The taxonomy and phylogeny of the Cyrtodactylus brevipalmatus group (Squamata: Gekkonidae) with emphasis on C. interdigitalis and C. ngati

Convergent morphological specializations for an arboreal lifestyle in most species of the Cyrtodactylus brevipalmatus group have been a confounding factor for establishing a stable taxonomy among its species. Recent references to C. intetdigitalis from throughout Thailand and Laos were made without comparisons to the type material from Tham Yai Nam Nao, Nam Nao National Park, Phetchabun Province, Thailand, but instead, were based on general morphological similarity and distribution. The taxonomy of C. interdigitalis is stabilized here by comparing the paratypes to other specimens from Thailand and Laos and recovering their phylogenetic relationships based on newly acquired genetic data, including those from the type locality. The phylogeny recovered all specimens outside the type locality to be either C. ngati from Vietnam or new species closely related to C. ngati. Cyrtodactylus interdigitalis is shown here to be a range-restricted upland endemic on the Phetchabun massif of northern Thailand. The phylogeny also indicates that C. ngati extends hundreds of kilometers farther south into northern Thailand and central Laos. We hypothesize that the significant morphological divergence in body shape of the types of C. ngati, compared to that of the Lao and Thai populations, may be due to local adaptions for utilizing karst (C. ngati) rather than vegetation (Lao and Thai populations). Additionally, phylogenetic and multivariate analyses identified a potentially new species from Phu Hin Rong Kla National Park, Phitsanulok Province, in northern Thailand and another from the Khlong Naka Wildlife Sanctuary, Ranong Province, in southern Thailand. A series of newly examined specimens from Kaeng Krachan National Park, Phetchaburi Province, Thailand represents a possible similar to 82 km range extension to the southeast of C. rukhadeva. This research continues to underscore the high diversity of range-restricted upland endemics in Thailand and the importance of examining type material (if possible) in the context of a phylogeny so as to construct proper taxonomies that reveal, rather than obscure, diversity.

Automated summary

This study stabilized the taxonomy of Cyrtodactylus interdigitalis by comparing its paratypes to other specimens and analyzing their phylogenetic relationships based on genetic data. It also identified potentially new species and revealed the broader distribution of C. ngati. The study hypothesized that morphological divergence in body shape may be due to local adaptations for different environments.