Published August 9, 2023. Updated January 29, 2024. Open access. | Gallery ❯ |
Amazon Thornytail-Iguana (Uracentron flaviceps)
Reptiles of Ecuador | Sauria | Tropiduridae | Uracentron flaviceps
English common names: Amazon Thornytail Iguana, Tropical Thornytail Iguana.
Spanish common name: Trepatroncos espinoso.
Recognition: ♂♂ 19.2 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=13.0 cm. ♀♀ 13.1 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=9.6 cm..1–3 The Amazon Thornytail Iguana (Uracentron flaviceps) is unmistakable among lizards in the Ecuadorian Amazon by having a flat leaf-like tail with whorls of spinose scales.1 The dorsal scales are small, imbricate, and strongly keeled.1 The coloration is also unmistakable. Dominant adult males are almost entirely blackish with minute yellowish or orangish spots, a pale yellow nuchal band (present depending on the population), and a broad orange head with black spots.1–4 Females and juveniles have a greenish head, collar, and abundant green or cream pigment on the anterior half of the body (Fig. 1).1,2 The only similar Ecuadorian lizard in shape and coloration is Plica plica, but the tail in this reptile is long and thin.2–4
Figure 1: Individuals of Uracentron flaviceps from Ecuador: Cuyabeno Reserve, Sucumbíos province (); Yasuní National Park, Orellana province (). j=juvenile.
Natural history: Uracentron flaviceps is a strictly arboreal lizard that inhabits lowland seasonally-flooded forests and terra-firme forests.3–5 Though locally frequent, these lizards can be extremely difficult to observe given their occurrence in the upper rainforest strata, up to 40 m above the ground.6 Amazon Thornytail Iguanas are gregarious. They live in groups of 2–16 individuals in a single tree: one sexually mature adult male and one or more adult females and many juveniles.3,5 Additional adult males may be found in the same tree, but these have small testes and a subdued coloration.3 This species usually lives on the tallest trees and many individuals occupy the same hole as a nocturnal retreat.3,5 These iguanas are diurnal and can be active whenever the sun is out, but not during overcast days.3,7 The dominant males are usually the first to go out, an action that is followed by their survey of the territory. Active individuals of all age categories follow shortly and can be seen foraging and basking along the trunks and branches throughout the day. The diet of U. flaviceps is composed almost entirely on ants,7 but can also include beetles, flies, grasshoppers, and centipedes.2,4 When disturbed, individuals usually run across the trunks and disappear into tree holes.3 In flooded forests, they can also disappear below the water surface along the trunk, remaining up to three minutes submerged.6 Males defend their territories from non-resident males using visual displays. Females lay clutches of two eggs2 in communal nesting sites where 5–14 eggs may be found simoultaneously.2–6 Breeding seems to take place year around and the reproductive system is polygyny, with one male monopolizing access to all females.2,3,7
Conservation: Least Concern Believed to be safe from extinction given current circumstances..8 Uracentron flaviceps is listed in this category given its wide distribution, presumed stable populations, and presence in protected areas.8 Therefore, the species is considered to be facing no major immediate threats of extinction.8 However, since U. flaviceps is a strictly arboreal lizard, some populations are undoubtedly destined to disappear due to large-scale deforestation caused by the expansion of the agricultural frontier.
Distribution: Uracentron flaviceps is native to the upper Amazon basin of Brazil, Colombia, Ecuador (Fig. 2), and Peru.9
Figure 2: Distribution of Uracentron flaviceps in Ecuador. See Appendix 1 for a complete list of the presence localities included in the map.
Etymology: The generic name Uracentron comes from the Greek oura (=tail) and kentron (=spike),10 and refers to the unique tail architecture of this lizard. The specific epithet flaviceps is derived from the Latin words flavus (=yellow) and ceps (=head),10 and refers to the male coloration.
See it in the wild: Amazon Thornytail Iguanas can be seen almost every day on the emerging tree at the observation tower of Napo Wildlife Center. They are also comparatively common along the borders of Laguna Grande in Cuyabeno Reserve.
Special thanks to Suzana Lightman for symbolically adopting the Amazon Thornytail Iguana and helping bring the Reptiles of Ecuador book project to life.
Click here to adopt a species.
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) Amazon Thornytail-Iguana (Uracentron flaviceps). 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/QUKP3916
Literature cited:
- Etheridge R (1968) A review of the iguanid lizard genera Uracentron and Strobilurus. Bulletin of the British Museum (Natural History) 17: 47–64.
- Avila-Pires TCS (1995) Lizards of Brazilian Amazonia (Reptilia: Squamata). Zoologische Verhandelingen 299: 1–706.
- Vitt LJ, De la Torre S (1996) A research guide to the lizards of Cuyabeno. Pontificia Universidad Católica del Ecuador, Quito, 165 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.
- Dixon JR, Soini P (1986) The reptiles of the upper Amazon Basin, Iquitos region, Peru. Milwaukee Public Museum, Milwaukee, 154 pp.
- Field notes, Reptiles of Ecuador book project.
- Vitt LJ, Zani PA (1996) Ecology of the elusive tropical lizard Tropidurus [=Uracentron] flaviceps (Tropiduridae) in lowland rain forest of Ecuador. Herpetologica 52: 121–132.
- Avila-Pires TCS, Aparicio J, Moravec J, Perez P, Daza J, Cisneros-Heredia DF (2019) Uracentron flaviceps. The IUCN Red List of threatened species. Available from: www.iucnredlist.org. DOI: 10.2305/IUCN.UK.2019-2.RLTS.T44579982A44579991.en
- Ribeiro-Júnior MA (2015) Catalogue of distribution of lizards (Reptilia: Squamata) from the Brazilian Amazonia. I. Dactyloidae, Hoplocercidae, Iguanidae, Leiosauridae, Polychrotidae, Tropiduridae. Zootaxa 3983: 001–110. DOI: 10.11646/zootaxa.3983.1.1
- 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 Uracentron flaviceps in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used.
| Country | Province | Locality | Source |
| Colombia | Caquetá | Florencia | iNaturalist; photo examined |
| Colombia | Caquetá | San José del Fragua | iNaturalist; photo examined |
| Colombia | Putumayo | Puerto Leguízamo | ICN 2228; Calderón et al. 2023 |
| Colombia | Putumayo | Río Guamués | Etheridge 1968 |
| Colombia | Putumayo | Río Putumayo | Grant et al. 2023 |
| Ecuador | Morona Santiago | Macuma | iNaturalist; photo examined |
| Ecuador | Napo | Ahuano | Photo by Diego Piñán |
| Ecuador | Napo | Jatun Sacha Biological Reserve | Vigle 2008 |
| Ecuador | Orellana | Bloque 43, Campo ITT | Photo by María José Quiroz |
| Ecuador | Orellana | Comunidad Añangu | iNaturalist; photo examined |
| Ecuador | Orellana | El Coca | Ribeiro-Júnior 2015 |
| Ecuador | Orellana | Kawymeno | iNaturalist; photo examined |
| Ecuador | Orellana | Napo Wildlife Center | This work; Fig. 1 |
| Ecuador | Orellana | San José de Payamino | Maynard et al. 2017 |
| Ecuador | Orellana | Tiputini Biodiversity Station | Cisneros-Heredia 2003 |
| Ecuador | Pastaza | Balsaura | Ortega-Andrade 2010 |
| Ecuador | Pastaza | Cabeceras del Bobonaza | Ribeiro-Júnior 2015 |
| Ecuador | Pastaza | Cachiyacu | Ortega-Andrade 2010 |
| Ecuador | Pastaza | Canelos | Etheridge 1968 |
| Ecuador | Pastaza | Chichirota | CAS 16100; VertNet |
| Ecuador | Pastaza | Juyuintza | Ortega-Andrade 2010 |
| Ecuador | Pastaza | Río Copataza, mouth of | Avila-Pires 1995 |
| Ecuador | Pastaza | Río Lipuno | Ribeiro-Júnior 2015 |
| Ecuador | Pastaza | Río Pastaza | Etheridge 1968 |
| Ecuador | Pastaza | Río Pindo | USNM 201390; VertNet |
| Ecuador | Pastaza | Río Villano | iNaturalist; photo examined |
| Ecuador | Pastaza | Sarayacu | Etheridge 1968 |
| Ecuador | Pastaza | Tenevera | Photo by Dillon Anderson |
| Ecuador | Sucumbíos | Caiman Lodge | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Comunidad Zábalo | Cevallos Bustos 2010 |
| Ecuador | Sucumbíos | Cuyabeno | Reptiles of Ecuador book |
| Ecuador | Sucumbíos | Cuyabeno Reserve | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Lago Agrio | Duellman 1978 |
| Ecuador | Sucumbíos | Limoncocha Biological Reserve | Avila-Pires 1995 |
| Ecuador | Sucumbíos | Río Aguarico | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Santa Cecilia | Etheridge 1968 |
| Ecuador | Sucumbíos | Santa Elena | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Tarapoa | Ribeiro-Júnior 2015 |
| Peru | Amazonas | Huampami | MVZ 163072; VertNet |
| Peru | Amazonas | Río Caterpiza | MVZ 174844; VertNet |
| Peru | Loreto | Between Apaga and Nieva | Etheridge 1968 |
| Peru | Loreto | Misión de Sarayacu | Avila-Pires 1995 |
| Peru | Loreto | Moropon | TCWC 44573; VertNet |
| Peru | Loreto | Pongo de Maseriche | Etheridge 1968 |
| Peru | Loreto | Río Yubineto | Tapia del Águila et al. 2020 |
| Peru | Loreto | Yarina Cocha | Etheridge 1968 |