Parasesarma raouli, Rahayu, Dwi Listyo & Ng, Peter K. L., 2009

Rahayu, Dwi Listyo & Ng, Peter K. L., 2009, Two new species of Parasesarma De Man, 1895, from Southeast Asia (Crustacea: Decapoda: Brachyura: Sesarmidae), Zootaxa 1980, pp. 29-40 : 36-37

Parasesarma raouli n. sp.

( Figs. 5 , 6 )

Parasesarma melayuensis Serène — Yang, 1979: 51 (nomen nudum).

Material examined. HOLOTYPE: male (7.1 x 5.6 mm) ( ZRC 1973.11.3.6), Sungei Melayu, Johor Strait, Johor, Peninsular Malaysia, coll. C. L. Soh, 15 August 1969. PARATYPES: 5 males (7.6 x 5.7 mm, 7.6 x 5.7 mm, 8.0 x 6.3 mm, 7.7 x 6.0 mm, 7.3 x 5.3 mm), 1 female (7.6 x 5.7 mm), 1 ovigerous female (7.6 x 5.7 mm), same data as holotype ( ZRC 1973.11.3.7-13). – 2 males (11.0 x 9.0 mm, 9.8 x 8 mm) ( ZRC 1967.11.14.2), 1 ovigerous female (10.0 x 8.0 mm) ( ZRC 1967.11.14.3), 1 male (9.8 x 8.0 mm) ( ZRC 1967.11.14.4), 1 male (9.2 x 7.2 mm) ( ZRC 1967.11.14.5), 1 male (10.8 x 8.0 mm) ( ZRC 1967.11.14.6), 1 male (9.4 x 7.8 mm) ( ZRC 1967.11.14.7), 1 male (8.4 x 7.0 mm) ( ZRC 1967.11.14.8), 1 female (11.0 x 8.6 mm) ( ZRC 1967.11.14.9), Sungei Melayu, Johor Strait, Johor, Peninsular Malaysia, coll. C. L. Soh, 8 January 1967. – 1 female (10.8 x 7.6 mm) ( ZRC 1967.11.14.10), 1 female (11.8 x 8.8 mm) ( ZRC 1967.11.14.11), 1 male (13.4 x 10.0 mm) ( ZRC 1967.11.14.12), 1 female (10.0 x 8.0 mm) ( ZRC 1967.11.14.13), 1 female (7.0 x 5.4 mm) ( ZRC 1967.11.14.14), 1 male (9.6 x 6.4 mm) ( ZRC 1967.11.14.15), Johor Strait, Johor, Peninsular Malaysia, coll. C. L. Soh, 22 January 1966. – 1 male (8.3 x 6.4 mm) ( ZRC 1967.11.14.17), 1 male (7.6 x 6.0 mm) ( ZRC 1967.11.14.18), 1 ovigerous female (7.0 x 5.5 mm) ( ZRC 1967.11.14.19), 1 male (5.9 x 4.8 mm) ( ZRC 1967.11.14.20), 1 female (6.2 x 4.8 mm) ( ZRC 1967.11.14.21), Johor Strait, Johor, Peninsular Malaysia, coll. C. L. Soh, 10 November 1966.

Comparative material. Parasesarma charis Rahayu & Ng, 2005 : Holotype male (10.5 x 8.0 mm) ( MZB Cru 1512), Ajkwa, Timika, Papua, Indonesia, coll. D. L. Rahayu 15 October 2001. – Paratypes: 2 males (10.1 x 7.8 mm, 8.8 x 6.6 mm), 1 female (8.8 x 6.6 mm) ( ZRC 2002.594), 1 ovigerous female (10.0 x 7.5 mm) ( MZB Cru 1513), Kamora, high mangrove forest, Timika, Papua, Indonesia, coll. I. Ermayanti, 11 October 2001. – 1 male (9.8 x 7.4 mm) ( ZRC 2002.595), 1 ovigerous female (10.4 x 9.1 mm) ( MZB Cru 1514), Ajkwa, Timika, Papua, Indonesia, coll. I. Ermayanti, 15 October 2001. Parasesarma anambas Yeo, Rahayu & Ng, 2004 : Holotype male (8.1 x 6.9 mm) ( MZB), northern mangrove inlet, Teluk Jebung, Pulau Jemaja, Anambas Islands, Indonesia, coll. Anambas Expedition 2002 , 13 March 2002. – Paratypes: 1 male (8.1 x 7.1 mm), 1 female (4.2 x 3.4 mm) ( ZRC), 2 females (4.9 x 3.8 mm; 4.8 x 4.0 mm) ( MZB), waterfall, Sungei Temburun, Teluk Baruk, eastern Pulau Siantan, Anambas Is., Indonesia, coll. Anambas Expedition 2002 , 15 March 2002.

Diagnosis. Carapace 1.25 times broader than long; regions well defined; postfrontal regions distinct, separated into 4 lobes; frontal margin bilobed from dorsal view, each lobe broadly convex; external orbital tooth directed obliquely outwards; eyes extending slightly beyond lateral edge of external orbital tooth; upper surface of palm with 3 transverse, pectinated crests with 15–17, 2–15 and 6 corneous teeth respectively; outer surface of palm proximally striated, smooth to gently granular distally, inner surface of palm with several tubercles; dorsal surface of dactylus with 23 or 24 symmetrical tubercles, all distinct, small, upper surface with longitudinal ridge up to distal third, inner surface with longitudinal ridge; ambulatory legs long, slender, about 1.7 times carapace width; merus of third leg 2.8 times as long as wide; anterior margin of merus with acute subdistal spine; propodus of third leg almost 4 times as long as wide; dactylus 0.6 times length of propodus; male telson semicircular, as long as somite 6; G1 slender, apical process bent to form an angle of 45º, strongly produced, corneous part tapering, ending in truncate tip.

Description. Carapace 1.25 times broader than long; mesogastric, cardiac regions well defined, intestinal region moderately defined; lateral carapace surfaces lined with strong oblique striae; carapace surface glabrous, lateral margins with short setae. Postfrontal regions distinct, separated into 4 lobes by narrow grooves, median lobes larger than lateral lobes. Front deflexed downwards, margin bilobed from dorsal view, each lobe broadly convex, separated by very broad median concavity. Supraorbital margin gently convex, entire. External orbital tooth triangular, directed obliquely outwards, representing point of greatest width; contiguous with entire lateral carapace margin; antero-and posterolateral margins not demarcated, without trace of tooth or indentation, lateral margin sinuous, subparallel along most of length before curving to join almost straight posterior carapace margin. Eyes extending slightly beyond lateral edge of external orbital tooth. Antennal and antennular basal segments adjacent, not separated by septum; basal antennular segment swollen. Antennal flagellum relatively long, entering orbit. Ischium of third maxilliped with shallow median sulcus, merus with distinct submedian ridge; exopod slender, tip reaching to half length of outer margin of merus, flagellum long; inner margins of merus and ischium with long setae, proximal outer margin of ischium, base of exopod with long dense setae.

Chelipeds subequal, large, relatively robust in males. Merus with outer margin carinate, minutely tuberculate, without subdistal spine; inner margin with minute spines ending in large subdistal spine; outer surface with striation, inner surface with 2 longitudinal rows of setae. Carpus with inner angle not produced, outer margin, across dorsal surface striated, with few setae. Upper surface of palm with 3 transverse, pectinated crests. Primary crest composed of 15–17 high, narrow corneous teeth; second crest well developed, slightly shorter than primary crest, with 12–15 broader, more widely spaced corneous teeth; third crest with 6 much lower, broader, widely spaced chitinous teeth, followed by several blunt tubercles; several tufts of short setae present anterior of first crest, rows of small tubercles behind third crest. Outer surface of palm proximally striated, smooth to gently granular distally, glabrous; inner surface of palm with several tubercles. Fixed finger rounded, smooth on outer surface; inner surface with ventral ridge, moderately long. Length of cutting edge 0.3 times length of propodus. Cutting edge of fixed finger and dactylus with small, large rounded teeth. Dorsal surface of dactylus with 23 or 24 symmetrical tubercles, all distinct, small, closely spaced proximally, becoming larger, more widely spaced distally; upper surface with longitudinal ridge up to distal third, inner surface with longitudinal ridge. Several low tubercles on proximal third between inner and outer ridges, dactylar tubercles. Fingers with chitinous tips; adult males without gape when fingers closed.

Ambulatory legs long, slender, laterally flattened; second, third pairs subequal, longer than others, about 1.7 times carapace width. Merus of third leg 2.8 times as long as wide; anterior margin of merus with an acute subdistal spine. Meri of legs 1–4 each with transverse striae on upper surface. Carpi of legs 1–4 each with 2 accessory carinae on outer surface. Propodus of third leg almost 4 times as long as wide with accessory carina on inferior proximal portion of outer surface, dorsal, ventral margins with prominent long stiff setae. Dactylus 0.6 times length of propodus, tip slightly recurved, terminating in acute calcareous tip, dorsal, ventral margins with prominent long stiff setae.

Surfaces of thoracic sternites 1–3 setose. Sternites 1–3 completely fused. Sternites 3, 4 separated by low ridge lined with short, dense setae. Abdominal cavity reaching just below low ridge separating sternites 3, 4. Male abdomen relatively broad. Telson semicircular, evenly rounded, as long as preceding somite; somite 6 almost twice as long as wide, lateral margins slightly convex. Somites 3–5 progressively more trapezoidal, lateral margins of somites 4, 5 straight, lateral margins of somite 3 strongly convex, somites 1, 2 very narrow longitudinally. G1 relatively slender, straight; apical process bent to form an angle of 45º, strongly produced, corneous part long, tapering, ending in truncate tip; setae long, simple, originating at base of apical process, on palp. G2 very short, less than quarter length of G1.

Female with relatively smaller chelipeds, first pectinated crest on palm distinct, second, third crests not well developed, dactylar tubercles indistinct.

Etymology. Raoul Serène was the first to recognize this as a new species and proposed the name “ melayuensis ” for it but the name was never published. Both authors have the highest respect for a man we regard as one of the greatest carcinologists of the 20th Century, and as such, feel that it is much more appropriate to name the new taxon after him.

Remarks. Among the group of relatively long-legged species of Parasesarma , P. raouli n. sp. most closely resembles P. prashadi ( Chopra & Das, 1937) , P. anambas Yeo, Rahayu & Ng, 2004 , and P. charis Rahayu & Ng, 2005 , in having three pectinated crests on the cheliped palm. The number of dactylar tubercles is 27 in P. prashadi ( Chopra & Das 1937: Fig. 7), while in P. raouli n. sp. it is 23 or 24 ( Fig. 5 C, D), and the G1 of P. prashadi has a short and wide corneous tip ( Chopra & Das 1937: text fig. 20b, c) whereas that of P. raouli has a long, tapering tip. Although the shape of the G1 of P. raouli n. sp. is similar to that of P. anambas ( Fig. 6 A, B), P. raouli n. sp. has 23 or 24 dactylar tubercles, closely spaced proximally ( Fig. 5 C, D), while in P. anambas , it is more distantly spaced and only 17 in number. Furthermore, the lateral margin of the carapace is strongly sinuous in P. raouli n. sp. ( Fig. 5 A) (only slightly so in P. anambas ), and the male abdomen of P. raouli n. sp. is proportionately less wide ( Fig. 6 C). Parasesarma charis differs in the shape of its G1, which is slightly bent, with a large, long and truncated tip, while that of P. raouli n. sp. is distinctly bent with a tapering tip ( Fig. 6 A, B). In addition, P. r a o u l i n. sp. has 23 or 24 dactylar tubercles with a longitudinal ridge on the distal third of the upper and inner surfaces of the dactylus ( Fig. 5 C, D) while P. c h a r i s has 27 to 28 dactylar tubercles and there is no longitudinal ridge on the same area of the dactylus.

Figures

FIGURE 5. Parasesarma raouli n. sp. Holotype male (7.1 x 5.6 mm) (ZRC 1973.11.3.6), Kuantan, Pahang, Peninsular Malaysia. A, overall dorsal view; B, thoracic sternum and abdomen; C, frontal regions; D, outer view of right chela; E, dorsal view of dactylus of right chela showing tubercles.

FIGURE 6. Parasesarma raouli n. sp. Holotype male (7.1 x 5.6 mm) (ZRC 1973.11.3.6), Kuantan, Pahang, Peninsular Malaysia. A, B, left G 1 s (denuded); C, abdomen. Scales = 1.0 mm.