, separated from sternite 3 by distinct ridge; sternite 3 separated from sternite 4 by distinct ridge. Female abdomen broad ( Figs. 16B , 17C ) with 6 free somites and subtriangular telson. Colour. In life, the carapace and appendages are creamishwhite overall. Etymology. From the Latin latus for broad/wide, alluding to the broad carapace. Remarks. Although only female specimens were available, this species clearly belongs to Hexapinus as it has a broad and mesially convex ischium of the third maxilliped, and the P2–P4 are short. The broad carapace of H. latus , new species , is similar to H. simplex , new species . However, comparisons of similar-sized females show that H. latus has a proportionately broader abdomen with the telson as long as somite 6 ( Fig. 17C ) while in H. simplex the abdomen is narrow and the telson is shorter than the sixth abdominal somite ( Fig. 21D ). In addition, the merus of the third maxilliped of H. latus is shorter than the ischium ( Fig. 17B ), while in H. simplex , the merus is longer than the ischium ( Fig. 20G ). The posterolateral margin of the carapace of H. latus has only one protuberance ( Fig. 16A ) while in H. simplex it always has two protuberances ( Fig. 18B ). The dorsal carapace surface of H. latus is very smooth ( Fig. 16A ); specimens of H. simplex the size of H. latus on the other hand, are always distinctively pitted ( Fig. 18 ). Fig. 16. Hexapinus latus , new species , holotype female (8.1 × 5.0 mm) (MZB Cru 3918). A, overall view of carapace, chelipeds and P2–P4; B, ventral view of cephalothorax; C, frontal view of cephalothorax. Fig. 17. Hexapinus latus , new species , holotype female (8.1 × 5.0 mm) (MZB). A, dorsal view of carapace; B, left third maxilliped; C, abdomen and telson. Scale bars: A, C = 1.0 mm; B = 0.5 mm. Although H. latus was collected in the same island as H. simplex , the differences discussed above argue against them being conspecific. The habitats of also appear to be somewhat different. The specimens of H. latus were collected from coarse white sand in shallow depressions in the reef flat. The area had previously been mined for building material by local villagers. The area is always filled with some water, even during low tide. Hexapinus simplex on the other hand seems to prefer finer substrates (see next species). Hexapinus latus also differs from H. latipes in having broad female abdomen. In a female specimen of H. latipes (10.2 × 7.6 mm , NSMT-Cr 5694), which is slightly larger than the female type specimens of H. latus , the abdomen is still narrow and resembles that of a male ( Fig. 17C versus Fig. 13G ). The female abdomens of both H. latus and H. ceres , even though they are relatively small, are already broad. Hexapinus latus and H. ceres are easily distinguished; the carapace surface, chelipeds and P2–P4 of H. latus are smooth ( Fig. 17A ) but in H. ceres , these are covered with closely spaced granules ( Fig. 14A ). Type locality. Kecinan , Lombok , Indonesia Distribution. North coast of Lombok Island, Indonesia . Intertidal.