Published February 1, 2021. Open access.

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Ángel Whorltail-Iguana (Stenocercus angel)

Reptiles of Ecuador | Sauria | Tropiduridae | Stenocercus | 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 The Ángel Whorltail-Iguana (Stenocercus angel) differs from other lizards in its area of distribution by being larger and having keeled dorsal scales with pointed ends.3 Other co-occurring lizards are small, fossorial species in the genera Pholidobolus and Riama. Stenocercus guentheri is similar to S. angel, but it occurs south of the distribution of the latter and males of this species have a black gular patch (absent in S. angel).1 Another lizard, S. 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 (these features are absent in S. angel).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.2

Figure showing variation among individuals of Stenocercus angel

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

Natural history: UncommonUnlikely to be seen more than once every few months.. Stenocercus angel 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

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 of S. angel 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.1,2 The species occur at elevations between 1841 and 3651 m (Fig. 2).

Distribution of Stenocercus angel in Ecuador

Figure 2: Distribution of Stenocercus angel in Ecuador. 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 (meaning “narrow”) and kerkos (meaning “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 are not easily observed in the wild. There is only a ~3–5% certainty of spotting an individual even in protected areas like El Ángel Ecological Reserve. One way to increase the probability of observing lizards of this species is by walking along the border between cultivated fields and grasslands during hot sunny hours.

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: Biodiversity Field Lab, Khamai Foundation, Quito, Ecuador.

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

How to cite? Quezada A, Arteaga A (2021) Ángel Whorltail-Iguana (Stenocercus angel). In: Arteaga A, Bustamante L, Vieira J, Guayasamin JM (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.

ColombiaNariñoCumbalTorres-Carvajal 2007
ColombiaNariñoFunesTorres-Carvajal 2007
ColombiaNariñoHuecada del VergelAyerbe et al. 2007
ColombiaNariñoPáramo de Paja BlancaiNaturalist
ColombiaNariñoPáramo del ChilesBolaños 2009
ColombiaNariñoPastoTorres-Carvajal 2007
ColombiaNariñoPilcuan ViejoiNaturalist
ColombiaNariñoQuebrada de RamosICN051646
ColombiaNariñoSanta RosaTorres-Carvajal 2007
ColombiaNariñoSector Las JuntasIAvH-R Temp-AAJ666
ColombiaNariñoTanguaTorres-Carvajal 2007
EcuadorCarchi13.6 km vía Tulcán-Tufino Torres-Carvajal 2000
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 CarmeloTorres-Carvajal 2007
EcuadorCarchiEl FrailejónThis work
EcuadorCarchiEl PunTorres-Carvajal 2007
EcuadorCarchiEl VoladeroMECN 2261
EcuadorCarchiEstación Biológica GuanderaTorres-Carvajal 2007
EcuadorCarchiLa Libertad, 6.7 km NW ofThis work
EcuadorCarchiMonte RedondoAlmendáriz & Orcés 2004
EcuadorCarchiPáramo del ArtesónYánez-Muñoz 2005
EcuadorCarchiReserva Ecológica El ÁngelThis work
EcuadorCarchiReserva La BretañaThis work
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