Johora thaiana Leelawathanagoon, Lheknim & Ng, 2005 Figures 1E, 2E, 3E, 4E, 5E, 10A-D, 12E, 13E, 14E

Johora thaiana Leelawathanagoon, Lheknim & Ng, 2005: 60, figs 1, 2; Cumberlidge et al. 2009: table.

Material examined.

Paratypes: 1 male (22.2 × 18.6 mm) (ZRC 2006.0052), Huai Sam Sop, Ko Lok River Basin, Ban Ba La, 140 m above sea level, 5.71583°N, 101.83917°E, Wang District, Narathiwat Province, southern Thailand, coll. Lheknim V, 14 July 1999; 1 female (21.0 × 17.4 mm) (ZRC 2006.0053), Sirindthron Waterfall, Ban Ba La, 300 m above sea level, 5.8°N, 101.82083°E, Wang District, southern Thailand, coll. Lheknim V, 15 July 1999.

Diagnosis.

Adult carapace width to length ratio 1.10-1.21 (Figs 1E, 2E, 12E); dorsal surface gently convex in frontal view, not inflated (Fig. 3E); frontal margin almost straight (Fig. 2E); suborbital, pterygostomial and sub-branchial regions rugose, pterygostomial region covered with dense setae (Fig. 3E); epigastric cristae distinct, distinctly anterior to sharp postorbital cristae, postorbital cristae with lateral edges low, not joining lateral margin (Fig. 2E); external orbital tooth separated from epibranchial tooth by distinct cleft, epibranchial tooth sharp, distinct (Fig. 2E); anterolateral margin distinctly convex (Fig. 2E); posterolateral margin medially concave, distinctly converging towards gently convex, entire posterior carapace margin (Fig. 2E); posterior margin of epistome with triangular median triangle, lateral margin obliquely sloping (Fig. 3E); outer surfaces of third maxillipeds with dense, long stiff setae; ischium subrectangular, with shallow median oblique groove (Figs 3E, 4E); ambulatory legs not elongate, length to width ratio of merus of fourth ambulatory leg 2.7-2.8 (Figs 1E, 12E); G1 subterminal segment gradually tapering from broad proximal part to slender distal part, without distinct shelf-like structure along gently concave outer margin; terminal segment almost straight, ca. half length of subterminal segment, surfaces with numerous short setae (Fig. 10A-C); G2 longer than G1, distal segment long, about two-thirds length of basal segment (Fig. 10D). Female pleon ovate; somites 3-6 progressively narrower; telson semicircular (Fig. 13E). Vulvae large, on anterior half of sternite 6, slightly pushing into suture with sternite 5, lateral sternal vulvar cover semicircular (Fig. 14E).

Remarks.

The G1 structure of J. thaiana most closely resembles that of J. hoiseni in that the terminal segment is straight; but their subterminal segments differ. In J. thaiana, the subterminal segment gradually tapers from the broad proximal part to a slender distal section, without a shelf-like structure along the outer margin (Fig. 10A); in J. hoiseni, the distal part of the subterminal segment becomes slender more abruptly, resulting in distinct shelf-like structure on the outer margin (Fig. 8E). Biogeographically, the type localities of J. thaiana are less than 20 km from the J. erici sp. nov. in Jeli, Kelantan; but their carapace features and G1s differ markedly (Figs 2E, 10A-C versus Figs 2G, 7B, 11A-C, E-G).

Distribution.

Johora thaiana is known from the forest tributaries in southern Thailand, near the Malaysian border at Kelantan (Fig. 15). Its distribution is adjacent to that of J. erici sp. nov. which lives in the highlands of northern Malaysia.

Conservation.

The species has so far only been found in protected forests in southern Thailand and is not under any immediate threat; Cumberlidge et al. (2009) list it as of least concern.