Published May 21, 2021. Open access.

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Mist Whortail-Iguana (Stenocercus varius)

Reptiles of Ecuador | Sauria | Tropiduridae | Stenocercus | Stenocercus varius

English common names: Mist Whorltail-Iguana, Keeled Whorltail-Iguana.

Spanish common names: Guagsa de neblina, guagsa subtropical.

Recognition: ♂♂ 23.5 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=8.5 cm. ♀♀ 20.8 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=8.5 cm..1,2 The Mist Whorltail-Iguana (Stenocercus varius) can be identified from most other lizards in its area of distribution by having a greenish coloration, keel-shaped dorsal scales with pointed ends, and strictly arboreal habits.3 The only other member of the genus that occurs near the eastern distribution of S. varius is S. guentheri, a brownish primarily terrestrial lizard in which males have a black neck patch but without a fold (patch absent and neck strongly folded in S. varius).2,4 Males of S. varius differ from females by being more robust, having a broader head, a brighter green coloration, and a rhomboid black blotch on the shoulder.2 The most similar species is S. haenschi, which occurs further south and has keeled and imbricate (instead of smooth and granular) lateral body scales.2

Figure showing variation among individuals of Stenocercus varius

Figure 1: Individuals of Stenocercus varius from Tambo Tanda Lodge, Pichincha province (); and Otonga Reserve, Cotopaxi province (), Ecuador. j=juvenile.

Natural history: Locally frequentRecorded weekly in densities below five individuals per locality.. Stenocercus varius is a diurnal and arboreal lizard that inhabits old-growth to moderately disturbed evergreen montane forests and cloud forests.1,3 The species also occurs in forest clearings, cliffs, along roads, isolated trees in crops and pastures ,and on human-buildings.5,6 During sunny hours, Mist Whorltail-Iguanas can be seen basking or moving up and down tree trunks, rocky walls, and rooftops from ground level up to 7 m above the ground.3,7 Usually, there is no more than a single adult male per tree, rooftop, or boulder, although there may be several females and juveniles.8 When not active, individuals hide under rocks, fallen logs, piles of lumber, in crevices, and in holes at the base of poles. These lizards feed primarily on insects such as flies, moths, and ants, some of which are captured in the air.5,8 When startled, individuals take quick refuge in crevices, holes, and under rocks. If captured, they may shed the tail and bite.8 Gravid females contain two eggs.9

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Conservation: Near Threatened Not currently at risk of extinction, but requires some level of management to maintain healthy populations.. Stenocercus varius is proposed to be included in this category, instead of Endangered,6,10 following IUCN criteria,11 because the species has now been recorded at 43 localities (including 17 protected areas; see Appendix 1) and it is distributed over an area which retains most (~74%) of its forest cover.12 Therefore, the species is considered to be facing no major immediate extinction threats. However, some populations are likely to be declining due to deforestation by logging and large-scale mining, especially in the province Imbabura,13 where only four populations of the species are known.

Distribution: Stenocercus varius is endemic to an estimated 2,395 km2 area along the Pacific slopes of the Andes of northwestern Ecuador. The species occurs on the upper drainage of the Blanco and Toachi rivers at elevations between 1663 and 2391 m (Fig. 2).

Distribution of Stenocercus varius in Ecuador

Figure 2: Distribution of Stenocercus varius 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.14 The specific epithet varius is a Latin word meaning “diverse.”15 It could refer to the different shapes and sizes of the body scales of the lizard or it could be inspired in the variegated dorsal patter.4

See it in the wild: Mist Whorltail-Iguanas can be seen with ~10-20% certainty in forest edge situations during strongly sunny days in reserves such as Río Guajalito, Otonga, Santa Lucía, and Bellavista. Lizards may be spotted basking on walls, roofs, stacked boards, and cliffs having crevices.

Special thanks to Ysabela Coll for symbolically adopting the Mist Whorltail-Iguana and helping bring the Reptiles of Ecuador book project to life.

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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) Mist Whortail-Iguana (Stenocercus varius). 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/BJRH1367

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. Arteaga A, Bustamante L, Guayasamin JM (2013) The amphibians and reptiles of Mindo. Universidad Tecnológica Indoamérica, Quito, 257 pp.
  4. Boulenger GA (1885) Catalogue of the lizards in the British Museum. Taylor & Francis, London, 497 pp.
  5. Dávila M, Cisneros-Heredia DF (2017) Use of human-made buildings by Stenocercus lizards (Iguania, Tropiduridae). Herpetology Notes 10: 517–519.
  6. Cisneros-Heredia DF, Valencia J, Brito J, Almendáriz A, Muñoz G (2017) Stenocercus varius. The IUCN red list of threatened species. Available from: DOI: 10.2305/IUCN.UK.2017-2.RLTS.T50950734A50950739.en
  7. 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.
  8. Field notes, Reptiles of Ecuador book project.
  9. Almendáriz A, Orcés G (2004) Distribución de algunas especies de la herpetofauna de los pisos: altoandino, temperado y subtropical. Revista Politécnica 25: 97–150.
  10. 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.
  11. IUCN (2001) IUCN Red List categories and criteria: Version 3.1. IUCN Species Survival Commission, Gland and Cambridge, 30 pp.
  12. MAE (2012) Línea base de deforestación del Ecuador continental. Ministerio del Ambiente del Ecuador, Quito, 30 pp.
  13. Guayasamin JM, Cisneros-Heredia DF, Vieira J, Kohn S, Gavilanes G, Lynch RL, Hamilton PS, Maynard RJ (2019) A new glassfrog (Centrolenidae) from the Chocó-Andean Río Manduriacu Reserve, Ecuador, endangered by mining. PeerJ 7: e6400. DOI: 10.7717/peerj.6400
  14. 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
  15. Brown RW (1956) Composition of scientific words. Smithsonian Books, Washington D.C., 882 pp.

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

EcuadorCotopaxiOtonga Biological StationTorres-Carvajal 2007
EcuadorCotopaxiPeñas ColoradasTorres-Carvajal 2009
EcuadorCotopaxiSan Francisco de Las PampasTorres-Carvajal 2007
EcuadorImbaburaCuellaje, 7 km N ofiNaturalist
EcuadorImbaburaHacienda La FloridaPhoto by Carlos Zorrilla
EcuadorImbaburaIntag Cloud Forest ReserveFacebook
EcuadorImbaburaSanta RosaMZUTI 5114
EcuadorImbaburaWarimanPhoto by Peter Joost
EcuadorPichinchaBellavista Cloud Forest ReserveThis work
EcuadorPichinchaBosque Protector CambugánMECN 2009
EcuadorPichinchaBosque Protector VerdecochaMECN 2009
EcuadorPichinchaCampamento Silante, 2 km W ofKU 132492
EcuadorPichinchaChillogallo, 23 km W ofThis work
EcuadorPichinchaChiriboga, 5 km E ofTorres-Carvajal 2007
EcuadorPichinchaEstación Experimental La FavoritaAlmendáriz & Orcés 2004
EcuadorPichinchaFinca Santa LuciaKU 142704
EcuadorPichinchaHacienda Las Palmas Yánez-Muñoz 2007
EcuadorPichinchaHacienda San AgustíniNaturalist
EcuadorPichinchaLa HesperíaiNaturalist
EcuadorPichinchaLas Gralarias ReserveArteaga et al. 2013
EcuadorPichinchaLloa Mindo–San CarlosMECN 5844
EcuadorPichinchaMaquipucuna ReserveTorres-Carvajal 2007
EcuadorPichinchaNanegalito, 9 km SW ofiNaturalist
EcuadorPichinchaPacha Quindi Nature RefugeThis work
EcuadorPichinchaPahuma Orchid ReserveYánez-Muñoz 2007
EcuadorPichinchaPaz de las AvesPhoto by Rudy Gelis
EcuadorPichinchaQuebrada Loma RedondaiNaturalist
EcuadorPichinchaRío BlancoTorres-Carvajal 2009
EcuadorPichinchaRío BravoPhoto by Augusto Rodríguez
EcuadorPichinchaRío CristalMECN 508
EcuadorPichinchaSanta Lucía Cloud Forest ReserveThis work
EcuadorPichinchaSanta RosaArteaga et al. 2013
EcuadorPichinchaSaragoza–Río CintoMECN 2009
EcuadorPichinchaTambo Tanda LodgeThis work
EcuadorPichinchaTamboquinde Biological ReserveMECN 2009
EcuadorPichinchaTandapi*Torres-Carvajal 2007
EcuadorPichinchaTandayapa LodgeiNaturalist
EcuadorPichinchaVía a MindoiNaturalist
EcuadorPichinchaVía Lloa–MindoYánez-Muñoz & Ramírez 2008
EcuadorPichinchaYamboTorres-Carvajal 2007
EcuadorSanto Domingo de los TsáchilasChiriboga, 8.6 km SW ofiNaturalist
EcuadorSanto Domingo de los TsáchilasRío Guajalito Protected ForestDávila-Jativa & Cisneros-Heredia 2017