Published February 2, 2024. Open access.

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Amazonian Puffing-Snake (Phrynonax sexcarinatus)

Reptiles of Ecuador | Serpentes | Colubridae | Phrynonax sexcarinatus

English common name: Amazonian Puffing-Snake.

Spanish common name: Culebra silbadora amazónica, .

Recognition: ♂♂ 152.7 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=112.8 cm. ♀♀ 180.6 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=120 cm..13 Phrynonax sexcarinatus differs from other large diurnal snakes in Amazonian Ecuador by having dorsal scales arranged in 21–23 rows at mid-body, with the 3–6 median rows being feebly keeled.14 The iris pattern is diagnostic: mottled silvery with a dark median stripe.5 The coloration in this species changes throughout the organism’s lifespan. In juveniles, the dorsum is light brown with dark reddish brown crossbars and a contrasting postocular stripe.1,2 In adults, the dorsal coloration becomes uniformly brown (Fig. 1). This species can be confused with Spilotes sulphureus, but in the latter the dorsal scales are all strongly keeled and arranged in 19 rows at mid-body.6

Figure showing variation among individuals of Phrynonax sexcarinatus

Figure 1: Individuals of Phrynonax sexcarinatus: Jatun Sacha Biological Reserve, Napo province, Ecuador (); Napo Wildlife Center, Orellana province, Ecuador (); Leticia, Amazonas state, Colombia (). j=juvenile.

Natural history: Phrynonax sexcarinatus is a semi-arboreal snake that occurs in the rainforest floor as well as on shrubs and trees.3,7 These snakes are usually seen active on semi-open areas during sunny days.8 At night, they roost on shrubs 1.8–3.5 m above the ground.7 Puffing snakes are active hunters having an aglyphous dentition, meaning their teeth lack specialized grooves to deliver venom. The diet in P. sexcarinatus consists primarily on birds and their eggs,3,9 but also includes lizards and small mammals.7,10,11 Juveniles are insectivorous, feeding on beetles, moths, and grasshoppers.10 Gravid females have been found to contain 11 eggs,5 but the real clutch size is not known. Puffing snakes are known for their defense behavior. When threatened, they keep the anterior half of the body elevated in an “S” shape, while compressing it laterally and inflating the neck.8 With the mouth open, they produce a hissing sound and strike the observer.7,8

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Conservation: Least Concern Believed to be safe from extinction given current circumstances..12 Phrynonax sexcarinatus is listed in this category primarily on the basis of the species’ wide distribution, presence in protected areas, and adaptability to habitat modification provided there is tree cover remaining.12 The most important threat to some populations is deforestation and habitat fragmentation caused by large-scale cattle ranching and the creation of new roads. The survival of this arboreal snake is contingent upon the availability of trees, as they serve both as protective cover against predators and as a source of forage. Lastly, Amazonian Puffing-Snakes are usually killed on sight, as they are perceived to be dangerous.

Distribution: Phrynonax sexcarinatus is widely distributed throughout the Amazon basin of Bolivia, Brazil, Colombia, Ecuador (Fig. 2), French Guiana, Guyana, Peru, Suriname, and Venezuela. The species also occurs in Trinidad Island.

Distribution of Phrynonax sexcarinatus in Ecuador

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

Etymology: The generic name Phrynonax comes from the Greek words phryne (=toad) and anax (=king),13 and roughly translates to “master of the toads.” The specific name sexcarinatus comes from the Latin words sex (=six) and carinatus (=keeled),13 and refers to the number of keeled dorsal scale rows.

See it in the wild: Amazonian Puffing-Snakes are seen at a rate of about once every few weeks in forested localities throughout their area of distribution in Ecuador. These snakes are frequently sighted at Finca Heimatlos and Jatun Sacha Biological Reserve.

Authors: Gabriela SandovalaAffiliation: Pontificia Universidad Católica del Ecuador, Quito, Ecuador. and Alejandro ArteagabAffiliation: Khamai Foundation, Quito, Ecuador.

Photographers: Jose VieiracAffiliation: Tropical Herping (TH), Quito, Ecuador.,dAffiliation: ExSitu, Quito, Ecuador. and Sebastián Di DoménicoeAffiliation: Keeping Nature, Bogotá, Colombia.

How to cite? Sandoval G, Arteaga A (2024) Amazonian Puffing-Snake (Phrynonax sexcarinatus). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/YWAK9120

Literature cited:

  1. de Fraga R, Lima AP, da Costa Prudente AL, Magnusson WE (2013) Guia de cobras da região de Manaus - Amazônia Central. Editopa Inpa, Manaus, 303 pp.
  2. Lopes LV, Passos P (2023) Taxonomic status of the enigmatic Natrix sexcarinata Wagler, 1824 (Serpentes: Colubridae: Colubrinae). Zootaxa 5244: 123–144. DOI: 10.11646/zootaxa.5244.2.2
  3. Dixon JR, Soini P (1986) The reptiles of the upper Amazon Basin, Iquitos region, Peru. Milwaukee Public Museum, Milwaukee, 154 pp.
  4. Natera-Mumaw M, Esqueda-González LF, Castelaín-Fernández M (2015) Atlas serpientes de Venezuela. Dimacofi Negocios Avanzados S.A., Santiago de Chile, 456 pp.
  5. Beebe W (1946) Field notes on the snakes of Kartabo, British Guiana, and Caripito, Venezuela. Zoologica 31: 11–52.
  6. 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.
  7. Martins M, Oliveira ME (1998) Natural history of snakes in forests of the Manaus region, Central Amazonia, Brazil. Herpetological Natural History 6: 78–150.
  8. Field notes, Reptiles of Ecuador book project.
  9. Angulo F, Chávez G (2017) First report of predation on Speckled Chachalaca (Ortalis guttata) eggs by Puffing Snake (Phrynonax polylepis) in Central Peru. Boletín UNOP 12: 27–33.
  10. Cisneros-Heredia DF (2005) Pseustes poecilonotus and Pseustes shropshirei (Puffing Snakes): diet. Herpetological Review 36: 326–327.
  11. Cunha OR, Nascimento FP (1993) Ofídios da Amazônia. As cobras da região leste do Pará. Papéis Avulsos Museu Paraense Emílio Goeldi 40: 9–87.
  12. Murphy J (2021) Phrynonax polylepis. The IUCN Red List of threatened species. Available from: DOI: 10.2305/IUCN.UK.2021-3.RLTS.T64003414A64003426.en
  13. 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 Phrynonax sexcarinatus in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used.

ColombiaPutumayoOrito, 20 km W ofiNaturalist; photo examined
ColombiaPutumayoResguardo Indígena HuitoraRuiz Valderrama 2023
EcuadorMorona SantiagoLogroño, 4.6 km S ofJadin et al. 2014
EcuadorMorona SantiagoMacuma, 2.2 km E ofiNaturalist; photo examined
EcuadorMorona SantiagoMacuma, 2.8 km E ofiNaturalist; photo examined
EcuadorMorona SantiagoMacuma, 8.5 km N ofiNaturalist; photo examined
EcuadorMorona SantiagoPuerto Morona, 8 km W ofPazmiño-Otamendi 2020
EcuadorMorona SantiagoSua Entza, 9 km S ofiNaturalist; photo examined
EcuadorMorona SantiagoSucúaMZUA.Re.0047; examined
EcuadorNapoAhuano, 3.3 km SE ofiNaturalist; photo examined
EcuadorNapoAmaZOOnicoiNaturalist; photo examined
EcuadorNapoAnaconda LodgeNogueira et al. 2019
EcuadorNapoArchidona, 7.3 km E ofiNaturalist; photo examined
EcuadorNapoHuella Verde LodgeReptiles of Ecuador book database
EcuadorNapoIkiam UniversityiNaturalist; photo examined
EcuadorNapoJatun Sacha Biological StationReptiles of Ecuador book database
EcuadorNapoMisahuallíNogueira et al. 2019
EcuadorNapoPuente sobre el río UchuculinNogueira et al. 2019
EcuadorNapoRío PirañaNogueira et al. 2019
EcuadorNapoYachana ReserveWhitworth & Beirne 2011
EcuadorOrellana24 de MayoiNaturalist; photo examined
EcuadorOrellanaÁvila ViejoNogueira et al. 2019
EcuadorOrellanaEstación PUCE, 7.8 km N ofiNaturalist; photo examined
EcuadorOrellanaLoretoNogueira et al. 2019
EcuadorOrellanaPozo Petrolero Amo A-2Nogueira et al. 2019
EcuadorOrellanaPozo Petrolero Daimi INogueira et al. 2019
EcuadorOrellanaRío PayaminoFHGO 0192; VertNet
EcuadorOrellanaSan José de Suno, 7.2 km SE ofiNaturalist; photo examined
EcuadorOrellanaTiputini AirportiNaturalist; photo examined
EcuadorOrellanaTiputini Biodiversity StationiNaturalist; photo examined
EcuadorOrellanaVía Pompeya Sur–Iro, km 46Nogueira et al. 2019
EcuadorOrellanaYasuní Scientific StationReptiles of Ecuador book database
EcuadorPastazaAndoasNogueira et al. 2019
EcuadorPastazaAnga CochaNogueira et al. 2019
EcuadorPastazaChichirotaNogueira et al. 2019
EcuadorPastazaComunidad Santa CeciliaReptiles of Ecuador book database
EcuadorPastazaDiez de agosto, 3.6 km E ofUSNM 204172; VertNet
EcuadorPastazaFinca HeimatlosiNaturalist; photo examined
EcuadorPastazaMontalvoOrtega-Andrade 2010
EcuadorPastazaMontalvo, 5 km E ofUSNM 204167; VertNet
EcuadorPastazaMoretecocha, 11 km N ofUSNM 204174; VertNet
EcuadorPastazaRío CopatazaNogueira et al. 2019
EcuadorPastazaRío CotapinoNogueira et al. 2019
EcuadorPastazaRío TigreUSNM 204170; VertNet
EcuadorPastazaSarayacuNogueira et al. 2019
EcuadorPastazaSarayacu, 34 km SE ofUSNM 204175; VertNet
EcuadorPastazaTeresa Mama, 1.7 km S ofNMNH 204165; VertNet
EcuadorPastazaVía a CanelosReptiles of Ecuador book database
EcuadorPastazaVillanoNogueira et al. 2019
EcuadorSucumbíosBosque Protector AguaricoNogueira et al. 2019
EcuadorSucumbíosEl Dorado de Cascales, 7.7 km W ofiNaturalist; photo examined
EcuadorSucumbíosEstación PUCE en CuyabenoNogueira et al. 2019
EcuadorSucumbíosLago AgrioPhoto by Ernesto Arbeláez
EcuadorSucumbíosLimoncochaLSUMZ 37929; VertNet
EcuadorSucumbíosLumbaqui, 1.6 km W ofUTA-R 65493; VertNet
EcuadorSucumbíosNapo Wildlife CenterReptiles of Ecuador book database
EcuadorZamora ChinchipeEl Pangui, 6.8 km N ofiNaturalist; photo examined
EcuadorZamora ChinchipeReserva MaycuPazmiño-Otamendi 2020
EcuadorZamora ChinchipeTundayme, 3.7 km E ofMUTPL 395; GBIF
PeruAmazonasHuampamiMVZ 163310; VertNet
PeruAmazonasZona Reservada Santiago Comaina, 10 km S ofUSNM 566605; VertNet
PeruLoretoAndoas, 8.8 km N ofUSNM 204176; VertNet
PeruLoretoIquitosSDNHM 64407; VertNet
PeruLoretoManití, 7 km N ofMPM 11266; VertNet
PeruLoretoMedio Putumayo–Río AlgodónChávez et al. 2016
PeruLoretoMishana, Rio NanayTCWC 42185; VertNet
PeruLoretoMoroponTCWC 44297; VertNet
PeruLoretoPebasCAS 12496; VertNet