Parasesarma gracilipes, Li & Rahayu & Ng, 2018

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 : 469-470

publication ID	https://doi.org/ 10.11646/zootaxa.4482.3.2
publication LSID	lsid:zoobank.org:pub:3FBE11E2-9F97-4A29-92A9-67780C782E0D
DOI	https://doi.org/10.5281/zenodo.5986793
persistent identifier	https://treatment.plazi.org/id/376A1B4D-FFB6-FF95-D1CD-FC7C4548F812
treatment provided by	Plazi
scientific name	Parasesarma gracilipes
status	sp. nov.

Treatment

Parasesarma gracilipes View in CoL n. sp.

( Figs. 11 View FIGURE 11 , 12 View FIGURE 12 , 19E View FIGURE 19 , 20D View FIGURE 20 , 21E View FIGURE 21 )

Sesarma (Parasesarma) leptosoma, De Man 1902: 534 View in CoL .—Nobili 1905: 497.—Rathbun 1910: 309, pl. 4, fig. 1. Not Parasesarma leptosoma ( Hilgendorf, 1869) View in CoL .

Parasesarma leptosoma, Rahayu & Setyadi 2009: 51 View in CoL , unnumbered figure. Not Parasesarma leptosoma ( Hilgendorf, 1869) View in CoL .

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 View Materials ), Indonesia: Ajkwa River 3 August 1999, G. Setyadi. — 1 male (12.6× 10.9 mm) ( ZRC 2000.1882 View Materials ), Indonesia: Minajerwi , Papua, mangrove, 12 August 1999, G. Setyadi. — 1 male (14.2×12.0 mm) ( ZRC 2000.1883 View Materials ), Indonesia: Papua, Kamora mangrove Indonesia, 4 April 2000, D.L. Rahayu. — 1 female (13.4× 11.7 mm) ( ZRC 2018.0793 View Materials ), Indonesia: Papua: Ajkwa River , 11 June 2005, D. L. Rahayu.

Diagnosis. Carapace ( Figs. 11A, E View FIGURE 11 , 12A View FIGURE 12 ) 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 View FIGURE 11 ) 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 View FIGURE 11 , 12A View FIGURE 12 ). 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 View FIGURE 12 , 19E View FIGURE 19 ). 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 View FIGURE 20 ). G1 relatively stout ( Figs. 12E–H View FIGURE 12 , 20E View FIGURE 20 ); apical process corneous, elongated, slightly bent at angle of 45°, stout, ending in rounded tip. G2 longer than quarter length of G1 ( Fig. 21E View FIGURE 21 ).

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 View FIGURE 20 ). 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 View FIGURE 20 ). 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.