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Most aspects of the lives of ectotherms are temperature dependent. Achieving the warmer body temperatures (T b s) typically required for optimal performance can be particularly challenging for nocturnal ectotherms. Homonota darwinii-the world's southernmost gecko-is broadly distributed in southern Argentina (35-52 °S latitude) where cold climates over parts of its range likely pose an additional performance challenge for this nocturnal lizard. We hypothesized that the southernmost populations of this species would be the most thermally challenged, as evidenced by a decline in temperature-dependent sprint performance with increasing latitude. A temperature-dependent depression in locomotory performance may indicate suboptimal performance in other thermally dependent traits linked to fitness (e.g., foraging efficiency, metabolism). We measured sprint performance at five ecologically relevant T b s for four populations spanning most of the latitudinal range of H. darwinii. We also recorded annual operative temperatures (T e s) at each site on the surface and in refuges used by the geckos. Sprint data indicated differences in maximum performance over the range of H. darwinii, but not the latitudinal decline predicted. Instead, sprint performance was likely influenced by climatic variability associated with each site's elevation. Geckos from most populations had a broad range of T b s over which sprint performance was optimal, albeit twofold to threefold lower than other geckos. This is indicative of eurythermy, the ability to perform well over a wide range of temperatures. We discuss this finding in the context of alternative hypotheses concerning performance tradeoffs in nocturnal ectotherms., (© 2020 Wiley Periodicals, Inc.)

A phylogenetic taxonomic analysis of a monophyletic subgroup of the salamandrid genus Tylototriton revealed that a newly discovered population from Ngar Su Village, 1 km south of Ywangan, Shan State, Myanmar is a new species and most closely related to T. shanorum from approximately 80 km to the west in the vicinity of Taunggyi, Shan State. Tylototriton ngarsuensis sp. nov. differs from other closely related species of Tylototriton on basis of varying combinations of characteristics associated with it shorter head, larger size, rib nodule morphology, and overall drab, very dark, coloration, along with its genetic differentiation. Tylototriton ngarsuensis sp. nov. also appears to breed later in the year than most other species. Unfortunately, this species like many other Asian newts, is being harvested for the pet and medicinal trade and given its restricted distribution, this could pose a serious threat to its long-term survival.

A phylogenetic taxonomy of species in the Cyrtodactylus peguensis group from the Ayeyarwady Basin of Myanmar is constructed based on color pattern, morphology, and molecular systematic analyses using the mitochondrial gene NADH dehydrogenase subunit 2. Newly collected samples from the type locality of C. peguensis and other localities indicate that this clade is endemic to central Myanmar and contains at least seven species, four of which are undescribed. Three species, including C. peguensis occur in the low hills of the Bago Yoma Range within the central portion of the Ayeyarwady Basin. Two of these, C. myintkyawthurai sp. nov. from the northern and central Bago Yoma and C. meersi sp. nov. which is syntopic with C. peguensis in the southern Bago Yoma are described herein. As more lowland hilly areas bordering, and within the Ayeyarwady Basin are surveyed, more new species of this group are likely to be discovered. These discoveries continue the recent surge of descriptions of new species of Cyrtodactylus that are being discovered in Myanmar., Competing Interests: Aung Lin is employed by Fauna and Flora International.

A phylogenetic taxonomic analysis indicates that a newly discovered population of Cyrtodactylus from the vicinity of Ywangan Town in the Shan Hills, Shan State, Myanmar is a new species (C. ywanganensis sp. nov.) and the earliest diverging member of the linnwayensis group within the previously defined Indochinese clade. The DIVALIKE+J model of a BioGeoBEARS biogeographic analysis indicates that the Indochinese clade evolved in the Shan Hills and Salween Basin of eastern Myanmar and dispersed into Indochina on at least three separate occasions from 18.6-13.4 mya. Once there, uplift of the Tenasserim Mountains and Thai Highlands created the intermedius group, the oldhami group, and C. tigroides of western and southern Thailand which form sister lineages to the linnwayensis group, yathepyanensis group, and the sinyineensis group, respectively, of eastern Myanmar. Diverging lineages within the Indochinese clade highlight the importance of the Thai Highlands and Tenasserim Mountains in that group's evolution and speciation. The discovery of C. ywanganensis sp. nov. in karstic habitats in the Shan Hills continues to underscore the unrealized karst-associated herpetological diversity of this vast, relatively unexplored, upland region and the need for additional field studies.

Herbivory has evolved in many groups of vertebrates, but it is rare among both extinct and extant nonavian reptiles. Among squamate reptiles, (lizards, snakes, and their relatives), <2% of the >7,800 species are considered to be herbivorous, and herbivory is restricted to lizards. Here, we show that within a group of South American lizards (Liolaemidae, approximately 170 species), herbivory has evolved more frequently than in all other squamates combined and at a rate estimated to be >65 times faster. Furthermore, in contrast to other herbivorous lizards and to existing theory, most herbivorous liolaemids are small bodied and live in cool climates. Herbivory is generally thought to evolve only in reptile species that are large bodied, live in warm climates, and maintain high body temperatures. These three well known "rules" of herbivory are considered to form the bases of physiological constraints that explain the paucity of herbivorous reptile species. We suggest that the recurrent and paradoxical evolution of herbivory in liolaemids is explained by a combination of environmental conditions (promoting independent origins of herbivory in isolated cool-climate regions), ecophysiological constraints (requiring small body size in cool climates, yet high body temperatures for herbivores), and phylogenetic history. More generally, our study demonstrates how integrating information from ecophysiology and phylogeny can help to explain macroevolutionary trends.