P. orbiculare occurs in a wide range of primary habitats (dry scrubland, pine-oak forest, oak forest, juniper forest) and secondary habitats (agricultural land, and agave and Opuntia fields).[1]
^ abBeolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN978-1-4214-0135-5. (Phrynosoma orbiculare cortezii, p. 60; P. o. dugesii, p. 76).
Further reading
Boulenger GA (1885). Catalogue of the Lizards in the British Museum (Natural History). Second Edition. Volume II. Iguanidæ ... London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiii + 497 pp. + Plates I-XXIV. (Phrynosoma orbiculare, pp. 241–243).
Horowitz SB (1955). "An arrangement of the subspecies of the horned toad, Phrynosoma orbiculare (Iguanidae)". American Midland Naturalist54 (1): 204–218. (Phrynosoma orbiculare bradti, new subspecies; P. orbiculare orientale, new subspecies).
Linnaeus C (1758). Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio Decima, Reformata. Stockholm: L. Salvius. 824 pp. (Lacerta orbicularis, new species, p. 206). (in Latin).