Parasesarma gracilipes Li & Rahayu & Ng 2018, n. sp.
Creators: name: Li, Jheng-Jhang
name: Rahayu, Dwi Listyo
name: Ng, Peter K. L.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Sesarmidae
Parasesarma
Parasesarma gracilipes

description: Parasesarma gracilipes n. sp.
(Figs. 11, 12, 19E, 20D, 21E)
Sesarma (Parasesarma) leptosoma, De Man 1902: 534.—Nobili 1905: 497.—Rathbun 1910: 309, pl. 4, fig. 1. Not Parasesarma leptosoma (Hilgendorf, 1869).
Parasesarma leptosoma, Rahayu & Setyadi 2009: 51, unnumbered figure. Not Parasesarma leptosoma (Hilgendorf, 1869).
Material examined. HOLOTYPE: male (13.6× 11.9 mm) (MZB Cru 4803), Indonesia: Papua: Ajkwa River, 11 June 2005, D.L. Rahayu. PARATYPES: 1 female (12.5× 10.7 mm) (ZRC 2000.1881), Indonesia: Ajkwa River 3 August 1999, G. Setyadi. — 1 male (12.6× 10.9 mm) (ZRC 2000.1882), Indonesia: Minajerwi, Papua, mangrove, 12 August 1999, G. Setyadi. — 1 male (14.2×12.0 mm) (ZRC 2000.1883), Indonesia: Papua, Kamora mangrove Indonesia, 4 April 2000, D.L. Rahayu. — 1 female (13.4× 11.7 mm) (ZRC 2018.0793), Indonesia: Papua: Ajkwa River, 11 June 2005, D. L. Rahayu.
Diagnosis. Carapace (Figs. 11A, E, 12A) squarish in general outline, 1.1 times broader than long; regions well defined, separated by shallow grooves; surface with scattered tufts of short setae; postfrontal region distinct, separated into 4 lobes by deep grooves; front deflexed downwards (Figs. 11C, D) margin intensely concave in dorsal view; lateral margin straight, subparallel along most of length before curving to join almost straight posterior carapace margin; cornea extending or just reaching tip of external orbital tooth (Figs. 11A, E, 12A). Ischium of third maxilliped with shallow median sulcus, merus with distinct submedian ridge; exopod slender, tip reaching half-length of outer margin of merus, flagellum long. Male cheliped palm with 2 transverse pectinate crests (11 and 9 corneous teeth, respectively) on upper surface; upper surface of dactylus with 7 or 8 symmetrical, obliquely elongate dactylar tubercles, proximal 3 tubercles steep, sharp, the others tubercles large, distalmost tubercle indistinct (Figs. 12C, D, 19E). Ambulatory legs relatively slender for this species-complex, P3 and P4 about 1.6 times carapace width; P3 and P4 coxae without dense setae; P3 merus 3.1 times as long as broad; P3 propodus 5.9 times as long as broad; P3 dactylus 0.3 times length of propodus (Fig. 20D). G1 relatively stout (Figs. 12E–H, 20E); apical process corneous, elongated, slightly bent at angle of 45°, stout, ending in rounded tip. G2 longer than quarter length of G1 (Fig. 21E).
Colour in life. General colour dark brown. Carapace mottled light brown and dark brown, palm of cheliped yellow or whitish yellow, fingers reddish orange or light orange (Rahayu & Setyadi 2003).
Remarks. Parasesarma gracilipes n. sp. can easily be separated from other species in the species-complex by its relatively slender and longer ambulatory legs which are the longest among the members (Fig. 20D). The ratio of merus length/width of the P3 is 3.1 (other species as 2.40–2.67) while the P3 propodus is 5.9 times as long as broad (other species as 4.1–5.0) (Fig. 20D). Other features that distinguish this species from its congeners are given in Table 1.
De Man (1902) reported Parasesarma leptosoma from Halmahera, Indonesia [as Sesarma (Parasesarma)], and noticed that the specimens had more slender legs than those crabs from Africa he examined. Similarly, Rathbun (1910) recorded “ Sesarma (Parasesarma) leptosoma Hilgendorf, var. ” from Jobi Island, Dutch New Guinea (now Papua, Indonesia), and commented that the specimens had more slender legs than what De Man (1889; not 1902) mentioned in his description and figure. On this basis of these notes, and partly on the geography, we refer those previous records of P. leptosoma from Indonesia to P. gracilipes n. sp. for the time being.
Etymology. The name is derived from the Latin " gracilis " (slender) and " pes " (legs), referring to the slender ambulatory legs of the species.
Distribution. Indonesia: Jobi Island (Rathbun 1910), Halmahera (De Man 1902), Papua (Nobili, 1905; Rathbun 1910; Rahayu & Setyadi 2009).
Ecology. Parasesarma gracilipes n. sp. is active on muddy substrate in mangrove forest (Rahayu & Setyadi 2009), occurring in the intertidal, area some distance from the river bank. They move fast between mangrove roots even during the day.
description: Published as part of 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, pp. 451-490 in Zootaxa 4482 (3) on pages 469-470, DOI: 10.11646/zootaxa.4482.3.2, http://zenodo.org/record/1440707