Aspidoscelis dixoni (SCUDDAY, 1973)
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Aspidoscelis dixoni
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| Higher Taxa | Teiidae, Teiinae, Gymnophthalmoidea, Sauria, Squamata (lizards) |
| Subspecies | |
| Common Names | E: Gray Checkered Whiptail |
| Synonym | Cnemidophorus dixoni SCUDDAY 1973 Cnemidophorus tesselatus dixoni — STEBBINS 1985: 163 Cnemidophorus dixoni — WRIGHT 1993 Cnemidophorus dixoni — WALKER et al. 1994 Cnemidophorus dixoni — LINER 1994 Cnemidophorus dixoni — WALKER et al. 1997 Cnemidophorus dixoni — BARTLETT & BARTLETT 1999: 253 Aspidoscelis dixoni — REEDER et al. 2002 Aspidoscelis dixoni — LINER & CASAS-ANDREU 2008 Aspidoscelis dixoni — COLLINS & TAGGART 2009 Aspidoscelis dixoni — JONES & LOVICH 2009: 334 Aspidoscelis dixoni — LEMOS-ESPINAL 2015 Aspidoscelis dixoni — WEIDLER 2019 |
| Distribution | USA (New Mexico: Hidalgo County; Texas: Presidio County) Type locality: 24.5 mi NW Presidio (16.9 mi from Jct US 67 and FM 170, then 7.6 mi NE) on Ireneo Gonzales Ranch. |
| Reproduction | |
| Types | Holotype: TCWC 40691; paratypes: TCWC, UCM, LACM, SRSU |
| Diagnosis | Diagnosis (dixoni). Meristic data and means are based upon 44 Presidio County specimens only. Cnemidophorus dixoni is a moderate sized Cnemidophorus having a maximum snout-vent length (SVL) of 98 mm, average length 84.3 ± 1.71; number of granular scales around midbody (GAB) 94-108, X= 99.66 ±.72; femoral pores 39-44, X =41.53±.32; postantebrachial scales moder ately enlarged; scales bordering the gular fold (mesoptychial scales) greatly enlarged; circumorbital scales separating the 3rd supraocular from the parietal and frontoparietal scales (type III of Zweifel, 1965). 10-14 fine pale lines anteriorly, either continuing uninterrupted posteriorly to form 11 or 12 dark lines broken into small squarish blotches (pattern Class A), or else the dark lines fusing across the pale lines to form fine, linear bars at right angles to the longitudinal axis of the body (pattern class B). Dorsum of rear legs lightly reticulated, forelegs darkly reticulated; posterior of body variously suffused with orange brown over the rump and onto the base of tail; venter white, mature adults often with anterior margin of scutes bordered with black. Occasionally small dark spots may be present on throat. No known males. Cnemidophorus dixoni differs from C. gularis, inornatus, exsanguis, and septemvittatus by the complete disruption of the striped pattern into bars or squares and by its much higher GAB count. Both the GAB count and color pattern are similar to some populations of C. tigris, from which C. dixoni can always be distinguished by the enlarged mesotychials and enlarged to moderate sized postantebrachials. Cnemidophorus dixoni is distinguished from other species of the tesselatus group by the distinct color pattern (striped for neomexicanus, stripes disrupted into tesselations for tesselatus)', from neomexicanus, by possessing enlarged postantebrachials (granular in neomexicanus) and enlarged mesoptychials (intermediately enlarged in neomexicanus), Hatchlings of Cnemidophorus dixoni A and B are similar in color pattern, yet distinct from the similar color pattern shared by hatchlings of C. tesselatus C, D, and E. Differences in color pattern are the most distinguishing features between C. dixoni and C. tesselatus. Yet, based upon this feature alone there would be no reason to regard C. dixoni as more than a pattern class of C. tesselatus. However, scutellation differences are noted between annectant populations of C. tesselatus E, although such differences are obscured when compared with tesselatus E throughout its range. The high GAB count of dixoni (94-112) is nearest the high count found within a population of tesselatus E in west-central New Mexico (Zweifel, 1965). My count (89-97) for Presidio County tesselatus E is lower than Zweifel's (1965) count for west Texas tesselatus. This may be due to differences in method of counting or to differences in scutellation noted by Zweifel in different populations of tesselatus. My sample consisted of 127 specimens of tesselatus E from Presidio County, while Zweifel looked at 55 specimens from Culberson County. My counts for 6 specimens of C. tesselatus F (fide Zweifel) were within the range of that population as reported by Zweifel (1965). The most important differences between C. dixoni and C. tesselatus E are ecological. Throughout most of its range in west Texas, Cnemidophorus tesselatus E is sympatric with one of its putative generating species, C. tigris marmoratus. Except for a single locality on the floor of Pinto Canyon in the Chinati Mountains, C. tesselatus E has not been found with its other putative generating species, C. septemvittatus. Cnemidophorus dixoni on the other hand is often found with C. septemvittatus, but except for marginal contacts at the elevational lower end of its range, dixoni is seldom found in sympatry with C. tigris marmoratus (Scudday 1973). Additional details (43 characters) are available for collaborators and contributors. Please contact us for details. |
| Comment | Distribution: see map in Painter in Jones & Lovich 2009. Synonymy: previously considered a synonym of A. tesselatus, based on Cordes and Walker 2006, but often treated as valid species by more recent authors. See also A. tesselatus. |
| Etymology | Named after James R. Dixon, American herpetologist. |
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