Published April 14, 2024. Open access.

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Black-collared Snake (Drepanoides anomalus)

Reptiles of Ecuador | Serpentes | Colubridae | Drepanoides anomalus

English common names: Black-collared Snake, Amazon Egg-eating Snake.

Spanish common name: Falsa ratonera.

Recognition: ♂♂ 50.6 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=37.2 cm. ♀♀ 83.7 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=65.2 cm..13 Drepanoides anomalus can be identified by having a black snout with a white nuchal collar followed by a band of black scales ending at the start of the throat (Fig. 1).15 The eyes have a semi-elliptical pupil and the tongue is pink with a gray tip.3,6 The dorsum is uniformly vermillion with a black tip on each scale, and the ventral surfaces are immaculate white.1,3 This species differs from Pseudoboa coronata and from the juveniles of Clelia clelia by having dorsal scales arranged in 15 (instead of in 17 or 19) rows at mid-body.1,6

Figure showing variation among individuals of Drepanoides anomalus

Figure 1: Individuals of Drepanoides anomalus from Ecuador: Jatun Sacha Biological Reserve, Napo province (); Aguas Negras Lodge, Sucumbíos province ().

Natural history: Drepanoides anomalus is a primarily terrestrial snake that inhabits terra-firme rainforests,3,7,8 occurring in lower densities, or not at all, in semi-open habitats such as in pastures and crops. Black-collared Snakes have been recorded moving across bare ground, on low (less than 0.1 m) substrates, or crawling among roots at the base of trees.5 They also ascend to trunks and tree branches up to 3 m above the ground.3,5 During the day, inactive individuals have been found under rock boulders or between the cracks of a brick wall.1,9 Although D. anomalus is reported as being primarily nocturnal, diurnal activity is not uncommon.10,11 The diet in this species consists primarily of lizard eggs, including those of Gonatodes humeralis and various microteiid lizards.1,3,58 Nevertheless, adult lizards and snakes (including Helicops angulatus) are also consumed.12 In the presence of a disturbance, the Black-collared Snake will usually just flee into the leaf-litter; if grabbed, it can also release cloacal secretions without attempting to bite.7 There are recorded instances of predation on members of this species by the snake Clelia clelia.7 The breeding season in D. anomalus occurs between June and November in some parts of the Amazon.11 Given their small size, females of this species lay a maximum of 4 eggs, and the nests are usually hidden under logs and surrounded by decomposing organic matter.3,11

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Conservation: Least Concern Believed to be safe from extinction given current circumstances..13 Drepanoides anomalus is listed in this category because the species is widely distributed, occurs in many protected areas (at least 20 in Ecuador), and is considered to be facing no major immediate threats of extinction.13 The most important threat for the long-term survival of this strictly forest-dwelling snake is the loss of habitat due to large-scale deforestation.

Distribution: Drepanoides anomalus occurs throughout the Amazonian lowlands and adjacent slopes of the Andes in Bolivia, Brazil, Colombia, Ecuador (Fig. 2), French Guiana, Guyana, Peru, and Suriname.14

Distribution of Drepanoides anomalus in Ecuador

Figure 2: Distribution of Drepanoides anomalus in Ecuador. See Appendix 1 for a complete list of the presence localities included in the map.

Etymology: The genus name Drepanoides comes from the Greek word drepanon (=sickle) and the Latin suffix -oides (=similar to).15 It refers to the shape of the post-diastemal teeth. The specific epithet anomalus comes from the Greek anomalos (=irregular).15 It probably refers to the fact that, unlike other Pseudoboine Snakes, this species does not have grooved rear fangs.

See it in the wild: Black-collared Snakes can be seen at a rate of about once every few weeks, especially by scanning the forest floor during the first hours of the night. Prime localities for this species in Ecuador include Yasuní Scientific Station and Jatun Sacha Biological Reserve.

Authors: Tatiana Molina-Moreno,aAffiliation: Departamento de Biología, Universidad de los Llanos, Villavicencio, Colombia. Andrés F. Aponte-Gutiérrez,bAffiliation: Grupo de Investigación en Ciencias de la Orinoquía, Universidad Nacional de Colombia sede Orinoquía, Arauca, Colombia.,cAffiliation: Fundación Biodiversa Colombia, Bogotá, Colombia. and Danna Duque-TorresdAffiliation: Grupo de Ornitología, Universidad Nacional de Colombia, Bogotá, Colombia.

Editor: Alejandro ArteagaeAffiliation: Tropical Herping (TH), Quito, Ecuador.

Photographer: Jose VieirafAffiliation: Tropical Herping (TH), Quito, Ecuador.,gAffiliation: ExSitu, Quito, Ecuador.

How to cite? Molina-Moreno T, Aponte-Gutierrez AF, Duque-Torres D (2024) Black-collared Snake (Drepanoides anomalus). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/DVIX7893

Literature cited:

  1. 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.
  2. Dixon JR, Soini P (1986) The reptiles of the upper Amazon Basin, Iquitos region, Peru. Milwaukee Public Museum, Milwaukee, 154 pp.
  3. Martins M, Oliveira ME (1998) Natural history of snakes in forests of the Manaus region, Central Amazonia, Brazil. Herpetological Natural History 6: 78–150.
  4. da Silva AL, Strüssmann C, Rosenberg D, Magalhães F, Vitt L, Hoogmoed M, Bernarde PS, Paes R, Ribeiro RAK, Somaweera R, Albuquerque S, Morato SAA, Carvalho VT (2013) Guide to the snakes of the Manaus region - Central Amazonia. Inpa, Manaus, 303 pp.
  5. Duellman WE (2005) Cusco amazónico: the lives of amphibians and reptiles in an Amazonian rainforest. Cornell University Press, Ithaca, 433 pp.
  6. Cunha OR, do Nascimento FP (1994) Ofídios da Amazônia. As cobras da região leste do Pará. Boletim do Museu Paraense Emílio Goeldi 9: 1–191.
  7. Gaiarsa MP, Alencar LR, Martins M (2013) Natural history of pseudoboine snakes. Papéis Avulsos de Zoologia 53: 261–283. DOI: 10.1590/S0031-10492013001900001
  8. Alencar LR, Gaiarsa MP, Martins M (2013) The evolution of diet and microhabitat use in Pseudoboine Snakes. South American Journal of Herpetology 8: 60–66. DOI: 10.2994/sajh-d-13-00005.1
  9. Field notes, Reptiles of Ecuador book project.
  10. Vanzolini PE (1986) Levantamento herpetologico da área do estado de Rondônia , sob a influência da Rodovia BR 364. Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brasilia, 50 pp.
  11. dos Santos-Costa MC, Maschio GF, da Costa Prudente AL (2015) Natural history of snakes from Floresta Nacional de Caxiuanã, eastern Amazonia, Brazil. Herpetology Notes 8: 69–98.
  12. Crnobrna B, Armes M, Fonseca H (2016) Drepanoides anomalus (Amazon Egg-eating Snake): diet/ophiophagy. Herpetological Review 47: 478.
  13. Bolívar W, Castañeda MR, Cisneros-Heredia DF, Velasco J, Nogueira C, Catenazzi A, Gagliardi G, Gonzales L (2019) Drepanoides anomalus. The IUCN Red List of threatened species. Available from: DOI: 10.2305/IUCN.UK.2019-3.RLTS.T15177369A15177399.en
  14. Nogueira CC, Argôlo AJS, Arzamendia V, Azevedo JA, Barbo FE, Bérnils RS, Bolochio BE, Borges-Martins M, Brasil-Godinho M, Braz H, Buononato MA, Cisneros-Heredia DF, Colli GR, Costa HC, Franco FL, Giraudo A, Gonzalez RC, Guedes T, Hoogmoed MS, Marques OAV, Montingelli GG, Passos P, Prudente ALC, Rivas GA, Sanchez PM, Serrano FC, Silva NJ, Strüssmann C, Vieira-Alencar JPS, Zaher H, Sawaya RJ, Martins M (2019) Atlas of Brazilian snakes: verified point-locality maps to mitigate the Wallacean shortfall in a megadiverse snake fauna. South American Journal of Herpetology 14: 1–274. DOI: 10.2994/SAJH-D-19-00120.1
  15. Brown RW (1956) Composition of scientific words. Smithsonian Books, Washington D.C., 882 pp.

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

ColombiaAmazonasEl EncantoSINCHI 3350; GBIF
ColombiaAmazonasLa ChorreraSINCHI 3697; GBIF
ColombiaPutumayoBajo MansoyáGeopark S.A.S
ColombiaPutumayoLa PalestinaBorja-Acosta & Galeano 2024
ColombiaPutumayoPuerto AsísCárdenas Hincapié & Lozano Bernal 2023
ColombiaPutumayoVereda Alto Santa MaríaBorja-Acosta & Galeano 2024
EcuadorMorona SantiagoLos Tayos–Río CoangosNHMUK 19761855; GBIF
EcuadorMorona SantiagoMacas Wallach et al. 2014
EcuadorMorona SantiagoMacumaiNaturalist; photo examined
EcuadorMorona SantiagoQuebrado Río Napinaza Nogueira et al. 2019
EcuadorMorona SantiagoRío CangaimeWallach et al. 2014
EcuadorMorona SantiagoTurulaAMNH 28815; examined
EcuadorNapoArchidonaWallach et al. 2014
EcuadorNapoEl ChacoPhoto by Diego Piñán
EcuadorNapoHuella Verde LodgeReptiles of Ecuador book database
EcuadorNapoJatun Sacha Biological StationThis work; Fig. 1
EcuadorNapoReserva Forestal AlpayacuiNaturalist; photo examined
EcuadorNapoSan Marcos, 10 km W ofNogueira et al. 2019
EcuadorNapoSuchipakari LodgeReptiles of Ecuador book database
EcuadorNapoUniversidad IkiamiNaturalist; photo examined
EcuadorNapoWildSumaco Wildlife SanctuaryiNaturalist; photo examined
EcuadorOrellanaGuiyero, 3 km W ofNogueira et al. 2019
EcuadorOrellanaHacienda El CeiboNogueira et al. 2019
EcuadorOrellanaLaguna TaracoaMCZ 156871; VertNet
EcuadorOrellanaNPF, 5 km N ofNogueira et al. 2019
EcuadorOrellanaPacca HuasiKingsbury et al. 2008
EcuadorOrellanaParque Nacional YasuníiNaturalist; photo examined
EcuadorOrellanaPlataforma El EdénNogueira et al. 2019
EcuadorOrellanaSan José de PayaminoMaynard et al. 2016
EcuadorOrellanaTiputini Biodiversity StationCisneros-Heredia 2003
EcuadorOrellanaTiputini, 10 km NE ofNogueira et al. 2019
EcuadorOrellanaYarina LodgeReptiles of Ecuador book database
EcuadorOrellanaYasuní Scientific StationReptiles of Ecuador book database
EcuadorOrellana Pompeya, 5 km SE ofNogueira et al. 2019
EcuadorPastazaAndoasAMNH 49078; examined
EcuadorPastazaBalsauraOrtega-Andrade 2010
EcuadorPastazaBataburo LodgeNogueira et al. 2019
EcuadorPastazaCabeceras del Río ArajunoUSNM 204111; VertNet
EcuadorPastazaCampamento Petrolero de AGIPNogueira et al. 2019
EcuadorPastazaCanelosAMNH 35890; examined
EcuadorPastazaCentro Ecológico Zanja ArajunoiNaturalist; photo examined
EcuadorPastazaComunidad TarangaroNogueira et al. 2019
EcuadorPastazaConamboOrtega-Andrade 2010
EcuadorPastazaFinca Flora ManoiNaturalist; photo examined
EcuadorPastazaJuyuintzaOrtega-Andrade 2010
EcuadorPastazaKallanaMZUTI 5043; examined
EcuadorPastazaMontalvo, Río BobonazaUSNM 204112; VertNet
EcuadorPastazaShiripuno LodgeiNaturalist; photo examined
EcuadorPastazaSumak Kawsay In SituBentley et al. 2021
EcuadorPastazaVillanoPhoto by Álvaro Perez
EcuadorSucumbíosAguas Negras LodgeThis work; Fig. 1
EcuadorSucumbíosDurenoDuellaman 1978
EcuadorSucumbíosEstación Limoncocha LPFiNaturalist; photo examined
EcuadorSucumbíosGarzacochaPhoto by Ryan Lynch
EcuadorSucumbíosLa Primavera, 7 km NW ofKU 175409; VertNet
EcuadorSucumbíosLago AgrioiNaturalist; photo examined
EcuadorSucumbíosLaguna GrandeNogueira et al. 2019
EcuadorSucumbíosLos ÁngelesNogueira et al. 2019
EcuadorSucumbíosLumbaquiiNaturalist; photo examined
EcuadorSucumbíosMocoaiNaturalist; photo examined
EcuadorSucumbíosNapo Wildlife CenterReptiles of Ecuador book database
EcuadorSucumbíosReserva LimoncochaNogueira et al. 2019
EcuadorSucumbíosSaladero de DantasOMNH 36520; VertNet
EcuadorSucumbíosSan Pablo de KantesiyaMHNG 2410.057; collection database
EcuadorSucumbíosSani LodgeReptiles of Ecuador book database
EcuadorSucumbíosSingueiNaturalist; photo examined
EcuadorSucumbíosTerritorio Cofán DurenoYánez-Muñoz & Chimbo 2007
EcuadorZamora ChinchipeFinca YantzaiNaturalist; photo examined
PeruAmazonasCaterpizaUSNM 566568; VertNet
PeruLoretoMoroponDixon & Soini 1986