Published February 1, 2021. Updated January 27, 2024. Open access.

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Ángel Whorltail-Iguana (Stenocercus angel)

Reptiles of Ecuador | Sauria | Tropiduridae | Stenocercus angel

English common name: Ángel Whorltail-Iguana.

Spanish common names: Guagsa del Ángel, lagarto arcoiris de montaña.

Recognition: ♂♂ 21.4 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=8.7 cm. ♀♀ 15.5 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=7.6 cm..1,2 Stenocercus angel differs from other lizards in its area of distribution by being larger and having keeled dorsal scales with pointed ends.3 This species is similar to S. guentheri, which can be identified by having a black gular patch (absent in S. angel).1 Stenocercus chota also occurs near the known distribution of S. angel, but males of this other species have a black mid-ventral longitudinal line and females and juveniles have black blotches in the gular region.1 Furthermore, S. chota has a brown or grayish dorsal coloration (greenish in S. angel).2 Males of S. angel differ from females by being larger, more brightly colored, and having a raised middorsal crest (Fig. 1).2

Figure showing variation among individuals of Stenocercus angel

Figure 1: Individuals of Stenocercus angel from Páramo del Ángel, Carchi province, Ecuador. j=juvenile.

Natural history: Stenocercus angel is a rarely seen lizard that inhabits high evergreen montane forests, humid montane shrublands, Espeletia-dominated páramos, and highland grasslands.4,5 The species prefers areas with little degree of disturbance but may as well occur at the edge of cultivated fields and pastures.6 These lizards need extended periods of direct sunlight hitting the ground in order to become active. During sunny days, when the ambient temperature is above 5°C,4 Ángel Whorltail-Iguanas bask on the ground or on Espeletia shrubs, usually near terrestrial spiny bromeliads or tall grass, which they use as shelter.1,4,6 If captured, individuals may shed the tail or bite as a method of defense and escape.6 Males of S. angel are territorial and defend areas around burrows in the ground.4 Females lay clutches of two eggs.1,4

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Conservation: Vulnerable Considered to be facing a high risk of extinction in the mid-term future..7 Stenocercus angel is listed in this category, instead of Near Threatened,5 because the species meets the following IUCN Redlist8 criteria: the species’ extent of occurrence is estimated to be less than 20,000 km2, its habitat is severely fragmented, and there is continuing decline in the extent and quality of the ecosystems where it occurs. It is estimated9,10 that ~41% of the habitat of S. angel has been lost due to the expansion of the agricultural frontier and wildfires in the páramos.6 Additionally, the species occurs as fragmented populations and mostly outside protected areas, with the exception of El Ángel Ecological Reserve, Guandera Reserve, and La Bretaña Reserve. Under current scenarios of climate change, it is likely that some populations will become extinct, similar to what has been predicted for S. guentheri.11

Distribution: Stenocercus angel is native to the high Andes of southern Colombia and northern Ecuador in the upper drainage systems of the Aguarico (Atlantic drainage) and the Mira (Pacific drainage) rivers (Fig. 2).

Distribution of Stenocercus angel in Ecuador

Figure 2: Distribution of Stenocercus angel in Ecuador. The star corresponds to the type locality: El Ángel, Carchi province. See Appendix 1 for a complete list of the presence localities included in the map.

Etymology: The generic name Stenocercus, which comes from the Greek words stenos (=narrow) and kerkos (=tail), refers to the laterally-compressed tail in some members of this genus, which contrasts with the dorsally flattened tail of other Tropiduridae.12 The specific epithet angel refers to the Páramo del Ángel, where the species was found initially.1

See it in the wild: Ángel Whorltail-Iguanas can be spotted at a rate of about once every few days at El Ángel Ecological Reserve, but only during warm sunny days.

Acknowledgments: Special thanks to Frank Pichardo and Harry Turner for locating the specimens of Stenocercus angel photographed in this account.

Authors: Amanda QuezadaaAffiliation: Tropical Herping (TH), Quito, Ecuador.,bAffiliation: Laboratorio de Herpetología, Universidad del Azuay, Cuenca, Ecuador. and Alejandro ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador.

Photographer: Jose VieiraaAffiliation: Tropical Herping (TH), Quito, Ecuador.,cAffiliation: ExSitu, Quito, Ecuador.

How to cite? Quezada A, Arteaga A (2024) Ángel Whorltail-Iguana (Stenocercus angel). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/FMJO4408

Literature cited:

  1. Torres-Carvajal O (2000) Ecuadorian lizards of the genus Stenocercus (Squamata: Tropiduridae). Scientific Papers Natural History Museum, The University of Kansas 15: 1–38. DOI: 10.5962/bhl.title.16286
  2. Torres-Carvajal O (2007) A taxonomic revision of South American Stenocercus (Squamata: iguania) lizards. Herpetological Monographs 21: 76–178. DOI: 10.1655/06-001.1
  3. Peters JA, Donoso-Barros R (1970) Catalogue of the Neotropical Squamata: part II, lizards and amphisbaenians. Bulletin of the United States National Museum, Washington, D.C., 293 pp.
  4. Castro-Herrera F, Granados-Díaz H (1993) Distribución de Stenocercus guentheri (Sauria: Iguanidae) en el sur de los Andes de Colombia. Caldasia 17: 295–300.
  5. Cisneros-Heredia DF (2016) Stenocercus angel. The IUCN Red List of threatened species. Available from: DOI: 10.2305/IUCN.UK.2016-1.RLTS.T48616468A48616481.en
  6. Field notes, Reptiles of Ecuador book project.
  7. Carrillo E, Aldás A, Altamirano M, Ayala F, Cisneros-Heredia DF, Endara A, Márquez C, Morales M, Nogales F, Salvador P, Torres ML, Valencia J, Villamarín F, Yánez-Muñoz M, Zárate P (2005) Lista roja de los reptiles del Ecuador. Fundación Novum Millenium, Quito, 46 pp.
  8. IUCN (2001) IUCN Red List categories and criteria: Version 3.1. IUCN Species Survival Commission, Gland and Cambridge, 30 pp.
  9. MAE (2012) Línea base de deforestación del Ecuador continental. Ministerio del Ambiente del Ecuador, Quito, 30 pp.
  10. IDEAM (2014) Mapa de cobertura de la tierra adaptada para Colombia.
  11. Andrango MB, Sette C, Torres-Carvajal O (2016) Short-term predicted extinction of Andean populations of the lizard Stenocercus guentheri (Iguanidae: Tropidurinae). Journal of Thermal Biology 62: 30–36. DOI: 10.1016/j.jtherbio.2016.09.012
  12. Duméril AMC, Bibron G (1837) Erpétologie générale ou Histoire Naturelle complète des Reptiles. Librairie Encyclopédique de Roret, Paris, 571 pp. DOI: 10.5962/bhl.title.45973

Appendix 1: Locality data used to create the distribution map of Stenocercus angel in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used. Asterisk (*) indicates type locality.

ColombiaCaucaHacienda CorralejasAyerbe et al. 2007
ColombiaCaucaHacienda Las GuacasAyerbe et al. 2007
ColombiaCaucaMalvasáCastro-Herrera & Granados-Díaz 1993
ColombiaCaucaPuracéAyerbe et al. 2007
ColombiaCaucaSotaráAyerbe et al. 2007
ColombiaCaucaToma del SantoAyerbe et al. 2007
ColombiaNariñoContaderoiNaturalist; photo examined
ColombiaNariñoCumbalTorres-Carvajal 2007
ColombiaNariñoFunesTorres-Carvajal 2007
ColombiaNariñoHuecada del VergelAyerbe et al. 2007
ColombiaNariñoIpialesiNaturalist; photo examined
ColombiaNariñoLa PalmaiNaturalist; photo examined
ColombiaNariñoPáramo de Paja BlancaiNaturalist; photo examined
ColombiaNariñoPáramo del ChilesBolaños 2009
ColombiaNariñoPastoTorres-Carvajal 2007
ColombiaNariñoPilcuan ViejoiNaturalist; photo examined
ColombiaNariñoQuebrada de RamosCalderón et al. 2023
ColombiaNariñoSanta RosaTorres-Carvajal 2007
ColombiaNariñoSector Las JuntasBorja-Acosta & Galeano 2024
ColombiaNariñoTanguaTorres-Carvajal 2007
ColombiaNariñoTúquerresiNaturalist; photo examined
EcuadorCarchi13.6 km vía Tulcán-Tufino Torres-Carvajal 2000
EcuadorCarchiBolívariNaturalist; photo examined
EcuadorCarchiBosque Los EncinosYánez-Muñóz 2003
EcuadorCarchiCocha SecaTorres-Carvajal 2007
EcuadorCarchiCordillera de la Virgen NegraYánez-Muñoz 2005
EcuadorCarchiEl ÁngelTorres-Carvajal 2007
EcuadorCarchiEl Angel vía a Tulcan Torres-Carvajal 2000
EcuadorCarchiEl Ángel, 1.6 km N ofTorres-Carvajal 2000
EcuadorCarchiEl Ángel, 8 km N of*Torres-Carvajal 2000
EcuadorCarchiEl CarmeloTorres-Carvajal 2007
EcuadorCarchiEl FrailejónReptiles of Ecuador book database
EcuadorCarchiEl PunTorres-Carvajal 2007
EcuadorCarchiEstación Biológica GuanderaTorres-Carvajal 2007
EcuadorCarchiLa Libertad, 6.7 km NW ofReptiles of Ecuador book database
EcuadorCarchiMonte RedondoAlmendáriz & Orcés 2004
EcuadorCarchiPáramo del ArtesónYánez-Muñoz 2005
EcuadorCarchiReserva Ecológica El ÁngelThis work; Fig. 1
EcuadorCarchiReserva La BretañaReptiles of Ecuador book database
EcuadorCarchiTulcániNaturalist; photo examined
EcuadorImbaburaPimampiroiNaturalist; photo examined
EcuadorSucumbíosCaldera del Páramo MiradorTorres-Carvajal 2007
EcuadorSucumbíosLaguna NegraVriesendorp et al. 2009
EcuadorSucumbíosPlayón de San Francisco Torres-Carvajal 2000
EcuadorSucumbíosPlayón de San Francisco, 1 km E ofTorres-Carvajal 2007