Published October 14, 2021. Open access.

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Iridescent Whorltail-Iguana (Stenocercus iridescens)

Reptiles of Ecuador | Sauria | Tropiduridae | Stenocercus | Stenocercus iridescens

English common name: Iridescent Whorltail-Iguana.

Spanish common name: Guagsa iridiscente.

Recognition: ♂♂ 29.4 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=9.9 cm. ♀♀ 21.3 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=8.3 cm.. The Iridescent Whorltail-Iguana (Stenocercus iridescens) differs from most other medium-sized diurnal and terrestrial lizards in its area of distribution (particularly species in the family Teiidae) by having keeled dorsal scales with pointed ends instead of granular scales.1 Stenocercus iridescens occurs nearby, and is often confused with, S. puyango, S. limitaris, and Microlophus occipitalis. From S. puyango, it differs by lacking a post-femoral mite pocket and posterior circumorbital scales (both characters are present in S. puyango).2,3 From S. limitaris, it differs by having smooth, instead of keeled, head and ventral scales.2 From M. occipitalis, it differs by having 2–5, instead of 7–8, supraocular scales.2,4 Males of S. iridescens differ from females by having a colorful ventral coloration consisting of a pink belly, yellow chest, black neck, and reddish throat (belly cream or pale brown in females and juveniles).2

Figure showing variation among individuals of Stenocercus iridescens

Figure 1: Individuals of Stenocercus iridescens from Reserva Biológica Cerro Seco, Manabí province (); Cerro de Hayas, Guayas province (); Vinces, Los Ríos province (); and Reserva Las Balsas, Santa Elena province (), Ecuador. j=juvenile.

Natural history: Extremely commonLikely to be seen every day, usually in large numbers.. Stenocercus iridescens is diurnal and terrestrial lizard that inhabits a variety of natural habitats ranging from dry lowland shrublands and deciduous lowland forests to evergreen montane forests.5 It is a dominant species in dry forests throughout western Ecuador. Iridescent Whorltail-Iguanas prefer secondary forest areas and clearings in the interior of the forest, but are also adapted to human-modified environments such as pastures, crops, reforested areas, and infrastructures.610 Females are most often found on the ground between sticks while males occupy more prominent places such as tree trunks and shrubs up to 1.3 m above the ground.11 Individuals are most active during sunny days and may be seen basking on large rocks.10 At night, they sleep on the leaf-litter, on the ground, or on trunks, twigs, wood poles, shrubs, or agave plants up to 130 cm above the ground.10,12 The diet of this species includes a wide variety of arthropods, but the specific prey items are not known.11 Iridescent Whorltail-Iguanas escape predators by running or by remaining still and relying on their camouflage.11 If captured, they may shed the tail and bite as a method of defense and escape.10 There are records of birds (Caracara cheriway,13 Falco sparverius,14 and Athene cunicularia15) and snakes (Rhinobothryum bovallii16) preying upon individuals of this species. Stenocercus iridescens is a territorial lizard with an average home range area of 21 m2.17 Gravid females containing two eggs have been found in Ecuador,10 but the real clutch size is not known.

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Conservation: Least Concern Believed to be safe from extinction given current circumstances..1820 Stenocercus iridescens is listed in this category because the species is widely distributed, abundant throughout its range, and considered to be facing no major immediate extinction threats.18 It is also found in at least 16 protected areas (Appendix 1). Although the species is widely distributed and tolerates moderate habitat degradation, its populations are fragmented and occur over an area where most (~66%) of the forest cover has been transformed into plantations and human settlements.21 Therefore, S. iridescens may qualify for a threatened category in the near future if its habitat continues to be destroyed.

Distribution: Stenocercus iridescens is native to an estimated 58,468 km2 area on the Tumbesian lowlands and adjacent foothills of the Andes in Ecuador and southwestern Colombia. The species has been recorded at elevations between 0 and 2060 m (Fig. 2).

Distribution of Stenocercus iridescens in Ecuador

Figure 2: Distribution of Stenocercus iridescens in Ecuador. The star corresponds to the type locality: Pallatanga, Chimborazo 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 (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.22 The specific epithet iridescens, which comes from the Greek word iridos (meaning “rainbow”),23 probably refers to the colorful belly of the males in this species.

See it in the wild: Iridescent Whorltail-Iguanas can be seen with almost complete certainty during strongly sunny days in protected areas such like Machalilla National Park, Cerro Blanco Protected Forest Blanco, and Manglares Churute Ecological Reserve. The easiest way to observe lizards of this species is in open areas near vegetation cover.

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

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

Photographers: Jose Vieira,aAffiliation: Tropical Herping (TH), Quito, Ecuador.,cAffiliation: ExSitu, Quito, Ecuador. Alejandro Arteaga,aAffiliation: Tropical Herping (TH), Quito, Ecuador. and Sebastián Di DoménicodAffiliation: Keeping Nature, Bogotá, Colombia.

How to cite? Quezada A (2021) Iridescent Whorltail-Iguana (Stenocercus iridescens). 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/SDWL4438

Literature cited:

  1. 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.
  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. Torres-Carvajal O (2005) A new species of iguanian lizard (Stenocercus) from the western lowlands of southern Ecuador and northern Peru. Herpetologica 61: 78–85. DOI: 10.1655/04-32.2
  4. Boulenger GA (1885) Catalogue of the lizards in the British Museum. Taylor & Francis, London, 497 pp.
  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. Steihnke J (2016) A comparative study of herpetofauna in a primary forest and reforested area in coastal Ecuador. Journal of Young Investigators 30: 14–19.
  7. Cruz García FK (2017) Diversidad y preferencia de microhábitats de la herpetofauna del Bosque Protector Pedro Franco Dávila (Jauneche) y del Área Provincial Natural de Recreación Cerro de Hayas (Naranjal). BSc thesis, Universidad de Guayaquil, 94 pp.
  8. Dávila M, Cisneros-Heredia DF (2017) Use of human-made buildings by Stenocercus lizards (Iguania, Tropiduridae). Herpetology Notes 10: 517–519.
  9. 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.
  10. Field notes, Reptiles of Ecuador book project.
  11. Brennan R (2010) Un estudio ecológico de las lagartijas del valle seco de Buenavista y de los valles húmedos de La Josefina y Salango. Independent Study Project (ISP) Collection, Vermont, 828 pp.
  12. Valencia JA, Garzón K (2011) Guía de anfibios y reptiles en ambientes cercanos a las estaciones del OCP. Fundación Herpetológica Gustavo Orcés, Quito, 268 pp.
  13. Ramírez-Jaramillo S, Jácome-Chiriboga N, Alfaro-Ponce N, Cabrera L, Garzón-Santomaro C (2020) Registros de alimentación y reproducción del carancho norteño Caracara cheriway en el noroeste de Sudamérica. Revista Catalana d’Ornitologia 36: 46–55. DOI: 10.2436/20.8100.01.19
  14. Ramírez-Jaramillo S, Allan-Miranda A, Salazar M, Jácome-Chiriboga N, Robayo J, Marcayata A, Reyes-Puig J, Yánez-Muñoz MH (2018) Revisión de las presas vertebradas consumidas por Falco sparverius en América del sur y nuevos registros para Ecuador. Hornero 33: 51–57.
  15. Rodríguez-Reyes E (2015) Abundancia relativa y dieta del búho terrestre Athene cunicularia punensis (Chapman, 1914) en las zonas circundantes de la comuna Atahualpa, provincia de Santa Elena, Ecuador. BSc thesis, Universidad de Guayaquil, 94 pp.
  16. Photo by Ryan Lynch.
  17. Morales-Ordoñez M, Salas J (2019) Estimación del ámbito de hogar de Stenocercus iridescens (Günther, 1859)(Squamata: Tropiduridae) durante la época lluviosa en el Bosque Protector Cerro Blanco (Guayas, Ecuador). Revista de Ciencias Naturales y Ambientales 10: 89–96.
  18. Cisneros-Heredia DF, Velasco J, Bolívar W (2016) Stenocercus iridescens. The IUCN red list of threatened species. Available from: DOI: 10.2305/IUCN.UK.2016-1.RLTS.T44579917A44579924.en
  19. 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.
  20. 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.
  21. MAE (2012) Línea base de deforestación del Ecuador continental. Ministerio del Ambiente del Ecuador, Quito, 30 pp.
  22. 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
  23. 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 iridescens in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used. Asterisk (*) indicates type locality.

ColombiaNariñoBoca GrandeTorres-Carvajal 2007
ColombiaNariñoSan Andrés de TumacoICN 4225
EcuadorAzuayTamarindoFHGO 416
EcuadorCañarHidroeléctrica OcañaELECAUSTRO 2019
EcuadorCañarHuatacónThis work
EcuadorChimborazoHostería SantValThis work
EcuadorChimborazoHuigraMZUTI 5395
EcuadorChimborazoPallatanga*Günther 1859
EcuadorChimborazoPuente sobre el Río ChimboTorres-Carvajal 2007
EcuadorChimborazoRecinto SacramentoTorres-Carvajal 2007
EcuadorChimborazoSacramentoPhoto by David Salazar
EcuadorChimborazoVía Huigra–El TriunfoMZUTI 5397
EcuadorCotopaxiEl Jardín de los SueñosPhoto by Christophe Pellet
EcuadorCotopaxiLa ManáTorres-Carvajal 2007
EcuadorEl OroBuena VistaCadle 1991
EcuadorEl OroBuena Vista, 7 km SE ofTorres-Carvajal 2005
EcuadorEl OroBuenaventura Biological ReserveYánez-Muñóz et al. 2019
EcuadorEl OroCasacayiNaturalist
EcuadorEl OroCascadas de ManuelYánez-Muñóz et al. 2019
EcuadorEl OroLote TituanaThis work
EcuadorEl OroMachalaUSNM 200957
EcuadorEl OroMachala, 7 km SSE ofTorres-Carvajal 2005
EcuadorEl OroPasajeTorres-Carvajal 2007
EcuadorEl OroPasaje, 15 km E ofTorres-Carvajal 2007
EcuadorEl OroPasaje, 2 km S ofTorres-Carvajal 2007
EcuadorEl OroPiñasTorres-Carvajal 2007
EcuadorEl OroRemolinosYánez-Muñóz et al. 2019
EcuadorEl OroRío JubonesAMNH 21944
EcuadorEl OroRoad Santa Rosa-ChontaAMNH 22121
EcuadorEl OroSanta RosaTorres-Carvajal 2007
EcuadorEl OroSatayán, 2 km E ofiNaturalist
EcuadorEl OroTahuínYánez-Muñóz et al. 2019
EcuadorEsmeraldasAguacateMECN 2865
EcuadorEsmeraldasEsmeraldas, 13 km S and 8 km W KU 142697
EcuadorEsmeraldasEsmeraldas, 5 km E ofCadle 1991
EcuadorEsmeraldasGalera, 3 km SW ofiNaturalist
EcuadorEsmeraldasLa Unión de AtacamesTorres-Carvajal 2007
EcuadorEsmeraldasMontalvoMHNG 2438.006
EcuadorEsmeraldasPlaya EscondidaiNaturalist
EcuadorEsmeraldasRío EsmeraldasiNaturalist
EcuadorEsmeraldasRío TiaoneEPN 5906
EcuadorEsmeraldasSameTorres-Carvajal 2007
EcuadorEsmeraldasTonchigüeTorres-Carvajal et al. 2006
EcuadorEsmeraldasTonsupa, 6 km E ofTorres-Carvajal 2000
EcuadorGuayasBalzarTorres-Carvajal 2000
EcuadorGuayasBastión PopulariNaturalist
EcuadorGuayasBosque Protector La ProsperinaiNaturalist
EcuadorGuayasCasas ViejasSalvatierra et al. 2010
EcuadorGuayasCerrito de los MorreñosNacipucha Quintero 2014
EcuadorGuayasCerro Blanco Protected ForestiNaturalist
EcuadorGuayasCerro de HayasThis work
EcuadorGuayasCerro ParaísoiNaturalist
EcuadorGuayasEl EmpalmeUSNM 200996
EcuadorGuayasEl Empalme, 21 km SW ofTorres-Carvajal 2007
EcuadorGuayasEl MorroSaeteros Gallardo 2014
EcuadorGuayasEl TriunfoPhoto by Juan Carlos Sánchez
EcuadorGuayasEl Triunfo, 7 km E ofKU 164170
EcuadorGuayasEstación Experimental Cuatro HermanitosTorres-Carvajal 2005
EcuadorGuayasEstero de SoledadTorres-Carvajal 2005
EcuadorGuayasFuerte HuancavilcaiNaturalist
EcuadorGuayasGuayaquilTorres-Carvajal 2007
EcuadorGuayasHacienda San MiguelUSNM 200985
EcuadorGuayasIsla Puná, Subida AltaNavarrete 2011
EcuadorGuayasIsla SantayPhoto by Eduardo Zabala
EcuadorGuayasLa Resistencia, 6 km SE ofiNaturalist
EcuadorGuayasLago PARCONiNaturalist
EcuadorGuayasLas PiedrasiNaturalist
EcuadorGuayasManglares Churute Ecological ReserveAmanda Quezada, personal observation
EcuadorGuayasMilagroTorres-Carvajal 2007
EcuadorGuayasMilagro, 5 km E ofTorres-Carvajal 2007
EcuadorGuayasPapagayo Protected ForestGarcía Aguilera 2017
EcuadorGuayasPeñón del RíoRamírez-Jaramillo et al. 2020
EcuadorGuayasQuinta SandovaliNaturalist
EcuadorGuayasRío DauleMHNG 2438.062
EcuadorGuayasRío TauraiNaturalist
EcuadorGuayasVilla NuevaGBIF
EcuadorImbaburaApuelaTorres-Carvajal 2007
EcuadorImbaburaApuela, 1 km E ofTorres-Carvajal 2007
EcuadorImbaburaApuela, 2 km W ofTorres-Carvajal 2007
EcuadorImbaburaIntagPhoto by Peter Joost
EcuadorImbaburaPeñaherrera, 1 km SW ofTorres-Carvajal 2007
EcuadorImbaburaPeñaherrera, 10 km S ofTorres-Carvajal 2007
EcuadorImbaburaPeñaherrera, 3 km SW ofTorres-Carvajal 2007
EcuadorImbaburaRío Apuela, 2 km NE ofTorres-Carvajal 2005
EcuadorLos RiosCentro Científico Río PalenqueTorres-Carvajal 2000
EcuadorLos RiosHostería El Senor de los CaballosThis work
EcuadorLos RíosBosque Protector Pedro Franco DávilaCruz & Sánchez 2016
EcuadorLos RíosHacienda El Triunfo, ca. 30 km N Vinces Torres-Carvajal 2005
EcuadorLos RíosHacienda La ClementinaMHNG 1117.009
EcuadorLos RíosJaunecheTorres-Carvajal 2007
EcuadorLos RíosJauneche, 1 km E ofTorres-Carvajal 2007
EcuadorLos RíosMaculMZUA.RE.0162
EcuadorLos RíosPacaloriMZUA.RE.0162
EcuadorLos RíosPatricia PilarTorres-Carvajal 2000
EcuadorLos RíosQuevedo Torres-Carvajal 2007
EcuadorLos RíosReserva Forestal Cerro SamamaYánez-Muñoz et al. 2016
EcuadorLos RíosSan FranciscoiNaturalist
EcuadorLos RíosVentanasTorres-Carvajal 2007
EcuadorManabíAgua Blanca, 4 km SE ofiNaturalist
EcuadorManabíBosque Seco Lalo LooriNaturalist
EcuadorManabíCabo PasadoTorres-Carvajal 2007
EcuadorManabíCabuyalThis work
EcuadorManabíCalceta, 2 km SW ofiNaturalist
EcuadorManabíCalceta, 4 km W ofTorres-Carvajal 2007
EcuadorManabíCantalapiedraSalvatierra et al. 2014
EcuadorManabíCerro San SebastiánMECN 5966
EcuadorManabíChoneMNHG 2438.061
EcuadorManabíEl LimónMaldonado Vásquez 2017
EcuadorManabíHacienda SiberiaHamilton et al. 2014
EcuadorManabíHostería ChirijeiNaturalist
EcuadorManabíJama CampayThis work
EcuadorManabíJipijapa, 12 km NNE ofTorres-Carvajal 2007
EcuadorManabíJunínTorres-Carvajal 2007
EcuadorManabíLa CrespaiNaturalist
EcuadorManabíLos FrailesThis work
EcuadorManabíMachalilla National ParkAlmendáriz & Carr 2011
EcuadorManabíPacoche LodgeThis work
EcuadorManabíPiedra Larga, 2 km S ofiNaturalist
EcuadorManabíPlaya DoradaThis work
EcuadorManabíPlaya DoradaThis work
EcuadorManabíPuerto RicoTorres-Carvajal 2007
EcuadorManabíPunta PrietaHamilton et al. 2014
EcuadorManabíRancho San JuanMaldonado Vásquez 2017
EcuadorManabíReserva Biológica Cerro SecoThis work
EcuadorManabíReserva Jama CoaqueSteinke 2016
EcuadorManabíRío AyampeThis work
EcuadorManabíRío ChoneiNaturalist
EcuadorManabíRío JamaPhoto by Lisa Brunetti
EcuadorManabíSan Clemente, 2 km N of Torres-Carvajal 2007
EcuadorManabíSan Vicente, 27 km N ofTorres-Carvajal 2007
EcuadorManabíSan Vicente, 32 km N ofTorres-Carvajal 2007
EcuadorManabíSan Vicente, 9 km N ofTorres-Carvajal 2007
EcuadorManabíThree Forests TrailPhoto by Ryan Lynch
EcuadorManabíTito Santos Biological ReserveAlmendariz et al. 2011
EcuadorManabíVía Pedernales–CojimíesThis work
EcuadorManabíVicinity of Refinería del PacifícoThis work
EcuadorPichinchaCalacalí, 12 km N ofiNaturalist
EcuadorPichinchaSector InfiernilloOnline multimedia
EcuadorSanta ElenaComuna AtahualpaRodríguez Reyes 2015
EcuadorSanta ElenaDos MangasSalvatierra et al. 2014
EcuadorSanta ElenaDos Mangas, 5 km E ofiNaturalist
EcuadorSanta ElenaDos RíosiNaturalist
EcuadorSanta ElenaMonte VerdeRamírez-Jaramillo et al. 2018
EcuadorSanta ElenaReserva Las BalsasThis work
EcuadorSanto Domingo de los TsáchilasEl EsfuerzoiNaturalist