Published April 16, 2021. Open access.

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Cadle’s Whorltail-Iguana (Stenocercus cadlei)

Reptiles of Ecuador | Sauria | Tropiduridae | Stenocercus | 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).1

Figure showing variation among individuals of Stenocercus cadlei

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

Natural history: Locally extremely commonLikely to be seen every day, usually in large numbers.. 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 estimated 6,978 km2 area in the semi-xeric inter-Andean valleys and paramos of central Ecuador. The species has been recorded at elevations between 1956 and 4034 m (Fig. 2).

Distribution of Stenocercus cadlei in Ecuador

Figure 2: Distribution of Stenocercus cadlei 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.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 ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador.

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

How to cite? Quezada A, Arteaga A (2021) Cadle’s Whorltail-Iguana (Stenocercus cadlei). 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/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 AlausíThis work
EcuadorChimborazoAlausíMCZ R-146926
EcuadorChimborazoAlausí, 10 km NW ofUSNM 201221
EcuadorChimborazoAlausí, 5 km NE ofKU 134431
EcuadorChimborazoCebadasField notes of Elicio Tapia
EcuadorChimborazoColumbe Torres-Carvajal & Mafla-Endara 2013
EcuadorChimborazoComunidad Melán Torres-Carvajal & Mafla-Endara 2013
EcuadorChimborazoGuamote KU 134484
EcuadorChimborazoGuamote, 20.1 km S ofKU 141234
EcuadorChimborazoGuamote, 7 km SW ofKU 164174
EcuadorChimborazoGuamote, 9.5 km S ofKU 141229
EcuadorChimborazoGuaranda, 36.8 km NE ofKU 202939
EcuadorChimborazoMocha, 10.5 km SSW ofKU 179430
EcuadorChimborazoMt. ChimborazoUSNM 103277
EcuadorChimborazoPalmira, 11.3 km N ofTorres-Carvajal & Mafla-Endara 2013
EcuadorChimborazoPalmira, 2.5 km S ofKU 164173
EcuadorChimborazoPalmira, 5.2 km S ofKU 141248
EcuadorChimborazoPenipeBurneo & Boada 2012
EcuadorChimborazoPungala, 8.2 km SE ofKU 141256
EcuadorChimborazoRiobamba, 10 km N ofKU 134496
EcuadorChimborazoRiobamba, 12.1 km E ofKU 141257
EcuadorChimborazoRíobamba, 5 km W ofUSNM 201220
EcuadorChimborazoRiobamba, 6.7 km E ofKU 202941
EcuadorChimborazoRiobamba, 62 km S ofMECN 462
EcuadorChimborazoSan Juan, 4.1 km E ofKU 141259
EcuadorChimborazoSurrondings of TixánMZUTI 4550
EcuadorChimborazoTixán, 0.3 km S ofKU 141236
EcuadorChimborazoTixán, 1.1 km S ofKU 141238
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
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
EcuadorCotopaxiLa MercedChicaiza & Tapia 2016
EcuadorCotopaxiLaguna de YamboTorres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiLaguna QuilotoaiNaturalist
EcuadorCotopaxiLatacungaMCZ R-164907
EcuadorCotopaxiLatacunga, 1 km W ofKU 127103
EcuadorCotopaxiMirador Laguna QuilotoaThis work
EcuadorCotopaxiMulalóTorres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiPatate Torres-Carvajal & Mafla-Endara 2013
EcuadorCotopaxiPujilí, 37.8 km W ofKU 152173
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
EcuadorCotopaxiUrbina Torres-Carvajal & Mafla-Endara 2013
EcuadorTungurahuaAmbatoMCZ R-8430
EcuadorTungurahuaAmbato, 10 km E ofKU 134523
EcuadorTungurahuaBaños, 17.8 km W ofKU 141209
EcuadorTungurahuaChambo GrandeKU 146670
EcuadorTungurahuaMocha, 6 km N of*Torres-Carvajal & Mafla-Endara 2013
EcuadorTungurahuaPatate, 5.6 km SSE ofKU 141201
EcuadorTungurahuaRío Patate, 3 km S ofUSNM 201244
EcuadorTungurahuaSan AndrésThis work
EcuadorTungurahuaSan Miguelito, 3 km SSW ofKU 132491
EcuadorTungurahuaVingeKU 141195
EcuadorTungurahuaYaupiThis work