(Figs. 5–8)

Type locality. – Pharadorn Waterfall (17°02'12"N 101°03'27.6"E), Phu Hin Rong Kla National Park, Phitsanulok province, Thailand.

Material examined. – Female holotype, deposited in the Royal Belgian Institute of Natural Sciences (K.B.I.N./I. R.S.N.B., IG 30898 RIR 178), Brussels, Belgium.

Paratypes: two females deposited in the Royal Belgian Institute of Natural Sciences (K.B.I.N./I. R.S.N.B., IG 30898 RIR 179–180), Brussels, Belgium and two females deposited in the Natural History Museum, Mahasarakham University (MSU-ZRC 002–003), Mahasarakham, Thailand. All specimens from the type locality, coll. S. Savatenalinton, 3 Dec.2004.

Differential diagnosis. – Lecane martensi , new species, can be confused with Lecane paxiana Hauer (Fig. 9) by its small size and presence of pseudoclaws. The two can be distinguished by the relatively soft lorica, broad prepedal fold and large pseudosegment of Lecane martensi, new species. Although both species have toes that are fused basally, the degree of fusion in Lecane paxiana it distinctively less than in Lecane martensi, new species. Furthermore, no connective membrane between the toes exists in Lecane paxiana.

Description. – Female (male unknown): Lorica relatively soft. Dorsal plate wider than ventral, smooth, irregularly folded. Head aperture margins nearly coincident, ventrally and dorsally rather straight, antero-lateral corners angulate. Inner margins of head aperture with transverse rows of minute spinules. Ventral plate slightly longer than wide, with weak, incomplete transverse and elongate longitudinal folds, smooth. Lateral margins smooth or irregularly undulate. Foot plate broad, coxal plate rounded. Prepedal fold relatively broad, posterior margin with medial projection. Foot pseudosegment large, rectangular, not or slightly projecting. Toes fused basally, fixed in a spread position, connected basally by a membrane. Toes with distinct pseudoclaws. Trophi (Fig. 7): fulcrum short, curved, rod-shaped in ventral, squarish in oblique view. Rami asymmetrical, with rounded right, and curved left alulus. Inner margins of right ramus with three well-developed processi, left with indication of weaker processi. Unci asymmetrical, right stronger than left, consisting of fused plates with two unequal but large, and one much smaller tooth. Manubria elongate, distally curved, shafts expanded dorso-ventrally into broad lamellas.

Measurements. – Dorsal plate length 38–50 (45), width 43–53 (49), ventral plate length 40–53 (49), width 40–50 (46), toe length 11–13 (12), pseudoclaw 5–6 (5) (range and mean, in µm. All type specimens measured).

Etymology. – The species is named after Dr. Koen Martens (Royal Belgian Institute of Natural Sciences, Brussels) in recognition of his outstanding contributions to biodiversity of freshwater organisms.

Distribution and ecology. – Lecane martensi, new species is a rare species, with only a small number of specimens found inhabiting waterfall mosses. This species is to date only known from its type locality, during the cool season (December). Water temperature was 25ºC, pH was 7.2.