Published December 17, 2020. Updated November 22, 2023 Open access. Peer-reviewed.

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Günther’s Sun Tegu (Euspondylus guentheri)

Reptiles of Ecuador | Sauria | Gymnophthalmidae | Euspondylus guentheri

English common name: Günther’s Sun Tegu.

Spanish common name: Lagartija tegú de Günther.

Recognition: ♂♂ 24.9 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=9.4 cm. ♀♀ 22.8 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=8.4 cm..13 Species in the genus Euspondylus differ from other similar-sized arboreal microteiids (particularly those in the genera Anadia, Cercosaura, and Selvasaura) by having smooth or striated rectangular dorsal scales, scales on flanks smaller than dorsals, and no pale vertebral stripe.1,4 The Günther’s Sun Tegu (E. guentheri) differs from its only known Ecuadorian congener (E. maculatus) mainly on the basis of coloration. Adults have a dorsal pattern of black irregular crossbars or blotches on a lighter background color; juveniles have a striking pattern of black crossbars on a bright yellowish ground color.13 Some individuals of Anadia petersi have black dorsal blotches, and thus, resemble E. guentheri in coloration, but they also have a dark brown stripe running along the body (absent in E. guentheri). Lizards of the genus Cercosaura may also look similar but they have granular scales on the side of the neck, whereas in Euspondylus these scales are large and plate-like.4

Figure showing an adult male individual of Euspondylus guentheri

Figure 1: Adult male of Euspondylus guentheri from Cabeceras del Bobonaza, Pastaza province, Ecuador.

Natural history: Euspondylus guentheri is an extremely rare primarily diurnal and arboreal lizard that inhabits old-growth to moderately disturbed evergreen lowland and foothill forests (=rainforests), but also occasionally ventures near human settlements.5 Günther’s Sun Tegus have been seen active during the daytime in open areas, sunning at ground level among roots and leaf-litter5 or moving on branches ~1 m above the ground.6 One individual was active on a muddy wall inside the forest at night.3 Individuals have also been found hidden during the daytime, under fallen branches at ground level,3 under thick leaf-litter,7 or among woody fungi on the bark of standing trees 2 m above the ground.8 When threatened, Günther’s Sun Tegus quickly flee under cover. If captured, they aggressively try to bite or readily shed the tail.3,8

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Conservation: Least Concern Believed to be safe from extinction given current circumstances..9 Euspondylus guentheri is listed in this category because the species is distributed over an area that retains most (~87%) of its original forest cover, and therefore is considered to be facing no major immediate threats of extinction.9,10 Also, Günther’s Sun Tegus occur in at least four protected areas: Colonso-Chalupas Biological Reserve, Río Bigal Biological Reserve, Wild Sumaco Wildlife Sanctuary, and El Quimi Biological Reserve. The most important threat to the long-term survival of the species is habitat destruction due to mining and the expansion of the agricultural frontier.

Distribution: Euspondylus guentheri is endemic to an area of approximately 38,747 km2 in the upper Amazon basin and adjacent foothills of the Andes in Ecuador (Fig. 2).

Distribution of Euspondylus guentheri in Ecuador

Figure 2: Distribution of Euspondylus guentheri in Ecuador. See Appendix 1 for a complete list of the presence localities included in the map.

Etymology: The generic name Euspondylus, which is derived from the Greeks words eu (=easy) and spondylos (=vertebra),11 probably refers to the ease with which the caudal vertebrae in lizards of this genus can become detached to allow the shedding of the tail. The specific epithet guntheri honors Albert Günther (1830–1914), a German-born British zoologist, ichthyologist, and herpetologist, best known for his role as Keeper of Zoology at the Natural History Museum in London.

See it in the wild: Euspondylus guentheri is one of the rarest lizards in the Amazon rainforest. A total of 20 sightings, including 11 museum specimens and photographs of 9 live individuals, have ever been reported. At Río Bigal Biological Reserve individuals have been observed more than once, albeit by chance. However, the likelihood of encountering an individual can increase if the search includes digging in areas of thick damp leaf-litter as well as turning over rocks and logs.

Acknowledgments: Special thanks to Alexis Barahona, Danilo Media, Jorge Flores, José Simbaña, and Thierry García for providing locality and natural history data of Euspondylus guentheri. This account was published with the support of Secretaría Nacional de Educación Superior Ciencia y Tecnología (programa INEDITA; project: Respuestas a la crisis de biodiversidad: la descripción de especies como herramienta de conservación; No 00110378), Programa de las Naciones Unidas (PNUD), and Universidad San Francisco de Quito (USFQ).

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

Academic reviewer: Jeffrey D CamperbAffiliation: Department of Biology, Francis Marion University, Florence, USA.

Photographer: Jose VieiracAffiliation: Tropical Herping (TH), Quito, Ecuador.,dAffiliation: ExSitu, Quito, Ecuador.

How to cite? Arteaga A (2023) Günther’s Sun Tegu (Euspondylus guentheri). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/VRFJ2435

Literature cited:

  1. Chávez G, Catenazzi A, Venegas PJ (2017) A new species of arboreal microteiid lizard of the genus Euspondylus (Gymnophtalmidae: Cercosaurinae) from the Andean slopes of central Peru with comments on Peruvian Euspondylus. Zootaxa 4350: 301–316. DOI: 10.11646/zootaxa.4350.2.6
  2. Boulenger GA (1885) Catalogue of the lizards in the British Museum. Taylor & Francis, London, 497 pp.
  3. Field notes, Reptiles of Ecuador book project.
  4. 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.
  5. Danilo Medina, pers. comm.
  6. Jose Simbaña, pers. comm.
  7. Thierry García, pers. comm.
  8. Alexis Barahona, pers. comm.
  9. Lehr E, Doan TM (2016) Euspondylus guentheri. The IUCN Red List of threatened species. Available from: DOI: 10.2305/IUCN.UK.2016-1.RLTS.T178658A50867804.en
  10. MAE (2012) Línea base de deforestación del Ecuador continental. Ministerio del Ambiente del Ecuador, Quito, 30 pp.
  11. 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 Euspondylus guentheri in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used.

EcuadorMorona SantiagoChiguazaKöhler & Lehr 2004
EcuadorMorona SantiagoMacumaUIMNH 65696
EcuadorMorona SantiagoValle del Río QuimiBetancourt et al. 2018
EcuadorNapoColonso Chalupas Biological ReserveAlexis Barahona, pers. comm.
EcuadorNapoNarupayacuPhoto by José Simbaña
EcuadorNapoWild Sumaco Wildlife SanctuaryCamper et al. (in press)
EcuadorOrellanaReserva Biológica Río BigalPhoto by Thierry García
EcuadorPastazaAlto CurarayKöhler & Lehr 2004
EcuadorPastazaCabeceras del Río BobonazaThis work; Fig. 1
EcuadorPastazaCentro de Rescate YanacochaReptiles of Ecuador book database
EcuadorPastazaMazaramuOrtega-Andrade 2010
EcuadorPastazaMontalvoPeters 1959
EcuadorPastazaPindoyacuOrtega-Andrade 2010
EcuadorPastazaPuyoPhoto by Danilo Medina
EcuadorPastazaRío LliquinoKöhler & Lehr 2004
EcuadorPastazaSantanaKöhler & Lehr 2004
EcuadorPastazaSarayacuO’Shaughnessy 1881