Scandarma raymondi, Ng, Peter K. L., 2013

Ng, Peter K. L., 2013, A new species of Scandarma (Crustacea: Brachyura: Sesarmidae) from Sabah, Borneo, Malaysia, Zootaxa 3652 (2), pp. 289-294 : 289-293

Scandarma raymondi sp. nov.

( Figs. 1–3 )

Material examined. Holotype: male (12.9 x 11.9 mm) (ZRC 2013.0614), 200 m asl, mixed forest with flowering plants and bamboo, crawling across small road near Conservation Building, Sabah Museum compound, adjacent to small stream about 1.6 km from sea, Kota Kinabalu, Sabah, Malaysia, coll. R. Goh, 1 November 1990.

Diagnosis. Carapace quadrate, wider than long ( Fig. 1 A, B); external orbital tooth triangular, directed anteriorly; epibranchial teeth almost undiscernible, lateral margin with 2 small crenulations ( Fig. 1 A, B); exopod of third maxilliped slender, with long flagellum ( Figs. 3 A); dorsal margin of palm with longitudinal row of 19–22 small, rounded granules along entire length ( Fig. 2 B, C); dorsal margin of dactylus of chela with 5 or 6 sharp granules with pectinated tips ( Fig. 2 B, C); ambulatory legs not elongated ( Fig. 1 A); male abdomen bell-shaped; lateral margin of somite 6 convex, telson as long as somite 6 ( Figs. 2 A, 3B); G1 stout, short, distal part chitinous, bent outwards at around 45°, forming beak-like structure ( Fig. 3 C–F).

Description. Carapace quadrate, wider than long; dorsal surface almost smooth, with flattened granules on anterior half, glabrous, slightly convex longitudinally, transversely, regions well defined, separated by shallow grooves ( Fig. 1 A, B). Front prominent, surface of frontal region concave; frontal margin sharply deflexed downwards, slightly sinuous, vaguely divided into broad lobes; postfrontal cristae distinct, sharp; median pair broader, separated by deep Y-shaped furrow, separated from lateral pair by shallower groove; approximately level with base of ocular peduncle. Lateral regions covered with low, oblique striae ( Fig. 1 A, B). Posterior carapace margin almost straight ( Fig. 1 A, B). Supraorbital margin gently curved, smooth, entire, contiguous with external orbital tooth ( Fig. 1 B). Infraorbital tooth low, reaching about halfway to outer angle of frontal margin; antenna short, basal antennal article adjacent to antennules, not separated by ridge; antennal flagellum short, enters orbit; infraorbital margin relatively narrow, outer part granular; suborbital region with transverse depression along infraorbital margin ( Fig. 1 C). Epistome distinct, covered by short setae, posterior margin with 5 triangular lobes, lateral margin concave ( Fig. 1 C). External orbital tooth triangular, sharp, tip directed anteriorly; epibranchial teeth almost undiscernible, lateral margin with 2 small crenulations marking rudimentary teeth; lateral margins slightly diverging ( Fig. 1 A, B). Orbit large, cornea subequal in width to base of short peduncle ( Fig. 1 B, C). Third maxilliped with distinct rhomboidal gape between inner margins; merus ovate, almost as long as ischium; ischium with oblique median sulcus; exopod slender, almost completely hidden behind endopod when appressed against it, with long flagellum, as long as width of merus ( Figs. 1 C, 3A).

Male chelipeds subequal; basis-ischium with tuberculated inner margin; merus short, with short transverse rows of flattened tubercles on outer surface, dorsal margin granular, ventral margins serrated, distal inner part slightly foliaceous ( Fig. 1 A, B). Outer surface of carpus with flattened granules, inner distal angle rounded, without spine or tooth ( Figs. 1 A, B). Palm relatively high, thick; outer, inner surfaces granular, inner surface slightly swollen, with numerous granules, base of pollex with large tubercle; outer surface with low oblique swelling near base of pollex, ventral margin with 3–5 sharp granules, those on proximal half larger; dorsal margin with low continuous longitudinal row of 19–22 small granules adjacent to carpus to base of finger, granules rounded without pectinated tip ( Figs. 1 B, 2B, C). Tips of fingers corneous, scalloped on inner surface. Pollex with large and small teeth on cutting edge, 2 large teeth on proximal quarter just proximal to tip, median tooth largest, inner subventral margin with 4–6 sharp granules. Dactylus curved, dorsal margin with 5 or 6 sharp granules with pectinated tips, first granule with 2 rounded granules adjacent to it, distal ones lower; cutting edge with various sized teeth, large tooth just before tip, 2 large subproximal teeth ( Figs. 1 B, 2B, C).

Ambulatory legs slender, not elongated; second longest when stretched laterally; coxae with setae on anterior surfaces, tuft of setae distinct on second, third legs; meri with rough dorsal surface; dorsal, ventral margins slightly cristate, subdistal angle of dorsal margin with low but distinct tooth; carpi with 1 or 2 longitudinal ridges on outer surface; dactylus with distal part sharp, corneous; propodi, dactyli lined with short bristles ( Fig. 1 A).

Anterior thoracic sternum broadly triangular; surface smooth; sternites 1, 2 fused, forming triangular plate, separated from fused sternites 3, 4 by prominent straight groove; lateral margins of sternites 3, 4 concave, cristate, weakly granular ( Fig. 2 A). Sternoabdominal cavity deep, reaching imaginary line between anterior margin of coxae of chelipeds ( Fig. 2 A); sternites 4–7 medially interrupted; deep longitudinal median groove present between sternites 7, 8; male abdominal locking mechanism is peg-like edge of posterior margin of sternite 4 on sternoabdominal cavity, no visible tubercle on sternite 5. Abdomen bell-shaped; somite 4 abruptly narrowed, somites 4–6 trapezoidal, lateral margin of somite 6 convex; telson longer than wide, as long as somite 6 ( Figs. 2 A, 3B).

G1 stout, short, lateral margins gently sinuous, subdistal inner margin smoothly curved outwards, subdistal part as wide as subproximal part; distal part short, chitinous, bent outwards at around 45°, forming beak-like structure, tip rounded ( Fig. 3 C–F). G2 stout, short, tip bilobed ( Fig. 3 G).

Colour. The specimen has lost almost all its colour. The carapace was yellowish-brown and the chelipeds yellow when freshly preserved in alcohol.

Etymology. The species honours an old friend, Raymond Goh, who during his years as curator of zoology at the Sabah Museum, made many important contributions to his state’s biodiversity, and generously helped the author with his fish and crustacean studies in Sabah in the 1990s.

Remarks. Compared to S. splendidum which was described from Sarawak, the carapace of S. raymondi sp. nov. is proportionately wider ( Fig. 1 A, B) (Naruse & Ng 2007: figs. 1, 2a); the granules along the longitudinal row on the dorsal margin of the palm are more widely spaced ( Fig. 2 C) (more closely packed in S. splendidum, Naruse & Ng 2007: fig. 1); the ambulatory legs are proportionately shorter ( Fig. 1 A) (Naruse & Ng 2007: figs. 1, 2d); the male abdomen is proportionately broader, especially somite 6 ( Fig. 2 A, 3B) (Naruse & Ng 2007: fig. 2e); and the G1 has the distal pectinated part relatively stouter and less strongly bent ( Fig. 3 C–F) (Naruse & Ng 2007: fig. 3a– c). The colour in life is quite different. In S. splendidum , the dorsal surface of the carapace is mostly blackishbrown or with the anterior parts red or orange, the chelae being bright red orange (Naruse & Ng 2007: Fig. 1 ). The carapace is a more uniform yellowish-brown in life and the chelae yellow in S. raymondi sp. nov.

The male abdomen of S. raymondi sp. nov. ( Figs. 2 A, 3B) is similar to that of S. lintou Schubart, Liu & Cuesta, 2003 , described from Taiwan (Schubart et al. 2003: fig. 3C; Maenosono & Naruse 2011: fig. 2F), but the other characters are substantially different. The external orbital angle of S. lintou is more acutely triangular and relatively longer (Schubart et al. 2003: fig. 1A, B; Maenosono & Naruse 2011: figs. 1A, 2A) but it is more broadly triangular and relatively shorter in S. raymondi sp. nov. ( Fig. 1 A, B). There are also relatively fewer granules along the longitudinal row of the dorsal margin of the dactylus of the male chela in S. raymondi sp. nov. ( Fig. 2 C) (Schubart et al. 2003: fig. 2A–C; Maenosono & Naruse 2011: fig. 2C), the ambulatory legs are distinctly shorter ( Fig. 1 A) (much longer in S. lintou ; Schubart et al. 2003: fig. 1A), and the G1 is proportionately longer than in S. lintou , with the distal pectinated part relatively more slender ( Fig. 3 C–F) (see Schubart et al. 2003: fig. 4). Their colours in life are quite different, with S. lintou possessing a prominent white margin along the lateral carapace margin (Schubart et al. 2003: figs. 1A, B, 5; Maenosono & Naruse 2011: figs. 1A, 2A), a character visible even in recently preserved specimens. This margin is absent in S. raymondi sp. nov. even when it was first collected.

All Scandarma species have been collected from near the sea and have been found associated with trees and shrubs (Schubart et al. 2003; Naruse & Ng 2007; Maenosono & Naruse 2011). S. raymondi sp. nov. was found in an area with dense vegetation and is probably likely to be an arboreal or partially arboreal species. The type locality of S. raymondi sp. nov. is adjacent to a river less than two kilometres from the sea.

Figures

FIGURE 1. Scandarma raymondi sp. nov., holotype male (12.9 x 11.9 mm) (ZRC 2013.0614), Sabah, Malaysia. A, overall view; B, dorsal view of carapace; C, frontal view of carapace.

FIGURE 2. Scandarma raymondi sp. nov., holotype male (12.9 x 11.9 mm) (ZRC 2013.0614), Sabah, Malaysia. A, anterior thoracic sternum and abdomen; B, outer view of left chela; C, dorsal view of left chela.

FIGURE 3. Scandarma raymondi sp. nov., holotype male (12.9 x 11.9 mm) (ZRC 2013.0614), Sabah, Malaysia. A, left third maxilliped; B, abdominal somites 3 – 6 and telson; C, left G 1, ventral view; D, left G 1, dorsal view; E, left G 1 distal part, ventral view; F, left G 1 distal part, dorsal view; G, left G 2. All structures denuded. Scales A, B = 2.0 mm, C – G = 0.5 mm.