Published February 15, 2024. Open access.

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Arango’s Ground Snake (Atractus arangoi)

Reptiles of Ecuador | Serpentes | Colubridae | Atractus arangoi

English common name: Arango’s Ground Snake.

Spanish common name: Tierrera de Arango.

Recognition: ♂♂ 36.4 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=30.9 cm. ♀♀ 46.2 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=41.2 cm..1 Atractus arangoi differs from other snakes in its area of distribution by having a round head similar in width to the neck, small red eyes, and a unique coloration.1 The dorsal surfaces are light brown with a series of cream-bordered dark brown bars and a pair of blotches (sometimes fused into a single band) on the nape (Fig. 1).13 Older individuals may be uniformly brown. This species is often confused with A. major, from which it differs by being much smaller, lacking complete irregular dark bands anteriorly, having no dark brown or black nape stripe, and having a lower number of ventral scales.1,2 The juvenile coloration is orangish-brown with contrasting alternating black bands and a pair of conspicuous black nape blotches.

Figure showing variation among individuals of Atractus arangoi

Figure 1: Individuals of Atractus arangoi from Jatun Sacha Biological Reserve, Napo province, Ecuador.

Natural history: Atractus arangoi is a rarely seen semi-fossorial snake that inhabits pristine to heavily disturbed lowland and foothill rainforests.1,4 Arango’s Ground Snakes have been seen crawling on the leaf-litter at night or during the day.4,5 Curiously, the majority of individuals have been spotted at night roosting or foraging on leaves, ferns, stems, rotting logs, and mossy tree trunks 0.5–2.5 m above the ground.610 Clutches consist of 3–4 eggs.10,11 Ground snakes in general feed primarily on earthworms,3,12,13 but the specific prey items consumed by A. arangoi are not known.

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Conservation: Least Concern Believed to be safe from extinction given current circumstances.. Atractus arangoi is proposed to be listed in this category because current information1 suggests that the species has a wide (greater than 75,000 km2) distribution spanning many protected areas. However, some populations, including those from the type locality, are probably destined to disappear due to rural-urban expansion. The Amazonian landscape between Puerto Asís in Colombia and Lago Agrio in Ecuador is now a matrix of rainforest islands surrounded by pastures and plantations.

Distribution: Atractus arangoi is native to an area of approximately 75,177 km2 in the upper Amazon lowlands and adjacent foothills of the Andes in Colombia and Ecuador (Fig. 2).

Distribution of Atractus arangoi in Ecuador

Figure 2: Distribution of Atractus arangoi in Ecuador. The star corresponds to the type locality: Puerto Asís, Putumayo department, Colombia. See Appendix 1 for a complete list of the presence localities included in the map.

Etymology: The name Atractus, which is a latinization of the Greek word άτρακτος (=spindle),1416 probably refers to the fact that snakes of this genus have a uniform width throughout the body and a narrow tail, resembling an antique spindle used to spin fibers. The specific epithet arangoi honors Colombian physician and naturalist Dr. Andrés Posada Arango (1839–1923).2

See it in the wild: Arango’s Ground Snakes can be found at a rate of about once every few years throughout the northern Amazon of Ecuador. Prime locations for this species include Reserva Biológica Jatun Sacha and San José de Payamino, where the snakes have been found by sampling forest trails at night.

Autor: Alejandro ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador.

Photographer: Jose VieirabAffiliation: Tropical Herping (TH), Quito, Ecuador.,cAffiliation: ExSitu, Quito, Ecuador.

How to cite? Arteaga A (2024) Arango’s Ground Snake (Atractus arangoi). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/EEKM8629

Literature cited:

  1. Arteaga A, Quezada A, Vieira J, Guayasamin JM (2022) Leaving no stone unturned: three additional new species of Atractus ground snakes (Serpentes, Colubridae) from Ecuador discovered using a biogeographical approach. ZooKeys 1121: 175–210. DOI: 10.3897/zookeys.1121.89539
  2. Prado A (1939) Cinco especies novas de serpentes colombianas do genero Atractus Wagler. Memórias do Instituto Butantan 13: 1–9.
  3. Duellman WE (1978) The biology of an equatorial herpetofauna in Amazonian Ecuador. Publications of the Museum of Natural History, University of Kansas 65: 1–352.
  4. Field notes, Reptiles of Ecuador book project.
  5. Photo by Harold Rodríguez.
  6. Photo by Morley Read.
  7. Photo by Martín Rosero.
  8. Photo by Bert Willaert.
  9. Photo by Darwin Varela.
  10. Eric Osterman, pers. comm.
  11. Photo by Ross Maynard.
  12. Arteaga A, Bustamante L, Guayasamin JM (2013) The amphibians and reptiles of Mindo. Universidad Tecnológica Indoamérica, Quito, 257 pp.
  13. Balestrin RL, Di-Bernardo M, Moreno AG (2007) Feeding ecology of the neotropical worm snake Atractus reticulatus in southern Brazil. The Herpetological Journal 17: 62–64.
  14. Woodward SP, Tate R (1830) A manual of the Mollusca: being a treatise on recent and fossil shells. C. Lockwood and Company, London, 750 pp.
  15. Beekes R (2010) Etymological dictionary of Greek. Brill, Boston, 1808 pp.
  16. Duponchel P, Chevrolat L (1849) Atractus. In: d’Orbigny CD (Ed) Dictionnaire universel d’histoire naturelle. MM. Renard, Martinet et Cie., Paris, 312.

Appendix 1: Locality data used to create the distribution map of Atractus arangoi in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used. Asterisk (*) indicates type locality.

ColombiaMetaEl RetiroiNaturalist; photo examined
ColombiaPutumayoEl PepinoiNaturalist; photo examined
ColombiaPutumayoOritoArteaga et al. 2022
ColombiaPutumayoPuerto Asís*Daniel 1949; Prado 1940
ColombiaPutumayoPuerto CaicedoSilva-Haad 2004
ColombiaPutumayoReserva Doña BlancaiNaturalist; photo examined
ColombiaPutumayoReserva La Isla EscondidaArteaga et al. 2022
ColombiaPutumayoSan Miguel de MocoaArteaga et al. 2022
EcuadorNapoHostería Los HelechosArteaga et al. 2022
EcuadorNapoJatun SachaArteaga et al. 2022
EcuadorNapoSelina LodgeArteaga et al. 2022
EcuadorOrellanaSan José de PayaminoMaynard et al. 2017
EcuadorSucumbíosBloque 27, Sector Blanca AArteaga et al. 2017
EcuadorSucumbíosLago AgrioDuellman 1973
EcuadorSucumbíosRío CuyabenoArteaga et al. 2022
EcuadorSucumbíosSanta CeciliaDuellman 1978