Published November 18, 2021. Open access.

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Ornate Whorltail-Iguana (Stenocercus ornatus)

Reptiles of Ecuador | Sauria | Tropiduridae | Stenocercus | Stenocercus ornatus

English common name: Ornate Whorltail-Iguana.

Spanish common name: Guagsa ornamentada.

Recognition: ♂♂ 29.4 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=8.5 cm. ♀♀ 20.7 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=7.1 cm..1,2 The Ornate Whorltail-Iguana (Stenocercus ornatus) differs from other lizards in its area of distribution (small, fossorial species in the genera Pholidobolus and Macropholidus) by being larger and having keeled dorsal scales with pointed ends.3 In its range of distribution, S. ornatus can be confused with S. S. rhodomelas and S. festae. From the former, it differs by having a small antehumeral fold and by lacking an extensive black patch on the gular region in adult males (antehumeral fold absent and black patch on the gular region in adult males present in S. rhodomelas).1,2 From the latter, it differs by having a white to pale green moustachial stripe (fully formed stripe indistinct or absent in S. festae). Stenocercus humeralis co-occurs with S. ornatus, but it has granular scales on the dorsum and lacks a dorsal crest (dorsal crest present in S. ornatus).1,2 Stenocercus limitaris can also co-occur with S. ornatus, but it has keel-shaped ventral scales and males have a gular black patch (smooth ventral scales and patch absent in S. ornatus).2 Males of S. ornatus differ from females by having a large black spots on each shoulder, a large dorsal crest, and yellow pectoral and pelvic regions.4,5

Figure showing variation among individuals of Stenocercus ornatus

Figure 1: Individuals of Stenocercus ornatus from Guanazán (), El Oro province, and Alamor (), Loja province, Ecuador. sa=subadult.

Natural history: Locally frequentRecorded weekly in densities below five individuals per locality.. Stenocercus ornatus is a diurnal and terrestrial lizard that inhabits humid to seasonally dry montane shrublands, high evergreen montane forests, and paramos.1,6 This species is found mainly in open areas, secondary vegetation,7,8 in the outskirts of cities, and near houses.9 On sunny days Ornate Whorltail-Iguanas can be found basking and foraging on the ground, rocks, shrubby vegetation, or on the leaves of Agave plants.7,9 When not active, they hide under rocks or in crevices in dirt walls.9 If they are manipulated, they may shed the tail and bite as a method of defense and escape.9 Gravid females have been found to contain two eggs,1 but the real clutch size has not been confirmed.

Conservation: Vulnerable Considered to be facing a high risk of extinction in the mid-term future..10,11 Stenocercus ornatus is included in this category mainly because its extent of occurrence does not exceed 7,000 km2 and more than 60% of the native vegetation in this area has already been lost due to human activities such as urban, agricultural and livestock expansion.10,12 The species is found in protected areas such as Podocarpus National Park and the San Francisco Scientific Station, but more than 97% of the potential distribution of S. ornatus is outside these areas.

Distribution: Stenocercus ornatus is endemic to an estimated 6,082 km2 area in the Pacific slopes, inter-Andean basins, and upper valleys of the Catamayo (Pacific drainage) and Zamora (Atlantic drainage) rivers in the high Andes of southern Ecuador, Azuay, El Oro and Loja provinces. The species has been recorded at elevations between 1400 m and 2772 m (Fig. 2).

Distribution of Stenocercus ornatus in Ecuador

Figure 2: Distribution of Stenocercus ornatus in Ecuador. The star corresponds to the type locality: Loja. 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.13 The specific epithet ornatus, which is a Latin word meaning “decorated” or “ornamented,”14 probably refers to the vivid colors and spotting patterns along the body of males of this species.

See it in the wild: Ornate Whorltail-Iguanas are becoming increasingly difficult to observe in the wild, but in some places, like Cerro Villonaco and in the vicinity of the town Saraguro, individuals can be seen with almost complete certainty. The easiest way to observe lizards of this species is by walking along the edge of dirt roads in areas having remnants of native shrubland during hot sunny hours.

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

Editor: Alejandro ArteagaaAffiliation: Biodiversity Field Lab, Khamai Foundation, Quito, Ecuador.

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

How to cite? Quezada A (2021) Ornate Whorltail-Iguana (Stenocercus ornatus). 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/WRPZ2411

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. Gray JE (1845) Catalogue of the specimens of lizards in the collection of the British Museum. Trustees of the British Museum, London, 289 pp.
  5. 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.
  6. 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.
  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. 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.
  9. Field notes, Reptiles of Ecuador book project.
  10. Cisneros-Heredia DF, Valencia J, Muñoz G, Almendáriz A, Brito J (2019) Stenocercus ornatus. The IUCN red list of threatened species. Available from: DOI: 10.2305/IUCN.UK.2019-3.RLTS.T50950684A50950693.en
  11. 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.
  12. MAE (2012) Línea base de deforestación del Ecuador continental. Ministerio del Ambiente del Ecuador, Quito, 30 pp.
  13. 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
  14. 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 ornatus in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used. Asterisk (*) indicates type locality.

EcuadorAzuayPoetateThis work
EcuadorEl OroChivaturcoGarzón-Santomaro et al. 2019
EcuadorEl OroGuanazánThis work
EcuadorEl OroLa EnramadaGarzón-Santomaro et al. 2019
EcuadorLojaAlamorThis work
EcuadorLojaCascada La EraiNaturalist
EcuadorLojaCascada NamandaiNaturalist
EcuadorLojaCelicaTorres-Carvajal 2007
EcuadorLojaCerro UritusingaTorres-Carvajal 2007
EcuadorLojaCerro Villonaco Torres-Carvajal 2007
EcuadorLojaCuenca–SaraguroThis work
EcuadorLojaEl YuroTorres-Carvajal et al. 2019
EcuadorLojaLoja*Fritts 1974
EcuadorLojaLoja, 1 km E ofTorres-Carvajal 2007
EcuadorLojaLoja, 2 km E ofTorres-Carvajal 2007
EcuadorLojaLoja, 5 km N ofTorres-Carvajal 2007
EcuadorLojaLoja, 6 km S ofTorres-Carvajal 2007
EcuadorLojaLoja, 7.9 km W ofKU 202944
EcuadorLojaMadrigal del PodocarpusiNaturalist
EcuadorLojaMirador El EspejoGBIF
EcuadorLojaParque JipiroMZUA.RE.0068
EcuadorLojaPurunumaTorres-Carvajal 2007
EcuadorLojaReserva Biológica UtuanaThis work
EcuadorLojaRío OñaMHNG 2437.059
EcuadorLojaSan BartoloTorres-Carvajal 2007
EcuadorLojaSaraguroThis work
EcuadorLojaVilcabamba, environs ofTorres-Carvajal 2007
EcuadorLojaYangana, 10.6 km S ofTorres-Carvajal 2007
EcuadorZamora ChinchipeSan Francisco Scientific StationMZUA.Re.0159