Published October 30, 2021. Open access.

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Merten’s Coralsnake (Micrurus mertensi)

Reptiles of Ecuador | Serpentes | Elapidae | Micrurus | Micrurus mertensi

English common name: Merten’s Coralsnake.

Spanish common name: Coral de Mertens.

Recognition: ♂♂ 80 cmMaximum distance from the snout to the tip of the tail. ♀♀ 91.5 cmMaximum distance from the snout to the tip of the tail..1 In western Ecuador, true coral snakes (genus Micrurus) can be distinguished from most, but no all, false coral snakes by having brightly colored rings that encircle the body (rings evident on the belly), small eyes that are about the same size as the post-ocular scales, and no loreal scale.1,2 Micrurus mertensi is one of three species of the genus occurring in the dry forests of southwestern Ecuador. From these, it is the only one having a tricolored pattern and black body rings arranged in monads (Fig. 1).1,2 This species differs from M. bocourti by lacking black accessory rings.1,2 Males of the Merten’s Coralsnake differ from females by having longer tails with a greater (7–9 vs 5–6) number of black rings.2 The combination of small eyes and black rings arranged in monads separates M. mertensi from the Ecuadorian Milksnake (Lampropeltis micropholis).3

Figure showing an adult male individual of Micrurus mertensi

Figure 1: Adult male of Micrurus mertensi from Sabiango, Loja province, Ecuador.

Natural history: Micrurus mertensi is an uncommon terrestrial to semi-fossorial snake that inhabits pristine to heavily disturbed seasonally dry forests, usually close to bodies of water.1,2 This species also occurs in human-modified environments adjacent forested areas.1 Individuals have been seen active on soil, leaf-litter, or crossing roads during day or at night.1,4 These snakes forage actively in search of prey, which includes blind snakes (Epictia subcrotilla5), vipers,5 and colubrids.1 Merten’s Coralsnakes rely on their warning coloration as a primary defense mechanism. Individuals are usually calm and try to flee when threatened. If disturbed, they engage in complex and seemingly erratic behavior: they hide the head beneath body coils, crawl spasmodically forward and then backward, and display their bright tails as a decoy.1,4 They are also capable of striking if provoked. The venom of M. mertensi is neurotoxic and is probably lethal to humans, but no published records of envenomation exist.1

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Conservation: Least Concern Believed to be safe from extinction given current circumstances..6 Micrurus mertensi is listed in this category because the species is distributed over an area greater than 10,000 km2 and is currently facing no major widespread immediate extinction threats. However, in Ecuador, the species may qualify for a threatened conservation category. Approximately 42% of the native dry forest habitat of M. mertensi has already been destroyed in this country, mostly due to cattle ranching.7 Furthermore, vehicular traffic and human persecution are also confirmed sources of mortality for the species.4 Fortunately, Peruvian populations appear to be in better shape, and a major part of the species’ range is in the Cerros Amotape National Park and Tumbes Reserved Zone.

Distribution: Micrurus mertensi is native to the Tumbesian foothills of extreme southwestern Ecuador (Fig. 2) and northwestern Perú.

Distribution of Micrurus mertensi in Ecuador

Figure 2: Distribution of Micrurus mertensi in Ecuador. The type locality is Pacasmayo, Peru. See Appendix 1 for a complete list of the presence localities included in the map.

Etymology: The name Micrurus is derived from the Greek words mikros (=small) and oura (=tail), referring to the short tail in members of this genus.2 The species epithet mertensi honors European herpetologist Robert Friedrich Wilhelm Mertens (1894–1975), director of the Senckenberg Museum and author of herpetology books and papers describing new species of reptiles.2

See it in the wild: Merten’s Coralsnakes are found at a rate of about once every few weeks in southern Ecuador. The localities having the greatest number of recent observations of Micrurus mertensi are Jorupe Reserve and the town Yangana, where these snakes are typically found crossing dirt roads around sunset.

Acknowledgments: This account was published with the support of Secretaría Nacional de Educación Superior Ciencia y Tecnología (programa INEDITA; project: Respuestas a la crisis de biodiversidad: la descripción de especies como herramienta de conservación; No 00110378), Programa de las Naciones Unidas (PNUD), and Universidad San Francisco de Quito (USFQ).

Author and photographer: Alejandro ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador.

How to cite? Arteaga A (2021) Merten’s Coralsnake (Micrurus mertensi). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/FPAZ6837

Literature cited:

  1. Valencia JH, Garzón-Tello K, Barragán-Paladines ME (2016) Serpientes venenosas del Ecuador: sistemática, taxonomía, historial natural, conservación, envenenamiento y aspectos antropológicos. Fundación Herpetológica Gustavo Orcés, Quito, 653 pp.
  2. Campbell JA, Lamar WW (2004) The venomous reptiles of the western hemisphere. Cornell University Press, Ithaca, 774 pp.
  3. Peters JA (1960) The snakes of Ecuador; check list and key. Bulletin of the Museum of Comparative Zoology 122: 489–541.
  4. Field notes, Reptiles of Ecuador book project.
  5. Roze JA (1996) Coral snakes of the Americas: biology, indentification, and venoms. Krieger Publishing Company, Malabar, 328 pp.
  6. Lehr E, Cisneros-Heredia DF, Valencia J (2021) Micrurus mertensi. The IUCN Red List of threatened species. Available from: DOI: 10.2305/IUCN.UK.2017-2.RLTS.T203303A2763534.en
  7. MAE (2012) Línea base de deforestación del Ecuador continental. Ministerio del Ambiente del Ecuador, Quito, 30 pp.

Appendix 1: Locality data used to create the distribution map of Micrurus mertensi in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used.

EcuadorAzuaySanta IsabelValencia et al. 2016
EcuadorLojaAlgodonalCampbell & Lamar 2004
EcuadorLojaCelicaPhoto by Jorge Castillo
EcuadorLojaHacienda JuanesParker 183
EcuadorLojaJorupe ReserveThis work
EcuadorLojaPinto CastilloThis work
EcuadorLojaReserva Natural Rumi WilcoValencia et al. 2016
EcuadorLojaSabiango, 1 km N ofThis work
EcuadorLojaValle del CatamayoValencia et al. 2016
EcuadorLojaVilcabambaPhoto by Eduardo Zavala
EcuadorLojaYamburaraValencia et al. 2016
EcuadorLojaYanganaValencia et al. 2016
EcuadorLojaYangana, 1 km S ofValencia et al. 2016
EcuadorLojaYangana, 1.87 km WiNaturalist
PeruPiuraBarriosMCZ 45913
PeruPiuraHacienda San MartíniNaturalist
PeruTumbesQuebrada FaicalLSUMZ 38324
PeruTumbesQuebrada Los NaranjosTello 1998