Resumen   ̶   En 2006 y 2014 se encontraron dos individuos diferentes del cachorón de roca o chuckwalla espinoso (Sauromalus hispidus) en la pequeña, plana, volcánica y aislada isla Rasa, localizada en la Región de las Grandes Islas, en el Golfo de California, México. No se había registrado la existencia de esta especie en la isla antes de estas observaciones. Una prospección de campo en 2014 revela la presencia de un único individuo hembra de la especie habitando la parte sur-central de la isla, localidad llamada Valle del Tapete Verde, y en un territorio no mayor a 100 m por 100 m. El análisis de heces revela que el único alimento consumido por el animal es la hierba alcalina (Cressa truxilliensis) que forma alfombras discontinuas en el valle. El individuo carece de varias falanges tanto en manos como en patas, que parecen marcas intencionales por amputación. Se concluye que los dos individuos observados fueron introducidos intencionalmente por humanos a la isla.

Six hatchlings of the Common or Sonoran Desert Chuckwalla (Sauromalus ater) ranging from 60 mm to 93 mm (SVL) as well as 10 subadult individuals (mostly ♀) ranging from 110 mm to 146 mm (SVL) were recorded during three casual walks on the small island San Francisco, Baja California Sur, Gulf of California, México, in January and February, 2019. The presence of these hatchlings and subadult females could be an important sign of chuckwallas’ recovery and of continued population’s recruitment following eradication of feral cats and goats from the island in 1999 and 2000 respectively, and despite the intense presence of humans (fishermen and tourists) on the island. The chuckwalla population seems to be growing and becoming conspicuous on San Francisco after almost two decades of rare and infrequent records of individuals. Also, the vegetation shows more abundance and diversity, and more extensive covering than in previous years. Other vertebrate species, like the Baja California Rattlesnake (Crotalus enyo) and the Burrowing Owl (Athene cunicularia) were recorded as well during the walks. All these observations possibly indicate a whole and progressive biota restoration on this tiny island after devastation by invasive fauna, combined with previous good wet years.

Apalone spinifera atra (Family Trionychidae), endemic to the Cuatrociénegas Basin of Coahuila, Mexico, is an enigmatic and severely threatened softshell turtle. On the basis of morphology, it has been regarded as a full species (Apalone ater), but by phylogenetic molecular analyses it is currently considered a subspecies of A. spinifera. The discovery of color morphs correlated to substrate coloration in different localities and the recognition of hybridization between A. s. atra and A. s. emoryi have led to additional taxonomic uncertainty. In addition, A. s. atra has a very restricted distribution with an apparently small population size that is also being affected by genetic introgression from A. s. emoryi. These factors, combined with recent anthropogenic draining and alteration of its limited freshwater habitats, have placed A. s. atra at very high risk for extinction in the near future, if careful conservation actions are not taken immediately. In addition, a lack of information about its ecology has made its relationships and survival prospects more difficult to discern. It is listed as Critically Endangered by the IUCN Red List, included on Appendix I of CITES, listed as Endangered by US ESA, and as a Species of Special Concern by the Mexican Secretaría de Medio Ambiente y Recursos Naturales. distribution. -Mexico. Restricted to the Cuatrociénegas Basin, Coahuila.

II present an unpublished list of 59 plant species of 19 families that constitute a source of food for the insular reptiles Ctenosaura conspicuosa, C. hemilopha, Sauromalus varius, S. hispidus, S. slevini, S. klauberi, S. ater, Dipsosaurus dorsalis, D. catalinensis, and Petrosaurus thalassinus on 15 islands of the Gulf of California based on 711 direct observations of feeding events. Two reptile species climb to the tops of cardon cacti branches to purposely eat flowers and fruits and accidentally dislodge plant parts that partially subsidize ground organisms; the rest forage mainly on the ground, but do show a strong evolutionary, ecological, and behavioral tendency to climb on low trees and bushes to eat leaves and flowers. The reptiles’ food habits influence other populations, species, trophic levels, and even the whole insular communities, both up (to predators), down (to producers and primary consumers) and horizontally (to competitors). Insular herbivorous and omnivorous lizards, as primary and secondary consumers, and even as predators, are in the middle of complex food webs. In these interactions, the cardon cactus provides vast amounts of biomass and energy to the whole insular communities.