Previous taxonomic assessments of species in this genus recognized six groups of species that shared similar morphologies (see Brown and Alcala, 1980). Subsequent analyses of morphology and phylogenetic studies have not supported the monophyly of these species groups, and large taxonomic revisions are needed in this diverse group of ground skinks to sort out the true species diversity and appropriate generic assignments of its members. This species has traditionally been considered a member of Group 5 species in the genus Sphenomorphus. Group 5 represents the jagori complex of species as well as their morphologically similar allies. Members of this group likely represent multiple complexes of morphologically simliar, but disparate species, and large scale taxonomic revisions are likely needed.
In recent study of Philippine forest skinks, Linkem et al. (2011) used molecular data to test the monophyly of previously hypothesized species groups within the genus Sphenomorphus. Results of the study indicated widespread taxonomic instability, and as a result, broad taxonomic changes were made to the genus, resurrecting available names as well as describing new genera. Sphenomorphus coxi coxi is now recognized to be a member of the genus Pinoyscincus.
Pinoyscincus coxi coxi can be distinguished from congeners by the following combination of characters (1) medium to large body size (SVL 65.0–85.0 mm); (2) paravertebral scales 62–72; (3) midbody scales 32–38; (4) number of supraoculars contacting frontal 2; (5) Toe IV lamellae 19–26; (6) prefrontal scales in contact or separated; (7) frontoparietal scales fused; (8) venter ivory.
This subspecies has been recorded from the southern Philippine islands, including the islands of Mindanao, Camiguin Sur, Leyte, and Samar.
Mindanao Pleistocene Aggregate Island Complex (PAIC; Brown and Diesmos, 2002).
SVL 65.0–85.0 mm
Bunawan, Agusan Province, Mindanao Island; type lost in the World War II bombin of the Philippine Bureau of Science; Paratypes (MCZ 26330-31; CM 1730; CAS 62067)
