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Systematics, ecomorphology, cryptic speciation and biogeography of the lizard genus Tytthoscincus Linkem, Diesmos & Brown (Squamata: Scincidae) from the sky-island archipelago of Peninsular Malaysia

2017; Oxford University Press; Volume: 183; Issue: 3 Linguagem: Inglês

10.1093/zoolinnean/zlx067

1096-3642

L. Lee Grismer, Perry L. Wood, Evan S. H. Quah, Shahrul Anuar Mohd Sah, Ehwan Ngadi, Nur Amalina Mohd Izam, Norhayati Ahmad,

Genetic diversity and population structure

An integrative taxonomic analysis reveals a remarkable degree of cryptic speciation between sympatric, specialized, leaf-litter species in an upland clade of the scincid genus Tytthoscincus across the sky-island archipelago of Peninsular Malaysia. Bayesian inference and maximum likelihood phylogenies based on the mitochondrial gene ND2 indicate that this clade is composed of a lineage of limb, digit and tympanum-reduced, semi-fossorial species and a lineage of leaf-litter generalist bearing longer, more robust limbs and digits, and well-developed tympanae. Behavioural differences inferred from differing ecomorphologies form the basis of hypotheses proposed to account for resource partitioning at Fraser’s Hill, Pahang between the sympatric leaf-litter generalist T. bukitensis and the new semi-fossorial species T. kakikecil sp. nov. However, this hypothesis does not account for the extreme case of cryptic speciation and syntopy between T. bukitensis and a new leaf-litter generalist T. martae sp. nov. at Genting Highlands, Pahang. The phylogenetic analyses also indicate there is an additional new, upland, semi-fossorial species, T. jaripendek sp. nov., from Cameron Highlands and a new lowland, leaf-litter generalist, Tytthoscincus sp., from Hulu Terengganu, Terengganu. The specific identities of the new upland populations are corroborated by morphological analyses using combinations of principal component analysis, discriminant analysis of principal components, analysis of variance, Tukey HSD (honest significant difference) tests and Welch two-way t-tests. The Hulu Terengganu specimen was too damaged to provide a reliable description. A biogeographic scenario inferred from a time-calibrated BEAST analysis suggests that speciation in the upland clade has been ongoing since the Upper Pliocene following repeated episodes of secondary contact associated with glacier-driven climatic oscillations generating upland forest expansion and retraction. These analyses highlight the increasing levels of herpetological diversity and endemism being discovered in the montane regions of Peninsular Malaysia and bring to light the understudied ecological complexity of Peninsular Malaysia’s leaf-litter ecosystems and the growing need for its conservation.