{{Short description|Species of snake}} {{Use dmy dates|date=June 2020}} {{Speciesbox | image = Crotalus scutulatus 02.JPG | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 18 November 2021">{{cite iucn |author=Mendoza-Quijano, F. |author-link=species:Fernando Mendoza-Quijano |author2=Hammerson, G.A. |author2-link=species:Geoffrey A. Hammerson |date=2007 |title=''Crotalus scutulatus '' |volume=2007 |article-number=e.T64332A12771270 |doi=10.2305/IUCN.UK.2007.RLTS.T64332A12771270.en |access-date=18 November 2021}}</ref> | genus = Crotalus | species = scutulatus | authority = ([[Robert Kennicott|Kennicott]], 1861) | synonyms = *''Caudisona scutulata'' <br />{{small|[[Robert Kennicott|Kennicott]], 1861}} *''C''[''rotalus'']. ''scutulatus'' <br />{{small|— [[Edward Drinker Cope|Cope]] ''In'' [[H.C. Yarrow|Yarrow]] ''in'' [[George Montague Wheeler|Wheeler]], 1875}} *''Crotalus adamanteus scutulatus'' <br />{{small|— Cope, 1875}} *''Crotalus scutulatus'' <br />{{small|— [[George Albert Boulenger|Boulenger]], 1896}} *''Crotalus confluentus kellyi'' <br />{{small|[[Afrânio Pompílio Gastos do Amaral|Amaral]], 1929}} *''Crotalus scutulatus scutulatus'' <br />{{small|— [[Howard K. Gloyd|Gloyd]], 1940}} | synonyms_ref = <ref name="McD99">[[Roy Wallace McDiarmid|McDiarmid RW]], [[Jonathan A. Campbell|Campbell JA]], [[T'Shaka A. Touré|Touré TA]] (1999). ''Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1''. Washington, District of Columbia: Herpetologists' League. 511 pp. {{ISBN|1-893777-00-6}} (series). {{ISBN|1-893777-01-4}} (volume).</ref> }}

'''''Crotalus scutulatus''''' is [[species]] of [[rattlesnake]], a [[Venomous snake|venomous]] [[Pit viper|pitviper]] in the [[Family (taxonomy)|family]] [[Viperidae]].

The species is known [[Common name|commonly]] as the '''Mohave Rattlesnake'''.<ref>{{Cite book |last1=Crother |first1=B.I. |author1-link=Brian I. Crother |url=https://ssarherps.org/wp-content/uploads/2014/07/HC_39_7thEd.pdf |title=Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confidence in Our Understanding |last2=Boundy |first2=J. |author2-link=Jeff Boundy |last3=Burbrink |first3=F.T. |author3-link=Frank T. Burbrink |last4=Campbell |first4=J.A. |last5=de Queiroz |first5=K. |author5-link=Kevin de Queiroz |last6=Frost |first6=D.R. |author6-link=Darrel Frost |last7=Green |first7=D.M. |author7-link=David M. Green |last8=Highton |first8=R. |author8-link=Richard Highton |last9=Iverson |first9=J.B. |author9-link=John B. Iverson |publisher=Society for the Study of Amphibians and Reptiles |year=2012 |isbn=978-0-916984-85-4 |edition=7th |pages=57–58}}</ref><ref name=":0">{{Cite book |last1=Crother |first1=B.I. |url=https://ssarherps.org/wp-content/uploads/2017/10/8th-Ed-2017-Scientific-and-Standard-English-Names.pdf |title=Scientific and Standard English names of Amphibians and reptiles of North America North of Mexico, With Comments Regarding Confidence in Our Understanding |last2=Bonett |first2=R.M. |author2-link=species:Ronald M. Bonett |last3=Boundy |first3=J. |last4=Burbrink |first4=F.T. |last5=de Queiroz |first5=K. |last6=Frost |first6=D.R. |last7=Highton |first7=R. |last8=Iverson |first8=J.B. |last9=Jockusch |first9=E.L. |author9-link=species:Elizabeth Lacy Jockusch |publisher=Society for the Study of Amphibians and Reptiles |year=2017 |isbn=978-1-946681-00-3 |edition=8th |pages=64–65}}</ref> Other common English names include '''Mojave Rattlesnake''' <ref name="Stebbins">[[Robert C. Stebbins|Stebbins, R.C.]] (2003). ''A Field Guide to Western Reptiles and Amphibians''. Boston: Houghton Mifflin & Co. pp. 416–417. {{ISBN|0-395-98272-3}}</ref><ref name="C&L04">Campbell JA, [[species:William W. Lamar|Lamar WW]] (2004). ''The Venomous Reptiles of the Western Hemisphere''. Ithaca and London: Comstock Publishing Associates. 870 pp., 1,500 plates. {{ISBN|0-8014-4141-2}}.</ref> and, referring specifically to the nominate (northern) subspecies: Northern Mohave Rattlesnake<ref name=":0" /> and Mojave Green Rattlesnake,<ref>{{Cite book |last1=Crother |first1=B.I. |title=Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confidence in Our Understanding |last2=Boundy |first2=J. |last3=Campbell |first3=J.A. |last4=de Queiroz |first4=K. |last5=Frost |first5=D.R. |last6=Highton |first6=R. |last7=Iverson |first7=J.B. |last8=Meylan |first8=P.A. |author8-link=Peter Andre Meylan |last9=Reeder |first9=T.W. |author9-link=species:Tod W. Reeder |publisher=Society for the Study of Amphibians and Reptiles |year=2000 |isbn=978-0-916984-54-0 |edition=1st |pages=60}}</ref><ref name="Stebbins" /> the latter name commonly shortened to the more colloquial "Mojave green".<ref name=":1">{{Cite book |last=Cardwell |first=Mike |title=The Mohave Rattlesnake and How It Became an Urban Legend |publisher=ECO Publishing |year=2020 |isbn=978-1-938850-30-1 |location=Rodeo, New Mexico}}</ref> Campbell and Lamar (2004) supported the English name "Mohave (Mojave) rattlesnake" with some reluctance because so little of the snake's range lies within the [[Mojave Desert]].<ref name="C&L04" /> The spelling of the English name with an "h" has been advocated by multiple authors in recent years for various reasons.<ref name=":1" /> The most recent iteration of standard English names for North American reptiles, endorsed by the major herpetological societies in the United States and Canada, concludes that spelling with either a "j" or an "h" is correct, based on "whether the word is used in a Spanish or English context." Thus, their standard English names list adopted the "h" spelling.<ref name=":0" />

''Crotalus scutulatus'' is a highly venomous pitviper (family Viperidae, [[subfamily]] [[Crotalinae]]) found in the [[desert]]s of the southwestern [[United States]] and deep into mainland [[Mexico]]. It is perhaps best known for producing two distinctly different [[venom]] types in different [[Population (biology)|population]]s.

Two [[subspecies]] are currently recognized.<ref>{{Cite web |title=Integrated Taxonomic Information System |url=https://www.usgs.gov/tools/integrated-taxonomic-information-system-itis |access-date=6 February 2024}}</ref> This account describes the widely distributed [[Nominotypical subspecies|nominate subspecies]], the Northern Mohave Rattlesnake, ''Crotalus scutulatus scutulatus''.<ref name=":0" /> The other subspecies, ''[[Crotalus scutulatus salvini|C. scutulatus salvini]]'', occurs in a relatively small area deep in mainland [[Mexico]].<ref>{{Cite book |last=Gloyd |first=H.K. |author-link=Howard K. Gloyd |title=The Rattlesnakes – Genera ''Crotalus'' and ''Sistrurus'' |publisher=Chicago Academy of Sciences |location=Chicago |year=1940 |pages=201–202}}</ref>

==Type specimen and type locality== The type specimen ([[holotype]]) of ''Crotalus scutulatus'' is ANSP 7069, in the collection of the Philadelphia Academy of Natural Sciences (formerly one of two specimens of USNM 5027 at the Smithsonian Institution).<ref name=":3">{{Cite journal |last1=Cardwell |first1=M.D. |last2=Gotte |first2=S.W. |author2-link=species:Steve W. Gotte |last3=McDiarmid |first3=R.W. |last4=Gilmore |first4=N. |last5=Poindexter |first5=J.A. |date=2013 |title=Type specimen of ''Crotalus scutulatus'' (Chordata: Reptilia: Squamata: Viperidae) re-examined, with new evidence after more than a century of confusion |url=https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-7998.2007.00358.x |journal=Proceedings of the Biological Society of Washington |volume=126 |issue=1 |pages=11–16|doi=10.1111/j.1469-7998.2007.00358.x |url-access=subscription }}</ref><ref name="C&L04" /><ref name="McD99"/>{{rp|293–295}} The [[Type locality (biology)|type locality]] is "Fort Buchanan, Arizona". The ruins of Fort Buchanan are in present day Santa Cruz County, Arizona.<ref>{{Cite book |last=Cope |first=E.D. |author-link=Edward Drinker Cope |title=Annual Report of the Board of Regents of the Smithsonian Institution |publisher=U.S. Government Printing Office |location=Washington, D.C. |year=1900 |pages=1158–1160 |chapter=The crocodilians, lizards, and snakes of North America}}</ref><ref name=":3" />

==Description== ''Crotalus scutulatus'' grows to an average total length (tail included) of less than {{convert|100|cm|ft|abbr=on}}, with a maximum total length of 123.6&nbsp;cm (4.1&nbsp;ft) for males and 92.2&nbsp;cm (3.0&nbsp;ft) for females.<ref name=":1" /><ref>{{Cite journal |last1=Mrinalini |author1-link=species:Mrinalini |last2=Hicks |first2=James J. |last3=Wüster |first3=Wolfgang |author3-link=Wolfgang Wüster |title=''Crotalus scutulatus'' (Mohave Rattlesnake). Maximum size. |url=https://ssarherps.org/herpetological-review-pdfs/ |journal=Herpetological Review |date=2015 |volume=46 |issue=2 |page=271}}</ref> [[File:0534 C. scutulatus on white.jpg|thumb|Typical adult Mohave rattlesnake]] There is no single visual trait that reliably identifies ''C. scutulatus'' and the most reliable visual identifications result from careful consideration of multiple traits. ''C. scutulatus'' is broadly sympatric with ''[[Western diamondback rattlesnake|C. atrox]]'' (the Western Diamond-backed Rattlesnake), which it closely resembles. The dorsal color of ''C. scutulatus'' varies from shades of green to browns, grays, and even yellowish. ''C. scutulatus'' has a row of large diamond-shaped dorsal blotches closely resembling ''C. atrox'' but lacking the abundant dark speckling, both coarse and fine, found throughout the dorsal surfaces of ''C. atrox''. Additionally, ''C. scutulatus'' lacks the white margins along the caudal edges of the dorsal "diamonds" that are found in most ''C. atrox''. The postocular light facial stripe usually bends toward the neck and does not intersect with the mouth in ''C. scutulatus'', as it does in ''C. atrox''. The tail is usually marked with alternating pale and dark rings in both species, with the dark rings often (but not always) being narrower than the pale ones in ''C. scutulatus'' and the colors are usually less distinct than the bright white and dark black caudal rings of most ''C. atrox''. The proximal rattle segment contains live tissue and is usually bicolor – yellow and black, or entirely yellow, in ''C. scutulatus'', but entirely black (sometimes with a brush of white) in ''C. atrox''.<ref name=":2">{{Cite journal |last1=Cardwell |first1=Michael D. |last2=Massey |first2=Daniel J. |last3=Wüster |first3=Wolfgang |date=2022 |title=Mohave Rattlesnake (''Crotalus scutulatus'') Identification Revisited |url=https://www.sciencedirect.com/science/article/pii/S1080603222000047 |journal=Wilderness and Environmental Medicine |volume=33 |issue=2 |pages=210–218 |doi=10.1016/j.wem.2022.01.003 |pmid=35221167 |via=Elsevier Science Direct|doi-access=free }}</ref><ref name=":1" />

The crown scales (between the supraoculars) of ''C. scutulatus'' are relatively large compared to other rattlesnakes like ''C. atrox'' (but see ''[[Black-tailed rattlesnake|C. molossus]]'' and ''[[Black-tailed rattlesnake|C. ornatus]]''), and the enlarged scales spill out behind the supraocular scales in a fan shape, usually with a well-defined margin. The minimum number of scales separating the supraoculars varies from two to four in ''C. scutulatus''. Crown scales on ''C. atrox'' are usually smaller, more numerous, and they do not produce the well-defined fan where they integrate into the scales behind the crown.<ref name=":2" /><ref name=":1" /> {| class="wikitable" | colspan="5" |Comparison of the most significant distinguishing traits between ''C. scutulatus'' and other commonly-encountered sympatric rattlesnakes. Adapted from Cardwell et al. 2022<ref name=":2" /> |- |Trait |''Crotalus scutulatus'' |''Crotalus atrox'' |''Crotalus molossus*'' |''Crotalus viridis'' |- |Greenish color |Sometimes |No |Sometimes |Often |- |Pattern speckling |Little or none |Obvious, course and fine |Little or none |Little or none |- |Tail color & caudal rings |Dark gray, black, or brown rings on pale gray or white background |High-contrast black rings on white background |Tail uniformly black, gray, or dark brown, with occasional faint pale rings |Narrow dark and pale rings, same colors as dorsum, with little or no whitish color |- |Proximal rattle segment |Yellow or bicolor (yellow and black) |Black with occasional brush of white |Black |Black |- |Pale postocular stripe |Passes above the mouth |Intersects with mouth |Absent |Passes above the mouth |- |Crown scales |Large and irregular, spilling out onto parietal area |Small and granular, indistinct from parietal area |Large and square anteriorly, others small and uniform |Small and granular, indistinct from parietal area |- | colspan="5" |* Same traits as ''C. ornatus'' |}

==Geographic range== [[File:C. scutulatus distribution.jpg|thumb]] ''Crotalus scutulatus'' is found in arid habitats in the southwestern [[United States]], from the [[Mojave Desert|Mohave Desert]] in [[California]]'s [[Los Angeles County, California|Los Angeles]] and [[San Bernardino County, California|San Bernardino Counties]], across most of western and southern [[Arizona]] (southwest of the [[Mogollon Rim]]), and from [[El Paso County, Texas|El Paso County]] south through the [[Big Bend (Texas)|Big Bend region]] of western [[Texas]]. It also occurs as far north as [[Lincoln County, Nevada|Lincoln County]] in [[Nevada]], the southwest corner of [[Washington County, Utah|Washington County]] in [[Utah]], and portions of extreme southern [[New Mexico]]. In [[Mexico]], it is found in [[Sonora]], [[Chihuahua (state)|Chihuahua]], and south on the [[Mexican Plateau]] to the states of [[State of Mexico|Mexico]], [[Puebla]], and [[Veracruz]]. It is found in [[desert]]s and other areas with [[Deserts and xeric shrublands|xeric]] vegetation from near sea level to about {{cvt|2,500|m|ft}} elevation.<ref name="C&L04" />

==Habitat== ''Crotalus scutulatus'' is primarily an inhabitant of broad [[desert]] valleys or lower mountain slopes, ''C. scutulatus'' is often found in sparsely vegetated areas containing predominantly [[Larrea tridentata|creosote]] (''[[Larrea]]''), [[Ragweed|sage]] (''[[Ragweed|Ambrosia]]''), [[mesquite]] (''[[Prosopis]]''), various [[Cactus|cacti]] ([[Cactus|Cactaceae]]), and [[Yucca brevifolia|Joshua trees]] (''[[Yucca brevifolia]]''), as well as [[juniper]] (''[[Juniper]]us'') [[woodland]] and [[grassland]] ([[Poaceae]]) habitats in some places. In general, ''C. scutulatus'' tends to avoid densely vegetated and extremely rocky areas, preferring relatively flat, open, and xeric habitats.<ref name="C&L04" />

==Conservation status== ''Crotalus scutulatus'' is classified as Least Concern (LC) on the [[IUCN Red List]] of Threatened Species (v 3.1, 2001).<ref name="ICUN">{{Redlist species|no=64332|genus=Crotalus|species=scutulatus|date=6 February|year=2024}}</ref> Species are listed as such due to their wide distribution, presumed large population, or because they are unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend was stable when assessed in 2007.<ref>{{Cite book |date=2012 |title=IUCN Red List categories and criteria, version 3.1, 2nd edition |isbn=978-2-8317-1435-6 |url=https://portals.iucn.org/library/node/10315 |access-date=7 February 2024}}</ref>

==Behavior== [[File:Rattlesnakes-are-extremely-fast-and-variable-when-striking-at-kangaroo-rats-in-nature-Three-srep40412-s1.ogv|thumb|A ''C. scutulatus'' attacking a [[Merriam's kangaroo rat|kangaroo rat]]]] ''Crotalus scutulatus'' is most active from April to September. They are ambush predators, eating mostly small [[rodent]]s and [[lizard]]s. Courtship begins in late summer/fall, is interrupted by winter, and resumes in the spring. Females [[Ovoviviparity|bear live young]], from two to 17 (average about eight), from July through September.<ref name="Kla97">[[Laurence Monroe Klauber|Klauber LM]] (1997). ''Rattlesnakes: Their Habitats, Life Histories, and Influence on Mankind. Second Edition''. First printing in 1972. Berkeley: University of California Press. {{ISBN|0-520-21056-5}}.</ref><ref>{{Cite book |last1=Schuett |first1=G.W. |author1-link=Gordon W. Schuett |title=Biology of the Vipers |last2=Carlisle |first2=S.L. |last3=Holycross |first3=A.T. |author3-link=species:Andrew T. Holycross |last4=O'Leile |first4=J.K. |last5=Hardy |first5=D.L. |last6=Van Kirk |first6=E.A. |last7=Murdoch |first7=W.J. |publisher=Eagle Mountain Publishing |year=2002 |isbn=0-9720154-0-X |editor-last=Schuett |editor-first=G.W. |pages=515–532 |chapter=Mating system of male Mojave rattlesnakes (''Crotalus scutulatus''): Seasonal timing of mating, agonistic behavior, spermatogenesis, sexual segment of the kidney, and plasma sex steroids |editor-last2=Höggren |editor-first2=M. |editor2-link=species:Mats Höggren |editor-last3=Douglas |editor-first3=M.E. |editor3-link=species:Michael E. Douglas |editor-last4=Greene |editor-first4=H.W. |editor4-link=species:Harry W. Greene}}</ref><ref>{{Cite journal |last=Cardwell |first=M.D. |title=The reproductive ecology of Mohave rattlesnakes |journal=Journal of Zoology |date=2008 |volume=274 |issue=1 |pages=65–76|doi=10.1111/j.1469-7998.2007.00358.x }}</ref><ref name=":4">{{Cite book |last=Cardwell |first=M.D. |title=Rattlesnakes of Arizona |publisher=ECO Publishing |year=2016 |isbn=978-1-938850-18-9 |editor-last=Schuett |editor-first=G.W. |volume=1 |location=Rodeo, New Mexico |pages=563–605 |chapter=Mohave rattlesnake ''Crotalus scutulatus'' (Kennicott 1861) |editor-last2=Feldner |editor-first2=M.J. |editor-last3=Smith |editor-first3=C.F. |editor-last4=Reiserer |editor-first4=R.S. |editor4-link=Randall S. Reiserer}}</ref>

This species is not known to den communally and they have no need to seasonally migrate between winter dens and summer foraging areas, as do some other species living at higher elevations and higher latitudes. Instead, individuals occupy well defined [[home range]]s year around, taking shelter during the winter and hot summer weather in burrows excavated by animals like [[rodent]]s, [[tortoise]]s, and [[kit fox]]es.<ref name=":1" /><ref name=":4" />

Like other rattlesnakes, this species is routinely preyed upon by larger predators like [[coyote]]s, [[bobcat]]s, and [[Bird of prey|raptors]]. As a result, it is shy, cryptic, and does not seek out confrontations with larger creatures, including humans. But like other rattlesnake species, it will strike and bite vigorously when disturbed, especially if surprised or when there is no nearby vegetation or burrow into which the snake can escape.<ref name=":1" /><ref name=":4" />

== Recent genetic and morphological analyses == Robust genetic analyses have revealed the [[Population structure (genetics)|population structure]] of ''Crotalus scutulatus'' throughout the species' range, correlating genetic evidence of [[Genetic isolation|isolation]] and subsequent [[secondary contact]] of subpopulations with corresponding geologic and climatic events. As a result, four genetically distinct clades among present-day ''C. scutulatus'' have been described''.''<ref name=":9">{{Cite journal |last1=Schield |first1=Drew R. |last2=Adams |first2=Richard H. |last3=Card |first3=Daren C. |last4=Corbin |first4=Andrew B. |last5=Jezkova |first5=Tereza |author5-link=Tereza Jezkova |last6=Hales |first6=Nicole R. |last7=Meik |first7=Jesse M. |author7-link=species:Jesse M. Meik |last8=Perry |first8=Blair W. |last9=Spencer |first9=Carol L. |last10=Smith |first10=Lydia L. |last11=García |first11=Gustavo Campillo |author11-link=species:Gustavo Campillo-García |last12=Bouzid |first12=Nassima M. |last13=Strickland |first13=Jason L. |author13-link=species:Jason L. Strickland |last14=Parkinson |first14=Christopher L. |author14-link=species:Christopher L. Parkinson |last15=Borja |first15=Miguel |date=2018 |title=Cryptic genetic diversity, population structure, and gene flow in the Mojave rattlesnake (''Crotalus scutulatus'') |journal=Molecular Phylogenetics and Evolution |volume=127 |pages=669–681 |doi=10.1016/j.ympev.2018.06.013 |pmid=29902574 |bibcode=2018MolPE.127..669S |issn=1055-7903}}</ref> [[File:C. scutulatus phylogenetic map & tree.jpg|thumb|Phylogenetic map and tree of Crotalus scutulatus. Divergence of Northern Clade from the Southern Clade (A), the Huamantlan rattlesnake from the Central Mexican Plateau Clade (B), and the Mojave-Sonoran Clade from the Chihuahuan Clade (C). Adapted from Cardwell 2020<ref name=":1" /> (map), and Schield et al. 2018<ref name=":9" /> (tree).]] The earliest split occurred at the northern margin of the Central Mexican Plateau about 4.1 million years ago (MYA), separating the species into northern and southern subpopulations. Then about 1.8 MYA, the subpopulation now identified as ''C. scutulatus salvini'' diverged genetically from the animals on the Central Mexican Plateau. Most recently, the northern subpopulation was divided at the [[Continental Divide of the Americas|Continental Divide]] (Cochise Filter) about 1.5 MYA, creating the Mojave-Sonoran clade to the west and the Chihuahuan clade to the southeast. Note that the boundaries between these clades correspond to elevational clines where climatic shifts during [[Pleistocene]] [[Quaternary glaciation|glacial advances and retreats]] likely isolated the subpopulations during cold periods but allowed secondary contact and resumption of [[gene flow]] during warmer periods, including the present.<ref name=":9" />

These analyses indicate that the Central Mexican Plateau clade is more closely related (i.e., more recently shared a common ancestor) to the Huamantlan Rattlesnake (currently ''C. scutulatus salvini'') than it is to the northern (Mojave-Sonoran and Chihuahuan) clades, suggesting that the designation of ''salvini'' as a subspecies of all other ''C. scutulatus'' is problematic.<ref name=":9" />

More recently, qualitative, [[Meristic trait|meristic]], and [[Morphometrics|morphometric]] traits from 347 specimens of ''C. scutulatus'' were analyzed, producing the conclusion that the species "is [[phenotypically]] cohesive without discrete subgroups, and that [[Morphology (biology)|morphology]] follows a continuous cline in primary color pattern and meristic traits across the major axis of its expansive distribution," suggesting that "multiple episodes of isolation and secondary contact among [[metapopulation]]s during the [[Pleistocene]] were sufficient to produce distinctive genetic populations, which have since experienced [[gene flow]] to produce clinal variation in phenotypes without discrete or diagnosable distinctions among these original populations." It was recommended that, for [[Taxonomy|taxonomic]] purposes, ''Crotalus scutulatus'' "be retained as a single [[species]], although it is possible that ''C. s. salvini'', which is [[Morphology (biology)|morphologically]] the most distinctive population, could represent a peripheral isolate in the initial stages of [[speciation]]."<ref>{{Cite journal |last1=Watson |first1=Jessica A. |last2=Spencer |first2=Carol L. |last3=Schield |first3=Drew R. |last4=Butler |first4=Brett O. |author4-link=species:Brett Oliver Butler |last5=Smith |first5=Lydia L. |last6=Flores-Villela |first6=Oscar |author6-link=Oscar Flores-Villela |last7=Campbell |first7=Jonathan A. |last8=Mackessy |first8=Stephen P. |last9=Castoe |first9=Todd A. |author9-link=Todd Adam Castoe |last10=Meik |first10=Jesse M. |date=2019-10-07 |title=Geographic variation in morphology in the Mohave Rattlesnake (''Crotalus scutulatus'' Kennicott 1861) (Serpentes: Viperidae): implications for species boundaries |journal=Zootaxa |volume=4683 |issue=1 |pages=129–143 |doi=10.11646/zootaxa.4683.1.7 |pmid=31715939 |issn=1175-5334}}</ref>

== Venom ==

=== History === For decades, the bite of ''Crotalus scutulatus'' has been considered to be extraordinarily deadly, often described as "the" (or "one of the") deadliest or most dangerous rattlesnakes. For example: "the most lethal of the North American rattlesnake venoms";<ref>{{Cite journal |last=Russell |first=F.E. |author-link=Findlay E. Russell |date=1969 |title=Clinical aspects of snake venom poisoning in North America |url=https://www.sciencedirect.com/science/article/abs/pii/0041010169901603 |journal=Toxicon |volume=7 |issue=1 |pages=33–37 |doi=10.1016/0041-0101(69)90160-3 |pmid=5804764 |bibcode=1969Txcn....7...33R |via=Elsevier|url-access=subscription }}</ref> "one of the most lethal venoms among the world's reptiles";<ref>{{Cite journal |last1=Wingert |first1=Willis A. |last2=Chan |first2=Linda |date=1988 |title=Rattlesnake bites in southern California and rationale for recommended treatment |journal=Western Journal of Medicine |volume=148 |issue=1 |pages=37–44|pmid=3277335 |pmc=1026007 }}</ref> "an extremely dangerous snake";<ref name="Stebbins" /> "probably the most dangerous snake in the United States";<ref>{{Cite book |last1=Ernst |first1=C.H. |author1-link=Carl H. Ernst |title=Venomous Reptiles of the United States, Canada, and Northern Mexico |last2=Ernst |first2=E.M. |author2-link=Evelyn M. Ernst |publisher=Johns Hopkins University Press |isbn=978-0-8018-9876-1 |volume=2 |location=Baltimore |publication-date=2012 |pages=218–232}}</ref> and "considered among the most venomous snakes on Earth".<ref>{{Cite book |last=Jones |first=Lawrence L.C. |title=Venomous Animals of the United States and Mexico |publisher=Rio Nuevo Publishers |isbn=978-1-940322-08-7 |location=Tucson |publication-date=2022 |pages=435–440}}</ref>

Such claims are usually attributed to the neurotoxin produced by most populations of ''C. scutulatus'' in the United States and Mexico, which has been reported to be capable of causing delayed respiratory paralysis with little or no local tissue injury. This neurotoxin was isolated and described in 1975 and named "Mojave toxin".<ref>{{Cite journal |last1=Bieber |first1=Allan L. |last2=Tu |first2=Tsuchih |last3=Tu |first3=Anthony T. |date=1975 |title=Studies of an acidic cardiotoxin isolated from the venom of Mojave rattlesnake (''Crotalus scutulatus'') |url=https://www.sciencedirect.com/science/article/abs/pii/0005279575901397 |journal=Biochimica et Biophysica Acta (BBA) - Protein Structure |volume=400 |issue=1 |pages=178–188 |doi=10.1016/0005-2795(75)90139-7 |pmid=238654 |via=Elsevier|url-access=subscription }}</ref><ref>{{Cite journal |last1=Ho |first1=C.L. |last2=Lee |first2=C.Y. |date=1981 |title=Presynaptic actions of Mojave toxin isolated from Mojave rattlesnake (''Crotalus scutulatus'') venom |journal=Toxicon |volume=19 |issue=6 |pages=889–892 |doi=10.1016/0041-0101(81)90086-6 |pmid=7336451 |bibcode=1981Txcn...19..889H |issn=0041-0101}}</ref> In 1978, an area in southcentral Arizona was identified where the venom of ''C. scutulatus'' is significantly less lethal to laboratory mice than venom from the balance of the species' range. The more lethal (and more widely distributed) variant was named "venom A" and the less lethal variant was named "venom B". The difference in lethality was later determined to be lack of Mojave toxin in the venom B population. Thus, venom A became known as the neurotoxic variant and venom B became the non-neurotoxic variant. In addition to the absence of Mojave toxin, ''C. scutulatus'' venom B was found to contain tissue-destroying [[toxin]]s, predominantly [[metalloproteinase]]s, similar to the venoms of many other rattlesnakes. Some animals in the [[Intergradation|intergrade]] zone between venom A and B populations produce venom containing both Mojave toxin and significant metalloproteinase and they have been labeled "venom A+B".<ref>{{Cite journal |last1=Glenn |first1=J.L. |last2=Straight |first2=R. |date=1978 |title=Mojave rattlesnake ''Crotalus scutulatus scutulatus'' venom: variation in toxicity with geographical origin |journal=Toxicon |volume=16 |issue=1 |pages=81–84 |doi=10.1016/0041-0101(78)90065-x |pmid=622731 |bibcode=1978Txcn...16...81G |issn=0041-0101}}</ref><ref>{{Cite journal |last1=Glenn |first1=James L. |last2=Straight |first2=Richard C. |last3=Wolfe |first3=Martha C. |last4=Hardy |first4=David L. |date=1983 |title=Geographical variation in ''Crotalus scutulatus scutulatus'' (Mojave rattlesnake) venom properties |journal=Toxicon |volume=21 |issue=1 |pages=119–130 |doi=10.1016/0041-0101(83)90055-7 |pmid=6342208 |bibcode=1983Txcn...21..119G |issn=0041-0101}}</ref><ref>{{Cite journal |last1=Glenn |first1=James L. |last2=Straight |first2=Richard C. |date=1989 |title=Intergradation of two different venom populations of the Mojave rattlesnake (''Crotalus scutulatus scutulatus'') in Arizona |journal=Toxicon |volume=27 |issue=4 |pages=411–418 |doi=10.1016/0041-0101(89)90203-1 |pmid=2499081 |bibcode=1989Txcn...27..411G |issn=0041-0101}}</ref><ref>{{Cite journal |last1=Wilkinson |first1=J.A. |last2=Glenn |first2=J.L. |last3=Straight |first3=R.C. |last4=Sites |first4=J.W. |author4-link=Jack W. Sites Jr |date=1991 |title=Distribution and generic variation in venom A and B populations of the Mojave rattlesnake (''Crotalus scutulatus scutulatus'') in Arizona |journal=Herpetologica |volume=47 |issue=1 |pages=54–68 |jstor=3892815 }}</ref><ref>{{Cite journal |last1=Massey |first1=Daniel J. |last2=Calvete |first2=Juan J. |last3=Sánchez |first3=Elda E. |last4=Sanz |first4=Libia |last5=Richards |first5=Kelvin |last6=Curtis |first6=Ryan |last7=Boesen |first7=Keith |date=2012 |title=Venom variability and envenoming severity outcomes of the ''Crotalus scutulatus scutulatus'' (Mojave Rattlesnake) from Southern Arizona |url=https://www.sciencedirect.com/science/article/abs/pii/S1874391912001340 |journal=Journal of Proteomics |volume=75 |issue=9 |pages=2576–2587 |doi= 10.1016/j.jprot.2012.02.035|pmid=22446891 |issn= |via=Elsevier Science Direct|url-access=subscription }}</ref><ref>{{Cite journal |last1=Zancolli |first1=G. |last2=Calvete |first2=J.J. |last3=Cardwell |first3=M.D. |last4=Greene |first4=H.W. |last5=Hayes |first5=W.K. |last6=Hegarty |first6=M.J. |last7=Herrmann |first7=H.W. |author7-link=species:Hans-Werner Herrmann |last8=Holycross |first8=A.T. |last9=Lannutti |first9=D.I. |last10=Mulley |first10=J.F. |last11=Sanz |first11=L. |last12=Travis |first12=Z.D. |last13=Whorley |first13=J.R. |last14=Wüster |first14=C.E. |author14-link=species:Catharine E. Wüster |last15=Wüster |first15=W. |date=2019 |title=When one phenotype is not enough: divergent evolutionary trajectories govern venom variation in a widespread rattlesnake species |journal=Proceedings of the Royal Society B: Biological Sciences |language=en |volume=286 |issue=1898 |article-number=20182735 |doi=10.1098/rspb.2018.2735 |issn=0962-8452 |pmc=6458317 |pmid=30862287}}</ref>

Other studies have noted that [[Pit viper|pitviper]] venoms can be divided generally into two dichotomous groups that have been termed "toxicity vs. tenderizers" (neurotoxic vs. tissue-destroying, respectively).<ref name=":5">{{Cite journal |last=Mackessy |first=Stephen P. |date=2010 |title=Evolutionary trends in venom composition in the Western Rattlesnakes (''Crotalus viridis'' sensu lato): Toxicity vs. tenderizers |journal=Toxicon |volume=55 |issue=8 |pages=1463–1474 |doi=10.1016/j.toxicon.2010.02.028 |pmid=20227433 |bibcode=2010Txcn...55.1463M |issn=0041-0101}}</ref> The more toxic (lethal to lab mice) venoms are dominated by [[presynaptic]] [[neurotoxin]]s (of which Mojave toxin is one homolog) but they lack significant amounts of [[Bleeding|hemorrhagic]] and tissue-destroying [[metalloproteinase]]s and [[Serine protease|serine proteinases]], while the "tenderizer" venoms are dominated by the hemorrhagic and tissue-destroying components but contain little or no neurotoxin. In the broader context of all pitvipers, the more common venoms containing higher levels of metalloproteinase and lacking significant neurotoxin have been termed "type I" venoms, while venoms containing high levels of neurotoxin but lacking hemorrhagic and tissue-destroying components are called "type II".<ref name=":5" /><ref name="Mackessy 2008 495–510">{{Cite book |last=Mackessy |first=S.P. |title=The Biology of Rattlesnakes |publisher=Loma Linda University Press |year=2008 |isbn=978-159410-011-6 |editor-last=Hayes |editor-first=W.K. |pages=495–510 |chapter=Venom composition in rattlesnakes: Trends and biological significance |editor-last2=Beaman |editor-first2=K.R. |editor-last3=Cardwell |editor-first3=M.D. |editor-last4=Bush |editor-first4=S.P.}}</ref> Thus, ''C. scutulatus'' venom A is a type II venom, and venom B is a type I venom.

=== Mojave toxin === Mojave toxin is a potent [[Synapse|presynaptic]] [[Neurotoxin|β-neurotoxin]] composed of two distinct peptide subunits.<ref name="Aird">Aird, S.D., et al. (1985). "Rattlesnake presynaptic neurotoxins: primary structures and evolutionary origin of the acidic subunit". ''Biochemistry'' '''24''': 7054–7058.</ref> The [[Base (chemistry)|basic]] [[Phospholipase A2|phospholipase A<sub>2</sub>]] (PLA<sub>2</sub>) subunit alone is mildly toxic while the [[acid]]ic subunit is not toxic by itself, but both subunits must be present to constitute Mojave toxin. The basic subunit is present in the venoms of many species of ''[[Crotalus]]'', including ''[[Eastern diamondback rattlesnake|adamanteus]]'', ''[[Crotalus pyrrhus|pyrrhus]]'', ''scutulatus'', ''[[Tiger rattlesnake|tigris]]'', and ''[[Crotalus viridis|viridis]]''. The acidic subunit is less commonly distributed and limited to individuals in populations that also express the basic subunit.<ref>{{Cite book |last1=Powell |first1=R.L. |title=The Biology of Rattlesnakes |last2=Lieb |first2=C.S. |author2-link=species:Carl S. Lieb |last3=Rael |first3=E.D. |publisher=Loma Linda University Press |year=2008 |isbn=978-159410-011-6 |editor-last=Hayes |editor-first=WK |pages=537–550 |chapter=Geographic distribution of Mojave toxin and Mojave toxin subunits among selected ''Crotalus'' species |editor-last2=Beaman |editor-first2=KR |editor-last3=Cardwell |editor-first3=MD |editor-last4=Bush |editor-first4=SP}}</ref><ref name="Mackessy 2008 495–510"/><ref>{{Cite book |last=Mackessy |first=S.P. |title=Handbook of Venoms and Toxins of Reptiles |publisher=CRC Press |year=2021 |isbn=978-0-367-14974-1 |editor-last=Mackessy |editor-first=SP |edition=2 |location=Boca Raton |pages=3–18 |chapter=Reptile venoms and toxins – Unlimited opportunities for basic and applied research}}</ref>

==Human lethality==

=== Mortality === Mortality statistics have long shown that there are only about two to six people killed by venomous snakes annually in the United States, with most deaths reported in the southeastern states,<ref name=":6">{{Cite journal |last1=Greene |first1=Spenser C. |last2=Folt |first2=Jason |last3=Wyatt |first3=Kimberly |last4=Brandehoff |first4=Nicklaus P. |date=2021 |title=Epidemiology of fatal snakebites in the United States 1989–2018 |journal=The American Journal of Emergency Medicine |volume=45 |pages=309–316 |doi=10.1016/j.ajem.2020.08.083 |pmid=33046301 |issn=0735-6757}}</ref><ref name=":7">{{Cite journal |last1=Forrester |first1=Jared A. |last2=Weiser |first2=Thomas G. |last3=Forrester |first3=Joseph D. |date=2018 |title=An Update on Fatalities Due to Venomous and Nonvenomous Animals in the United States (2008–2015) |journal=Wilderness & Environmental Medicine |volume=29 |issue=1 |pages=36–44 |doi=10.1016/j.wem.2017.10.004 |pmid=29373216 |issn=1080-6032}}</ref> despite ''Crotalus scutulatus'' occurring only in the southwest, where it is commonly encountered and responsible for many bites each year. Thus, statistics from both the Centers for Disease Control<ref name=":7" /> and the American Association of Poison Control Centers<ref name=":6" /> suggest that bites by ''C. scutulatus'' are no more lethal than bites by other rattlesnake species.

=== Respiratory paralysis === Respiratory paralysis was reported in laboratory animals in the 1930s during comparison of venoms from North American pitvipers, confirming respiratory paralysis and indicating extreme lethality (aka toxicity) in pigeons caused by ''C. scutulatus'' venom.<ref>{{Cite journal |last=Githens |first=Thomas S. |date=1935 |title=Studies on the venoms of North American pit vipers |journal=The Journal of Immunology |volume=29 |issue=2 |pages=165–173 |doi=10.4049/jimmunol.29.2.165 |issn=0022-1767}}</ref><ref>{{Cite journal |last1=Githens |first1=Thomas S. |last2=Wolff |first2=Nigel O'C. |date=1939 |title=The Polyvalency of Crotalidic Antivenins I. The influence of the composition of polyvalent antigens |journal=The Journal of Immunology |volume=37 |issue=1 |pages=33–39 |doi=10.4049/jimmunol.37.1.33 |issn=0022-1767}}</ref><ref>{{Cite journal |last1=Githens |first1=T.S. |last2=Wolff |first2=N.O. |date=1939 |title=The Polyvalency of Crotalidic Antivenins III. Mice as test animals for study of antivenins |journal=The Journal of Immunology |volume=37 |issue=1 |pages=47–51 |doi=10.4049/jimmunol.37.1.47 |issn=0022-1767}}</ref> Numerous subsequent studies, mostly using mice, confirmed the relative lethality of ''C. scutulatus'' venom A in laboratory animals. In 1956, [[Laurence Monroe Klauber|Laurence Klauber]] quoted these studies in his widely-read rattlesnake reference, adding "…if future tests of the quality of the venom of ''C. s. scutulatus'' corroborate the m.l.d. [median lethal dose] figures now available, this may prove to be a very dangerous rattler."<ref name="Kla97"/>{{rp|788}} Apparently because of these early animal studies, warnings subsequently abounded about the extreme lethality and danger of respiratory paralysis following bites by ''C. scutulatus''.

=== Recent clinical studies === Recent investigations of human rattlesnake bites in regions where ''C. scutulatus'' is common have cast doubt on the legitimacy of concerns regarding extreme lethality and respiratory failure/paralysis in humans. A retrospective study of 3440 Arizona rattlesnake bites reported to the Arizona Poison and Drug Information Center (covering all of Arizona except Maricopa County) between January 1999 and December 2020, disclosed no reports of neurotoxic respiratory failure/paralysis.<ref name=":8">{{Cite journal |last1=Smelski |first1=Geoffrey |last2=Cardwell |first2=Michael |last3=Larsen |first3=Jaiva |date=2023 |title=Neurotoxic respiratory failure absent following Arizona rattlesnake bites |journal=Toxicon |language=en |volume=224 |article-number=107034 |doi=10.1016/j.toxicon.2023.107034|doi-access=free |pmid=36690088 |bibcode=2023Txcn..22407034S }}</ref> Another retrospective study of 289 rattlesnake bites treated at a tertiary referral hospital in Maricopa County between July 1994 and November 2000, also found no reports of neurotoxic respiratory failure/paralysis.<ref>{{Cite journal |last1=Brooks |first1=Daniel E. |last2=Graeme |first2=Kimberlie A. |last3=Ruha |first3=Anne-Michelle |last4=Tanen |first4=David A. |date=2002 |title=Respiratory compromise in patients with rattlesnake envenomation |journal=The Journal of Emergency Medicine |volume=23 |issue=4 |pages=329–332 |doi=10.1016/s0736-4679(02)00573-5 |pmid=12480008 |issn=0736-4679}}</ref>

These published findings are consistent with anecdotal reports from southern California, where ''C. scutulatus'' is the predominant biting rattlesnake in the flat creosote bush scrub of the Mohave Desert, where all animals tested thus far have expressed neurotoxic (type II/venom-A) venom, and where [[Sympatry|sympatric]] ''C. atrox'' is not present to confuse snake identification. A literature search for published case reports (that was not limited in scope, either geographically or temporally)<ref name=":8" /> revealed only one case of neurotoxic respiratory failure.<ref>{{Cite journal |last1=Jansen |first1=Paul W. |last2=Perkin |first2=Ronald M. |last3=Van Stralen |first3=Daved |date=1992 |title=Mojave rattlesnake envenomation: Prolonged neurotoxicity and rhabdomyolysis |journal=Annals of Emergency Medicine |volume=21 |issue=3 |pages=322–325 |doi=10.1016/s0196-0644(05)80898-4 |pmid=1536496 |issn=0196-0644}}</ref>

While the [[Physiology|physiological]] effects of Mojave toxin are almost certainly [[Dose–response relationship|dose-dependent]], many other variables affect how an organism (pigeon, lab mouse, squirrel, human, etc.) is affected, including such factors as the organism's body mass, age, health, [[Comorbidity|comorbidities]], [[Allergy|allergies]], [[Genome|genetic profile]], and many others.

=== Prognosis of bite victims === While ''C. scutulatus'' is capable of inflicting a life-threatening bite, the prognosis of ''C. scutulatus'' bite victims appears to be no worse than that of victims bitten by other rattlesnakes of similar size. Factors that worsen the prognosis of pitviper bites include delay in reaching advanced medical care, small victim size, and large snake size.<ref>{{Cite journal |last1=Gerardo |first1=Charles J. |last2=Vissoci |first2=João R.N. |last3=Evans |first3=C. Scott |last4=Simel |first4=David L. |last5=Lavonas |first5=Eric J. |date=2019 |title=Does This Patient Have a Severe Snake Envenomation?: The Rational Clinical Examination Systematic Review |url=http://archsurg.jamanetwork.com/article.aspx?doi=10.1001/jamasurg.2018.5069 |journal=JAMA Surgery |language=en |volume=154 |issue=4 |pages=346–354 |doi=10.1001/jamasurg.2018.5069 |pmid=30758508 |issn=2168-6254|url-access=subscription }}</ref><ref name=":8" />

===Antivenoms=== Both [[antivenom]]s available in the United States are licensed by the [[Food and Drug Administration|US Food and Drug Administration]] for the treatment of bites by all native pitvipers, including [[envenomation]]s by ''C. scutulatus''.<ref>{{Cite web |title=CroFab {{!}} Copperhead, Cottonmouth, and Rattlesnake Antivenom {{!}} CroFab.com |url=https://crofab.com/ |access-date=2024-02-07 |website=crofab.com}}</ref><ref>{{Cite web |title=ANAVIP Home |url=https://anavip-us.com/ |access-date=2024-02-07 |website=ANAVIP® [crotalidae immune F(ab')₂ (equine)] |language=en-US}}</ref> Each product contains antibodies raised against the venoms of multiple carefully selected pitviper species. [[Neurotoxicity|Neurotoxic]] ''C. scutulatus'' venom is used in the manufacture of [[Crotalidae polyvalent immune fab|CroFab]]<sup>®</sup>, while the venom of a tropical rattlesnake (''[[Crotalus simus|C. simus]]'') that expresses a very similar neurotoxin, is used in the production of [[Anavip]]<sup>®</sup>. Thus, both products are designed to be effective against neurotoxic ''C. scutulatus'' envenomations, and venoms from other species used in the production of both products are protective against type I/venom-B (non-neurotoxic) ''C. scutulatus'' bites.

==Subspecies== {|cellspacing=0 cellpadding=2 border=1 style="border-collapse: collapse;" !bgcolor="#f0f0f0"|Subspecies<ref name="ITIS">{{ITIS|id=174317|taxon=''Crotalus scutulatus ''|access-date=10 February 2024}}</ref> !bgcolor="#f0f0f0"|Taxon author<ref name="ITIS"/> !bgcolor="#f0f0f0"|Common name !bgcolor="#f0f0f0"|Geographic range<ref name="C&L04"/> |- |''[[Crotalus scutulatus salvini|C. scutulatus salvini]]'' |[[Albert Günther|Günther]], 1895 |Huamantlan rattlesnake<ref name="Kla97" /> |style="width:40%"|[[Mexico]], from [[Hidalgo (Mexico)|Hidalgo]] through [[Tlaxcala]] and [[Puebla]] to southwestern [[Veracruz]] |- |''C. scutulatus scutulatus'' |([[Robert Kennicott|Kennicott]], 1861) |Northern Mojave rattlesnake<ref name=":0" /> |The [[United States]] from [[California]] eastward to west [[Texas]] and southward to [[Querétaro]] in Mexico |- |}

The [[Trinomen|subspecific name]], ''salvini'', is in honor of English [[Herpetology|herpetologist]] [[Osbert Salvin]].<ref>[[Bo Beolens|Beolens, Bo]]; [[Michael Watkins (zoologist)|Watkins, Michael]]; [[Michael Grayson|Grayson, Michael]] (2011). ''The Eponym Dictionary of Reptiles''. Baltimore: Johns Hopkins University Press. xiii + 296 pp. {{ISBN|978-1-4214-0135-5}}. (''Crotalus scutulatus salvini'', p. 232).</ref>

==References== {{Reflist|colwidth=35em}}

==Further reading== *{{cite book |last1=Behler |first1=J.L. |author1-link=John L. Behler |last2=King |first2=F.W. |author2-link=Frederic Wayne King |title=The Audubon Society Field Guide to North American Reptiles and Amphibians |date=1979 |publisher=Alfred A. Knopf |location=New York |isbn=0-394-50824-6}} 743 pp. (''Crotalus scutulatus'', pp. 692–693 + Plate 622). *{{cite book |last1=Boulenger |first1=G.A. |author1-link=George Albert Boulenger |title=Catalogue of the Snakes in the British Museum (Natural History). Volume III., Containing the ... Viperidæ |date=1896 |publisher=Trustees of the British Museum (Natural History) |location=London}} (Taylor and Francis, printers). xiv + 727 pp. + Plates I–XXV. (''Crotalus scutulatus'', pp. 575–576). *{{cite book |last1=Conant |first1=R. |author1-link=Roger Conant (herpetologist) |title=A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition |date=1975 |publisher=Houghton Mifflin |location=Boston |isbn=0-395-19977-8}} (paperback). xviii + 429 pp. + Plates 1–48. (''Crotalus scutulatus'', p. 236–237+ Plate36 + Map 181). *{{cite book |last1=Günther |first1=A.C.L.G. |author1-link=Albert Günther |title=Biologia Centrali-Americana. Reptilia and Batrachia |date=1895 |publisher=Godman and Salvin |location=London}} (Taylor and Francis, printers). xx + 326 pp. + Plates 1–76. (''Crotalus salvini'', new species, pp. 193–194 + Plate 59, figure A). *{{cite book |last1=Hubbs |first1=B. |author1-link=species:Brian Hubbs |last2=O'Connor |first2=B. |author2-link=species:Brendan O'Connor |title=A Guide to the Rattlesnakes and other Venomous Serpents of the United States |date=2012 |publisher=Tricolor Books |location=Tempe, Arizona |isbn=978-0-9754641-3-7}} 129 pp. (''Crotalus scutulatus'', pp. 44–45). *{{cite journal |last1=Kennicott |first1=R. |author1-link=Robert Kennicott |title=On three new forms of Rattlesnakes |journal=Proceedings of the Academy of Natural Sciences of Philadelphia |date=1861 |volume=13 |pages=206–208}} (''Caudisona scutulata'', new species, pp. 207–208). *{{cite book |last1=Powell |first1=R. |author1-link=Robert Powell (herpetologist) |last2=Conant |first2=R. |last3=Collins |first3=J.T. |author3-link=Joseph T. Collins|title=Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America, Fourth Edition |date=2016 |publisher=Houghton Mifflin Harcourt |location=Boston and New York |isbn=978-0-544-12997-9}} xiv + 494 pp., 47 color plates, 207 figures. (''Crotalus scutulatus'', p. 442 + Plate 47 + Figure 168 on p. 356). *{{cite book |last1=Smith |first1=H.M. |author1-link=Hobart Muir Smith |last2=Brodie |first2=E.D., Jr. |author2-link=Edmund Darrell Brodie Jr. |title=Reptiles of North America: A Guide to Field Identification |date=1982 |publisher=Golden Press |location=New York |isbn=0-307-13666-3}} 240 pp. (''Crotalus scutulatus'', pp. 204–205). *{{cite book |last1=Wright |first1=A.H. |author1-link=Albert Hazen Wright |last2=Wright |first2=A.A. |author2-link=Anna Allen Wright |title=Handbook of Snakes of the United States and Canada |date=1957 |publisher=Comstock Publishing Associates, a division of Cornell University Press |location=Ithaca and London}} 1,105 pp. (in two volumes). (''Crotalus scutulatus'', pp. 992, 994–999, Figures 283–284 + Map 66 on p. 943).

==External links== {{Commons}} * {{NRDB species|genus=Crotalus|species=scutulatus|date=12 December|year=2007}} * [http://www.reptilesofaz.com/Snakes-Subpages/h-c-scutulatus.html Mojave Rattlesnake, ''Crotalus scutulatus''] {{Webarchive|url=https://web.archive.org/web/20051027191147/http://www.reptilesofaz.com/Snakes-Subpages/h-c-scutulatus.html |date=27 October 2005 }} at [http://www.reptilesofaz.com/ AZ PARC]. Accessed 3 February 2007. * [http://www.emedicine.com/emerg/topic541.htm Snake Envenomations, Mojave Rattle] at [http://www.emedicine.com/ eMedicine]. Accessed 3 February 2007. * [http://www.blueplanetbiomes.org/mojave_rattlesnake.htm Mojave Rattlesnake] at [http://www.blueplanetbiomes.org/ Blue Planet Biomes]. Accessed 3 February 2007. * [http://www.zo.utexas.edu/research/txherps/snakes/crotalus.scutulatus.html ''Crotalus scutulatus''] at [http://www.zo.utexas.edu/research/txherps/ Herps of Texas] {{Webarchive|url=https://web.archive.org/web/20120717011825/http://www.zo.utexas.edu/research/txherps/ |date=17 July 2012 }}. Accessed 3 February 2007. * [https://web.archive.org/web/20070315123744/http://www.michaelcardwell.com/scutulatus.htm Why study Mohave Rattlesnakes?] at [https://web.archive.org/web/20070313213619/http://www.michaelcardwell.com/ Michael Cardwell homepage]. Accessed 3 February 2007. * [https://web.archive.org/web/20070927230002/http://astroforecast.org:8080/BigBend/compare.htm Identifying ''C. scutulatus'' and ''C. atrox''] at [https://web.archive.org/web/20070927225940/http://astroforecast.org:8080/BigBend/ Jeff's Big Bend National Park page]. Accessed 8 April 2007. * [https://web.archive.org/web/20100129084719/http://www.venomousreptiles.org/articles/305 Account of severe ''C. scutulatus'' envenomation] at [https://web.archive.org/web/20080409033049/http://www.venomousreptiles.org/ venomousreptiles.org]. Accessed 6 December 2007.

{{Taxonbar|from=Q953286}}

[[Category:Crotalus|scutulatus]] [[Category:Fauna of the Colorado Desert]] [[Category:Fauna of the Mojave Desert]] [[Category:Fauna of the Sonoran Desert]] [[Category:Fauna of the Chihuahuan Desert]] [[Category:Reptiles described in 1861]] [[Category:Taxa named by Robert Kennicott]]