# Horned adder

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{{Short description|Species of snake}}
{{distinguish|text=the [many-horned adder](/source/many-horned_adder) (''Bitis cornuta'')}}
{{Speciesbox
| image = Bitis caudalis00a.jpg
| status = LC | status_system = IUCN3.1
| status_ref = <ref name=IUCN>{{cite iucn |author=Alexander, G.J. |author2=Tolley, K.A. |year=2021 |title=''Bitis caudalis'' |volume=2021 |article-number=e.T22475165A110344127 |doi=10.2305/IUCN.UK.2021-3.RLTS.T22475165A110344127.en |access-date=5 February 2022}}</ref>
| genus = Bitis
| species = caudalis
| authority = ([A. Smith](/source/Andrew_Smith_(zoologist)), 1839)
| synonyms = *''Vipera ocellata'' <small>A. Smith, 1838</small>
*''Cerastes ocellatus'' <br /><small>&mdash; A. Smith, 1838</small>
*''Vipera caudalis'' <small>A. Smith, 1839</small><ref>[Boulenger GA](/source/George_Albert_Boulenger). 1896. ''Catalogue of the Snakes in the British Museum (Natural History). Volume III., Containing the...Viperidæ.'' London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers.) xiv + 727 pp. + Plates I.- XXV. (''Bitis caudalis'', pp. 498-499.)</ref>
*''Vipera (Cerastes) caudalis'' <br /><small>&mdash; A. Smith, 1839</small>
*''Cerastes caudalis'' <br /><small>&mdash; [Gray](/source/John_Edward_Gray), 1842</small>
*''Vipera caudalis'' <small>&mdash; [Jan](/source/Giorgio_Jan), 1859</small>
*''V''[''ipera'']. (''Cerastes'') ''caudalis'' <small>&mdash; Jan, 1863</small>
*''Bitis caudalis'' <br /><small>&mdash; [Boulenger](/source/George_Albert_Boulenger), 1896</small>
*''Cobra caudalis'' <br /><small>&mdash; [Mertens](/source/Robert_Mertens), 1937</small>
*''Bitis caudalis caudalis'' <br /><small>&mdash; Mertens, 1955</small>
*''Bitis caudalis'' <small>&mdash; Branch, 1991</small><ref name="McD99">McDiarmid RW, [Campbell JA](/source/Jonathan_A._Campbell), Touré T. 1999. ''Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1''. Herpetologists' League. 511 pp. {{ISBN|1-893777-00-6}} (series). {{ISBN|1-893777-01-4}} (volume).</ref>
}}

The '''horned adder''' ('''''Bitis caudalis''''') is a [viper](/source/Viperinae) [species](/source/species).<ref name=IUCN/><ref name="RDB"/> It is found in the [arid](/source/arid) region of southwest [Africa](/source/Africa), in Angola, Botswana, Namibia; South Africa, and Zimbabwe.<ref name=IUCN/> It is easily distinguished by the presence of a single, large horn-like scale over each eye.{{citation needed|date=February 2022}} No [subspecies](/source/subspecies) are currently recognized.<ref name="RDB"/><ref name="ITIS">{{ITIS |id=634951 |taxon=''Bitis caudalis'' |accessdate=5 February 2022}}</ref> Like all other vipers, it is [venomous](/source/venomous_snake).

==Common names==
The species is commonly known as the '''horned adder''',<ref name=IUCN/><ref name="RDB">{{NRDB species|genus=Bitis|species=caudalis |accessdate=5 February 2022}}</ref><ref name="SB95">Spawls S, Branch B. 1995. ''The Dangerous Snakes of Africa''. Ralph Curtis Books. Dubai: Oriental Press. 192 pp. {{ISBN|0-88359-029-8}}.</ref> '''horned puff adder''',<ref name="Mal03">Mallow D, Ludwig D, Nilson G. 2003. ''True Vipers: Natural History and Toxinology of Old World Vipers''. Krieger Publishing Company, Malabar, Florida. 359 pp. {{ISBN|0-89464-877-2}}.</ref> or '''horned viper'''.<ref name="USN91">U.S. Navy. 1991. ''Poisonous Snakes of the World''. US Government. New York: Dover Publications Inc. 203 pp. {{ISBN|0-486-26629-X}}.</ref>

==Description==
A short, stout little viper, it usually averages {{convert|30|–|40|cm|in|round=0.5|abbr=on}} in total length (body + tail). The largest specimen reported being seen is a female from southern [Botswana](/source/Botswana) measuring {{convert|51.5|cm|in|abbr=on}} total length.<ref name="SB95"/>

==Geographic range==
The snake is found in far arid regions of southwest Africa: southwest [Angola](/source/Angola), [Namibia](/source/Namibia), across the [Kalahari Desert](/source/Kalahari_Desert) of southern [Botswana](/source/Botswana), into northern [Transvaal](/source/Transvaal_Province) and southwestern [Zimbabwe](/source/Zimbabwe). In [South Africa](/source/South_Africa), it is found from the [Northern Cape](/source/Northern_Cape) province south to the [Great Karoo](/source/Great_Karoo).

Its [type locality](/source/Type_locality_(biology)) is given as "...&nbsp;the sandy districts north of the Cape Colony..." [South Africa].<ref name="McD99"/>

==Habitat==
Horned adders are mostly found in sparsely vegetated [desert](/source/desert) and [semiarid](/source/Semi-arid_climate) [scrub](/source/Scrubland) country.<ref name="SB95"/>

==Venom==
Bites are assumed to be rare and no epidemiological data is available.<ref name="Mal03"/>
Little information is available regarding the toxicity and amount of venom produced. Spawls and Branch (1995) reported an average yield of 85&nbsp;mg of wet venom,<ref name="SB95"/> while Christensen (1971) offered an {{LD50}} value of 1.2&nbsp;mg/kg [IV](/source/Intravenous_therapy).<ref name="Bro73">Brown JH. 1973. ''Toxicology and Pharmacology of Venoms from Poisonous Snakes''. Springfield, Illinois: Charles C. Thomas. 184 pp. LCCCN 73-229. {{ISBN|0-398-02808-7}}.</ref>
Other research has found the LD<sub>50</sub>{{ambiguous|date=December 2020}} to be between 0.15 and 0.22&nbsp;mg/kg <ref>C Y Lee et al. 1982. "Site of action of caudoxin, a neurotoxic phospholipase A2 from the horned puff adder (Bitis caudalis) venom". Toxicon, 20(3), 637-647</ref>

Based on this LD<span style="font-size:100%;"><sub>50</sub></span> value, Spawls and Branch (1995) estimated about 300&nbsp;mg of this venom would be required to kill an adult. They regarded this venom as one of the weakest of the genus,<ref name="SB95"/> although the tests are conducted solely on mice, which might have a different reaction from humans to the venom. On the other hand, an older report by the U.S. Navy (1965, 1991) suggested it is highly toxic and a number of deaths have occurred as a result.<ref name="USN91"/><ref name="USN65">U.S. Navy. 1965. ''Poisonous Snakes of the World''. US Government. Washington, District of Columbia: US Govt. Printing Office. 212 pp.</ref> According to [Broadley](/source/%3Afr%3ADonald_George_Broadley) and Cock (1975), envenomation symptoms in humans include swelling, severe pain, nausea, vomiting and shock. Blisters and necrotic ulcers may form around the bite site.<ref name="Mal03"/>

The National Antivenom and Vaccine Production Centre in [Riyadh](/source/Riyadh), [Saudi Arabia](/source/Saudi_Arabia), produces a polyvalent antivenin that includes a paraspecific antibody that protects against bites from this species.<ref name="Mavin">[http://www.toxinfo.org/antivenoms/indication/BITIS_CAUDALIS.html ''Bitis caudalis''] at [http://www.toxinfo.org/antivenoms/ Munich AntiVenom INdex (MAVIN)]. Accessed 21 April 2007.</ref> According to the U.S. Navy (1965, 1991),<ref name="USN91"/><ref name="USN65"/> [polyvalent antivenins](/source/snake_antivenom) produced by SAIMR and the [Pasteur Institute](/source/Pasteur_Institute) are said to be effective, while Mallow et al. (2003) reported currently available antivenins are of limited effectiveness.<ref name="Mal03"/>

Viljoen et al. (1982) isolated a protein, a [neurotoxic](/source/Neurotoxin) [phospholipase A<span style="font-size:100%;"><sub>2</sub></span>](/source/Phospholipase_A2), from the venom, which they called "caudoxin". According to Lee et al. (1983), this is a [presynaptic](/source/Chemical_synapse) toxin similar to [bungarotoxin](/source/bungarotoxin), but with different binding sites.<ref name="Mal03"/>

==Taxonomy==
A number of authors, including [Mertens](/source/Robert_Mertens) (1955), use a trinomial to refer to this species, even though no subspecies are recognized.<ref name="McD99"/>

==References==
{{Reflist}}

==Further reading==
{{refbegin}}
*[Branch, Bill](/source/William_Roy_Branch). 2004. ''Field Guide to Snakes and Other Reptiles of Southern Africa''. Sanibel Island, Florida: Ralph Curtis Books. 399 pp. {{ISBN|0-88359-042-5}}. (''Bitis caudalis'', p.&nbsp;116 + Plate 13.) 
*[Broadley DG](/source/%3Afr%3ADonald_George_Broadley), Cock EV. 1975. ''Snakes of Rhodesia''. Zimbabwe: Longman Zimbabwe Ltd. 126 pp. ASIN B0006CM8SE.
*Christensen PA. 1971. The venoms of Central and South Africa. ''In'' Bücherl W, Deulofeu V, Buckley EE. ''Venomous Animals and Their Venoms, Vol. I.'' New York: Academic Press. pp.&nbsp;437–462. {{ISBN|0-12-138902-2}}.
*[Smith A](/source/Andrew_Smith_(zoologist)). 1839. ''Illustrations of the Zoology of South Africa; Consisting Chiefly of Figures and Descriptions of the Objects of Natural History Collected during an Expedition into the Interior of South Africa, in the Years 1834, 1835, and 1836; Fitted out by "The Cape of Good Hope Association for Exploring Central Africa:" together with a Summary of African Zoology, and an Inquiry into the Geographical Ranges of Species in that Quarter of the Globe.'' [Volume 3.] London: Lords Commissioners of Her Majesty's Treasury. (Smith, Elder and Co., printers.) 48 Plates + unnumbered pages of text. (''Vipera caudalis'', Plate 7.)
*Viljoen CC, Botes DP, Kruger H. 1982. Isolation and characterization of the amino acid sequence of caudoxin, a presynaptic acting toxic phospholipase A2 from the venom of the horned puff adder (''Bitis caudalis''). Toxicon '''20''' (4): 715–737.
{{refend}}

==External links==
{{Commons}}
* {{YouTube|1KloMZdyNiY|Video of ''B. caudalis'' and ''B. cornuta''}}. Accessed 1 March 2007.
* {{YouTube|IHBJ6aBSwnM|Video of ''B. caudalis'' drinking}}. Accessed 1 March 2007.

{{Taxonbar|from=Q1498639}}

Category:Bitis
Category:Snakes of Africa
Category:Reptiles of Angola
Category:Reptiles of Botswana
Category:Reptiles of Namibia
Category:Reptiles of South Africa
Category:Reptiles of Zimbabwe
Category:Reptiles described in 1839
Category:Taxa named by Andrew Smith (zoologist)

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Adapted from the Wikipedia article [Horned adder](https://en.wikipedia.org/wiki/Horned_adder) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Horned_adder?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.