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DOI10.47051/VIQX3499 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 1: Individuals of Stenocercus guentheri from Ecuador: Tambopaxi Lodge, Cotopaxi province (); Tabacundo, Pichincha province (). sa=subadult.

Natural history: Stenocercus guentheri inhabits dry and humid ecosystems in areas of evergreen montane forest, highland shrubland, and páramo. 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 clutch^2,8 and males defend territories by performing push-up displays and fighting with intruders.⁵

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 páramos of northern Ecuador (Fig. 2).

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 Quezada^aAffiliation: Tropical Herping (TH), Quito, Ecuador.^,bAffiliation: Laboratorio de Herpetología, Universidad del Azuay, Cuenca, Ecuador.

Editor: Alejandro Arteaga^cAffiliation: Khamai Foundation, Quito, Ecuador.

Photographers: Jose Vieira^aAffiliation: Tropical Herping (TH), Quito, Ecuador.^,dAffiliation: ExSitu, Quito, Ecuador. and Alejandro Arteaga^cAffiliation: 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: www.reptilesofecuador.com. 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: www.iucnredlist.org. 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.

Country	Province	Locality	Source
Ecuador	Cotopaxi	Cotopaxi National Park	iNaturalist; photo examined
Ecuador	Cotopaxi	Entrance to Cotopaxi National Park	iNaturalist; photo examined
Ecuador	Cotopaxi	Quebrada Agualongo	iNaturalist; photo examined
Ecuador	Cotopaxi	Tambopaxi Lodge	Reptiles of Ecuador book database
Ecuador	Cotopaxi	Volcán Rumiñahui	iNaturalist; photo examined
Ecuador	Imbabura	Atuntaqui	Torres-Carvajal 2007
Ecuador	Imbabura	Atuntaqui, 2 km NW of	iNaturalist; photo examined
Ecuador	Imbabura	Cerro Imbabura	iNaturalist; photo examined
Ecuador	Imbabura	Cotacachi	Reptiles of Ecuador book database
Ecuador	Imbabura	Cotacachi, 2.5 km W of	iNaturalist; photo examined
Ecuador	Imbabura	Hidroeléctrica Antigua	Ayerbe et al. 2007
Ecuador	Imbabura	Ibarra, 5 km S of	KU 134562; VertNet
Ecuador	Imbabura	Ibarra, El Tejar	iNaturalist; photo examined
Ecuador	Imbabura	Ibarra, La Merced	MCZ R-8069; VertNet
Ecuador	Imbabura	Laguna de Cuicocha	iNaturalist; photo examined
Ecuador	Imbabura	Lagunas de Mojanda	Torres-Carvajal 2007
Ecuador	Imbabura	Otavalo	KU 134555; VertNet
Ecuador	Imbabura	Otavalo, 7.5 km N of	Torres-Carvajal 2007
Ecuador	Imbabura	San Juan de Ilumán, 2 km E of	iNaturalist; photo examined
Ecuador	Imbabura	San Pablo del Lago	Andrango et al. 2016
Ecuador	Imbabura	San Roque	iNaturalist; photo examined
Ecuador	Imbabura	Terreno familia Morales	Reptiles of Ecuador book database
Ecuador	Imbabura	Urcuquí, 6.8 km W of	iNaturalist; photo examined
Ecuador	Imbabura	Yachay Tech University	iNaturalist; photo examined
Ecuador	Imbabura	Zuleta	Guijarro Fuertes 2010
Ecuador	Napo	Laguna de la Mica, 2 km N of	iNaturalist; photo examined
Ecuador	Pichincha	Alangasí	iNaturalist; photo examined
Ecuador	Pichincha	Alangasí, 1.5 km S of	iNaturalist; photo examined
Ecuador	Pichincha	Bosque Protector Jerusalem	iNaturalist; photo examined
Ecuador	Pichincha	Bosque Protector Jerusalem, 2 km W of	Torres-Carvajal 2007
Ecuador	Pichincha	Calacalí	Guerra-Correa et al. 2020
Ecuador	Pichincha	Calacalí, 1 km NE of	iNaturalist; photo examined
Ecuador	Pichincha	Calacalí, 2.7 km NE of	iNaturalist; photo examined
Ecuador	Pichincha	Cangahua	MCZ R-80964; VertNet
Ecuador	Pichincha	Casitagua	Andrango et al. 2016
Ecuador	Pichincha	Cayambe volcano slopes	Torres-Carvajal 2007
Ecuador	Pichincha	Cayambe, 7.7 km NW of	iNaturalist; photo examined
Ecuador	Pichincha	Central Hidroeléctrica Pasochoa	Ramírez-Jaramillo et al. 2015
Ecuador	Pichincha	Cerro Casitagua	iNaturalist; photo examined
Ecuador	Pichincha	Cerro La Marca, San Antonio de Pichincha	KU 134652; VertNet
Ecuador	Pichincha	Ciudad Mitad del Mundo	iNaturalist; photo examined
Ecuador	Pichincha	Connecticut	Photo by María Jose Quiroz
Ecuador	Pichincha	Conocoto, av. Ponce Enríquez	iNaturalist; photo examined
Ecuador	Pichincha	Cotopaxi Pungo	iNaturalist; photo examined
Ecuador	Pichincha	Cráter del Pulhulahua	iNaturalist; photo examined
Ecuador	Pichincha	Cuendina	Ramírez-Jaramillo et al. 2015
Ecuador	Pichincha	Cusubamba	PDOT Cusubamba 2015
Ecuador	Pichincha	Escuela Superior Militar Eloy Alfaro	Torres-Carvajal 2007
Ecuador	Pichincha	Granja Urkuwayku	iNaturalist; photo examined
Ecuador	Pichincha	Guayllabamba	MCZ R-8407; VertNet
Ecuador	Pichincha	Guayllabamba, calle Ideyo	Torres-Carvajal 2007
Ecuador	Pichincha	Ilaló, northern slope	iNaturalist; photo examined
Ecuador	Pichincha	Ilaló, southern slope	iNaturalist; photo examined
Ecuador	Pichincha	Laguna de Limpiopungo	iNaturalist; photo examined
Ecuador	Pichincha	Lloa	Torres-Carvajal 2007
Ecuador	Pichincha	Machachi	MCZ R-8420; VertNet
Ecuador	Pichincha	Machachi, planta de Tesalia	Torres-Carvajal 2007
Ecuador	Pichincha	Mirador del Isco	Reptiles of Ecuador book database
Ecuador	Pichincha	Mirador del Pulhulahua	iNaturalist; photo examined
Ecuador	Pichincha	Molinuco Ecological Refuge	iNaturalist; photo examined
Ecuador	Pichincha	Monumento Mitad del Mundo	CAS 152053; VertNet
Ecuador	Pichincha	Nono, 1.75 km W of	Reptiles of Ecuador book database
Ecuador	Pichincha	Nono, 4 km N of	iNaturalist; photo examined
Ecuador	Pichincha	Olmedo, 8 km NE of	iNaturalist; photo examined
Ecuador	Pichincha	Parque Arqueológico Rumipamba	iNaturalist; photo examined
Ecuador	Pichincha	Parque de Guápulo	Photo by Lorena Benítez
Ecuador	Pichincha	Parque Itchimbía	iNaturalist; photo examined
Ecuador	Pichincha	Pasochoa Volcano Forest	MCZ R-175060; VertNet
Ecuador	Pichincha	Pifo	Reptiles of Ecuador book database
Ecuador	Pichincha	Pintag–Antisana road	Torres-Carvajal 2007
Ecuador	Pichincha	Pintag, 2 km S of	iNaturalist; photo examined
Ecuador	Pichincha	Pucará de Rumicucho	iNaturalist; photo examined
Ecuador	Pichincha	Puembo	MCZ R-164422; VertNet
Ecuador	Pichincha	Pululahua Geobotanical Reserve 1	iNaturalist; photo examined
Ecuador	Pichincha	Pululahua Geobotanical Reserve 2	iNaturalist; photo examined
Ecuador	Pichincha	Pululahua, 6.1 km NW of	iNaturalist; photo examined
Ecuador	Pichincha	Quito, Bellavista	iNaturalist; photo examined
Ecuador	Pichincha	Quito, Calderón	iNaturalist; photo examined
Ecuador	Pichincha	Quito, calle Jorge Juan	Torres-Carvajal 2007
Ecuador	Pichincha	Quito, Carcelén	iNaturalist; photo examined
Ecuador	Pichincha	Quito, Guápulo	iNaturalist; photo examined
Ecuador	Pichincha	Quito, La Tola	iNaturalist; photo examined
Ecuador	Pichincha	Quito, Parque La Carolina	iNaturalist; photo examined
Ecuador	Pichincha	Quito, Parque Metropolitano del Sur	iNaturalist; photo examined
Ecuador	Pichincha	Quito, San Miguel de Amagasi	iNaturalist; photo examined
Ecuador	Pichincha	Quito, San Vicente	iNaturalist; photo examined
Ecuador	Pichincha	Quito, Tréboles del Sur	iNaturalist; photo examined
Ecuador	Pichincha	Quito, valle Valparaíso	USNM 201235; VertNet
Ecuador	Pichincha	Reserva Chakana	iNaturalist; photo examined
Ecuador	Pichincha	Río Chiche, 3.5 km E of	KU 152172; VertNet
Ecuador	Pichincha	San Antonio de Pichincha, calle Moraspungo	iNaturalist; photo examined
Ecuador	Pichincha	San Antonio de Pichincha, Caspigasi	iNaturalist; photo examined
Ecuador	Pichincha	San Antonio de Pichincha*	Fritts 1974
Ecuador	Pichincha	San Rafael, Los Cedros	iNaturalist; photo examined
Ecuador	Pichincha	Santa Marianita de Pingulmi	LACM 58808; VertNet
Ecuador	Pichincha	Santa Rosais Farm	MCZ R-8435; VertNet
Ecuador	Pichincha	Slopes of Cotopaxi volcano	This work; Fig. 1
Ecuador	Pichincha	Tababela	Ramírez-Jaramillo et al. 2015
Ecuador	Pichincha	Tababela, Aeropuerto	Cadena-Ortiz et al. 2017
Ecuador	Pichincha	Tabacundo, 4.8 km N of	This work; Fig. 1
Ecuador	Pichincha	Tanlahua	iNaturalist; photo examined
Ecuador	Pichincha	Tumbaco	iNaturalist; photo examined
Ecuador	Pichincha	Uyumbicho	Torres-Carvajal 2007
Ecuador	Pichincha	Yaruquí, 2 km E of	iNaturalist; photo examined

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