Thermal ecophysiology of Basiliscus galeritus (Squamata: Corytophanidae) in two populations at different altitudes: Does the crest participate actively in thermoregulation?

Thermoregulation is a critical process for ectotherms as non-avian reptiles, since their vital physiological processes depend on it. These organisms have a temperature range where their physiological processes are more efficient, this range is usually a requirement set phylogenetically even though they vary in the use of habitats. This research compares the thermal ecophysiology of Basiliscus galeritus (western basilisk) in two populations with altitudinal differences in the northwestern of Ecuador. The results suggest that the difference of altitude between the two locations (500 m) influences the thermal ecophysiology of the species since the body temperature (Tb), operative temperature (Te) and preferred body temperature (Tset) showed significative differences. Furthermore, B. galeritus obtains its Tb through heliothermy and it behaves as an active thermoregulator. On the other hand, the crest temperatures reach higher values than their Tset, the results suggested that the species uses the crest as an alternative to regulate its body temperature when exceeding its Tset. Besides, this thermoregulatory behavior has been suggested only in some extinct synapsids.

A new species of Lepidophyma (Squamata: Xantusiidae) from San Luis Potosí, México, with notes on its physiological ecology.

In recent years, there has been an increase in the descriptions of members of the lizard genus Lepidophyma. Herein, we describe a new species of Lepidophyma from the Huasteca Potosina region of Mexico, previously confused with L. gaigeae, from which it differs in lacking parietal spot, among other characteristics. We inferred its phylogenetic position and provide information on its thermal and hydric physiology, as well as on some other aspects of natural history. Molecular and morphological data supported the independent taxonomic status of the new species, indicating its placement as the sister taxon of L. gaigeae and a wide morphological separation between these species. Lepidophyma lusca sp. nov. has a diurnal-crepuscular activity period and occurs at lower elevations than L. gaigeae. Also, the new species differ from its sister taxon in its physiology, as reflected by its tendency toward higher thermal parameters and water loss rates. With the description of L. lusca sp. nov., the number of species in the genus Lepidophyma rises to 21.

Corytophanids Replaced the Pleurodont XY System with a New Pair of XY Chromosomes.

Almost all lizard families in the pleurodont clade share the same XY system. This system was meticulously studied in Anolis carolinensis, where it shows a highly degenerated Y chromosome and a male-specific X chromosome dosage compensation mechanism. Corytophanids (casque-headed lizards) have been proposed as the only family in the pleurodont clade to lack the XY system. In this study, we worked with extensive genomic and transcriptomic data from Basiliscus vittatus, a member of the Corytophanidae family that inhabits the tropical rainforests of Mexico. We confirmed that B. vittatus underwent a sex chromosome system turnover, which consisted in the loss of the pleurodont XY system and the gain of a new pair of XY chromosomes that are orthologous to chicken chromosome 17. We estimated the origin of the sex chromosome system to have occurred ∼63 Ma in the ancestor of corytophanids. Moreover, we identified 12 XY gametologues with particular attributes, such as functions related to the membrane and intracellular trafficking, very low expression levels, blood specificity, and incomplete dosage compensation in males.