Published February 11, 2021. Open access.

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Chota Whorltail-Iguana (Stenocercus chota)

Reptiles of Ecuador | Sauria | Tropiduridae | Stenocercus | Stenocercus chota

English common name: Chota Whorltail-Iguana.

Spanish common name: Guagsa del Chota.

Recognition: ♂♂ 20.7 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=9.7 cm. ♀♀ 17.3 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=6.5 cm..1,2 The Chota Whorltail-Iguana (Stenocercus chota) 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.3 Stenocercus guentheri is similar to S. chota, but it occurs south of the distribution of the latter. Additionally, males have a black throat patch (absent in S. chota) and females have gray stripes on the throat (black blotches in S. chota). Another whorltail iguana, S. angel occurs close to, but north of, the distribution of S. chota, and it can be identified because males of this species lack a mid-ventral longitudinal black line (present in most males of S. chota) and because their overall coloration is green (brownish in S. chota).1,2 Males are larger than females, have a well-developed dorsal crest, and lack dark blotches in the throat (present in females).2

Figure showing variation among individuals of Stenocercus chota

Figure 1: Individuals of Stenocercus chota from Pimampiro, Ecuador. sa=subadult, j=juvenile.

Natural history: Locally extremely commonLikely to be seen every day, usually in large numbers.. Stenocercus chota is a diurnal and terrestrial lizard restricted to areas of dry highland shrubland.1,4 The species usually occurs in open areas with shrubby vegetation both in undisturbed areas as well as along roads or in pastures, rural gardens, houses, and plantations.1,5 Chota Whorltail-Iguanas are active during sunny hours, basking on large rocks or on the ground.1 If disturbed, individuals retreat into holes in the substrate, between rocks, or under bushes, fallen logs, branches, or thorny shrubs.1,5 If captured, they may shed the tail or bite. There are unpublished observations of snakes (Drymarchon melanurus and Mastigodryas pulchriceps) preying upon individuals of this species.1 Females lay clutches of two eggs.1

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Conservation: Vulnerable Considered to be facing a high risk of extinction in the mid-term future..6,7 Although Stenocercus chota is considered a common species adaptable to human-modified environments,8 it meets the IUCN red list criteria9 to be included in the Vulnerable, instead of the Least Concern,8 category: the species’ extent of occurrence is less than 2,000 km2, its habitat is severely fragmented, and there is continuing decline in the extent and quality of the ecosystem where it occurs. It is estimated that ~57% of the habitat of S. chota has been transformed into a matrix of human settlements, pastures, and agricultural fields.10 Additionally, the species is not found within protected areas.8

Distribution: Stenocercus chota is native to an estimated 702 km2 area in the xeric inter-Andean valley known as El Chota, the headwaters of the Río Mira in northern Ecuador.1,2 The species occur at elevations between 1305 and 2422 m (Fig. 2).

Distribution of Stenocercus chota in Ecuador

Figure 2: Distribution of Stenocercus chota in Ecuador. See Appendix 1 for a complete list of the presence localities (not shown for clarity) used to create the distribution model 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 lizards in the family Tropiduridae.11 The specific epithet chota refers to the Valle del Chota, inhabited by this species.1

See it in the wild: Chota Whorltail-Iguanas can be seen with almost complete certainty during strongly sunny days in areas having adequate vegetation cover throughout El Chota Valley. The best time to look for members of this species is during the first hours after sunrise, when the lizards are active and approachable.

Acknowledgments: Special thanks to Frank Pichardo and Harry Turner for helping locate the specimens of Stenocercus chota photographed in this account.

Authors: Amanda QuezadaaAffiliation: Tropical Herping (TH), Quito, Ecuador.,bAffiliation: Laboratorio de Herpetología, Universidad del Azuay, Cuenca, Ecuador. and Alejandro ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador.

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

How to cite? Quezada A, Arteaga A (2021) Chota Whorltail-Iguana (Stenocercus chota). 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/AZYE5437

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, 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.
  5. Field notes, Reptiles of Ecuador book project.
  6. Carrillo E, Aldás A, Altamirano M, Ayala F, Cisneros-Heredia DF, Endara A, Márquez C, Morales M, Nogales F, Salvador P, Torres ML, Valencia J, Villamarín F, Yánez-Muñoz M, Zárate P (2005) Lista roja de los reptiles del Ecuador. Fundación Novum Millenium, Quito, 46 pp.
  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, Brito J, Yánez-Muñoz M (2017) Stenocercus chota. The IUCN red list of threatened species. Available from: DOI: 10.2305/IUCN.UK.2017-2.RLTS.T50950651A50950654.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 chota in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used.

EcuadorCarchiAmbuquí–Monte Olivo roadTorres-Carvajal 2007
EcuadorCarchiEl Chota, 5 km N ofTorres-Carvajal 2007
EcuadorCarchiLa ConcepciónTorres-Carvajal 2000
EcuadorCarchiRío ApaquíMECN 3604
EcuadorCarchiSalinas, 10.4 km N ofUSNM 201126
EcuadorImbabura28 km N Rio TaguandoMVZ 178428
EcuadorImbaburaAmbuquíTorres-Carvajal 2007
EcuadorImbaburaAmbuquí–Monte olivo roadTorres-Carvajal 2000
EcuadorImbaburaAmbuquí, 2.3 km W ofThis work
EcuadorImbaburaCahuasquíPhoto by Diego Piñán
EcuadorImbaburaEl JuncalTorres-Carvajal 2005
EcuadorImbaburaFinca El DescansoiNaturalist
EcuadorImbaburaFinca San Ignacio AltoTorres-Carvajal 2007
EcuadorImbaburaIbarraUIMNH 91615
EcuadorImbaburaLa DolorosaiNaturalist
EcuadorImbaburaLa PrimaveraiNaturalist
EcuadorImbaburaMira, 2 km E ofiNaturalist
EcuadorImbaburaMirador del Codor, way toThis work
EcuadorImbaburaPablo ArenasDiego Piñán, pers. comm.
EcuadorImbaburaPimampiro, 1.5 km W ofThis work
EcuadorImbaburaPimampiro, 1.7 km NW ofThis work
EcuadorImbaburaPlaya de la CruzPhoto by Diego Piñán
EcuadorImbaburaQuebrada CruzhuaicField notes of Luis Coloma
EcuadorImbaburaQuebrada de la VertienteTorres-Carvajal 2007
EcuadorImbaburaQuebrada HierbabuenaOnline multimedia
EcuadorImbaburaRío AmarilloThis work
EcuadorImbaburaRío AmbiThis work
EcuadorImbaburaRío ChotaTorres-Carvajal 2007
EcuadorImbaburaSalinasTorres-Carvajal 2000
EcuadorImbaburaSalinas, 3.9 km N ofMECN 5412
EcuadorImbaburaSan Blas, UrcuquíiNaturalist
EcuadorImbaburaTumbabiroTorres-Carvajal 2000
EcuadorImbaburaTumbabiro, 1.9 km E ofThis work
EcuadorImbaburaTunas y Cabras LodgeThis work
EcuadorImbaburaUniversidad YachayiNaturalist
EcuadorImbaburaUrcuquí, 4 km E ofInaturalist
EcuadorImbaburaValle del ChotaTorres-Carvajal 2000