Published November 10, 2021. Updated January 28, 2024. Open access.

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Quito Whorltail-Iguana (Stenocercus guentheri)

Reptiles of Ecuador | Sauria | Tropiduridae | Stenocercus guentheri

English common names: Quito Whorltail-Iguana, Günther’s Whorltail Iguana.

Spanish common names: Guagsa de Quito, guagsa de Günther.

Recognition: ♂♂ 22.5 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=9.6 cm. ♀♀ 18.8 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=7.3 cm..1,2 Stenocercus guentheri differs from other lizards in its area of distribution (small, fossorial species in the genera Pholidobolus and Riama) by being larger and having keeled dorsal scales with pointed ends.3 The most similar whorltail-iguanas occurring nearby S. guentheri are S. angel and S. cadlei. However, these species occur north and south, respectively, of the known distribution of S. guentheri, and the males of these other lizards lack a black gular patch (patch present in most males of S. guentheri).4 The Quito Whorltail-Iguana can be differentiated from S. chota because males of the latter species lack a black gular patch and females have black blotches on the throat.2 Males of S. guentheri differ from females by being larger, more robust, and by generally having a more vivid color that includes a black throat patch (Fig. 1).2

Figure showing variation among individuals of Stenocercus guentheri

Figure 1: Individuals of Stenocercus guentheri from Ecuador: Tambopaxi Lodge, Cotopaxi pronvince (); Tabacundo, Pichincha province (). sa=subadult.

Natural history: Stenocercus guentheri inhabits dry and humid ecosystems in areas of evergreen montane forest, highland shrubland, and paramo. The species also occurs in human-modified environments such as rural gardens, plantations, pastures, and along roads.5,6 Quito Whorltail-Iguanas are diurnal and terrestrial. They forage on exposed soil, grass, and leaf-litter, and use stone walls, rocks, Agave plants, and shrubs less than 50 cm above the ground mainly for basking.5,7 These lizards are usually only active between 9:00 am and 3:30 pm during strongly sunny days,7 but they can also remain active during cloudy days.5,6 At night, individuals hide inside holes, crevices, or under rocks, but may also roost on shrubs or herbaceous vegetation up to 60 cm above the ground.7 Males occupy rocks and other elevated positions for basking and feeding while females tend to occupy the ground level.8 The diet of S. guentheri is composed primarily of arthropods, especially ants and beetles,9,10 but cannibalism has also been reported.9 Quito Whorltail-Iguanas are preyed upon by snakes (Erythrolamprus albiventris and Mastigodryas pulchriceps),11 the Andean Fox,12 and raptors such as the Carunculated Caracara (Phalcoboenus carunculatus)13 and hawks of the genus Parabuteo.7 When threatened, individuals seek refuge in holes, crevices, under rocks, or at the base of Agave and Stipa plants.8 If captured, they can bite or shed the tail.5 There is a record of a specimen with scoliosis, a malformation characterized by a sideways curvature of the spine.14 Stenocercus guentheri breeds throughout the year. Females lay clutches of two eggs per clutch2,8 and males defend territories by performing push-up displays and fighting with intruders.5

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Conservation: Vulnerable Considered to be facing a high risk of extinction in the mid-term future..15 Stenocercus guentheri is listed in this category instead of Least Concern,16 because although it is a common species that tolerates a moderate degree of habitat disturbance, it meets IUCN Red List criteria17 to be included in the threatened category: the species’ extent of occurrence is less than 5,000 km2, its habitat is severely fragmented, and there is continuing decline in the extent and quality of the ecosystems where it occurs. Based on maps of Ecuador’s vegetation cover published in 2012,18 no more than ~35% of the potential area of distribution of the species still holds native vegetation. Although S. guentheri is found in several protected areas (including Cotopaxi National Park, Cayambe-Coca National Park, Pululahua Geobotanical Reserve, Antisana Ecological Reserve, and Jerusalém Recreational Park), only 5.9% of the species’ total potential area of distribution is inside these areas. Since S. guentheri has a narrow thermal tolerance, it is expected that, as a result of rising ambient temperatures, 26.7% of populations will have a high risk of extinction by 2050.6

Distribution: Stenocercus guentheri is endemic to an area of approximately 4,266 km2 in the inter-Andean valleys and paramos of northern Ecuador (Fig. 2).

Distribution of Stenocercus guentheri in Ecuador

Figure 2: Distribution of Stenocercus guentheri in Ecuador. The star corresponds to the type locality: San Antonio de Pichincha. 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.19 The specific epithet guentheri honors Albert Günther (1830–1914), a German-born British zoologist, ichthyologist, and herpetologist, best known for his role as Keeper of Zoology at the Natural History Museum in London.

See it in the wild: Quito Whorltail-Iguanas can be seen with almost complete certainty in protected areas such as Cotopaxi National Park and Pululahua Geobotanical Reserve. The lizards are most easily observed during sunny days along rock walls and living fences in semi-open areas nearby remnants of native vegetation.

Author: Amanda QuezadaaAffiliation: Tropical Herping (TH), Quito, Ecuador.,bAffiliation: Laboratorio de Herpetología, Universidad del Azuay, Cuenca, Ecuador.

Editor: Alejandro ArteagacAffiliation: Khamai Foundation, Quito, Ecuador.

Photographers: Jose VieiraaAffiliation: Tropical Herping (TH), Quito, Ecuador.,dAffiliation: ExSitu, Quito, Ecuador. and Alejandro ArteagacAffiliation: Khamai Foundation, Quito, Ecuador.

How to cite? Quezada A (2024) Quito Whorltail-Iguana (Stenocercus guentheri). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/VIQX3499

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. Torres-Carvajal O, Mafla-Endara P (2013) A new cryptic species of Stenocercus (Squamata: Iguanidae) from the Andes of Ecuador. Journal of Herpetology 47: 184–190. DOI: 10.1670/11-211
  5. Field notes, Reptiles of Ecuador book project.
  6. Guerra-Correa ES, Merino-Viteri A, Andrango MB, Torres-Carvajal O (2020) Thermal biology of two tropical lizards from the Ecuadorian Andes and their vulnerability to climate change. PLoS ONE 15: e0228043. DOI: 10.1371/journal.pone.0228043
  7. Ramírez-Jaramillo SM, Bejarano-Muñoz P, Rodríguez-Badillo M, Yánez-Muñoz M (2015) Uso de perchas nocturnas por Stenocercus guentheri (Iguanidae: Tropidurinae) en dos ecosistemas del distrito metropolitano de Quito (Ecuador). Boletín de la Asociación Herpetológica Española 26: 29–32.
  8. Fritts TH (1974) A multivariate and evolutionary analysis of the Andean iguanid lizards of the genus Stenocercus. Memoirs of the San Diego Society of Natural History 7: 1–89.
  9. Carvajal-Campos A (2009) Reproducción y dieta de la lagartija andina Stenocercus guentheri (Squamata: Iguania) en el Bosque Protector Jersualém. BSc thesis, Pontificia Universidad Católica del Ecuador, 97 pp.
  10. Photo by Juan Carlos Ríos.
  11. Cadena-Ortiz H, Barahona A, Bahamonde-Vinueza D, Brito J (2017) Anecdotal predation events of some snakes in Ecuador. Herpetozoa 30: 93–96.
  12. Reina Moreno DS (2019) Componentes alimentarios en la dieta del lobo de páramo Lycalopex culpaeus en la plataforma del aeropuerto Mariscal Sucre, parroquia Tababela, Cantón Quito, Pichincha, Ecuador. Avances en Ciencias e Ingeniería 11: 444–451. DOI: 10.18272/aci.v11i2.828
  13. de Vries T (2008) Historia natural del curiquingue (Phalcoboenus carunculatus) en los páramos del Antisana y Cotopaxi del Ecuador. Ediciones de la Universidad Católica, Quito, 83 pp.
  14. Ramírez-Jaramillo SM (2018) Primer reporte de cifoescoliosis en Stenocercus guentheri (Iguania: Tropiduridae), Andes Norte de Ecuador. Cuadernos de Herpetología 32: 55–57. DOI: 10.31017/CdH.2018.(2017-33)
  15. Reyes-Puig C (2015) Un método integrativo para evaluar el estado de conservación de las especies y su aplicación a los reptiles del Ecuador. MSc thesis, Pontificia Universidad Católica del Ecuador, 73 pp.
  16. Cisneros-Heredia DF, Yánez-Muñoz M, Brito J, Reyes-Puig C (2017) Stenocercus guentheri. The IUCN Red List of threatened species. Available from: DOI: 10.2305/IUCN.UK.2017-2.RLTS.T44579900A44579911.en
  17. IUCN (2001) IUCN Red List categories and criteria: Version 3.1. IUCN Species Survival Commission, Gland and Cambridge, 30 pp.
  18. MAE (2012) Línea base de deforestación del Ecuador continental. Ministerio del Ambiente del Ecuador, Quito, 30 pp.
  19. 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 guentheri in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used. Asterisk (*) indicates type locality.

EcuadorCotopaxiCotopaxi National ParkiNaturalist; photo examined
EcuadorCotopaxiEntrance to Cotopaxi National ParkiNaturalist; photo examined
EcuadorCotopaxiQuebrada AgualongoiNaturalist; photo examined
EcuadorCotopaxiTambopaxi LodgeReptiles of Ecuador book database
EcuadorCotopaxiVolcán RumiñahuiiNaturalist; photo examined
EcuadorImbaburaAtuntaquiTorres-Carvajal 2007
EcuadorImbaburaAtuntaqui, 2 km NW ofiNaturalist; photo examined
EcuadorImbaburaCerro ImbaburaiNaturalist; photo examined
EcuadorImbaburaCotacachiReptiles of Ecuador book database
EcuadorImbaburaCotacachi, 2.5 km W ofiNaturalist; photo examined
EcuadorImbaburaHidroeléctrica AntiguaAyerbe et al. 2007
EcuadorImbaburaIbarra, 5 km S ofKU 134562; VertNet
EcuadorImbaburaIbarra, El TejariNaturalist; photo examined
EcuadorImbaburaIbarra, La MercedMCZ R-8069; VertNet
EcuadorImbaburaLaguna de CuicochaiNaturalist; photo examined
EcuadorImbaburaLagunas de MojandaTorres-Carvajal 2007
EcuadorImbaburaOtavaloKU 134555; VertNet
EcuadorImbaburaOtavalo, 7.5 km N ofTorres-Carvajal 2007
EcuadorImbaburaSan Juan de Ilumán, 2 km E ofiNaturalist; photo examined
EcuadorImbaburaSan Pablo del LagoAndrango et al. 2016
EcuadorImbaburaSan RoqueiNaturalist; photo examined
EcuadorImbaburaTerreno familia MoralesReptiles of Ecuador book database
EcuadorImbaburaUrcuquí, 6.8 km W ofiNaturalist; photo examined
EcuadorImbaburaYachay Tech UniversityiNaturalist; photo examined
EcuadorImbaburaZuletaGuijarro Fuertes 2010
EcuadorNapoLaguna de la Mica, 2 km N ofiNaturalist; photo examined
EcuadorPichinchaAlangasíiNaturalist; photo examined
EcuadorPichinchaAlangasí, 1.5 km S ofiNaturalist; photo examined
EcuadorPichinchaBosque Protector JerusalemiNaturalist; photo examined
EcuadorPichinchaBosque Protector Jerusalem, 2 km W ofTorres-Carvajal 2007
EcuadorPichinchaCalacalí Guerra-Correa et al. 2020
EcuadorPichinchaCalacalí, 1 km NE ofiNaturalist; photo examined
EcuadorPichinchaCalacalí, 2.7 km NE ofiNaturalist; photo examined
EcuadorPichinchaCangahuaMCZ R-80964; VertNet
EcuadorPichinchaCasitaguaAndrango et al. 2016
EcuadorPichinchaCayambe volcano slopes Torres-Carvajal 2007
EcuadorPichinchaCayambe, 7.7 km NW ofiNaturalist; photo examined
EcuadorPichinchaCentral Hidroeléctrica PasochoaRamírez-Jaramillo et al. 2015
EcuadorPichinchaCerro CasitaguaiNaturalist; photo examined
EcuadorPichinchaCerro La Marca, San Antonio de PichinchaKU 134652; VertNet
EcuadorPichinchaCiudad Mitad del MundoiNaturalist; photo examined
EcuadorPichinchaConnecticutPhoto by María Jose Quiroz
EcuadorPichinchaConocoto, av. Ponce EnríqueziNaturalist; photo examined
EcuadorPichinchaCotopaxi PungoiNaturalist; photo examined
EcuadorPichinchaCráter del PulhulahuaiNaturalist; photo examined
EcuadorPichinchaCuendinaRamírez-Jaramillo et al. 2015
EcuadorPichinchaCusubambaPDOT Cusubamba 2015
EcuadorPichinchaEscuela Superior Militar Eloy AlfaroTorres-Carvajal 2007
EcuadorPichinchaGranja UrkuwaykuiNaturalist; photo examined
EcuadorPichinchaGuayllabambaMCZ R-8407; VertNet
EcuadorPichinchaGuayllabamba, calle IdeyoTorres-Carvajal 2007
EcuadorPichinchaIlaló, northern slopeiNaturalist; photo examined
EcuadorPichinchaIlaló, southern slopeiNaturalist; photo examined
EcuadorPichinchaLaguna de LimpiopungoiNaturalist; photo examined
EcuadorPichinchaLloaTorres-Carvajal 2007
EcuadorPichinchaMachachiMCZ R-8420; VertNet
EcuadorPichinchaMachachi, planta de TesaliaTorres-Carvajal 2007
EcuadorPichinchaMirador del IscoReptiles of Ecuador book database
EcuadorPichinchaMirador del PulhulahuaiNaturalist; photo examined
EcuadorPichinchaMolinuco Ecological RefugeiNaturalist; photo examined
EcuadorPichinchaMonumento Mitad del MundoCAS 152053; VertNet
EcuadorPichinchaNono, 1.75 km W ofReptiles of Ecuador book database
EcuadorPichinchaNono, 4 km N ofiNaturalist; photo examined
EcuadorPichinchaOlmedo, 8 km NE ofiNaturalist; photo examined
EcuadorPichinchaParque Arqueológico RumipambaiNaturalist; photo examined
EcuadorPichinchaParque de GuápuloPhoto by Lorena Benítez
EcuadorPichinchaParque ItchimbíaiNaturalist; photo examined
EcuadorPichinchaPasochoa Volcano Forest MCZ R-175060; VertNet
EcuadorPichinchaPifoReptiles of Ecuador book database
EcuadorPichinchaPintag–Antisana roadTorres-Carvajal 2007
EcuadorPichinchaPintag, 2 km S ofiNaturalist; photo examined
EcuadorPichinchaPucará de RumicuchoiNaturalist; photo examined
EcuadorPichinchaPuemboMCZ R-164422; VertNet
EcuadorPichinchaPululahua Geobotanical Reserve 1iNaturalist; photo examined
EcuadorPichinchaPululahua Geobotanical Reserve 2iNaturalist; photo examined
EcuadorPichinchaPululahua, 6.1 km NW ofiNaturalist; photo examined
EcuadorPichinchaQuito, BellavistaiNaturalist; photo examined
EcuadorPichinchaQuito, CalderóniNaturalist; photo examined
EcuadorPichinchaQuito, calle Jorge JuanTorres-Carvajal 2007
EcuadorPichinchaQuito, CarceléniNaturalist; photo examined
EcuadorPichinchaQuito, GuápuloiNaturalist; photo examined
EcuadorPichinchaQuito, La TolaiNaturalist; photo examined
EcuadorPichinchaQuito, Parque La CarolinaiNaturalist; photo examined
EcuadorPichinchaQuito, Parque Metropolitano del SuriNaturalist; photo examined
EcuadorPichinchaQuito, San Miguel de AmagasiiNaturalist; photo examined
EcuadorPichinchaQuito, San VicenteiNaturalist; photo examined
EcuadorPichinchaQuito, Tréboles del SuriNaturalist; photo examined
EcuadorPichinchaQuito, valle ValparaísoUSNM 201235; VertNet
EcuadorPichinchaReserva ChakanaiNaturalist; photo examined
EcuadorPichinchaRío Chiche, 3.5 km E ofKU 152172; VertNet
EcuadorPichinchaSan Antonio de Pichincha, calle MoraspungoiNaturalist; photo examined
EcuadorPichinchaSan Antonio de Pichincha, CaspigasiiNaturalist; photo examined
EcuadorPichinchaSan Antonio de Pichincha*Fritts 1974
EcuadorPichinchaSan Rafael, Los CedrosiNaturalist; photo examined
EcuadorPichinchaSanta Marianita de PingulmiLACM 58808; VertNet
EcuadorPichinchaSanta Rosais FarmMCZ R-8435; VertNet
EcuadorPichinchaSlopes of Cotopaxi volcanoThis work; Fig. 1
EcuadorPichinchaTababelaRamírez-Jaramillo et al. 2015
EcuadorPichinchaTababela, AeropuertoCadena-Ortiz et al. 2017
EcuadorPichinchaTabacundo, 4.8 km N ofThis work; Fig. 1
EcuadorPichinchaTanlahuaiNaturalist; photo examined
EcuadorPichinchaTumbacoiNaturalist; photo examined
EcuadorPichinchaUyumbichoTorres-Carvajal 2007
EcuadorPichinchaYaruquí, 2 km E ofiNaturalist; photo examined