Western green mamba

{{Short description|Species of snake}} {{Speciesbox | name = Western green mamba | image = Dendroaspis viridisPCCA20051227-1885B.jpg | image_upright = 1.1 | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 19 November 2021">{{cite iucn |author=Luiselli, L. |author2=Segniagbeto, G. |date=2013 |title=''Dendroaspis viridis'' |volume=2013 |article-number=e.T13265799A13265808 |doi=10.2305/IUCN.UK.2013-1.RLTS.T13265799A13265808.en |access-date=19 November 2021}}</ref> | display_parents = 2 | genus = Dendroaspis | species = viridis | authority = (Hallowell, 1844)<ref name="ITIS">{{ITIS|id=700484|taxon=''Dendroaspis viridis''|access-date=4 March 2014}}</ref> | range_map = Dendroaspis viridis distribution map.png | range_map_caption = ''Dendroaspis viridis'' range | synonyms_ref = <ref name=boulenger1896>{{cite book | first=George Albert | last= Boulenger| year= 1896 | title= Catalogue of the Snakes in the British Museum (Natural History), Volume III| volume= 3| location= London | publisher=Natural History Museum (London) Publications | page= 435 | url=https://www.biodiversitylibrary.org/page/38014638}}</ref><ref name=RDB>{{NRDB species|genus=Dendroaspis |species=viridis |access-date=2 February 2016}}</ref> | synonyms = * ''Leptophis viridis'' Hallowell, 1844 * ''Dinophis hammondii'' Hallowell, 1852 * ''Dendroaspis viridis hallowelli'' Yeomans, 1993 * ''Dendroaspis viridis hallowelli'' – Barnett & Emms, 2005 }}

The '''western green mamba''' ('''''Dendroaspis viridis''''') is a long, thin, and highly venomous snake species of the mamba genus, ''Dendroaspis''. This species was first described in 1844 by American herpetologist Edward Hallowell. The western green mamba is a fairly large and predominantly arboreal species, capable of navigating through trees swiftly and gracefully. It will also descend to ground level to pursue prey such as rodents and other small mammals.

The western green mamba is a shy and agile snake that lives mainly in the coastal tropical rainforest, thicket, and woodland regions of western Africa. Its venom is a highly potent mixture of rapid-acting presynaptic and postsynaptic neurotoxins (dendrotoxins), cardiotoxins and fasciculins. Some consider this species not to be a particularly aggressive snake, but others have suggested that they are extremely nervous and are prone to attack aggressively when cornered. Conflict with humans is low compared to some other species found in the region. Bites to people by this species are quite uncommon. Their mortality rate, however, is high; many of the recorded bites have been fatal. Rapid progression of severe, life-threatening symptoms are hallmarks of mamba bites. Bites with envenomation can be rapidly fatal.

==Taxonomy== The western green mamba was first described by the American herpetologist and physician Edward Hallowell in 1844 as ''Leptophis viridis'', from a specimen collected in Liberia.<ref name="Hallowell">{{cite journal | lccn=12030019 | oclc=1382862 | url=https://www.biodiversitylibrary.org/part/16091 | title=Description of new species of African reptiles | journal=Proceedings of the Academy of Natural Sciences of Philadelphia | last=Hallowell | first=E. | year=1844 | volume=2 | pages=169–172}}</ref> The specific name ''viridis'' is the Latin adjective "green".<ref name=viridis>{{cite web|title=Definition of "viridis"|url=http://latinlexicon.org/definition.php?p1=1017588 |work=Numen — The Latin Lexicon |access-date=4 March 2014}}</ref> In 1852, Hallowell described ''Dinophis hammondii'' from two specimens of western green mambas collected in Liberia, naming it for his friend Ogden Hammond of South Carolina.<ref>{{cite journal |last1=Hallowell |first1=Edward |title=On a new genus and two new species of African serpents |journal=Proceedings of the Academy of Natural Sciences of Philadelphia |date=1852 |volume=6 |pages=203–204 |url=https://www.biodiversitylibrary.org/page/1779739}}</ref> These were later deemed the same species by Belgian-British zoologist George Albert Boulenger.<ref name=boulenger1896/>

The genus was misspelt as ''Dendraspis'' by Dumeril in 1856, and generally uncorrected by subsequent authors. In 1936, Dutch herpetologist Leo Brongersma pointed the correct spelling was ''Dendroaspis''.<ref>{{cite journal |last1=Brongersma |first1=Leo Daniel |title=Herpetological note XIII |journal=Zoologische Mededelingen |date=1936 |volume=19 |page=135}}</ref> Analysis of the components of the venom of all mambas places the western green mamba as sister species to Jameson's mamba.<ref name="ainsworth 2018" /> In addition to being called the western green mamba, this species is also commonly known as the West African green mamba,<ref name=Navy>{{cite book|last=Department of the Navy Bureau of Medicine and Surgery|title=Venomous Snakes of the World: A Manual for Use by U.S. Amphibious Forces|year=2013|publisher=Skyhorse Publishing|location=New York|isbn=978-1-62087-623-7|page=200| url=https://books.google.com/books?id=zQlECgAAQBAJ&dq=%22West+African+Green+Mamba%22&pg=PA200}}</ref> and formerly Hallowell's green mamba.<ref>{{cite book |last1=Cansdale |first1=George Soper |title=Reptiles of West Africa |date=1955 |publisher=Penguin Books |location=London |page=42}}</ref>

Analysis of the components of the venom of all mambas places the western green mamba sister to Jameson's mamba (''Dendroapsis j. jamesoni and j. kaimosae''), as shown in the cladogram below.<ref name="ainsworth 20182">{{cite journal|last1=Ainsworth|first1=Stuart|last2=Petras|first2=Daniel|last3=Engmark|first3=Mikael|last4=Süssmuth|first4=Roderich D.|author4-link=Roderich D. Süssmuth|last5=Whiteley|first5=Gareth|last6=Albulescu|first6=Laura-Oana|last7=Kazandjian|first7=Taline D.|last8=Wagstaff|first8=Simon C.|last9=Rowley|first9=Paul|last10=Wüster|first10=Wolfgang|last11=Dorrestein|first11=Pieter C.|date=2018|title=The medical threat of mamba envenoming in sub-Saharan Africa revealed by genus-wide analysis of venom composition, toxicity and antivenomics profiling of available antivenoms|url=https://archive.lstmed.ac.uk/7572/1/J_Proteomics_The%20medical%20threat%20of%20mamba.docx|journal=Journal of Proteomics|volume=172|pages=173–189|doi=10.1016/j.jprot.2017.08.016|pmid=28843532|first12=Ana Silvia|last12=Arias|first16=Juan J.|last15=Casewell|first15=Nicholas R.|last14=Harrison|first14=Robert A.|last13=Gutiérrez|first13=José M.|last16=Calvete|s2cid=217018550 |hdl=10261/279110|hdl-access=free}}</ref>{{clade|{{clade |1={{clade |1=''Ophiophagus hannah'' }} |2={{clade |1={{clade |1={{clade |1=''Dendroaspis j. jamesoni'' |2=''Dendroaspis j. kaimosae'' }} |2= '''''Dendroaspis viridis''''' }} |2={{clade |1=''Dendroaspis angusticeps'' |2=''Dendroaspis polylepis'' }} }} }}}}

==Description== left|thumb The western green mamba has a long and slender body with a long tapering tail. The average length of an adult is between {{convert|1.4|m|ft}} and {{convert|2.1|m|ft|0}}, with large approaching {{convert|2.4|m|ft|0}} long.<ref name=S&B95/> The long thin head has a distinct canthus above the medium-sized eyes, which have round pupils and yellowish brown irises.<ref name="WCH">{{cite web|title=''Dendroaspis viridis''|url=http://www.toxinology.com/fusebox.cfm?fuseaction=main.snakes.display&id=SN0171|work=Clinical Toxinology Resource|publisher=University of Adelaide|access-date=4 March 2014}}</ref> When threatened or otherwise aroused, the western green mamba is capable of flattening its neck area into a slight hood.<ref>{{cite journal |last1=Pitman |first1=Charles R.S. |title=Hood-spreading by the mambas of the African genus ''Dendroaspis'' Schlegel |journal=Journal of East African Natural History |date=1965 |volume=25 |issue=2 |pages=110–115 |url=https://journals.co.za/doi/pdf/10.10520/AJA00128317_459}}</ref> The snake is bright green fading to yellow or orange towards the tail. Its scales have prominent black margins, giving the species a networked pattern.<ref name="c&j19"/>

The western green mamba can be mistaken for similar species such as green bushsnakes of the genus ''Philothamnus'' or the boomslang (''Dispholidus typus'').<ref name=ASI>{{cite web |last1=Marais |first1=Johan |title=Western Green Mamba |url=https://www.africansnakebiteinstitute.com/snake/african-snakes-western-green-mamba/ |website=African Snakebite Institute |date=19 September 2019 |access-date=8 May 2021}}</ref>

===Scalation=== {{See also|Snake scale#Nomenclature of scales}} The number and pattern of scales on a snake's body are a key element of identification to species level.<ref>{{cite web |last1=Hutchinson |first1=Mark |first2=Ian |last2=Williams |title=Key to the Snakes of South Australia |url=https://www.samuseum.sa.gov.au/Upload/Files-Biological-Sciences/R-and-A-text/Key-to-the-Snakes-of-South-Australia.pdf |website=South Australian Museum |publisher=Government of South Australia |date=2018 |access-date=8 February 2019 |archive-date=18 July 2019 |archive-url=https://web.archive.org/web/20190718130858/http://www.samuseum.sa.gov.au/Upload/Files-Biological-Sciences/R-and-A-text/Key-to-the-Snakes-of-South-Australia.pdf }}</ref> The western green mamba has 13 rows of long and thin dorsal scales at midbody, fewer than any similar species. Each is double the length of the ventral scales. There are 211 to 225 ventral scales, 105 to 128 divided subcaudal scales, and a divided anal scale.{{efn|A divided scale is one split down the midline into two scales.<ref>{{cite web |last1=Macdonald |first1=Stewart |title=snake scale count search |url=http://www.arod.com.au/arod/scale/ |website=Australian Reptile Online Database |access-date=3 May 2019}}</ref>}} Its mouth is lined with 7 to 9 supralabial scales above, the fourth and sometimes fifth one located under the eye, and 9–10 sublabial scales below.<ref name="c&j19">{{cite book |last1=Chippaux |first1=Jean-Phillipe |last2=Jackson |first2=Kate |title=Snakes of Central and Western Africa |date= 2019 |publisher=Johns Hopkins University Press |isbn=978-1-4214-2719-5 |page=109 |edition=1}}</ref>

==Distribution and habitat== The western green mamba is native to West Africa from Gambia and southern Senegal to Benin, including the intervening countries (from west to east) Guinea-Bissau, Guinea, Sierra Leone, Liberia, Côte d'Ivoire (Ivory Coast), Ghana, and Togo.<ref name="iucn status 19 November 2021" /> It is common in Togo, found as far north as the Alédjo Wildlife Reserve, though may theoretically be found in Sarakawa and Djamdé forests in the Kara Region.<ref name="S et al."/> Records from Nigeria are dubious,<ref name="iucn status 19 November 2021" /> and reports from the Central African Republic are more likely to be misidentification of Jameson's mamba.<ref>{{cite journal |last1=Chirio |first1=Laurent |last2=Ineich |first2=Ivan |title=Biogeography of the Reptiles of the Central African Republic |journal=African Journal of Herpetology |date=2006 |volume=2006 |issue=1 |pages=23–59 |doi=10.1080/21564574.2006.9635538 |bibcode=2006AfJH...55...23C |url=https://www.podarcis.de/AF/Bibliografie/BIB_5390.pdf}}</ref>

Western green mambas live mainly in the coastal tropical rainforest, thicket, and woodland regions of western Africa.<ref name=S&B95>{{cite book|last1=Spawls| first1= Steve|last2=Branch | first2= Bill|title=The Dangerous Snakes of Africa|year=1995|publisher=Blandford|isbn=978-0-88359-029-4|pages=51–52}}</ref> The majority of records of the western green mamba are from within the continuous forest, but the Gambia and Guinea-Bissau records are from isolated forests. The species persists in areas where the tree cover has been removed, providing that sufficient hedges and thicket remain. Found in some suitably vegetated suburbs and towns and parklands therein.<ref name=S&B95/> It is largely confined to areas where rainfall exceeds {{convert|1,500|mm|in|round=5}}.<ref name=T&M06>{{cite book|last1=Trape | first1= J.F.|last2=Mané| first2= Y.|title=Guide des serpents d'Afrique occidentale: Savane et désert | language = French|date=2006|publisher=IRD Orstom|isbn=978-2-7099-1600-4}}</ref> In Togo, however, its range extends into the drier open forests of the north, the Guinean savannas of the west, and the littoral zone.<ref name="S et al.">{{cite journal|last1=Segniagbeto|first1=Gabriel Hoinsoude|last2=Trape| first2=Jean François |last3=David | first3= Patrick |last4=Ohler | first4= Annemarie |last5=Dubois | first5= Alain |last6= Glitho | first6=Isabelle Adolé |title=The snake fauna of Togo: systematics, distribution and biogeography, with remarks on selected taxonomic problems |journal=Zoosystema |date=2011 |volume=33 |issue=3 |pages=325–360 |doi=10.5252/z2011n3a4 |s2cid=84017614|url=http://sciencepress.mnhn.fr/sites/default/files/articles/pdf/z2011n3a4_0.pdf }}</ref>

===Conservation status=== This species is classified as Least Concern (LC) on the IUCN Red List of Threatened Species (v3.1, 2011). The conservation status of this species was last assessed in July 2012 and published in 2013, and it was classed as such due to a wide distribution, fairly generalist habits, stable population and the lack of major threats. However, its habitat and population is highly fragmented.<ref name="iucn status 19 November 2021" /> Despite not being listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the western green mamba is collected and sold internationally, and is one of the more expensive African snake species.<ref name=jensen18>{{cite journal |doi=10.1007/s10531-018-1632-9|title=Exploring the international trade in African snakes not listed on CITES: Highlighting the role of the internet and social media|year=2019|last1=Jensen|first1=Timm Juul|last2=Auliya|first2=Mark|last3=Burgess|first3=Neil David|last4=Aust|first4=Patrick Welby|last5=Pertoldi|first5=Cino|last6=Strand|first6=Julie|journal=Biodiversity and Conservation|volume=28|issue=1 |pages=1–19|bibcode=2019BiCon..28....1J |s2cid=57373462}}</ref>

==Behaviour and ecology== Mostly diurnal, the western green mamba spends most of its time in the forest canopy, at times at considerable height, though on occasion commonly go to the ground. When it wants to sleep it seeks out tree branches that offer dense cover. It generally retreats if encountered.<ref name=S&B2020>{{cite book|last1=Spawls |first1= Steve|last2=Branch | first2= Bill|title=The Dangerous Snakes of Africa|orig-date=1995| year=2020|publisher=Bloomsbury | url=https://books.google.com/books?id=IqXeDwAAQBAJ&dq=jameson%27s+mamba&pg=PA123 |isbn=978-1-4729-6028-3|pages=125–126}}</ref> The oldest recorded western green mamba was a captive specimen that lived 18.7 years.<ref>{{cite web|title=AnAge entry for Dendroaspis viridis|url=http://genomics.senescence.info/species/entry.php?species=Dendroaspis_viridis|work=AnAge:The Animal Ageing and Longevity Database|publisher=Human Ageing Genomic Resources|access-date=24 July 2021}}</ref>

==Breeding== The species lays a clutch of 6 to 14 eggs.<ref name=S&B2020/>

===Diet and predators=== The western green mamba generally hunts in trees though can also hunt on the ground. It preys on birds and small mammals, including rodents and squirrels.<ref name=S&B2020/>

==Venom== left|thumb The western green mamba is classified as a snake of medical importance in western SubSaharan Africa by the World Health Organization,{{efn|1=Snakes of Medical Importance include those with highly dangerous venom resulting in high rates of morbidity and mortality, or those that are common agents in snakebite.<ref name=who/>}}<ref name=who>{{cite web |last1=WHO Expert Committee on Biological Standardization |title=Guidelines for the production, control and regulation of snake antivenom immunoglobulins |url=https://www.who.int/bloodproducts/AntivenomGLrevWHO_TRS_1004_web_Annex_5.pdf |access-date=1 January 2019 | pages=224–226 | work= WHO Technical Report Series, No. 964}}</ref> although bites from this species are rare as it is rarely encountered.<ref name=S&B95/> When bitten, symptoms rapidly begin to manifest, usually within the first 15 minutes or less. The extraordinary speed with which the venom spreads through tissue and produces rapid manifestations of life-threatening symptoms is unique to mambas. Common symptoms of a bite from a western green mamba include local pain and swelling, although uncommon, local necrosis can be moderate, ataxia, headache, drowsiness, difficulty breathing, vertigo, hypotension (low blood pressure), diarrhea, dizziness, and paralysis. Left untreated, new and more severe symptoms rapidly progress. All symptoms worsen and the victim eventually dies due to suffocation resulting from paralysis of the respiratory muscles. Bites with envenomation can be rapidly fatal, which can be possible in 30 minutes.<ref name="WCH"/><ref name=WGMBite>{{cite web|title=Immediate First Aid for bites by Western Green Mamba (''Dendroaspis viridis'')|url=http://toxicology.ucsd.edu/Snakebite%20Protocols/Dendroa4.htm|work=Toxicology|publisher=University of California, San Diego|access-date=4 March 2014|archive-date=15 March 2016|archive-url=https://web.archive.org/web/20160315022339/http://toxicology.ucsd.edu/Snakebite%20Protocols/Dendroa4.htm}}</ref>

Similar to the venom of most other mambas, the western green mamba's contains predominantly three-finger toxin agents. The exception is the black mamba, whose venom lacks the potent alpha-neurotoxin as well. It is thought this may reflect the species' preferred prey—small mammals for the mainly land-dwelling black mamba, versus birds for the other predominantly arboreal mambas. Unlike that of many snake species, the venom of mambas has little phospholipase A2. Overall, the venom of the western green mamba is more potent than that of the eastern green mamba, similar or slightly less potent than that of Jameson's mamba, and much less potent than that of the black mamba.<ref name="ainsworth 2018">{{cite journal |last1=Ainsworth | first1=Stuart | first2=Daniel| last2=Petras| first3=Mikael |last3=Engmark| first4=Roderich D.|last4=Süssmuth | first5=Gareth |last5=Whiteley | first6=Laura-Oana |last6=Albulescu | first7=Taline D. |last7=Kazandjian | first8=Simon C. |last8=Wagstaff | first9=Paul |last9=Rowley | first10=Wolfgang |last10=Wüster| first11=Pieter C. |last11=Dorrestein | first12=Ana Silvia |last12=Arias | first13=José M. |last13=Gutiérrez | first14=Robert A. |last14=Harrison | first15=Nicholas R. |last15=Casewell| first16=Juan J. |last16=Calvete |title=The medical threat of mamba envenoming in sub-Saharan Africa revealed by genus-wide analysis of venom composition, toxicity and antivenomics profiling of available antivenoms |journal=Journal of Proteomics |date=2018 |volume=172 |pages=173–189 [178] |doi=10.1016/j.jprot.2017.08.016| pmid=28843532 | s2cid=217018550 | url=https://archive.lstmed.ac.uk/7572/1/J_Proteomics_The%20medical%20threat%20of%20mamba.docx|hdl=10261/279110 |hdl-access=free }}</ref>

The venom consists mainly of both pre-synaptic and post-synaptic neurotoxins, cardiotoxins,<ref name=WGMBite/> and fasciculins. The toxicity of the venom can vary tremendously depending on various factors including diet, geographical location, age-dependent change, and other factors. The SC and IV {{LD50}} for this species is 0.79 mg/kg and 0.71 mg/kg, respectively (Christensen and Anderson (1967)).<ref name="WCH"/> One study determined the LD50 of the venom administered to mice via the intraperitoneal (IP) route was 0.33 mg/kg.<ref name="S et al">{{cite journal|last=Shipolin|first=RA.|author2=Bailey, GS |author3=Edwardson, JA |author4= Banks, BCE. |title=Separation and Characterization of Polypeptides from the Venom of ''Dendroaspis viridis''|journal=European Journal of Biochemistry|date=August 1973|volume=40|issue=2|pages=337–344|doi=10.1111/j.1432-1033.1973.tb03202.x|pmid=4360896|doi-access=free}}</ref> In another test using mice that were administered the western green mamba's venom via the intraperitoneal (IP) route the LD50 was 0.045 mg/kg.<ref name=Gill>{{cite journal|last=Gill|first=DM.|title=Bacterial Toxins: A Table of Lethal Amounts|journal=Microbiological Reviews|volume=46|issue=1|pages=86–94|url=http://www.ouhsc.edu/ibc/documents/ToxinLD50Reference.pdf|access-date=17 March 2014|pmid=6806598|pmc=373212|year=1982|doi=10.1128/MMBR.46.1.86-94.1982|archive-date=24 January 2014|archive-url=https://web.archive.org/web/20140124012756/http://www.ouhsc.edu/ibc/documents/ToxinLD50Reference.pdf}}</ref> Another experimental IV LD50 toxicity of 0.5 mg/kg has been reported, with an average wet venom yield of 100 mg.<ref name=S&B95/> Like other mamba species, western green mamba venom is among the most rapid-acting venom of snakes.<ref name="Chippaux">{{cite book | title=Snake Venoms and Envenomations | publisher=Krieger Publishing Company | last=Chippaux | first=JP. | year=2006 | location=United States | page=300 | isbn=978-1-57524-272-9}}</ref> ===Treatment=== The speed of onset of envenomation means that urgent medical attention is needed.<ref name=S&B2020/> Standard first aid treatment for any bite from a suspected venomous snake is the application of a pressure bandage, minimisation of the victim's movement, and rapid conveyance to a hospital or clinic. Due to the neurotoxic nature of green mamba venom, an arterial tourniquet may be beneficial.<ref name=ECAJS>{{cite journal|first1=S. B.|last1= Dreyer|first2=J. S.|last2= Dreyer|title=Snake Bite: A review of Current Literature|journal=East and Central African Journal of Surgery|date=November 2013|volume=18|issue=3|pages=45–52|url=http://www.ajol.info/index.php/ecajs/article/viewFile/100408/89653 |issn=2073-9990}}</ref> Tetanus toxoid is sometimes administered, though the main treatment is the administration of the appropriate antivenom.<ref>{{cite journal |title=Snakebite envenoming |journal= Nature Reviews Disease Primers|volume= 3|date=2017 |issue=3 |page= 17063|doi=10.1038/nrdp.2017.63|pmid= 28905944|last1= Gutiérrez|first1= José María|last2= Calvete|first2= Juan J.|last3= Habib|first3= Abdulrazaq G.|last4= Harrison|first4= Robert A.|last5= Williams|first5= David J.|last6= Warrell|first6= David A.|s2cid= 4916503|url= https://archive.lstmed.ac.uk/7633/1/Nat_Rev_Dis_Primers_17063_2017_Accepted.pdf|doi-access= free}}</ref>

==Notes== {{notelist}}

==References== {{Reflist|30em}}

==External links== {{Commons category-inline|Dendroaspis viridis}} * [http://www.bushdrums.com/news/index.php?shownews=2353 Bushdrums.com] - Green Mamba Video filmed in Gabon

{{DEFAULTSORT:mamba, green, western}} Category:Dendroaspis Category:Snakes of Africa Category:Reptiles of West Africa western green mamba Category:Taxa named by Edward Hallowell (herpetologist)