Published January 3, 2021. Open access.

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Olive Ground Snake (Atractus roulei)

Reptiles of Ecuador | Serpentes | Colubridae | Atractus roulei

English common names: Olive Ground Snake, Roule’s Ground Snake.

Spanish common names: Tierrera aceituna, culebra tierrera de Roule.

Recognition: ♂♂ 38.5 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=33 cm. ♀♀ 42.9 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=39.6 cm.. In its area of distribution, the Olive Ground Snake (Atractus roulei) can be recognized by its round head similar in width to the neck, small eyes, dorsal scales arranged in 15 rows at mid-body, and dorsum uniformly yellowish to olive brown.1,2 The dorsal coloration is similar to other Ground Snakes, but A. roulei is the only member of its genus known to occur in the Alausí valley.1,2 Atractus carrioni resembles A. roulei in external appearance but, unlike most specimens of A. roulei, this species lacks a loreal scale and occurs in the southwestern Ecuadorian Andes.1

Figure showing an adult female individual of Atractus roulei

Figure 1: Adult female of the Olive Ground Snake (Atractus roulei) from near Tixán, Chimborazo province, Ecuador.

Natural history: Localy frequentRecorded weekly in densities below five individuals per locality.. Atractus roulei is a semi-fossorial (living underground and at ground level) snake that inhabits remnants of dry montane shrublands, irrigated pastures, and agricultural fields.2,3 Based on what is know about the diet of other Atractus, this species probably feeds on earthworms or slugs.4,5 Olive Ground Snakes have been found hidden under rocks and logs during the daytime.3 When exposed, their defensive behavior consists mainly of trying to flee. Also, when an individual is handled, it can use its tail for poking.3 Atractus roulei occurs in sympatry (existing in the same geographic area) with Saphenophis atahuallpae, Tantilla andinista, and Mastigodryas pulchriceps.3

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Conservation: Critically Endangered Considered to be facing imminent risk of extinction.. Atractus roulei is here proposed to be included in this category, instead of Vulnerable,6 because new estimates indicate that the species meets the following IUCN criteria: extremely small distribution range (~16 km2), habitat severely fragmented due to deforestation and agricultural expansion, and continuing decline in the extent and quality of its habitat. There is virtually no native vegetation remaining in the area where true individuals of A. roulei have been registered.7 An ongoing genetic study of populations of A. roulei indicates that individuals from Azuay, Cañar, and El Oro provinces belong to a different species. Thus, the Olive Ground Snake seems to be restricted to nearby the type locality.

Distribution: Atractus roulei is endemic to an estimated ~16 km2 area in the Alausí inter-Andean valley in west-central Ecuador. True individuals of A. roulei have been recorded only in Chimborazo province at elevations between 2350 and 2892 m (Fig. 2).

Distribution of Atractus roulei in Ecuador

Figure 2: Distribution of Atractus roulei in Ecuador. 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),810 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 roulei honors French zoologist Louis Roule (1861–1942), chair of zoology at the Muséum National d’Histoire Naturelle (MNHN) in Paris.11

See it in the wild: Olive Ground Snakes can be seen with ~5–10% certainty around the towns Tixán and Alausí, Chimborazo province, provided they are searched for by turning over rocks and logs in pastures nearby remnants of native vegetation.

Authors: Duvan ZambranoaAffiliation: Universidad del Tolima, Ibagué, Colombia. and Alejandro ArteagabAffiliation: Tropical Herping (TH), Quito, Ecuador.

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

How to cite? Zambrano D, Arteaga A (2021) Olive Ground Snake (Atractus roulei). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/FQBG6954

Literature cited:

  1. Passos P, Echevarría LY, Venegas PJ (2013) Morphological variation of Atractus carrioni (Serpentes: Dipsadidae). South American Journal of Herpetology 8: 109–120. DOI: 10.2994/SAJH-D-12-00025.1
  2. Savage JM (1960) A revision of the Ecuadorian snakes of the Colubrid genus Atractus. Miscellaneous Publications, Museum of Zoology, Univesity of Michigan 112: 1–184.
  3. Field notes, Reptiles of Ecuador book project.
  4. 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.
  5. Cisneros-Heredia DF (2005) Report of molluscivory in Atractus carrioni Parker, 1930. Herpetozoa 18: 185–186.
  6. Cisneros-Heredia DF, Almendáriz A (2017) Atractus roulei. The IUCN red list of threatened species. Available from: DOI: 10.2305/IUCN.UK.2017-2.RLTS.T176360A54445808.en
  7. MAE (2012) Línea base de deforestación del Ecuador continental. Ministerio del Ambiente del Ecuador, Quito, 30 pp.
  8. 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.
  9. Beekes R (2010) Etymological dictionary of Greek. Brill, Boston, 1808 pp.
  10. Duponchel P, Chevrolat L (1849) Atractus. In: d’Orbigny CD (Ed) Dictionnaire universel d’histoire naturelle. MM. Renard, Martinet et Cie., Paris, 312.
  11. Despax R (1910) Mission géodésique de l’Équateur. Collections recueillies par M. le Dr. Rivet. Liste des Ophidiens et description des espèces nouvelles. Bulletin du Muséum National d’Histoire Naturelle 16: 368–376. DOI: 10.5962/bhl.part.20432

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

EcuadorChimborazoAlausíDespax 1910
EcuadorChimborazoAlausí valleySavage 1960
EcuadorChimborazoTixán, 1 km S ofArteaga et al. 2017
EcuadorChimborazoTixán, 4.9 km S ofKU 141268
EcuadorChimborazoTixán, 2 km SW ofThis work