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Pygmy copperhead

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Pygmy copperhead
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Elapidae
Genus: Austrelaps
Species:
A. labialis
Binomial name
Austrelaps labialis
(Jan, 1859)
Distribution (in green; click to enlarge)
Synonyms

Alecto labialis Jan, 1859

The pygmy copperhead (Austrelaps labialis) is an Australian venomous elapid snake species[1][2] found on Kangaroo Island and the Fleurieu Peninsula in South Australia.[3] It is from the Austrelaps genus along with two other species of copperhead, the Highland and Lowland copperhead snakes.

Adult pygmy copperhead snakes grow to an average of 80 cm (31 in)[4] making it the smallest of Australian copperheads. It preys on small reptiles and frogs.[5] Their bite is considered possibly lethal[6] but they are unlikely to attack unless stepped on or purposely provoked.[3]

They are not considered to be in need of conservation.

Taxonomy

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The pygmy copperhead was first described as the Alecto Labialis by Giorgio Jan in 1859.[7] This name was also briefly given to the White-lipped Snake in 1873 by Jan and associate Ferdinando Sordelli.[8]

It was formerly included in Austrelaps superbus[2] which, at the time, also included the highland and lowland copperhead snakes under the same name. The three species were officially separated in 1991 in a publication from P. A. Rawlinson, detailing key differences in appearance, distribution and behaviour between each type.[9] This publication renames the pygmy copperhead to Austrelaps labialis, with Austrelaps superbus remaining the name for the highland copperhead.

Snake-catcher Raymond Hoser has disputed the separation of species in Austrelaps, claiming the main separation is related only to environmentally influenced changes.[10] His paper has however been challenged by the wider community.[11]

The common naming of the snake refers to the colouration of the scales on top of its body and those surrounding the snake’s snout and eyes,[12] and "pygmy" refers to the species being smaller than the highland and lowland counterparts. Other common names include the pigmy copperhead, dwarf copperhead,[4] Adelaide Hills copperhead and Jan’s copperhead.[13]

It is not closely related to the American copperhead, Agkistrodon contortrix (Viperidae).

Description

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The pygmy copperhead is the smallest of Australian copperhead snakes. It is expected for the males to grow to a larger size than the females, but the pygmy copperhead's ratio is more marked than most other snake species.[14] On average, the adult male snake reaches 80 cm (31.5 in) in length, with larger specimens reaching 120 cm (47.2 in) long.[4] The total length the snake can reach has been debated, with previous publications and research only finding specimens of 60 cm, 70 cm and 85 cm.[5][15][16]

On both sexes, the dorsal scales come in shades of brown to grey, with a notable darker stripe along the spine.[16] The abdominal area is cream to light-grey in colouration, with varying intensities of red along the edges before transitioning to the brown-grey backside.[16] The labial scales of the pygmy copperhead are barred[5] with dark colouration.[16] There can be from 140 to 165 ventral scales and 35–55 subcaudal scales, with an average of 15 rows of scales along their mid-bodies, and a single anal scale.[5]

Newborns often have paler backsides in comparison to adult pygmy copperheads.

  • Austrelaps labialis head
    Austrelaps labialis head

Distribution and habitat

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The pygmy copperhead is endemic to Australia and restricted to a small section of South Australia (state), particularly Kangaroo Island and immediately adjacent mainland within the Fleurieu Peninsula and the Mount Lofty Ranges.[1]

The limited area is characteristically moist, with an average yearly rainfall of 600–800 mm (23.6–31.5 in) and milder summer temperatures, 23–25 °C (73.4–77.0 °F).[5] They are found living in concentrated numbers[15] near streams, in swamps, marshland and open sclerophyll woodlands and forests. The cold temperatures in these areas are notably too low for many other reptilian species.[15]

There have been sightings of individual pygmy copperheads in the Adelaide Hills, as well as on islands between the Australian mainland and Tasmania, including Flinders Island, Hunter Island, Kangaroo Island, King Island, Preservation Island and Great Dog Island, probably from having accidentally stowed away on boats.[5]

Behaviour and relationship with humans

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The pygmy copperhead is a common species but rarely seen. It is generally unobtrusive, commonly hiding under leaf litter, old iron and haystacks. The lowland and highland species can be potentially dangerous, but being smaller, the pygmy is not known for being aggressive. They are all considered non-threatening unless provoked.[17] Combat between males signifies sexual maturity in snakes, but it has not been observed in pygmy copperheads, despite the lowland and highland species exhibiting at two years of age.[5]

Feeding

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Being carnivorous, the pygmy copperhead's diet consists of smaller ectotherms, most commonly including small lizards, frogs and tadpoles. They are known to feed more frequently than highland and lowland copperheads.[5] There have also been reports of cannibalism in the pygmy copperheads.[12]

Venom

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Bites are considered lethal without prompt anti-venom intervention, with possible irreversible presynaptic damage.[6] The pygmy copperhead’s venom is classed as strongly neurotoxic, with toxicity similar to that of the Indian cobra. It is weakly coagulant and strongly anticoagulant, with the ability to be both blood and muscle destroying.[5] Antivenom developed through the tiger snake is unable to completely neutralise the neurotoxicity of the whole venom, nor a modified version in research lab trials.[6]

Reproduction

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The pygmy copperhead is viviparous, commonly giving live birth to seven young in each litter,[14] with an average maximum of 20 young in a single litter.[5] The litter size is half that of the other Australian copperheads, attributed to their smaller body size and the maternal snout-vent length (SVL) and litter size ratio.[18] There also appears to be a skewed sex ratio towards males.[5] Female ovulation in the pygmy copperhead is in spring, but field research found that only two thirds of surveyed (apparently adult) females were reproductive, suggesting that females do not reproduce every year.[14]

References

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  1. ^ a b c Fenner, A.; Hutchinson, M.; McDonald, P.; Robertson, P. (2018). "Austrelaps labialis". IUCN Red List of Threatened Species. 2018: e.T2417A83452129. doi:10.2305/IUCN.UK.2018-1.RLTS.T2417A83452129.en. Retrieved 20 November 2021.
  2. ^ a b Austrelaps labialis at the Reptarium.cz Reptile Database. Accessed 26 April 2021.
  3. ^ a b Cermak, Michael (2008). Spectacular Snakes of Australia. doi:10.1071/9780643101371. ISBN 9780643101371.
  4. ^ a b c Cogger, Harold (2014). Reptiles and Amphibians of Australia. doi:10.1071/9780643109773. ISBN 9780643109773.
  5. ^ a b c d e f g h i j k Mirtschin, Peter; Rasmussen, Arne; Weinstein, Scott (2017). Australia's Dangerous Snakes. doi:10.1071/9780643106741. ISBN 9780643106741.
  6. ^ a b c Marcon, Francesca; Nicholson, Graham M. (October 2011). "Identification of presynaptic neurotoxin complexes in the venoms of three Australian copperheads (Austrelaps spp.) and the efficacy of tiger snake antivenom to prevent or reverse neurotoxicity". Toxicon. 58 (5): 439–452. doi:10.1016/j.toxicon.2011.08.003. hdl:10453/18515. ISSN 0041-0101. PMID 21854797.
  7. ^ Jan, G. (1859). "Plan d'une iconographie descriptive des ophidiens et description sommaire de nouvelles espèces de serpents". Revue et Magasin de Zoologie Pure et Appliquée, Paris. Série 2. 11: 122–130 [128]. doi:10.5962/bhl.title.12473.
  8. ^ Jan, G.; Sordelli, Ferdinando (1860). Iconographie générale des ophidiens / par M. le professor Jan ... [en collaboration avec Mr. F. Sordelli.] ... Milan: chez l'auteur [etc.] doi:10.5962/bhl.title.45246.
  9. ^ Schwaner, Terry D. (September 1991). "Spatial Patterns in Tiger Snakes (Notechis ater: Elapidae) on Offshore Islands of Southern Australia". Journal of Herpetology. 25 (3): 278–283. doi:10.2307/1564585. ISSN 0022-1511. JSTOR 1564585.
  10. ^ "Opinion 2468 (Case 3601) – Spracklandus Hoser, 2009 (Reptilia, Serpentes, Elapidae) and Australasian Journal of Herpetology issues 1–24: confirmation of availability declined; Appendix A (Code of Ethics): not adopted as a formal criterion for ruling on Cases". The Bulletin of Zoological Nomenclature. 78 (1). 2021-04-30. doi:10.21805/bzn.v78.a012. ISSN 0007-5167. S2CID 233448875.
  11. ^ Naish, Darren. "Taxonomic vandalism and the Raymond Hoser problem". Scientific American Blog Network. Retrieved 2021-05-17.
  12. ^ a b Beatson, Cecilie (13 April 2021). "Copperhead Snake". The Australian Museum.
  13. ^ "Bibliography of the genus Austrelaps / RepFocus". www.repfocus.dk. Retrieved 2021-05-17.
  14. ^ a b c Shine, Richard (March 1987). "Ecological Ramifications of Prey Size: Food Habits and Reproductive Biology of Australian Copperhead Snakes (Austrelaps, Elapidae)". Journal of Herpetology. 21 (1): 21–28. doi:10.2307/1564373. JSTOR 1564373. S2CID 31316793.
  15. ^ a b c WEIGEL, JOHN (2007-12-18). "Maintenance and breeding of the Superb dragon Diporiphora superba at the Australian Reptile Park, Gosford". International Zoo Yearbook. 28 (1): 122–126. doi:10.1111/j.1748-1090.1989.tb03266.x. ISSN 0074-9664.
  16. ^ a b c d Swan, Gerry; Wilson, Steve (September 2015). "Where do they all come from? Animal movement immediately following a hummock grassland fire". Australian Zoologist. 37 (4): 485–491. doi:10.7882/az.2015.012. ISSN 0067-2238.
  17. ^ Cermak, Michael (2008). Spectacular Snakes of Australia. CSIRO Publishing. doi:10.1071/9780643101371. ISBN 9780643101371.
  18. ^ Manjarrez, Javier; San-Roman-Apolonio, Emma (March 2015). "Timing of Birth and Body Condition in Neonates of Two Gartersnake Species from Central México". Herpetologica. 71 (1): 12–18. doi:10.1655/HERPETOLOGICA-D-13-00098. ISSN 0018-0831. S2CID 85044052.
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