Parasesarma macaco 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 macaco

description: Parasesarma macaco n. sp.
(Figs. 7, 8, 19C, 20B, 21C, 22B, 23B, 24C, 25B–D)
Material examined. HOLOTYPE: male (13.8× 12.3 mm) (NMNS-7779-005), Taiwan: Pingtung: mouth of Paoli River, north bank (on Clerodendrum inerme (L.) Gaertn.), 29 September 2015, J.- J. Li. PARATYPES: 1 male (12.3× 11.8 mm) (ZRC 2018.0788), Taiwan: Pingtung: mouth of Paoli River, 5 July 2016, J.- J. Li. — 1 male (11.6×10.0 mm) (ZRC 2018.0789), Taiwan: Pingtung: mouth of Paoli River, 30 September 2015, J.- J. Li. — 1 male (15.2× 13.4 mm) (NMNS-7779-008), Taiwan: Pingtung: mouth of Paoli River, 6 June 2016, J.- J. Li. — 1 male (13.9× 12.5 mm) (NMNS-7779-009), Taiwan: Pingtung: mouth of Kangkou River, 22 June 2016, J.- J. Li. — 1 male (9.7× 8.4 mm) (NMNS-7779-010), Mindoro, Philippines, 5 March 2016, W.- B. Chan. — 2 males (10.1× 8.9 mm, 12.9× 11.8 mm) (NMNS-7779-012), Taiwan: Pingtung: mouth of Paoli River, 19 March 2016, J.- J. Li. —1 male (12.8× 11.3 mm), 1 female (14.4×13.0 mm) (NMNS-7779-013), Taiwan: Tainan: Taijiang National Park: Sicao Mangrove Green Tunnel, South bank, 4 October 2015, J.- J. Li. — 1 female (12.7× 11.2 mm) (NMNS-7779- 014), Taiwan: Pingtung: mouth of Paoli River, 4 October 2016, J.- J. Li. — 1 male (12.4× 10.8 mm) (NMNS-7779- 007), Taiwan: Pingtung: Kenting National Park: mouth of Kangkou River, 26 September 2015, J.- J. Li. Other material: 2 males (12.7× 10.8 mm, 9.5× 10.9 mm), 3 females (12.3× 10.8 mm, 11.8×10.0 mm, 8.4× 7.5 mm) (NMNS- 7779-020), Philippines: Bohol Island: Loboc River, 18 May 2004, H.- C. Liu. — 1 male (9.9×8.4) (NMNS-7779- 011), Philippines: Mindoro, 5 March 2016, W.- B. Chan.
Diagnosis. Carapace (Figs. 7A, E, 8A, 22B) squarish in general outline, 1.1 times broader than long; regions well defined, separated by deep grooves; postfrontal region distinct, separated into 4 lobes by deep grooves; front deflexed downwards (Figs. 7C, 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. 77A, E, 8A, 22B). 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 (13 and 10 corneous teeth, respectively) on upper surface; upper surface of dactylus with 6 to 8 (average 7) symmetrical, obliquely elongate dactylar tubercles, proximal 3 tubercles steep, sharp, the others tubercles large, distalmost 2 tubercles indistinct (Figs. 8C, 19C). Ambulatory legs relatively slender for this species-complex, P3 and P4 about 1.5 times carapace width; P3 and P4 coxae without dense setae; P3 merus 2.5 times as long as broad; P3 propodus 5.0 times as long as broad; P3 dactylus 0.4 times length of propodus (Fig. 20B). G1 relatively slender; apical process corneous, elongated, slightly bent at angle of 45°, long, stout, ending in rounded tip (Figs. 8E, F, 21C). G2 longer than quarter length of G1 (Fig. 21C).
Colour in life. In large individuals, the carapace is dark brown, mottled with darker and lighter blotches; females and juveniles occasionally have light orange blotches on the gastric region (Fig. 25C). Chelipeds are yellowish orange, but brighter in males. Ambulatory legs are gray to brown (Figs. 22B, 23B, 24C).
Remarks. Parasesarma macaco n. sp. is most easily separated from other members of the species-complex by the medially concave frontal margin, and in having 6–8 dactylar tubercles of the chela (all tubercles are counted, including the small proximal and obsolescent distal ones). The specimens from Bohol Island, Philippines, differ from the other specimens in having a slightly longer G1 but the tip is of the same shape. The features that distinguish this species from its closest congeners are summarized in Table 1.
Etymology. Derived from the Portuguese " macaco " meaning “monkey”. It alludes to the agility of this treeclimbing species and its habit of jumping around branches. The name is used as a noun in apposition.
Distribution. Taiwan: Kangkou River and Paoli River (Pingtung county) and Sicao (Tainan city); Philippines: Mindoro and Bohol Island.
Ecology. Parasesarma macaco n. sp. is a common species in Paoli River, Taiwan. In Taiwan and Philippines, most of specimens of P. macaco were collected at night, with specimens observed climbing the trees along the river banks of the estuary. The common host plants are Talipariti tiliaceum (L.) Fryxell, Clerodendrum inerme (L.) Gaertn. (in Taiwan) (Figs. 25A–C), Bruguiera gymnorhiza (L.) Lam. and Avicennia marina (Forsk.) Vierh. (in Philippines). When the water levels (from the rising tide and rainfall) reach the host plant, the crabs would climb downward and submerge in the water. Parasesarma macaco n. sp. rarely ventures onto the ground except for breeding (Fig. 25D). Ovigerous females were found almost all year around, but mainly in July to October.
Parasesarma macaco n. sp. occurs sympatrically with P. kui n. sp. (Taiwan) and Metopograpsus latifrons (Taiwan and Philippines), the niche and ecology appear to be generally similar (see “Ecology” for P. kui).
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 464-466, DOI: 10.11646/zootaxa.4482.3.2, http://zenodo.org/record/1440707