On the Occurrence of a Throat-Fan in Callisaurus ventralis gabbii and Two Species of Crotaphytus

Abstract

INCE reporting the occurrence of a distinctly developed throat-fan in two males of the ocellated sand lizard Urna notata (COPEIA, 1931, No. 1, pp. 15-16, fig. 1), I have observed the structure in other iguanid lizards. In view of the fact that the genera Unta and Callisaurus are very closely related, it is not surprising that a throat-fan very similar in every respect to that of the adult males of Umra notata should now be found in an adult male of Callisaurus ventralis gabbii, which was collected by Mr. Charles M. Bogert of Los Angeles, at Lovejoy Springs, Los Angeles County, California, on April 10, 1931. Mr. Bogert has written that the lizard appeared to be interested in displaying his throat-fan when discovered that it was no difficulty to collect him and that although the mating season for Californian lizards had not quite begun, this individual posed on conspicuously large rocks as it operated its throat-fan (which has a patch of bright pink near its center) and curled its tail over its back. The latter action is no doubt designed to effect a display of the distinctive series of transverse black bars which are present beneath the otherwise immaculately white tail. Another feature of the mating preliminaries, as inferred from observations in the laboratory, seems to be a raising of the body high in the air through a vertical extension of the relatively well developed forelimbs in order to bring into view the beautiful blue-green patches which surround the piominent deep-black ventrolateral bars which are present on each side of adult males of this species. During times of decided excitement, such as those brought about by excessive rubbing and tickling, the throat-fan of the lizard under discussion is thrown out and drawn in, but under normal conditions it is characteristically kept hidden from view so that repeated observations and even ordinary handlings are usually insufficient to cause its release. From this it is to be inferred that the throat-fan of Callisaurus ventralis gabbii would ordinarily be overlooked in both living and preserved material. The throat-fan of a Texan male of the reticulated mountain-boomer, Crotaphytus reticulatus, has been shown to me recently by Dr. Edward H. Taylor of Kansas University, and I have found a very similar one to be present in a series of males of the collared lizard, Crotaphytus collaris, which was also collected in Texas. in Crotaphytus the throat-fan is blunter, less extensible, and more pouch-like than in Uma and Callisaurus, the skin bordering the fan being somewhat inflated when exposed, rather than pulled tightly over a sharp, laterally compressed fan-element. It is probable that the relatively incomplete throat-fan of the collared lizard plays an important role in the mating preliminaries of the species, in that its extension brings the unusually beautiful, orange-tinted throat into full view.