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Crotalus ornatus HALLOWELL, 1854

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Higher TaxaViperidae, Crotalinae, Colubroidea, Alethinophidia, Serpentes, Squamata (snakes) 
Common NamesE: Black-tailed Rattlesnake 
SynonymCrotalus ornatus HALLOWELL 1854: 192
Crotalus ornatus — ANDERSON & GREENBAUM 2012
Crotalus ornatus — WALLACH et al. 2014: 193 
DistributionUSA (Texas), Mexico (Chihuahua, Nuevo León)

Type locality: near Pecos River, N. W. Texas.  
TypesHolotype: USNM 486, adult female; Fig. 10) collected by A. Heermann. The specimen was collected during the survey of a railroad route to the Pacific, led by Lieutenant Parke, US Topographical Engineer (collection date unknown). 
DiagnosisDiagnosis. Crotalus ornatus (Fig. 11) can be distinguished from most congeners by having (1) a medium-sized SVL (adults 70– 100 cm, rarely to 130 cm SVL); (2) two large, triangular internasal scales; (3) two large prefrontals; (4) two large frontal scales; (5) 6– 10 prefoveals; (6) 2–4 loreals; (7) two preocu- lars; (8) five postoculars; (9) 2–7 intersuprao- culars; (10) 16–18 supralabials; (11) 14–21 infralabials; (12) 23–29 dorsal scale rows at midbody; (13) 164–205 ventrals; (14) 16–30 subcaudals (16–26 in females and 21–30 in males); (15) internasal–prefrontal region and supraoculars black or dark brown; (16) dark pigmentation of dorsal pattern extends from nape to occipital and parietal regions; (17) 22– 33 (mean 5 29) rhomboid dorsal body blotches that often coalesce with lateral blotches at midbody to form bands or chevrons (dorsal blotches of some specimens may become diffuse posteriorly, represented by barely distinct or absent bands anterior to vent); (18) light medial spots longer than wide on anterior portion of body, becoming broader at midbody and separating dorsal blotches; (19) medial spots often become indistinguishable from ground color on posterior one-quarter of body; (20) two white or light grey, irregular paraver- tebral spots present within each dorsal blotch, usually separated by 1–6 dorsal scale rows on anterior portion of body, but darken slightly and grow to extend across midline of dorsum to fill interior of dorsal blotches on posterior half of body; (21) tail black or dark brown with faint crossbands sometimes visible; (22) proximal rattle segment black or dark brown (Tables 6–7; from ANDERSON & GREENBAUM 2012). 
CommentSynonymy: Crotalus ornatus was revalidated from the synonymy of C. molossus by Anderson & Greenbaum 2012, hence C. ornatus has been subsumed under C. molossus in the older literature. 
  • Anderson, Christopher G. and Eli Greenbaum 2012. Phylogeography of Northern Populations of the Black-Tailed Rattlesnake (Crotalus molossus Baird And Girard, 1853), With the Revalidation of C. ornatus Hallowell, 1854. Herpetological Monographs 26 (1): 19-57. - get paper here
  • Davis DR, LaDuc TJ 2018. Amphibians and reptiles of C. E. Miller Ranch and the Sierra Vieja, Chihuahuan Desert, Texas, USA ZooKeys 735: 97-130 - get paper here
  • García-Padilla, Elí, Gerson Josué Herrera-Enríquez, Manuel Nevárez de los Reyes, David Lazcano, Vicente Mata-Silva, Jerry D. Johnson and Larry David Wilson. 2016. Crotalus ornatus Hallowell, 1854. Mexico, Nuevo León. Mesoamerican Herpetology 3 (3): 778 - get paper here
  • Hallowell,E. 1854. Notices of new reptiles from Texas. Proc. Acad. Nat. Sci. Philad. 1854: 192-193 - get paper here
  • Heimes, P. 2016. Snakes of Mexico. Chimaira, Frankfurt, 572 pp
  • Hernandez T, Herr MW, Stevens S, Cork K, Medina-Nava C, Vialpando CJ, Warfel T, Fields N, Brodie C, Graham SP 2019. New distribution records for amphibians and reptiles in eastern Chihuahua, Mexico. Check List 15(1): 79-86 - get paper here
  • Nevárez de Los Reyes, Manuel, David Lazcano and Javier Banda-Leal. 2016. Geographic Distribution: Crotalus ornatus (Eastern Black-tailed Rattlesnake). Herpetological Review 47 (2): 261 - get paper here
  • Nevárez-de-los-Reyes, Manuel, David Lazcano, Elí García-Padilla, Vicente Mata-Silva, Jerry D. Johnson and Larry David Wilson. 2016. The Herpetofauna of Nuevo León, Mexico: Composition, Distribution, and Conservation. Mesoamerican Herpetology 3 (3): 558–638 - get paper here
  • Spinner, L. 2017. Die Klapperschlangen der USA in Natur und Terrarium Reptilia (Münster) 22 (124): 18-33 - get paper here
  • Wallach, Van; Kenneth L. Williams , Jeff Boundy 2014. Snakes of the World: A Catalogue of Living and Extinct Species. [type catalogue] Taylor and Francis, CRC Press, 1237 pp.
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