Published October 14, 2021. Updated January 27, 2024. Open access.

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Cloudy Whorltail-Iguana (Stenocercus carrioni)

Reptiles of Ecuador | Sauria | Tropiduridae | Stenocercus carrioni

English common names: Cloudy Whorltail-Iguana, Carrión’s Whorltail-Iguana.

Spanish common names: Guagsa nebulosa, guagsa de Carrión.

Recognition: ♂♂ 17.6 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=7.4 cm. ♀♀ 16.9 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=7.1 cm..1 The Cloudy Whorltail-Iguana (Stenocercus carrioni) differs from most other medium-sized diurnal and arboreal lizards in its area of distribution by having keeled dorsal scales with pointed ends instead of granular scales (Fig. 1).2 In some areas, S. carrioni occurs alongside with S. limitaris, S. ornatus, and S. puyango. These other lizards are not arboreal, have non-spiny caudal scales (spiny tail in S. carrioni), and lack a gular fold (neck strongly folded in S. carrioni).3,4 There is no strong sexual dimorphism in this species; however males are larger and have more robust heads than females.1

Figure showing variation among individuals of Stenocercus carrioni

Figure 1: Individuals of Stenocercus carrioni from Alamor, Loja province, Ecuador.

Natural history: Stenocercus carrioni is a rarely seen diurnal lizard that inhabits the semi-deciduous foothill forest ecosystem.5 Cloudy Whorltail-Iguanas are arboreal. They dwell in the intermediate and lower strata of old-growth forests, forest borders, and secondary vegetation.6,7 In Alamor, Loja province, individuals were seen active on lamp posts and trees during a sunny morning.7 When threatened, these lizards run up or down tree-trunks away from the threat or retreat in holes and crevices.7 If captured, they may shed the tail and bite as a method of defense and escape. Gravid females have been found in August and September.4

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Conservation: Endangered Considered to be facing a high risk of extinction in the near future..8,9 Stenocercus carrioni is listed in this category because the species has an extremely small area of distribution, occurs in less than ten localities, and its habitat is declining in extent and quality due to the conversion of forests into pastures for livestock.8 Based on maps of Ecuador’s vegetation cover published in 2012,10 the majority (~76%) of the species’ forest habitat has been destroyed. In total, there is no more than ~476 km2 of suitable habitat remaining for S. carrioni. Also, the information available about the natural history of the species suggests that it cannot persist in pastures and other areas without arboreal vegetation. Furthermore, S. carrioni has not been reported in any protected area and continuous deforestation threatens its survival.8 Conservation efforts are urgently needed.

Distribution: Stenocercus carrioni is endemic to an area of approximately 2,009 km2 in the Tumbesian foothills of the Andes in extreme southwestern Ecuador (provinces El Oro and Loja; Fig. 2).

Distribution of Stenocercus carrioni in Ecuador

Figure 2: Distribution of Stenocercus carrioni 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 (=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 epithet carrioni honors Professor Clodoveo Carrión Mora (1883–1957), an Ecuadorian naturalist and paleontologist who collected the holotype of the species.12

See it in the wild: Cloudy Whorltail-Iguanas are uncommon lizards. They are arboreal in an area where most trees have been cut down and the localities were individuals remain are not in protected areas. However, a visit to the immediate environs of the town Alamor, Loja province, holds the possibility of observing these lizards. Cloudy Whorltail-Iguanas may be located by carefully scanning large bromeliad-covered trees during bright sunny days.

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

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

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

How to cite? Quezada A (2024) Cloudy Whorltail-Iguana (Stenocercus carrioni). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/CDFQ5792

Literature cited:

  1. Cadle JE (1991) Systematics of Lizards of the genus Stenocercus (Iguania: Tropiduridae) from Northern Perú: new Species and comments on relationships and distribution patterns. Proceedings of the Academy of Natural Sciences of Philadelphia 143: 1–96.
  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. Parker HW (1934) Reptiles y amphibians from southern Ecuador. Annals and Magazine of Natural History 14: 268–270.
  4. 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
  5. 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
  6. Yánez-Muñoz MH, Bejarano-Muñoz P, Sánchez-Nivicela JC (2019) Anfibios y reptiles del páramo al manglar. Capítulo II. In: Garzón-Santomaro C, Sánchez-Nivicela JC, Mena-Valenzuela P, González-Romero D, Mena-Jaén JL (Eds) Anfibios, reptiles y aves de la provincia de El Oro. GADPEO–INABIO, Quito, 45–86.
  7. Field notes, Reptiles of Ecuador book project.
  8. Cisneros-Heredia DF, Reyes-Puig C, Yánez-Muñoz M, Sánchez J, Brito J (2019) Stenocercus carrioni. The IUCN Red List of threatened species. Available from: DOI: 10.2305/IUCN.UK.2019-3.RLTS.T50950640A50950645.en
  9. 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.
  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
  12. Uetz P, Freed P, Hošek J (2021) The reptile database. Available from:

Appendix 1: Locality data used to create the distribution map of Stenocercus carrioni in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used. Asterisk (*) indicates type locality.

EcuadorEl OroBalsasJuan Carlos Sánchez, pers. comm.
EcuadorEl OroLlano de GuavosTorres-Carvajal 2007
EcuadorEl OroMarcabelíYánez-Muñóz et al. 2019
EcuadorEl OroPiñasJuan Carlos Sánchez, pers. comm.
EcuadorLojaAlamorTorres-Carvajal 2007
EcuadorLojaCelica, 10 km N ofTorres-Carvajal 2007
EcuadorLojaGuaincheTorres-Carvajal 2007
EcuadorLojaRío LunamáTorres-Carvajal 2007
EcuadorLojaSeboyalTorres-Carvajal 2007