Leptolalax sabahmontanus was described in 2013 from around Gunung Kinabalu HQ and Crocker Range National Park.  It's elevational range is currently known to range from approx. 754–1.500 m asl. It inhabits primary montane forest. The species lives on the forest floor but also uses low vegetation or logs for perching put to 1 m above the ground.  This species lives sympatric with L. arayai, L. pictus, or L. fritinniens depending on site.

Differences to other Bornean Leptolalax comprise size, morphometric traits, and coloration. The presence of ventral markings separates it from L. pictus, L. arayai, and L. hammed. L. sabahmontanus is similar to L. gracilis in the absence of dark cross bars on the upper arm. It but differs from L. gracilis by a smaller male and stockier body, and less developed ventral dark marking. Leptolalax sabahmontanus and L. gracilis are markedly different in advertisement calls (see below). From L. fritinniens, the new species differs by the smaller body size  and having a single, medially arranged vocal sac in males; L. fritinniens have bipartite sacs.

Males SVL 25.4–27.9 mm; females 35 mm.

The tadpoles are unknown but presumable similar to the known tadpoles of other species in the genus (see for example, L. arayai) 

Literature: Matsui M, Nishikawa K, Yambun P (2013) A new Leptolalax from the mountains of Sabah, Borneo (Amphibia, Anura, Megophryidae). Zootaxa 3753:440–452.