Parasesarma limbense (Rathbun, 1914)

Li, Jheng-Jhang, Rahayu, Dwi Listyo & Ng, Peter K. L., 2018, Identity of the tree-spider crab, Parasesarma leptosoma (Hilgendorf, 1869) (Decapoda: Brachyura: Sesarmidae), with descriptions of seven new species from the Western Pacific, Zootaxa 4482 (3), pp. 451-490 : 456-460

Parasesarma limbense (Rathbun, 1914)

( Figs. 2I –N , 3 )

Sesarma (Holometopus) limbense Rathbun, 1914: 79 .

Sesarma (Holometopus) limbensis, Tesch 1917: 169 (list), 237 (key).

Material examined. LECTOTYPE: male (7.1× 6.8 mm) ( USNM 45920 ) (here designated), Indonesia: North Sulawesi: Lembeh Island , 12 November 1909 . PARALECTOTYPES: 2 females (13.1× 11.6 mm, 12.6× 11.4 mm) ( USNM 120523 ), same data as lectotype .

Diagnosis. Carapace ( Figs. 3A, H, I ) squarish in general outline, 1.1 times broader than long; regions well defined, separated by shallow grooves; postfrontal region distinct, separated into 4 lobes by shallow grooves; frontal margin nearly straight; lateral margin straight, subparallel most of length before curving to join almost straight posterior carapace margin; cornea reaching tip of external orbital tooth ( Figs. 3A, H, I ). Ischium of third maxilliped with shallow median sulcus, merus with distinct submedian ridge; exopod slender, tip reaching halflength of outer margin of merus, flagellum long ( Fig. 2N ). Male cheliped palm with 2 transverse pectinate crests (c. 10–18 corneous teeth, distal and proximal crests, respectively) on upper surface; upper surface of dactylus with 9 symmetrical, obliquely elongate dactylar tubercles, proximal 3 tubercles large, tubercles 4–7 small, smaller distally, distalmost tubercle indistinct ( Figs. 3D, E ). Ambulatory legs relatively slender for this species-complex, P3 and P4 about 1.8 times carapace width; P3 and P4 coxae without dense setae; P3 merus 2.6 times as long as broad; P3 propodus 4.4 times as long as broad; P3 dactylus 0.4 times length of propodus ( Fig. 3G ). G1 relatively stout; apical process corneous, relatively short, slightly bent at angle of 60°, ending in truncated tip ( Figs. 2I –M ). G2 condition not known.

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Colour in life. Not known.

Remarks. Parasesarma limbense was originally described on the basis of one male and two female specimens (including one ovigerous) from Limbe (= Lembeh Island), Sulawesi, Indonesia. It has been regarded as a junior synonym of P. leptosoma by Serène (1968) without comment, and this was followed by Ng et al. (2008). Rahayu & Ng (2009) questioned the synonymy but did not resolve the matter. We have examined the three type specimens of P. limbense in the USNM and confirmed that the taxon is specifically distinct from P. leptosoma . The most noticeable difference is seen in the shape of the carapace, which is squarish ( Figs. 3A, H, I ), and the form of G1, which is relatively slender with a truncate tip in P. limbense ( Figs. 2I –M ). In P. leptosoma , by contrast, the carapace is trapezoidal with posteriorly converging lateral margins ( Figs. 1A, E, G , 2A ), and the G1 is relatively stout with a rounded tip ( Figs. 2E–H ). Other characters that distinguish this species from other closely related congeners are given in Table 1.

Di s tribution. So far known only from Lembeh Island, northern Sulawesi (Rathbun 1914).

Ecology. Not known.

Figures

FIGURE 1. Parasesarma leptosoma (Hilgendorf, 1869). A–C, holotype female (17.5×16.0 mm) (ZMB 3181), Tanzania; D–F, male (16.0×14.8 mm) (ZRC 2000.1718), Kenya; G, H, female (14.9×12.7 mm) (ZRC 2000.1718), Kenya. A, E, G, dorsal views; B, F, H, ventral views; C, D, frontal views.

FIGURE 2. A–H, Parasesarma leptosoma (Hilgendorf, 1869), male (17.5×16.0 mm) (ZRC 2000.1718), Kenya; I–N, P. limbense (Rathbun, 1914), lectotype male (7.1×6.8 mm) (USNM 45920), Lembeh Island, Sulawesi. A, dorsal view of carapace; B–D, tip of left cheliped; E–M, left G1; N, left third maxilliped (setae denuded). B, lateral view of pectinated cristae on palm; C, dorsal view of palm and dactylar finger; D, lateral view of dactylar finger; E, G, I, dorsal (sternal) view; F, H, J, M, ventral (pleonal) view; K, sub-ventral (pleonal) view; L, side view; E, F, L, M, distal part of G1. Scale bars: 1.0 mm.

FIGURE 3. Parasesarma limbense (Rathbun, 1914). A–G, lectotype male (7.1×6.8 mm) (USNM 45920), Lembeh Island, Sulawesi; H, paralectotype female (13.1×11.6 mm) (USNM 120523-1), same locality; I, paralectotype female (12.6×11.4 mm) (USNM 120523-2), same locality. A, H, I, dorsal views; B, ventral view; C, mouth part; D, E, left cheliped; F, frontal views; G, right third and fourth legs. D, outer view of palm; E, dorsal view of dactylar finger.