Hybrid Cnemidophorus (Sauria: Teiidae) in Ninemile Valley of the Purgatoire River, Colorado

Abstract

Canonical variate analysis (CVA) of color pattern and scutellation characters in lizards collected in Ninemile Valley of the Purgatoire River at Higbee, Otero Co., Colorado graphically depicted two forms of parthenogenetic Cnemidophorus tesselatus (diploid color pattern class C and triploid color pattern class B), gonochoristic C. sexlineatus, and hybrid C. tesselatus x C. sexlineatus as four morphologically distinctive groups. A newly obtained male specimen with a C. tesselatus-like color pattern entered as an unknown was classified to the hybrid group in the CVA. It represented the fourth tetraploid hybrid C. tesselatus B(3n) x C. sexlineatus collected in the valley. A female specimen was also classified to the hybrid group by the CVA. A triploid karyotype (3n = 69) and color pattern identified this female as a putative C. tesselatus C(2n) x C. sexlineatus hybrid. Whereas male hybrids are presumably sterile and biological novelties at most, the possibility remains that a female hybrid could be the founder of a new parthenogenetic lineage. Zweifel (1965) informally described six color pattern classes of parthenogenetic lizards (A, B, C, D, E, F) in the Cnemidophorus tesselatus complex (family Teiidae) of which four (A-D) were reported from Colorado. Wright and Lowe (1967a) found that pattern classes A and B were triploid hybrid derivatives and pattern classes CF were diploid hybrid derivatives. Analyses of morphology (Walker et al., 1990) and karyology (Cordes, 1991) identified three of Zweifel's pattern classes of C. tesselatus in sympatry in Ninemile Valley of the Purgatoire River at Higbee, Otero Co., Colorado rather than two as indicated by Zweifel (1965), Densmore et al. (1989), and Wright (1993). These included diploid C. tesselatus C and D and triploid B, not triploid pattern class C as indicated by Parker and Selander (1976), Densmore et al. (1989), Wright (1993), and Leuck (1993). We found that the Ninemile Valley triploid population was morphologically indistinguishable from the pattern class B population described by Zweifel (1965) from Pueblo Co., Colorado. In samples collected in the valley since 1960 by various workers, diploid C. tesselatus outnumbered triploid C. tesselatus by a combined ratio of over 7:1. Moderate numbers of the gonochoristic species C. sexlineatus, the paternal parent of triploid C. tesselatus B (Wright and Lowe, 1967a; Parker and Selander, 1976), were also found in many parts of the area sampled. Four hybrid male C. tesselatus x C. sexlineatus were included in these collections. Three of these were described, and their probable parental forms identified as triploid C. tesselatus B x C. sexlineatus, by Walker et al. (1990). In the present study we describe the most recently collected hybrid male Cnemidophorus, infer its putative parentage on the basis of critical morphological characters, and evaluate the possibility of a hybrid origin for a female specimen displaying an ambiguous combination of classification characters. MATERIALS AND METHODS-Characters of scutellation that were quantitatively analyzed included: number of granules around midbody (GAB), number of granules from occiput to rump (OR), sum of left and right femoral pores (FP), number of subdigital lamellae on the longest toe of the left pes (SDL), sum of left and right circumorbital scales (COS), sum of This content downloaded from 207.46.13.57 on Mon, 08 Aug 2016 05:24:23 UTC All use subject to http://about.jstor.org/terms 236 The Southwestern Naturalist vol. 39, no. 3