A single specimen of this species was first discovered in 1911 and described by Annandale in 1913, referring to it as Ixalus semiruber.

For the next 95 years since 1913, this species was not again seen alive, and the type specimen on which the original description was made, was confirmed to be lost from a Museum collection by 2001.

[3] Extensive field research conducted by Madhava Meegaskumbura in 2005, targeting molecular characterization of the Sri Lankan shrub frog species, lead to the re-discovery of this species from near a small forest reserve (Agra-Bopath) close to the Horton Plains National Park, Sri Lanka.

Tympanum distinct, oval, vertical, its outer rim narrow but clear.

Pseudophilautus semiruber is distinguished from P. simba, the sibling species of P. semiruber, by having the supratympanic fold indistinct (vs. distinct in P. simba); webbing present (vs. rudimentary) between all toes; throat, chest and belly smooth (vs. granular); white patches distinct, evenly distributed on throat, chest, anterior and mid-belly, fewer on posterior belly (vs. diffused white patches only on chest and anterior half of belly, absent on throat and lower belly); throat ashy brown, chest and belly reddish brown (vs. throat, chest and anterior belly black); entire upper arm and proximal half of lower arm dorsally red (vs. entire lower arm and fingers dorsally light brown in P. simba); thigh and inner shank dorsally red (vs. light brown in P. simba); and thigh and shank ventrally ‘light red’ with white patches (vs. light brown to dark brown, with white patches only in region of knee).

Pseudophilautus semiruber was originally described from a single specimen collected at Pattipola, Sri Lanka (06º51'21"N, 80º49’40"E; 1,850 m a.s.l.).