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Diamond Racer (Drymobius rhombifer)
Reptiles of Ecuador | Serpentes | Colubridae | Drymobius anomalus
English common names: Diamond Racer, Blotched Racer.
Spanish common names: Corredora diamante, culebra de rombos.
Recognition: ♂♂ 126.8 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=90.7 cm. ♀♀ 109.7 cmMaximum distance from the snout to the tip of the tail..1,2 Drymobius rhombifer is a medium-sized snake with keeled dorsal scales having a dark brown dorsum adorned with 16–24 diamond-shaped blotches featuring a pale brown center and dark edges (Fig. 1).1–5 The belly is creamy white, adorned with a series of tiny brown spots bordering the ventral scales.1–5 The head is uniformly brown, with large eyes and a bronze iris.3 This species differs from the similarly patterned Bothrops atrox, B. asper, and Xenodon rabdocephalus by lacking loreal pits and by having no dark postocular stripe.6,7
Figure 1: Individuals of Drymobius rhombifer from Ecuador: Napo Wildlife Center, Orellana province (); Reserva Río Bigai, Napo province ().
Natural history: Drymobius rhombifer is a terrestrial snake that inhabits pristine lowland rainforests and floodplain forests, usually near ponds.1–4 The species occurs in lower densities, or not at all, in semi-open habitats or forest-edge situations. Diamond Racers are typically active on the forest floor during the daytime, frantically foraging on the leaf-litter or on low vegetation in search for food. At night, they roost on understory vegetation 0.9 to 2 m above the ground.2,4 The diet in this species consists of amphibians and lizards.2,4,5 The Diamond Racer, when cornered, opens the mouth aggressively and strikes. Its tail is long, fragile, and breaks off easily when grabbed by a predator, enabling the escape and survival of the snake.8 There is a recorded instance of predation on an individual of D. rhombifer by a hawk in Peru.9 An observation in Costa Rica indicates that courtship in this species occurs in July.10
Conservation: Least Concern Believed to be safe from extinction given current circumstances..11 Drymobius rhombifer is listed in this category because the species is widely distributed, occurs in many protected areas (at least 10 in Ecuador), and is considered to be facing no major immediate threats of extinction.11 In addition, it is presumed that that populations of D. rhombifer are stable and largely unfragmented.11 However, this species, a strict forest dweller, is under constant threat due to large-scaled deforestation driven by agricultural and urban expansion. Finally, because of its resemblance to Bothrops atrox, the Diamond Racer is often killed on sight whenever encountered.
Distribution: Drymobius rhombifer is widely distributed throughout the Neotropics, from Mexico to northwestern Ecuador (Fig. 2), as well as throughout much of Amazonia.
Figure 2: Distribution of Drymobius rhombifer in Ecuador. The star corresponds to the type locality: Esmeraldas, Esmeraldas province. See Appendix 1 for a complete list of the presence localities included in the map.
Etymology: The genus name Drymobius is derived from the Greek word drymos (=oak forest) and bios (=manner of life).12 The specific epithet rhombifer comes from the Latin rhombus (=diamond) and the suffix -fero (=provided with).12 It refers to the rhomboidal dorsal markings.
See it in the wild: Drymobius rhombifer is considered a rare species in Ecuador, with no more than 1–2 individuals recorded per year at any given locality. The areas having the greatest number of observations of this elusive serpent are Centro Científico Río Palenque and Yasuní Scientific Station.
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.
Photographers: Jose VieirafAffiliation: Tropical Herping (TH), Quito, Ecuador.,gAffiliation: ExSitu, Quito, Ecuador. and Amanda QuezadaeAffiliation: Tropical Herping (TH), Quito, Ecuador.
How to cite? Molina-Moreno T, Aponte-Gutierrez AF, Duque-Torres D (2024) Diamond Racer (Drymobius rhombifer). 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/DXQC2118
Literature cited:
- Dixon JR, Soini P (1986) The reptiles of the upper Amazon Basin, Iquitos region, Peru. Milwaukee Public Museum, Milwaukee, 154 pp.
- 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.
- Savage JM (2002) The amphibians and reptiles of Costa Rica, a herpetofauna between two continents, between two seas. The University of Chicago Press, Chicago, 934 pp.
- Duellman WE (2005) Cusco amazónico: the lives of amphibians and reptiles in an Amazonian rainforest. Cornell University Press, Ithaca, 433 pp.
- Natera-Mumaw M, Esqueda-González LF, Castelaín-Fernández M (2015) Atlas serpientes de Venezuela. Dimacofi Negocios Avanzados S.A., Santiago de Chile, 456 pp.
- Campbell JA, Lamar WW (2004) The venomous reptiles of the western hemisphere. Cornell University Press, Ithaca, 774 pp.
- Valencia JH, Garzón-Tello K, Barragán-Paladines ME (2016) Serpientes venenosas del Ecuador: sistemática, taxonomía, historial natural, conservación, envenenamiento y aspectos antropológicos. Fundación Herpetológica Gustavo Orcés, Quito, 653 pp.
- Padilla-Pérez DJ, Murillo-Monsalve JD, Rincon-Barón EJ, Daza JM (2015) Non-specialized caudal pseudoautotomy in the Emerald Racer snake Drymobius rhombifer (Günther, 1860). Herpetology Notes 8: 567–569.
- Leite Pitman R, Champagne PS (2022) Drymobius rhombifer (Esmarald Racer): predation. Herpetological Review 53: 340.
- Leenders T (2019) Reptiles of Costa Rica: a field guide. Cornell University Press, Ithaca, 625 pp.
- Vargas Álvarez J, García Rodríguez A, Batista A, Acosta Chaves V, Nogueira CC, Gonzales L, Cisneros-Heredia DF, Gagliardi G, Hoogmoed MS (2019) Drymobius rhombifer. The IUCN Red List of threatened species. Available from: www.iucnredlist.org. DOI: 10.2305/IUCN.UK.2019-2.RLTS.T176799A1446864.en
- 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 Drymobius rhombifer in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used. Asterisk (*) indicates type locality.
| Country | Province | Locality | Source |
| Colombia | Caquetá | Belén de Andaquíes | Ruiz Valderrama 2023 |
| Colombia | Nariño | Tangareal del Mira | Dickey 2016 |
| Colombia | Putumayo | Centro Experimental Amazónico | iNaturalist; photo examined |
| Colombia | Putumayo | El Tigre | iNaturalist; photo examined |
| Colombia | Putumayo | Finca Mariposa | Calderon et al. 2023 |
| Colombia | Putumayo | Vereda Zarsal | Nogueira et al. 2019 |
| Ecuador | Esmeraldas | Canandé Biological Reserve | iNaturalist; photo examined |
| Ecuador | Esmeraldas | Esmeraldas* | Günther 1860 |
| Ecuador | Los Ríos | Centro Científico Río Palenque | MCZ R-149669; VertNet |
| Ecuador | Los Ríos | Hacienda Cerro Chico | MCZ 151577; VertNet |
| Ecuador | Los Ríos | Patricia Pilar, 4 km SW of | RMNH 50717 |
| Ecuador | Los Ríos | San Jacinto de Buena Fe | MCZ R-151577; VertNet |
| Ecuador | Morona Santiago | Chumbela | Nogueira et al. 2019 |
| Ecuador | Morona Santiago | Comunidad Amazonas | iNaturalist; photo examined |
| Ecuador | Morona Santiago | Macas | AMNH 28831; examined |
| Ecuador | Morona Santiago | Macuma | iNaturalist; photo examined |
| Ecuador | Morona Santiago | Normandía | AMNH 23270; examined |
| Ecuador | Morona Santiago | Río Yaupi | Nogueira et al. 2019 |
| Ecuador | Morona Santiago | Soldado Monge | iNaturalist; photo examined |
| Ecuador | Morona Santiago | Turula | AMNH 35963; examined |
| Ecuador | Napo | Ahuano | iNaturalist; photo examined |
| Ecuador | Napo | Chontapunta | iNaturalist; photo examined |
| Ecuador | Napo | El Bombón | KU 121880; VertNet |
| Ecuador | Napo | El Carmen, 3 km SE of | iNaturalist; photo examined |
| Ecuador | Napo | Jatun Sacha Biological Station | Hernández-Sánchez 2013 |
| Ecuador | Napo | Reserva Río Bigai | This work; Fig. 1 |
| Ecuador | Napo | Río Suno | Nogueira et al. 2019 |
| Ecuador | Napo | Tena | iNaturalist; photo examined |
| Ecuador | Orellana | Ávila | Nogueira et al. 2019 |
| Ecuador | Orellana | Florencia | Nogueira et al. 2019 |
| Ecuador | Orellana | Loreto | Nogueira et al. 2019 |
| Ecuador | Orellana | Napo Wildlife Center | This work; Fig. 1 |
| Ecuador | Orellana | Pozo Nashiño | AMNH 57344; examined |
| Ecuador | Orellana | Primavera | MHNG 2398.009; collection database |
| Ecuador | Orellana | San Jose de Dahuano | UMMZ 92043; VertNet |
| Ecuador | Orellana | Tiputini Biodiversity Station | Reptiles of Ecuador book database |
| Ecuador | Orellana | Yarina Lodge | iNaturalist; photo examined |
| Ecuador | Orellana | Yasuní Scientific Station | Nogueira et al. 2019 |
| Ecuador | Pastaza | Chontoa | KU 121333; VertNet |
| Ecuador | Pastaza | Conambo | Ortega-Andrade 2010 |
| Ecuador | Pastaza | Copataza | Nogueira et al. 2019 |
| Ecuador | Pastaza | Indillama | KU 121333; VertNet |
| Ecuador | Pastaza | Montalvo | Nogueira et al. 2019 |
| Ecuador | Pastaza | Río Maritayacu | Nogueira et al. 2019 |
| Ecuador | Pastaza | Río Tigre | USNM 204121; VertNet |
| Ecuador | Pastaza | Santana | Nogueira et al. 2019 |
| Ecuador | Pastaza | Sarayacu | USNM 204124; VertNet |
| Ecuador | Pastaza | Shell | Nogueira et al. 2019 |
| Ecuador | Pastaza | Simón Bolívar | SMF 90955; VertNet |
| Ecuador | Pastaza | Tambo | Nogueira et al. 2019 |
| Ecuador | Pastaza | Vía Puyo–Tena | Nogueira et al. 2019 |
| Ecuador | Pichincha | Puerto Quito | MHNG 2250.050; collection database |
| Ecuador | Pichincha | Reserva Mashpi Shungo | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Cooperativa Río Orienco | iNaturalist; photo examined |
| Ecuador | Sucumbíos | El Reventador | MHNG 2398.008; collection database |
| Ecuador | Sucumbíos | Hostería La Selva | Nogueira et al. 2019 |
| Ecuador | Sucumbíos | Limoncocha Biological Reserve | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Lumbaqui, 15 km ENE of | KU 121878; VertNet |
| Ecuador | Sucumbíos | Puerto Libre | Nogueira et al. 2019 |
| Ecuador | Sucumbíos | Reserva Cuyabeno | Nogueira et al. 2019 |
| Ecuador | Sucumbíos | Río Auca–Yaco | Nogueira et al. 2019 |
| Ecuador | Sucumbíos | San Pablo de Kantesiya | MHNG 2306.011; collection database |
| Ecuador | Sucumbíos | Santa Cecilia | Duellman 1978 |
| Ecuador | Zamora Chinchipe | Río Zamora | UMMZ 82892; VertNet |
| Ecuador | Zamora Chinchipe | Subcuenca del Río Tundayme | Betancourt et al. 2018 |
| Peru | Amazonas | Río Cenepa | MVZ 163272; VertNet |
| Peru | Loreto | Andoas | Nogueira et al. 2019 |