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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..1–3 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).1–5 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 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.1,3,5–8 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
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
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: www.reptilesofecuador.com. DOI: 10.47051/DVIX7893
Literature cited:
- 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.
- Dixon JR, Soini P (1986) The reptiles of the upper Amazon Basin, Iquitos region, Peru. Milwaukee Public Museum, Milwaukee, 154 pp.
- Martins M, Oliveira ME (1998) Natural history of snakes in forests of the Manaus region, Central Amazonia, Brazil. Herpetological Natural History 6: 78–150.
- 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.
- Duellman WE (2005) Cusco amazónico: the lives of amphibians and reptiles in an Amazonian rainforest. Cornell University Press, Ithaca, 433 pp.
- 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.
- Gaiarsa MP, Alencar LR, Martins M (2013) Natural history of pseudoboine snakes. Papéis Avulsos de Zoologia 53: 261–283. DOI: 10.1590/S0031-10492013001900001
- 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
- Field notes, Reptiles of Ecuador book project.
- 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.
- 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.
- Crnobrna B, Armes M, Fonseca H (2016) Drepanoides anomalus (Amazon Egg-eating Snake): diet/ophiophagy. Herpetological Review 47: 478.
- 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: www.iucnredlist.org. DOI: 10.2305/IUCN.UK.2019-3.RLTS.T15177369A15177399.en
- 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
- 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.
| Country | Province | Locality | Source |
| Colombia | Amazonas | El Encanto | SINCHI 3350; GBIF |
| Colombia | Amazonas | La Chorrera | SINCHI 3697; GBIF |
| Colombia | Putumayo | Bajo Mansoyá | Geopark S.A.S |
| Colombia | Putumayo | La Palestina | Borja-Acosta & Galeano 2024 |
| Colombia | Putumayo | Puerto Asís | Cárdenas Hincapié & Lozano Bernal 2023 |
| Colombia | Putumayo | Vereda Alto Santa María | Borja-Acosta & Galeano 2024 |
| Ecuador | Morona Santiago | Los Tayos–Río Coangos | NHMUK 19761855; GBIF |
| Ecuador | Morona Santiago | Macas | Wallach et al. 2014 |
| Ecuador | Morona Santiago | Macuma | iNaturalist; photo examined |
| Ecuador | Morona Santiago | Quebrado Río Napinaza | Nogueira et al. 2019 |
| Ecuador | Morona Santiago | Río Cangaime | Wallach et al. 2014 |
| Ecuador | Morona Santiago | Turula | AMNH 28815; examined |
| Ecuador | Napo | Archidona | Wallach et al. 2014 |
| Ecuador | Napo | El Chaco | Photo by Diego Piñán |
| Ecuador | Napo | Huella Verde Lodge | Reptiles of Ecuador book database |
| Ecuador | Napo | Jatun Sacha Biological Station | This work; Fig. 1 |
| Ecuador | Napo | Reserva Forestal Alpayacu | iNaturalist; photo examined |
| Ecuador | Napo | San Marcos, 10 km W of | Nogueira et al. 2019 |
| Ecuador | Napo | Suchipakari Lodge | Reptiles of Ecuador book database |
| Ecuador | Napo | Universidad Ikiam | iNaturalist; photo examined |
| Ecuador | Napo | WildSumaco Wildlife Sanctuary | iNaturalist; photo examined |
| Ecuador | Orellana | Guiyero, 3 km W of | Nogueira et al. 2019 |
| Ecuador | Orellana | Hacienda El Ceibo | Nogueira et al. 2019 |
| Ecuador | Orellana | Laguna Taracoa | MCZ 156871; VertNet |
| Ecuador | Orellana | NPF, 5 km N of | Nogueira et al. 2019 |
| Ecuador | Orellana | Pacca Huasi | Kingsbury et al. 2008 |
| Ecuador | Orellana | Parque Nacional Yasuní | iNaturalist; photo examined |
| Ecuador | Orellana | Plataforma El Edén | Nogueira et al. 2019 |
| Ecuador | Orellana | San José de Payamino | Maynard et al. 2016 |
| Ecuador | Orellana | Tiputini Biodiversity Station | Cisneros-Heredia 2003 |
| Ecuador | Orellana | Tiputini, 10 km NE of | Nogueira et al. 2019 |
| Ecuador | Orellana | Yarina Lodge | Reptiles of Ecuador book database |
| Ecuador | Orellana | Yasuní Scientific Station | Reptiles of Ecuador book database |
| Ecuador | Orellana | Pompeya, 5 km SE of | Nogueira et al. 2019 |
| Ecuador | Pastaza | Andoas | AMNH 49078; examined |
| Ecuador | Pastaza | Balsaura | Ortega-Andrade 2010 |
| Ecuador | Pastaza | Bataburo Lodge | Nogueira et al. 2019 |
| Ecuador | Pastaza | Cabeceras del Río Arajuno | USNM 204111; VertNet |
| Ecuador | Pastaza | Campamento Petrolero de AGIP | Nogueira et al. 2019 |
| Ecuador | Pastaza | Canelos | AMNH 35890; examined |
| Ecuador | Pastaza | Centro Ecológico Zanja Arajuno | iNaturalist; photo examined |
| Ecuador | Pastaza | Comunidad Tarangaro | Nogueira et al. 2019 |
| Ecuador | Pastaza | Conambo | Ortega-Andrade 2010 |
| Ecuador | Pastaza | Finca Flora Mano | iNaturalist; photo examined |
| Ecuador | Pastaza | Juyuintza | Ortega-Andrade 2010 |
| Ecuador | Pastaza | Kallana | MZUTI 5043; examined |
| Ecuador | Pastaza | Montalvo, Río Bobonaza | USNM 204112; VertNet |
| Ecuador | Pastaza | Shiripuno Lodge | iNaturalist; photo examined |
| Ecuador | Pastaza | Sumak Kawsay In Situ | Bentley et al. 2021 |
| Ecuador | Pastaza | Villano | Photo by Álvaro Perez |
| Ecuador | Sucumbíos | Aguas Negras Lodge | This work; Fig. 1 |
| Ecuador | Sucumbíos | Dureno | Duellaman 1978 |
| Ecuador | Sucumbíos | Estación Limoncocha LPF | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Garzacocha | Photo by Ryan Lynch |
| Ecuador | Sucumbíos | La Primavera, 7 km NW of | KU 175409; VertNet |
| Ecuador | Sucumbíos | Lago Agrio | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Laguna Grande | Nogueira et al. 2019 |
| Ecuador | Sucumbíos | Los Ángeles | Nogueira et al. 2019 |
| Ecuador | Sucumbíos | Lumbaqui | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Mocoa | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Napo Wildlife Center | Reptiles of Ecuador book database |
| Ecuador | Sucumbíos | Reserva Limoncocha | Nogueira et al. 2019 |
| Ecuador | Sucumbíos | Saladero de Dantas | OMNH 36520; VertNet |
| Ecuador | Sucumbíos | San Pablo de Kantesiya | MHNG 2410.057; collection database |
| Ecuador | Sucumbíos | Sani Lodge | Reptiles of Ecuador book database |
| Ecuador | Sucumbíos | Singue | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Territorio Cofán Dureno | Yánez-Muñoz & Chimbo 2007 |
| Ecuador | Zamora Chinchipe | Finca Yantza | iNaturalist; photo examined |
| Peru | Amazonas | Caterpiza | USNM 566568; VertNet |
| Peru | Loreto | Moropon | Dixon & Soini 1986 |