Published April 16, 2021. Updated January 27, 2024. Open access.

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Cadle’s Whorltail-Iguana (Stenocercus cadlei)

Reptiles of Ecuador | Sauria | Tropiduridae | Stenocercus cadlei

English common name: Cadle’s Whorltail-Iguana.

Spanish common name: Guagsa de Cadle.

Recognition: ♂♂ 21.3 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=8.5 cm. ♀♀ 18.4 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=7.4 cm..1 The Cadle’s Whorltail-Iguana (Stenocercus cadlei) differs from other lizards in its area of distribution (species in the genera Pholidobolus and Riama) by having keel-shaped dorsal scales with pointed ends.2 Stenocercus cadlei occurs north of the distribution of S. festae and south of S. guentheri, two similar lizard species that may be identified based on ventral coloration.1 Males of these two Stenocercus have a distinct, transverse black band on ventral surface of neck (band absent in S. cadlei) and the females usually have a uniformly-colored belly (bright yellow pectoral patch with a dark reticulation in S. cadlei).1 Additionally, S. festae has a black ante-humeral patch in adult males and distinctly keeled ventral scales in juveniles (patch absent in males and weakly keeled ventral scales in juveniles in S. cadlei).1 Males of S. cadlei differ from females by being larger and having a yellowish-green back (yellowish-brown in females; Fig. 1).1

Figure showing variation among individuals of Stenocercus cadlei

Figure 1: Individuals of Stenocercus cadlei from Ecuador: San Andrés, Tungurahua province (); Tixán, Chimborazo province (); Yaupi, Tungurahua province (). sa=subadult, j=juvenile.

Natural history: Stenocercus cadlei is a diurnal lizard that inhabits high evergreen montane forests, dry to humid highland shrublands, and paramos.3 This species also occurs in human-modified habitats, such as in grasslands, crops, and along roads.1,46 Cadle’s Whorltail-Iguanas are usually only seen active between 8:30 am and 2:00 pm during sunny days, basking or foraging at ground level among shrubs or on logs and rock walls.6 Apparently, these lizards prefer ambient temperatures below 29.8 C.1 When dormant, they can be found under rocks, logs, in holes in the ground, or at the base of tall grass tussocks.1,6 Individuals are capable of shedding the tail as an escape mechanism.1 Gravid females contain two eggs.1 Neonates have been found in different months, suggesting that S. cadlei has more than one reproductive season per year.1

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Conservation: Vulnerable Considered to be facing a high risk of extinction in the mid-term future..7 Stenocercus cadlei is included in this category instead of Least Concern8 because although it is a common species that tolerates a moderate degree of habitat disturbance,8 it meets IUCN Red List criteria9 to be included in this category: the species’ extent of occurrence is estimated to be less than 10,000 km2, its habitat is severely fragmented, and there is continuing decline in the extent and quality of the ecosystems where it occurs. Although S. cadlei is found in several protected areas (including Chimborazo Reserve, Llanganates National Park, and Sangay National Park),8 87% of the localities where the species occurs (see Appendix 1) are in heavily human-modified areas.1 Based on maps of Ecuador’s vegetation cover published in 2012,10 no more than ~26% of the potential distribution of the species still holds native vegetation.

Distribution: Stenocercus cadlei is endemic to an area of approximately 6,978 km2 in the semi-xeric inter-Andean valleys and paramos of central Ecuador (Fig. 2).

Distribution of Stenocercus cadlei in Ecuador

Figure 2: Distribution of Stenocercus cadlei in Ecuador. The star corresponds to the type locality: Santa Lucía, Tungurahua 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.11 The specific name cadlei honors US herpetologist John E. Cadle, who has made important contributions to the systematics of Stenocercus lizards.1

See it in the wild: Cadle’s Whorltail-Iguanas can be seen with almost complete certainty during strongly sunny days in protected areas like Chimborazo Reserve and Laguna de Quilotoa. The best time to look for lizards of this species is during the first hours after sunrise, when the lizards are active and approachable.

Authors: Amanda QuezadaaAffiliation: Tropical Herping (TH), Quito, Ecuador.,bAffiliation: Laboratorio de Herpetología, Universidad del Azuay, Cuenca, Ecuador. and 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, Arteaga A (2024) Cadle’s Whorltail-Iguana (Stenocercus cadlei). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/SOCG1715

Literature cited:

  1. 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
  2. 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.
  3. Torres-Carvajal O, Pazmiño-Otamendi G, Salazar-Valenzuela D (2019) Reptiles of Ecuador: a resource-rich online portal, with dynamic checklists and photographic guides. Amphibian & Reptile Conservation 13: 209–229.
  4. Dávila M, Cisneros-Heredia DF (2017) Use of human-made buildings by Stenocercus lizards (Iguania, Tropiduridae). Herpetology Notes 10: 517–519.
  5. Mantilla JC, Castaño J (2015) Distribution extension and ecology notes of endemic lizard Stenocercus bolivarensis Castro & Ayala, 1982 (Squamata: Tropiduridae). Herpetology Notes 8: 575–577.
  6. Field notes, Reptiles of Ecuador book project.
  7. 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.
  8. Cisneros-Heredia DF, Reyes-Puig C, Yánez-Muñoz M, Brito J (2017) Stenocercus cadlei. The IUCN Red List of threatened species. Available from: DOI: 10.2305/IUCN.UK.2017-2.RLTS.T50950631A50950634.en
  9. IUCN (2001) IUCN Red List categories and criteria: Version 3.1. IUCN Species Survival Commission, Gland and Cambridge, 30 pp.
  10. MAE (2012) Línea base de deforestación del Ecuador continental. Ministerio del Ambiente del Ecuador, Quito, 30 pp.
  11. 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 cadlei in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used. Asterisk (*) indicates type locality.

EcuadorChimborazoAbove AlausíReptiles of Ecuador book database
EcuadorChimborazoAlausíMCZ R-146926; VertNet
EcuadorChimborazoAlausí, 10 km NW ofUSNM 201221; VertNet
EcuadorChimborazoAlausí, 5 km NE ofKU 134431; VertNet
EcuadorChimborazoCebadasField notes of Elicio Tapia
EcuadorChimborazoColumbe Torres-Carvajal & Mafla-Endara 2013
EcuadorChimborazoComunidad Melán Torres-Carvajal & Mafla-Endara 2013
EcuadorChimborazoGuamote KU 134484; VertNet
EcuadorChimborazoGuamote, 20.1 km S ofKU 141234; VertNet
EcuadorChimborazoGuamote, 7 km SW ofKU 164174; VertNet
EcuadorChimborazoGuamote, 9.5 km S ofKU 141229; VertNet
EcuadorChimborazoGuaranda, 36.8 km NE ofKU 202939; VertNet
EcuadorChimborazoMocha, 10.5 km SSW ofKU 179430; VertNet
EcuadorChimborazoMt. ChimborazoUSNM 103277; VertNet
EcuadorChimborazoPalmira, 11.3 km N ofTorres-Carvajal & Mafla-Endara 2013
EcuadorChimborazoPalmira, 2.5 km S ofKU 164173; VertNet
EcuadorChimborazoPalmira, 5.2 km S ofKU 141248; VertNet
EcuadorChimborazoPenipeBurneo & Boada 2012
EcuadorChimborazoPungala, 8.2 km SE ofKU 141256; VertNet
EcuadorChimborazoRiobamba, 10 km N ofKU 134496; VertNet
EcuadorChimborazoRiobamba, 12.1 km E ofKU 141257; VertNet
EcuadorChimborazoRíobamba, 5 km W ofUSNM 201220; VertNet
EcuadorChimborazoRiobamba, 6.7 km E ofKU 202941; VertNet
EcuadorChimborazoSan Juan, 4.1 km E ofKU 141259; VertNet
EcuadorChimborazoSurrondings of TixánMZUTI 4550; VertNet
EcuadorChimborazoTixán, 0.3 km S ofKU 141236; VertNet
EcuadorChimborazoTixán, 1.1 km S ofKU 141238; VertNet
EcuadorChimborazoTixán, 14.5 km N ofTorres-Carvajal & Mafla-Endara 2013
EcuadorChimborazoTixán, 2.8 km S ofTorres-Carvajal & Mafla-Endara 2013
EcuadorChimborazoTixán, 5 km NE ofKU 164171; VertNet
EcuadorCotopaxiAngamarcaGP Angamarca 2019
EcuadorCotopaxiApagua Torres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiCaserío PoatugTorres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiChugchilán, 2 km S ofTorres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiCotalóTorres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiGuaytacamaiNaturalist; photo examined
EcuadorCotopaxiLa MercedChicaiza & Tapia 2016
EcuadorCotopaxiLaguna de YamboTorres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiLaguna QuilotoaiNaturalist; photo examined
EcuadorCotopaxiLatacungaMCZ R-164907; VertNet
EcuadorCotopaxiLatacunga, 1 km W ofKU 127103; VertNet
EcuadorCotopaxiMirador Laguna QuilotoaReptiles of Ecuador book database
EcuadorCotopaxiMulalóTorres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiPatate Torres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiPujilí, 37.8 km W ofKU 152173; VertNet
EcuadorCotopaxiRío Ambato Torres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiRío BarrancasTorres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiRoad Guaranda–Ambato Torres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiRoad to Píllaro Torres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiSan Juan de Pasto Calle Torres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiTanicuchiiNaturalist; photo examined
EcuadorCotopaxiUrbina Torres-Carvajal & Mafla-Endara 2013
EcuadorTungurahuaAmbatoMCZ R-8430; VertNet
EcuadorTungurahuaAmbato, 10 km E ofKU 134523; VertNet
EcuadorTungurahuaBaños, 17.8 km W ofKU 141209; VertNet
EcuadorTungurahuaChambo GrandeKU 146670; VertNet
EcuadorTungurahuaEntre Aguaján y AmbatoPhoto by David Velastegui
EcuadorTungurahuaPatate, 5.6 km SSE ofKU 141201; VertNet
EcuadorTungurahuaRío Patate, 3 km S ofUSNM 201244; VertNet
EcuadorTungurahuaSan AndrésThis work; Fig. 1
EcuadorTungurahuaSan Miguelito, 3 km SSW ofKU 132491; VertNet
EcuadorTungurahuaSanta Lucía*Torres-Carvajal & Mafla-Endara 2013
EcuadorTungurahuaVingeKU 141195; VertNet
EcuadorTungurahuaYaupiThis work; Fig. 1