Published July 25, 2021. Updated March 1, 2024. Open access.

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Orcés’ Ground Snake (Atractus orcesi)

Reptiles of Ecuador | Serpentes | Colubridae | Atractus orcesi

English common name: Orcés’ Ground Snake.

Spanish common names: Tierrera de Orcés, serpiente terrestre de Orcés.

Recognition: ♂♂ 28.5 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=25.1 cm. ♀♀ 33.8 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=31.2 cm..1 Atractus orcesi can be recognized by having a round head similar in width to the neck, small eyes, dorsal scales arranged in 15 rows at mid-body, and a unique coloration.1,2 The dorsum is dark brown with a complete or incomplete light neck collar and faint blackish dorsal stripes (Fig. 1).1,2 The belly is yellowish with a median black large stripe.1,2 This species differs from A. duboisi by lacking series of small yellowish dorsolateral spots.1 From A. occipitoalbus and A. gaigeae, it differs by having a ventral stripe, and from A. resplendens by having 15, instead of 17, dorsal scales rows at mid-body.2,3 From Ninia hudsoni, it differs by having smooth dorsal scales.4

Figure showing variation among adult individuals of Atractus orcesi

Figure 1: Individuals of Atractus orcesi from Sucumbíos province, Ecuador: El Higuerón (); La Bonita (). j=juvenile.

Natural history: Atractus orcesi is a semi-fossorial snake that inhabits evergreen foothill, lower-montane forests,1 and open areas such as grasslands, river banks,5 cultivated fields, dirt roads,6 and rural gardens.7 Snakes of this species may be observed active at night on leaf-litter,6 on rocks along streams,8 or buried in soft soil or hidden under rocks and logs during the day.7 Orcés’ Ground Snakes feed on earthworms9 and probably also on slugs, as is the case for other members of the genus.10,11 The defensive behavior in A. orcesi consists of trying to flee and using camouflage to hide.6,7 The reproductive ecology or reproductive season of the species is unknown; however, juveniles have been found in May.7

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Conservation: Least Concern Believed to be safe from extinction given current circumstances..8,12 Atractus orcesi is included in this category because the species’ current estimated extent of occurrence exceeds 20,000 km2, spans large protected areas, and because threats such as urban expansion, agricultural activities, and mortality from vehicular traffic are limited or localized.8,13 At the national level,12 in Ecuador, this snake is also listed as Least Concern, but Colombian populations are listed in the Vulnerable category due to loss of habitat caused by agricultural expansion.5

Distribution: Atractus orcesi is native to the Amazonian slopes of the Andes in Colombia and Ecuador (Fig. 2). Some authors mention that this species occurs at 3000 m above sea level,1 probably in reference to Colombian populations. However, the highest Colombian locality is “La Garganta del Balsayaco,” where these snakes have been found at 2400 m and more frequently below 2100 m.

Distribution of Atractus orcesi in Ecuador

Figure 2: Distribution of Atractus orcesi 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),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 orcesi honors Dr. Gustavo Orcés (1903–1999), a Ecuadorian zoologist of the Escuela Politécnica Nacional, who collected the holotype of the species.2 Gustavo Orcés made many contributions to the herpetology of Ecuador, and is considered to be the father of zoology in this country.

See it in the wild: Orcés’ Ground Snakes are easy to find around the towns La Bonita, Loreto, and General Leónidas Plaza Gutiérrez (Limón). These snakes also are encountered at Bigal River Biological Reserve and Wildsumaco Wildlife Sanctuary. Individuals may be detected by scanning the forest floor and leaf-litter along trails at night or by turning over rocks and logs in pastures near forest border during the day.

Acknowledgments: Special thanks to Jonh Jairo Mueses-Cisneros for providing natural history data on Atractus orcesi.

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 (2024) Orcés’ Ground Snake (Atractus orcesi). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/RQJS6453

Literature cited:

  1. Passos P, Chiesse A, Torres-Carvajal O, Savage JM (2009) Testing species boundaries within the Atractus occipitoalbus complex (Serpentes: Dipsadidae). Herpetologica 65: 384–403. DOI: 10.1655/08-024.1
  2. Savage JM (1955) Descriptions of new colubrid snakes, genus Atractus, from Ecuador. Proceedings of the Biological Society of Washington 68: 11–20.
  3. 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.
  4. 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.
  5. Morales-Betancourt MA, Lasso CA, Páez VP, Bock BC (2005) Libro rojo de reptiles de Colombia. Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Bogotá, 257 pp.
  6. Valencia JA, Garzón K (2011) Guía de anfibios y reptiles en ambientes cercanos a las estaciones del OCP. Fundación Herpetológica Gustavo Orcés, Quito, 268 pp.
  7. Field notes, Reptiles of Ecuador book project.
  8. Cisneros-Heredia DF, Ortega A (2019) Atractus orcesi. The IUCN Red List of threatened species. Available from: DOI: 10.2305/IUCN.UK.2019-3.RLTS.T44581282A44581285.en
  9. Rocha JC (2019) Influência de fatores ambientais e a relação entre os padrões de diversidade beta taxonômica e diversidade beta funcional de serpentes neotropicais. MSc thesis, Florianópolis, Universidade Federal de Santa Catarina, 119 pp.
  10. Cisneros-Heredia DF (2005) Report of molluscivory in Atractus carrioni Parker, 1930. Herpetozoa 18: 185–186.
  11. 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.
  12. Reyes-Puig C (2015) Un método integrativo para evaluar el estado de conservación de las especies y su aplicación a los reptiles del Ecuador. MSc thesis, Pontificia Universidad Católica del Ecuador, 73 pp.
  13. Torres-Carvajal O, Pazmiño-Otamendi G, Salazar-Valenzuela D (2019) Reptiles of Ecuador: a resource-rich online portal, with dynamic checklists and photographic guides. Amphibian & Reptile Conservation 13: 209–229.
  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 orcesi in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used. Asterisk (*) indicates type locality.

ColombiaCaucaVereda El CajorPassos et al. 2009
ColombiaHuilaParque Nacional Natural Cueva de los GuácharosPassos et al. 2009
ColombiaPutumayoLa Garganta del BalsayacoJonh Jairo Mueses Cisneros, pers. comm.
ColombiaPutumayoVereda BalsayacoPassos et al. 2009
EcuadorMorona SantiagoBetween Chiguaza and MacumaPassos et al. 2009
EcuadorMorona SantiagoCentro Fauna de la AmazoníaPhoto by Andreas Kay
EcuadorMorona SantiagoLimónPassos et al. 2009
EcuadorMorona SantiagoLimón, 6 km N ofMantilla Espinoza 2021
EcuadorMorona SantiagoNormandíaAMNH 28786; VertNet
EcuadorMorona SantiagoQuebrada Río NapinazaMantilla Espinoza 2021
EcuadorNapoAlto Río ArajunoPassos et al. 2009
EcuadorNapoHidroeléctrica Coca Codo SinclairMantilla Espinoza 2021
EcuadorNapoLa Merced de JondachiiNaturalist; photo examined
EcuadorNapoNarupayacuPhoto by Jhomy Varela
EcuadorNapoRío HollínPassos et al. 2009
EcuadorNapoWayra ReserveiNaturalist; photo examined
EcuadorNapoWildsumaco Wildlife SanctuaryCamper et al. 2021
EcuadorOrellanaLoreto, 21.6 km N ofiNaturalist; photo examined
EcuadorOrellanaLoreto*Savage 1955
EcuadorOrellanaRío Bigal Biological ReserveiNaturalist; photo examined
EcuadorPastazaAlto Río BobonazaPassos et al. 2009
EcuadorPastazaEstación Agro-Ecológica FátimaProaño-Morales et al. 2017
EcuadorPastazaUpper Rio VillanoPassos et al. 2009
EcuadorSucumbíosEl HiguerónThis work; Fig. 1
EcuadorSucumbíosEstación CayagamaValencia & Garzón 2011
EcuadorSucumbíosLa BonitaPassos et al. 2009
EcuadorSucumbíosLago AgrioPassos et al. 2009