(Figs. 7A–I, 8A–E, 14A, B)

Material examined. Holotype: male (10.3 × 9.6 mm) (ZRC 2015.0607), Gunung Ampungan, Sadong River Basin, Serian, Sarawak, coll. J Grinang et al., 8 February 2015. Paratypes: 2 females (larger 9.8 × 9.2 mm), 2 ovigerous females (larger 10.3 × 9.8 mm) (SBC.C.00435–39), data same as holotype; 14 males (largest 11.3 × 10.6 mm, 10.5 × 9.6 mm, 11.8 × 10.9 mm), 8 females (largest 11.2 × 9.8 mm) (ZRC 2015.0292), on sides of small stream, mudstone and rocks substrate, densely forest covered slope of hill Gunung Ampungan, Sadong River Basin, Serian, Sarawak, coll. PKL Ng, J Grinang & PYC Ng, 18 and 20 June 2015.

Diagnosis. Carapace quadrate, surface relatively flat, smooth, anterolateral margins smooth; antero- and posterolateral regions rugose; epibranchial tooth undiscernible; external orbital tooth with outer margin concave, smooth; serrated projection on frontal region distinct; epigastric and postorbital cristae distinct, high, margins serrated; cervical and H-grooves relatively deep, not confluent (Fig. 7A, B, D); ischium of third maxilliped rhomboidal, much longer than broad, with incomplete median sulcus (Fig. 7F); inner margin of merus of chelipeds with relatively lower serrated projection (Fig. 7G); carpus of chelipeds rugose, inner angle with broad, low triangular tooth (Fig. 7A); fingers of adult major male chela narrowly gaping (Fig. 7H, I); ambulatory legs short, merus of fourth ambulatory legs about half of length of carapace (Fig. 7A, E); male abdomen triangular, somite 6 width and length subequal, subequal to length of telson (Fig. 7C); G1 stout, sinuous in ventral view, straight in dorsal view; terminal segment straight in dorsal view, gently curving outwards in ventral view (Fig. 8A, B, D, E); G2 with long distal segment, about three-quarters length of basal segment (Fig. 8C).

Colour. In life, males are yellowish-red carapace, reddishbrown ambulatory legs and yellowish chelipeds. Females are light brown overall (Fig. 14A, B).

Etymology. The name is after Michael Lo in recognition of his kind help in helping us search for these interesting animals.

Remarks. Lepidothelphusa loi, new species, can be easily distinguished from L. cognettii s. str., L. flavochela, new species, L. limau, new species, and L. padawan, new species, in having relatively shorter ambulatory legs (Fig. 7A, E versus Figs. 1A, E, 3A, E, 5A, E, 9A, E, 11A, E). The distal segment of the G2 of L. loi is relatively longer than congeners (Fig. 8C versus Figs. 2C, 4C, 6C, 10C, 12C). See also discussion for L. flavochela and L. limau.

Habitat. The habitat is a gentle slope, with the substrate composed of moist mud and sand, with leaf litter. The site is shaded, has a spring, and is part of a disturbed dipterocarp forest. The base substrate is sandstone, and the site is more than 500 m above sea level.