Abstract
A new species of Dixonius is described on the basis of three specimens from the karst forests around Thakhek town, Khammouane Province, Laos. The new species from Laos can be distinguished from other species of Dixonius based on molecular and morphological divergences. It is characterized by a maximum SVL of 55.4 mm; 20–23 longitudinal rows of dorsal tubercles at mid-body; 23–24 longitudinal rows of ventrals across the abdomen; 8–10 supralabials, 7 or 8 in mid-orbital position; 7 or 8 infralabials; 8 precloacal pores in male; the male without femoral pores; precloacal and femoral pores absent in females; uniformly pebble brown dorsum. In phylogenetic analyses, the new species is shown to be the sister taxon to two undescribed taxa from Thailand but differs by at least 8.6% in genetic pairwise distance from the latter based on the complete sequences of the mitochondrial ND2 gene with partial or complete sequences of six adjacent tRNAs. This is the ninth known species of Dixonius, and the second recorded species from Laos.
References
Bauer, A.M., Good, A.D. & Branch, W.R. (1997) The taxonomy of the Southern African leaf-toed geckos (Squamata: Gekkonidae), with a review of Old World “Phyllodactylus” and the description of five new genera. Proceedings of the California Academy of Sciences, 49, 44–497.
Bauer, A.M., Sumontha, M., Grossmann, W., Pauwels, O.S.G. & Vogel, G. (2004) A new species of Dixonius (Squamata: Gekkonidae) from Kanchanaburi Province, western Thailand. Current Herpetology, 23 (1), 17–26.
https://doi.org/10.5358/hsj.23.17
Botov, A., Phung, T.M., Nguyen, T.Q., Bauer, A.M., Brennan, I.G. & Ziegler, T. (2015) A new species of Dixonius (Squamata: Gekkonidae) from Phu Quy Island, Vietnam. Zootaxa, 4040 (1), 48–58.
https://doi.org/10.11646/zootaxa.4040.1.4
Boulenger, G.A. (1898) Third report on additions to the lizard collection in the Natural History Museum. Proceedings of the Zoological Society London, 1898, 912–923.
https://doi.org/10.1111/j.1096-3642.1898.tb03194.x
Das, I. (2004) A new species of Dixonius (Sauria: Gekkonidae) from southern Vietnam. The Raffles Bulletin of Zoology, 52, 145–150.
Grismer, L.L., Wood Jr., P.L., Thura, M.K., Win, N.M., Grismer, M.S., Trueblood, L.A. & Quah, E.S.H. (2018a) A re-description of Cyrtodactylus chrysopylos Bauer (Squamata: Gekkonidae) with comments on the adaptive significance of bright orange coloration in hatchlings and descriptions of two new species from eastern Myanmar (Burma). Zootaxa, 4527 (2), 151–185.
https://doi.org/10.11646/zootaxa.4527.2.1
Grismer, L.L., Wood Jr., P.L., Thura, M.K., Quah, E.S.H., Grismer, M.S., Murdoch, M.L., Espinoza, R.E. & Lin, A. (2018d) A new Cyrtodactylus Gray (Squamata, Gekkonidae) from the Shan Hills and the biogeography of Bent-toed Geckos from eastern Myanmar. Zootaxa, 4446 (4), 477–500.
https://doi.org/10.11646/zootaxa.4446.4.4
Grismer, L.L., Wood Jr., P.L., Thura, M.K., Zin, T., Quah, E.S.H., Murdoch, M.L., Grismer, M.S., Lin, A., Kyaw, H. & Ngwe, L. (2018b) Twelve new species of Cyrtodactylus Gray (Squamata: Gekkonidae) from isolated limestone habitats in east-central and southern Myanmar demonstrate high localized diversity and unprecedented microendemism. Zoological Journal of the Linnean Society, 182, 862–959.
https://doi.org/10.1093/zoolinnean/zlx057
Grismer, L.L., Wood Jr., P.L., Thura, M.K., Zin, T., Quah, E.S.H., Murdoch, M.L., Grismer, M.S., Herr, M.W., Lin, A. & Kyaw, H. (2018c) Three more new species of Cyrtodactylus (Squamata: Gekkonidae) from the Salween Basin of eastern Myanmar underscores the urgent need for the conservation of karst habitats. Journal of Natural History, 52, 1243–1294.
https://doi.org/10.1080/00222933.2018.1449911
Hillis, D.M. & Bull, J.J. (1993) An empirical test of bootstrapping as a method for assessing confidence in phylogenetic analysis. Systematic Biology, 42, 182–192.
https://doi.org/10.1093/sysbio/42.2.182
Le, M., Raxworthy, C.J., McCord, W.P. & Mertz, L. (2006) A molecular phylogeny of tortoises (Testudines: Testudinidae) based on mitochondrial and nuclear genes. Molecular Phylogenetics and Evolution, 40, 517–531.
https://doi.org/10.1016/j.ympev.2006.03.003
Luu, V.Q., Bonkowski, M., Nguyen, T.Q., Le, M.D., Schneider, N., Ngo, H.T. & Ziegler, T. (2016) Evolution in karst massifs: Cryptic diversity among bent-toed geckos along the Truong Son Range with descriptions of three new species and one new country record from Laos. Zootaxa, 4107 (2), 101–140.
https://doi.org/10.11646/zootaxa.4107.2.1
Luu, V.Q., Calame, T., Nguyen, T.Q., Le, M.D. & Ziegler, T. (2015) Morphological and molecular review of the Gekko diversity of Laos with descriptions of three new species. Zootaxa, 3986 (3), 279–306.
https://doi.org/10.11646/zootaxa.3986.3.2
Macey, J.R., Larson, A., Ananjeva, N.B., Fang, Z. & Papenfuss, T.J. (1997) Two novel gene orders and the role of light-strand replication in rearrangement of the vertebrate mitochondrial genome. Molecular Biology and Evolution, 14, 91–104.
https://doi.org/10.1093/oxfordjournals.molbev.a025706
Ngo, V.T. & Ziegler, T. (2009) A new species of Dixonius from Nui Chua National Park, Ninh Thuan Province, southern Vietnam (Squamata, Gekkonidae). Zoosystematics and Evolution, 85 (1), 117–125.
https://doi.org/10.1002/zoos.200800018
Nguyen, L.-T., Schmidt, H.A., von Haeseler, A. & Bui, M.Q. (2015) IQ-TREE: A fast and effective stochastic algorithm for estimating maximum likelihood phylogenies. Molecular Biology and Evolution, 32, 268−274.
https://doi.org/10.1093/molbev/msu300
Posada, D. & Crandall, K.A. (1998) MODELTEST: testing the model of DNA substitution. Bioinformatics, 14, 817–818.
https://doi.org/10.1093/bioinformatics/14.9.817
Pyron, R.A., Burbrink, F.T. & Wiens, J.J. (2013) A phylogeny and revised classification of Squamata, including 4161 species of lizards and snakes. BMC Evolutionary Biology, 12, 93.
https://doi.org/10.1186/1471-2148-13-93
Ronquist, F., Teslenko, M., van der Mark, P., Ayres, D.L., Darling, A., Höhna, S., Larget, B., Liu, L., Suchard, M.A. & Huelsenbeck, J.P. (2012) MrBayes 3.2: efficient Bayesian phylogenetic inference and model choice across a large model space. Systematic Biology, 61, 539–542.
https://doi.org/10.1093/sysbio/sys029
Simmons, J.E. (2002) Herpetological collecting and collections management. Revised edition. Society for the Study of Amphibians and Reptiles. Herpetological Circular, 31, 1–153.
Sumontha, M., Chomngam, N., Phanamphon, E., Pawangkhanant, P., Viriyapanon, C., Thanaprayotsak, W. & Pauwels, O.S.G. (2017) A new limestone-dwelling leaf-toed gecko (Gekkonidae: Dixonius) from Khao Sam Roi Yot massif, peninsular Thailand. Zootaxa, 4247 (5), 556–568.
https://doi.org/10.11646/zootaxa.4247.5.2
Swofford, D.L. (2001) PAUP*. Phylogenetic Analysis Using Parsimony (*and Other Methods). Version 4. Sinauer Associates, Sunderland, Massachusetts. [program]
Taylor, E.H. (1962) New Oriental reptiles. University of Kansas Science Bulletin, 43, 209–263.
https://doi.org/10.5962/bhl.part.13346
Thompson, J.D., Gibson, T.J., Plewniak, F., Jeanmougin, F. & Higgins, D.G. (1997) The ClustalX windows interface: Flexible strategies for multiple sequence alignment aided by quality analysis tools. Nucleic Acids Research, 25, 4876–4882.
https://doi.org/10.1093/nar/25.24.4876
Ziegler, T., Botov, A., Nguyen, T.T., Bauer, A.M., Brennan, I.G., Ngo, H.T. & Nguyen, Q.T. (2016) First molecular verification of Dixonius vietnamensis Das, 2004 (Squamata: Gekkonidae) with the description of a new species from Vinh Cuu Nature Reserve, Dong Nai Province, Vietnam. Zootaxa, 4136 (3), 553–566.
https://doi.org/10.11646/zootaxa.4136.3.7