Two new species of Dixonius from Vietnam and Laos with a discussion of the taxonomy of Dixonius (Squamata, Gekkonidae)

By

Luu, Vinh
Nguyen, Thuong Huyen
Le, Minh Duc, 1973-
Grismer, Jesse
Ha, Hong Bich
Sitthivong, Saly
Hoang, Tuoi Thi
Grismer, Lee

Type

Article

Date of Publication

2023

Original Publication

ZooKeys

Volume

1163

Pages

143--176

Subjects

Gekkota , Indochina , integrative taxonomy , molecular phylogeny , Morphology , new species , Southeast Asia

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers

Identifiers

DOI: https://doi.org/10.3897/zookeys.1163.101230

 

Abstract

Integrated analyses using maximum likelihood (ML), Bayesian inference (BI), principal component analysis (PCA), discriminate analysis of principal components (DAPC), multiple factor analysis (MFA), and analysis of variance (ANOVA) recovered two new diagnosable species of gekkonid lizards in the genus Dixonius, one from the Central Highlands, Gia Lai Province, Vietnam and another from the Vientiane Province, Laos. Phylogenetic analyses based on the mitochondrial NADH dehydrogenase subunit 2 gene (ND2) and adjacent tRNAs showed that Dixonius gialaiensissp. nov. is the sister species of D. minhlei from Dong Nai Province, Vietnam and is nested within a clade that also includes the sister species D. siamensis and D. somchanhae. Dixonius muangfuangensissp. nov. is the sister species to D. lao from Khammouane Province, Laos and is embedded in a clade with D. vietnamensis, D. taoi, and undescribed species from Thailand. Multivariate (PCA, DAPC, and MFA) and univariate (ANOVA) analyses using combinations of 15 meristic (scale counts), six morphometric (measurements), and five categorical (color pattern and morphology) characters from 44 specimens encompassing all eight species of Dixonius from Vietnam and Laos clearly illustrate Dixonius gialaiensissp. nov. and Dixonius muangfuangensissp. nov. are statistically different and discretely diagnosable from all closely related species of Dixonius. These integrative analyses also highlight additional taxonomic issues that remain unresolved within Dixonius and the need for additional studies. The discovery of these new species further emphasizes the underappreciated herpetological diversity of the genus Dixonius and illustrates the continued need for field work in these regions.