Species boundaries in Philippine montane forest skinks (Genus Sphenomorphus): three new species from the mountains of Luzon and clarification of the status of the poorly known S. beyeri, S. knollmanae, and S. laterimaculatus

Abstract

Recent collections of Sphenomorphus beyeri Taylor 1915 from the type locality (Mt. Banahao, Luzon Isl., Philippines) serve as the basis for a thorough analysis of topotypic variation in external morphology within the species, and allow for detailed comparisons to other taxa. We clarify the taxonomic status of S. beyeri with respect to other, phenotypically similar species and evaluate species boundaries between allopatric populations referred to this taxon. The high elevation (1400–1700 m) population of Sphenomorphus (Brown et al., 1995a) from the Zambales Mountains and Bataan Peninsula of Luzon Island (previously referred by us to S. beyeri) is a new species that we describe here. We also describe two additional new species from the isolated, high elevation (1650–1750 m) forests of the Northern Cordillera and the Sierra Madre of Luzon, specimens of both of which had been previously identified as S. beyeri. All three new species differ from each other and all other Sphenomorphus species by scalation, body size, and coloration and all have non-overlapping distributions, associated with separate, isolated, geological components of Luzon Island.

In this paper we also formally redescribe S. beyeri on the basis of a large series of specimens from the type locality (Mt. Banahao, southern Luzon Island) that we have accumulated over the last 15 years. We place S. knollmanae Brown, Ruedas, and Ferner 1995 in synonymy with S. laterimaculatus (Brown and Alcala, 1980) and redescribe the latter species on the basis of the holotype and 20 additional newly collected specimens from six localities on the Bicol Peninsula of Luzon Island and Marinduque Island. These and other data suggest that species boundaries in Philippine Sphenomorphus are poorly understood and that taxonomic diversity is substantially underestimated and in need of comprehensive taxonomic review.