Fasciarma fasciatum, (LANCHESTER, 1900), 2018

FASCIARMA FASCIATUM ( LANCHESTER, 1900) View in CoL COMB. NOV.

( FIGS 3F View Figure 3 , 4F View Figure 4 , 5F View Figure 5 , 6F View Figure 6 , 7F View Figure 7 , 8F View Figure 8 , 9F View Figure9 , 10F View Figure 10 , 11F View Figure 11 , 15 View Figure 15 )

Sesarma fasciata Lanchester, 1900: 758 View in CoL , pl. 47 fig. 12.

Sesarma (Chiromantes) siamens Rathbun, 1909: 109 .

Sesarma (Chiromantes) siamensis – Tesch, 1917: 199.

Sesarma (Parasesarma) fasciata View in CoL – Tesch, 1917: 153.

Sesarma (Chiromantes) fasciata View in CoL – Tweedie, 1936: 66, pl. 15 fig. 3; Dai & Yang, 1991: 539, pl. 69 fig. 5.

Sesarma fasciata View in CoL – Tweedie, 1950

Chiromantes fasciatus – Tan & Ng, 1994: 82 (in list).

Perisesarma fasciatum View in CoL – Guerao et al., 2004; Ng et al., 2008: 222 (in list); Davie, 2010: 204 (in key); Shahdadi & Schubart, 2015: 1083 (in Table 1).

Material examined: The examined material is listed in Table 1. The male animal (carapace width = 9.15) from the syntype series was selected as lectotype ( NHM 1900.10.22.274) (S 291 in Table 1) ( Fig. 15F, G View Figure 15 ) (present designation) .

Redescription: A small sized crab species (up to 1.36 cm carapace width among studied material, N = 19). Carapace squarish, greatest width between epibranchial prominences, slightly broader than long, about 1.15 ± 0.03 times as broad as long (N = 17), front c. 0.52 ± 0.02 times carapace width (N = 14), deflexed, with shallow median invagination. Carapace considerably punctuated (covered with coarse pits), regions not well defined, postfrontal region four-lobed, not well marked, separated by shallow furrows, median lobes broader than lateral ones, gastric region distinguishable, but not well marked, lateral surface lined with oblique striae consisting of rows of fine granules, anterolateral margins with an indentation (a distinct prominence) (in larger specimens also second prominence is visible), lateral margin straight, edged with row of short setae ( Fig. 15A, B View Figure 15 ).

Chelipeds equal to subequal. Merus with finely granulated borders, with small distal and subdistal spines. Carpus with rows of fine granules dorsally. Chelae large (palm length/carapace width in males = 0.71 ± 0.08, N = 7, in female = 0.57 ± 0.03, N = 7), quite robust (palm width/length in males = 0.57 ± 0.05, N = 7, in female = 0.55 ± 0.03, N = 7), palm smooth externally, with some granules internally, with two oblique to nearly longitudinal ridges or wrinkles dorsally, each one bearing chitinous caps, outer ridge shorter, positioned on distal third of upper surface of the palm, initiated from the angle between inner and distal margin, bearing 10–16 chitinous caps ( Fig. 3F View Figure 3 ), inner ridge initiated almost from the same angle and extending to proximal rim, with chitinous caps mostly on the distal half (17– 25 caps), two or three short rows of granules behind the inner ridge ( Fig. 3F View Figure 3 ). Fingers with chitinous tips, cutting edges with small and large sharp teeth (movable finger with 4 large, 5–6 small teeth, fixed finger with 3 large and 6–8 small teeth) and leaving no gap when closed ( Fig. 15C View Figure 15 ) [in animals with older cuticle, fingers without chitinous tips, blunt teeth, leaving a gap when closed ( Fig. 15D View Figure 15 )], length of palm cutting edge 0.43 ± 0.03 times length of propodus (N = 14), upper surface of the chela dactylus bears 5–8 low and smooth tubercles with chitinous peaks ( Fig. 15C–E View Figure 15 ).

Walking legs proportionally long, second and third pairs almost equal and longer than others. Third pair = 1.72 ± 0.09 times carapace width (N = 13), relatively narrow (e.g. merus = 2.88 ± 0.14 times as long as wide, N = 13), carpus, propodus and dactylus with tufts of thick and long setae on both margins ( Fig. 15B View Figure 15 ).

Male pleon relatively wide, triangular, somite 1 and 2 very narrow, somite 2 medially longer than lateral edges, somite 3 widest with lateral margins slightly convex, somites 4 and 5 trapezoidal, telson small, slightly wider than long ( Figs 5F View Figure 5 , 6F View Figure 6 ). Male press button absent ( Fig.7F View Figure 7 ).

G1 ( Fig. 8F View Figure 8 ) short, stout, apical process rather long and bent to form an angle of about 65° with vertical axis, tip truncated, aperture terminal. G2 short, bowshaped, fairly stout, basal part wider (2 times wider than apical part).

Females with proportionally smaller chelipeds. Pleon broadened, telson wider than long, inserted within somite 6 less than half of its length ( Fig. 9F View Figure9 ). Vulvae completely positioned on sternite 5, with elongated operculum on inner part rimmed perpendicular to sternal sutures ( Fig. 10E View Figure 10 ).

Distribution: Singapore (type locality) ( Lanchester, 1900; Tweedie, 1936), Selangore, Malaysia ( Tweedie, 1936), Hainan Island and Fujian, China ( Dai & Yang, 1991), Ko Kut, Thailand, Gulf of Siam ( Rathbun, 1909), Labuan, Malaysia ( Tweedie, 1950) and Hong Kong (present study).