Pigmy Slender-Coralsnake (Micrurus scutiventris)

Reptiles of Ecuador | Serpentes | Elapidae | Micrurus | Micrurus scutiventris

English common names: Pigmy Slender-Coralsnake, Little Black Coral Snake.

Spanish common names: Coralilla enana, coral negra pequeña.

Recognition: ♂♂ 37.3 cmMaximum distance from the snout to the tip of the tail. ♀♀ 44.5 cmMaximum distance from the snout to the tip of the tail..¹ In Ecuador, the Pigmy Slender-Coralsnake (Micrurus scutiventris) is one of two coralsnakes that lack complete body rings.² It can be distinguished from most other snakes by its long and slender body, short tail (3.8–5.8% of snout-vent length), and unique coloration.^1–3 It has an entirely black dorsum and head, interrupted only by a pale yellow nape band.¹ The ventral surfaces are also black, but have 24–38 bright yellow bands or spots. The tail bears 2–3 bright red bands that may encircle the whole body or be confined to the ventral side.^1,3 The only other snake having a similar coloration in Ecuador is M. melanotus. However, individuals of this species are longer in body size and have more than 40 red to yellow ventral bands.¹

Figure 1: Illustration of an adult male individual of Micrurus scutiventris based on photographs of specimens from Ecuador and Peru.

Natural history: Extremely rareTotal average number of reported observations per locality less than three.. Micrurus scutiventris is a semi-fossorial (living underground and at ground level) snake that inhabits pristine to moderately disturbed rainforests.^1–4 Individuals have been seen active on the leaf-litter at night.⁴ They also have been found hidden inside termite and ant nests.¹ These snakes forage actively in search of prey, which includes burrowing lizards.³ Pigmy Slender-Coralsnakes rely on their camouflage and secretive habits as a primary defense mechanism. Individuals of M. scutiventris are more calm and docile than other coralsnake species. 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 the brightly colored underside of the tail as a decoy.¹ They are also capable of striking if provoked. Individuals of M. scutiventris are proteroglyphous (having fixed enlarged teeth towards the front of the maxilla) and venomous. Their venom 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..⁵ Micrurus scutiventris is included in this category because the species is widely distributed, occurs in major protected areas, has presumed stable populations, and is currently facing no major widespread extinction threats.⁵ The most important threat to the long-term survival of some populations is habitat destruction mostly due to mining, oil extraction, and the expansion of the agricultural frontier.¹

Distribution: Micrurus scutiventris is native to the western Amazon basin and the adjacent foothills of the Andes in Brazil, Colombia, Ecuador, and Peru. In Ecuador, the species has been recorded at elevations between 220 and 491 m (Fig. 2).

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

Etymology: The generic name Micrurus, which is derived from the Latin words mikros (meaning “small”) and oura (meaning “tail”), refers to the short tail in members of this group.² The species epithet scutiventris, which comes from the Latin words scutum (meaning “scale”) and venter (meaning “belly”), refers to the number of ventral scales, which is comparatively higher than in other coralsnake species.²

See it in the wild: Pigmy Slender-Coralsnakes are usually found no more than once every few years at any given area. In Ecuador, there are only seven confirmed records (Appendix 1), and in no single locality the species has been spotted more than once. Therefore, individuals of Micrurus scutiventris cannot be expected to be seen reliably using standard methods of field herping.

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: Alejandro Arteaga^aAffiliation: Khamai Foundation, Quito, Ecuador.

Illustrator: Matt Patterson

How to cite? Arteaga A (2021) Pigmy Slender-Coralsnake (Micrurus scutiventris). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: www.reptilesofecuador.com. DOI: 10.47051/YBKN2524

Literature cited:

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.
Campbell JA, Lamar WW (2004) The venomous reptiles of the western hemisphere. Cornell University Press, Ithaca, 774 pp.
Roze JA (1996) Coral snakes of the Americas: biology, indentification, and venoms. Krieger Publishing Company, Malabar, 328 pp.
Dixon JR, Soini P (1986) The reptiles of the upper Amazon Basin, Iquitos region, Peru. Milwaukee Public Museum, Milwaukee, 154 pp.
Gagliardi G, Gonzales L, Nogueira C, Valencia J (2019) Micrurus scutiventris. The IUCN Red List of threatened species. Available from: www.iucnredlist.org. DOI: 10.2305/IUCN.UK.2019-2.RLTS.T44581913A44581920.en

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

Country	Province	Locality	Source
Ecuador	Orellana	El Edén	Valencia et al. 2016
Ecuador	Pastaza	Andoas	Campbell & Lamar 2004
Ecuador	Pastaza	Comunidad Puka Yaku	Valencia et al. 2016
Ecuador	Pastaza	Pandanuque	Villamil Gualinga & Shiguango Andi 2008
Ecuador	Pastaza	Sarayacu	Valencia et al. 2016
Ecuador	Sucumbíos	Lumbaqui	Valencia et al. 2016
Ecuador	Sucumbíos	Santa Elena	Valencia et al. 2016
Peru	Amazonas	Nazareth	Campbell & Lamar 2004
Peru	Amazonas	Santa Maria De Nieva	Campbell & Lamar 2004