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Drab-headed Forest-Racer (Dendrophidion prolixum)
Reptiles of Ecuador | Serpentes | Colubridae | Dendrophidion prolixum
English common name: Drab-headed Forest-Racer.
Spanish common name: Corredora selvática cabeciparda.
Recognition: ♂♂ 100.7 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=65.0 cm. ♀♀ 113.8 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=67.5 cm..1 Dendrophidion prolixum can be identified by having conspicuously large eyes, keeled dorsal scales arranged in 17 rows at mid-body, and a brown dorsum (with pale crossbars in juveniles), but without a black nuchal collar (Fig. 1).1,2 This species differs from D. clarkii by lacking a black nuchal collar and dark crossbands with embedded pale ocelli.2,3 From D. graciliverpa, it differs by having a reddish brown head (instead of green) and a higher number of pale body bands (57–87 vs 49–57) in juveniles.1
Figure 1: Individuals of Dendrophidion prolixum: Morromico Reserve, Chocó department, Colombia (); Canandé Reserve, Esmeraldas province, Ecuador (). j=juvenile.
Natural history: Dendrophidion prolixum is a diurnal snake that inhabits old-growth rainforest, occurring in lower densities, or not at all, in semi-open areas.1,4 Snakes of this species are most often seen active at ground level, actively foraging on the leaf-litter.1,4 At night, they tend to roost on low (less than 70 cm above the ground) understory vegetation, but an individual was found hidden under a trash lid inside a rural house.4 Drab-headed Forest-Racers are active hunters having an aglyphous dentition (meaning their teeth lack specialized grooves to deliver venom).1 Forest racers in general are frog-eating specialists.5,6 Their main defense mechanism is to flee quickly, but they can also strike or shed-off parts of their tail.4
Conservation: Least Concern Believed to be safe from extinction given current circumstances..7 Dendrophidion prolixum is listed in this category because the species is widely distributed, especially in areas that have not been heavily affected by deforestation, like the Colombian Pacific coast, and it is unlikely to be declining fast enough to qualify for a more threatened category.7 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: Dendrophidion prolixum is widely distributed throughout the Chocoan lowlands of Ecuador (Fig. 2) and Colombia.
Figure 2: Distribution of Dendrophidion prolixum in Ecuador. See Appendix 1 for a complete list of the presence localities included in the map.
Etymology: The generic name Dendrophidion comes from the Greek words Dendron (=tree) and ophidion (=small snake).8 The specific epithet prolixum is derived from the Latin prolixus (=long) and is used in reference to the unusually long hemipenis of this species compared with most other Dendrophidion.1
See it in the wild: In Ecuador, the majority of records of Dendrophidon prolixum come from Canandé Biological Reserve, where the species is spotted at a rate of about once every few weeks. These snakes, though diurnal, are most easily spotted sleeping on low vegetation along forest trails at night.
Author: Alejandro ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador.
Photographer: Jose VieirabAffiliation: Tropical Herping (TH), Quito, Ecuador.,cAffiliation: ExSitu, Quito, Ecuador.
How to cite? Arteaga A (2024) Drab-headed Forest-Racer (Dendrophidion prolixum). 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/ATQT9112
Literature cited:
- Cadle JE (2012) Systematics of the Neotropical snake Dendrophidion percarinatum (Serpentes: Colubridae), with descriptions of two new species from western Colombia and Ecuador and supplementary data on Dendrophidion brunneum. Bulletin of the Museum of Comparative Zoology 160: 259–344. DOI: 10.3099/0027-4100-160.6.259
- Arteaga A, Bustamante L, Guayasamin JM (2013) The amphibians and reptiles of Mindo. Universidad Tecnológica Indoamérica, Quito, 257 pp.
- Cadle JE, Savage JM (2012) Systematics of the Dendrophidion nuchale complex (Serpentes: Colubridae) with the description of a new species from Central America. Zootaxa 3513: 1–50. DOI: 10.11646/zootaxa.3513.1.1
- Field notes, Reptiles of Ecuador book project.
- Da Costa Prudente AL, Maschio GF, Yamashina CE, Santos-Costa MC (2007) Morphology, reproductive biology and diet of Dendrophidion dendrophis (Schlegel, 1837) (Serpentes, Colubridae) in Brazilian Amazon. South American Journal of Herpetology 2: 53–58.
- Cadle JE (2010) Systematics, natural history, and hemipenial morphology of Dendrophidion brunneum (Günther) (Serpentes: Colubridae), a poorly known snake from the Andes of Ecuador and Peru. Zootaxa 2433: 1–24. DOI: 10.11646/zootaxa.2433.1.1
- Bolívar W, Gutiérrez-Cárdenas P, Castañeda MR, Velasco J (2016) Dendrophidion prolixum. The IUCN Red List of threatened species. Available from: www.iucnredlist.org. DOI: 10.2305/IUCN.UK.2022-1.RLTS.T48328975A217808225.en
Appendix 1: Locality data used to create the distribution map of Dendrophidion prolixum 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 | Cauca | Quebrada Guanguí* | Cadle 2012 |
| Colombia | Chocó | Río Buey | Cadle 2012 |
| Colombia | Nariño | Quebrada El Muerto | Photo by Juan Pablo Guerrero |
| Colombia | Nariño | Reserva Natural El Pangán | iNaturalist; photo examined |
| Colombia | Nariño | Ricaurte | Cadle 2012 |
| Colombia | Risaralda | Between Pueblo Rico and Santa Cecilia | Cadle 2012 |
| Colombia | Valle del Cauca | Río Raposo | Cadle 2012 |
| Ecuador | Carchi | Chical | Guerra-Correa 2020 |
| Ecuador | Carchi | Chinambí | Photo by Andreas Kay |
| Ecuador | Esmeraldas | Canandé Reserve | This work; Fig. 1 |
| Ecuador | Esmeraldas | Gualpi | Reptiles of Ecuador book database |
| Ecuador | Esmeraldas | Itapoa Reserve | Photo by Raúl Nieto |
| Ecuador | Esmeraldas | La Mayronga | Torres-Carvajal et al. 2019 |
| Ecuador | Esmeraldas | Lote Rosero | Reptiles of Ecuador book database |
| Ecuador | Esmeraldas | Playa de Oro | Cadle 2012 |
| Ecuador | Esmeraldas | Río Cachabi | Cadle 2012 |
| Ecuador | Esmeraldas | San Javier de Cachabí | Cadle 2012 |
| Ecuador | Esmeraldas | Tundaloma Lodge | Reptiles of Ecuador book database |
| Ecuador | Imbabura | Intag | Cadle 2012 |
| Ecuador | Imbabura | La Casa de Chavi | iNaturalist; photo examined |
| Ecuador | Imbabura | Lita | Cadle 2012 |
| Ecuador | Imbabura | Paramba | Cadle 2012 |
| Ecuador | Imbabura | Sendero hacia Los Cedros | iNaturalist; photo examined |
| Ecuador | Pichincha | Hacienda Yellow House | iNaturalist; photo examined |
| Ecuador | Pichincha | Milpe Bird Sanctuary | iNaturalist; photo examined |
| Ecuador | Pichincha | Terreno de Eric Osterman en Mindo | Reptiles of Ecuador book database |
| Ecuador | Santo Domingo de los Tsáchilas | Otongachi Reserve | iNaturalist; photo examined |