Published October 14, 2021. Open access.

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Border Whorltail-Iguana (Stenocercus limitaris)

Reptiles of Ecuador | Sauria | Tropiduridae | Stenocercus | Stenocercus limitaris

English common name: Border Whorltail-Iguana.

Spanish common names: Guagsa limítrofe, guagsa de la frontera.

Recognition: ♂♂ 29.4 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=9.7 cm. ♀♀ 24.8 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=8.2 cm..1 The Border Whorltail-Iguana (Stenocercus limitaris) 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.2 Stenocercus limitaris occurs nearby, and is often confused with, S. puyango, S. iridescens, and Microlophus occipitalis. From S. puyango and S. iridescens, it differs by having keeled, instead of smooth, head and ventral scales.3 From M. occipitalis, it differs by having 3–5, instead of 7–8, supraocular scales.3,4 Males of S. limitaris differ from females by being larger and having a raised mid-dorsal crest.3

Figure showing variation among individuals of Stenocercus limitaris

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

Natural history: Locally frequentRecorded weekly in densities below five individuals per locality.. Stenocercus limitaris is a diurnal and terrestrial lizard that inhabits semi-deciduous foothill forests,5 open areas, secondary vegetation, and heavily disturbed areas such as pastures, crops, and roadsides.68 Border Whorltail-Iguanas are especially active during sunny hours, either on the ground among thickets and fencerows or on bushes and fences less than 1 m above the ground.1,6 During cool and overcast days, less lizards (usually only females or juveniles) are seen active.1 When threatened, individuals quickly take shelter under rocks, debris piles, or in crevices in walls.1,6 If captured, they may shed the tail and bite as a method of defense and escape.6

Conservation: Vulnerable Considered to be facing a high risk of extinction in the mid-term future..8 Stenocercus limitaris is included in this category because the species’ extent of occurrence is small, less than 5,000 km2, and its habitat is declining in extent and quality due to increased human activities such as infrastructure expansion, agriculture, and livestock grazing.8 Based on maps of Ecuador’s vegetation cover published in 2012,9 the majority (~54%) of the species’ forest habitat has been destroyed. Without forested areas, it is unknown if the populations of S. limitaris can survive in modified environments.8 Border Whorltail-Iguanas have only been recorded in two protected areas: Buenaventura Biological Reserve (Ecuador) and Reserva Nacional de Tumbes (Peru).

Distribution: Stenocercus limitaris is native to an estimated 4,627 km2 area in the Tumbesian foothills of the Andes in extreme southwestern Ecuador (provinces El Oro and Loja) and northwestern Peru (departments Piura and Tumbes). The species has been recorded at elevations between 813 m and 1904 m (Fig. 2).

Distribution of Stenocercus limitaris in Ecuador

Figure 2: Distribution of Stenocercus limitaris in Ecuador. The star corresponds to the type locality: Alamor, Loja 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.10 The specific epithet limitaris is a Latin word meaning “on the border.” It refers to the distribution of the species in the borderlands between Ecuador and Peru.1

See it in the wild: Border Whorltail-Iguana are not easily observed in the wild, as it appears their populations are fragmented and under pressure from habitat loss and predation by exotic species. The area having the greatest number of recent observation is the immediate environs of the town Alamor, Loja province. The easiest way to observe lizards of this species is during hot sunny hours, which is when individuals move and bask in open areas on top of vegetation.

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.,cAffiliation: ExSitu, Quito, Ecuador.

How to cite? Quezada A (2021) Border Whorltail-Iguana (Stenocercus limitaris). 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/KBPG2908

Literature cited:

  1. Cadle JE (1998) New species of lizards, genus Stenocercus (Iguania: Tropiduridae) from western Ecuador and Peru. Bulletin of the Museum of Comparative Zoology 155: 257–297.
  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. 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
  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. Field notes, Reptiles of Ecuador book project.
  7. 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.
  8. Sánchez J (2019) Stenocercus limitaris. The IUCN red list of threatened species. DOI: 10.2305/IUCN.UK.2019-3.RLTS.T50950675A50950678.en
  9. MAE (2012) Línea base de deforestación del Ecuador continental. Ministerio del Ambiente del Ecuador, Quito, 30 pp.
  10. 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 limitaris in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used. Asterisk (*) indicates type locality.

EcuadorEl OroBuenaventura Biological ReserveYánez-Muñoz et al. 2019
EcuadorEl OroMoromoroPhoto by Leodán Aguilar
EcuadorEl OroPiñasCadle 1998
EcuadorEl OroSalviasCadle 1998
EcuadorLojaAlamorTorres-Carvajal 2007
EcuadorLojaAlamor, 12.8 km N ofTorres-Carvajal 2007
EcuadorLojaCangonamá, 2 km E ofiNaturalist
EcuadorLojaCruzpambaTorres-Carvajal 2007
EcuadorLojaEl LimoiNaturalist
EcuadorLojaLa Hoyada, 1.5 km N ofiNaturalist
PeruPiuraBase of Cerro AyapateCadle 1998
PeruTumbesQuebrada FaicalCadle 1998