Johora thaiana Leelawathanagoon, Lheknim & Ng, 2005

Ng, Peter K. L., 2020, Revision of the freshwater crabs of the Johora tahanensis (Bott, 1966) species group (Crustacea, Brachyura, Potamidae), with a key to the genus, ZooKeys 994, pp. 1-34 : 1

publication ID	https://dx.doi.org/10.3897/zookeys.994.56810
publication LSID	lsid:zoobank.org:pub:DB1879C9-1904-4320-BE67-4D9F863F6775
persistent identifier	https://treatment.plazi.org/id/9CE1056C-862D-5E29-9822-55A0E22BFC13
treatment provided by	ZooKeys by Pensoft
scientific name	Johora thaiana Leelawathanagoon, Lheknim & Ng, 2005
status

Treatment

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

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 View Figure 1 , 2E View Figure 2 , 12E View Figure 12 ); dorsal surface gently convex in frontal view, not inflated (Fig. 3E View Figure 3 ); frontal margin almost straight (Fig. 2E View Figure 2 ); suborbital, pterygostomial and sub-branchial regions rugose, pterygostomial region covered with dense setae (Fig. 3E View Figure 3 ); epigastric cristae distinct, distinctly anterior to sharp postorbital cristae, postorbital cristae with lateral edges low, not joining lateral margin (Fig. 2E View Figure 2 ); external orbital tooth separated from epibranchial tooth by distinct cleft, epibranchial tooth sharp, distinct (Fig. 2E View Figure 2 ); anterolateral margin distinctly convex (Fig. 2E View Figure 2 ); posterolateral margin medially concave, distinctly converging towards gently convex, entire posterior carapace margin (Fig. 2E View Figure 2 ); posterior margin of epistome with triangular median triangle, lateral margin obliquely sloping (Fig. 3E View Figure 3 ); outer surfaces of third maxillipeds with dense, long stiff setae; ischium subrectangular, with shallow median oblique groove (Figs 3E View Figure 3 , 4E View Figure 4 ); ambulatory legs not elongate, length to width ratio of merus of fourth ambulatory leg 2.7-2.8 (Figs 1E View Figure 1 , 12E View Figure 12 ); 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 View Figure 10 ); G2 longer than G1, distal segment long, about two-thirds length of basal segment (Fig. 10D View Figure 10 ). Female pleon ovate; somites 3-6 progressively narrower; telson semicircular (Fig. 13E View Figure 13 ). Vulvae large, on anterior half of sternite 6, slightly pushing into suture with sternite 5, lateral sternal vulvar cover semicircular (Fig. 14E View Figure 14 ).

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 View Figure 10 ); 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 View Figure 8 ). 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 View Figure 2 , 10A-C View Figure 10 versus Figs 2G View Figure 2 , 7B View Figure 7 , 11A-C, E-G View Figure 11 ).

Distribution.

Johora thaiana is known from the forest tributaries in southern Thailand, near the Malaysian border at Kelantan (Fig. 15 View Figure 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.