Orcés’ Blue Whiptail (Holcosus orcesi)

Reptiles of Ecuador | Sauria | Teiidae | Holcosus orcesi

English common names: Orcés’ Blue Whiptail, Peter’s Ameiva.

Spanish common name: Lagartija azul de Orcés, ameivas del Jubones.

Recognition: ♂♂ 36.4 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=12.4 cm. ♀♀ 30 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=10.4 cm.. The Orcés’ Blue Whiptail (Holcosus orcesi) is the only striped diurnal and terrestrial lizard in the valley of the Jubones river. It differs from other lizards in the area (particularly Stenocercus) by having small granular dorsal scales, large squarish ventral scales, broad plate-like scales on the head, and no spiny crest along the back.^1–3 The dorsum is reddish brown with thin cream longitudinal stripes. The flanks and ventral surfaces are grayish in females, and bright cyan in males. Males are larger, more robust, and have thicker heads than females.^1,3 This species differs from H. septemlineatus by having a poorly-defined brownish lateral stripe that is not evident on the face (clearly-defined black stripe along the flanks and face in H. septemlineatus).³ Other similar-looking bluish whiptails in southwestern Ecuador are Medopheos edracanthus and Dicrodon guttulatum, but they occur at lower elevations.

Figure showing variation among individuals of Holcosus orcesi

Figure 1: Individuals of Holcosus orcesi from Azuay province, Ecuador.

Natural history: Holcosus orcesi is a diurnal and terrestrial lizard that inhabits xeric areas such as dry montane shrublands and seasonally dry forests.¹ The species is present in areas containing a matrix of rural gardens, pastures, crops, and remnants of native vegetation.³ Orcés’ Blue Whiptails are active only during totally sunny hours, primarily between 10:00 am and 3:00 pm.^1,3 They forage frantically, essentially never stopping as they search for food at ground level close to scrubby thickets or along stream-side vegetation.^1,3 As soon as the sunshine is gone, individuals retreat to their hideouts, which are holes in the ground and among roots.^1,3 Orcés’ Blue Whiptails are insectivorous. Their diet includes beetles and grasshoppers.³ They are jittery lizards; always on the lookout for potential predators. Wariness and sprint speed are their main defense mechanisms, but they may also bite or readily shed the tail if captured.³ In the presence of a potential predator, most individuals take refuge among plants with thorns and spines; however, they do not disappear from sight and continue to forage within cover.³ Orcés’ Blue Whiptails are preyed upon by feral cats, dogs, and chickens.³ This species exists in the same geographic area as Stenocercus rhodomelas, Phyllodactylus leoni, P. reisii, Epictia subcrotilla, Mastigodryas pulchriceps, and Lampropeltis micropholis.³ In captivity, one female laid two eggs that hatched after ~2.5–3 months.⁴

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Conservation: Critically Endangered Considered to be facing imminent risk of extinction..⁵ Holcosus orcesi is listed in this category because the species is restricted to an extremely small (here estimated to be ~204 km²) inter-Andean valley area which has seen ~61.5% of its natural vegetation cover destroyed and replaced by human settlements and crops.^5,6 We estimate that, in total, there is no more than ~77.4 km² of suitable habitat remaining for H. orcesi. This is considered to be the lizard species closest to extinction in Ecuador.⁵ It was deemed “possibly extinct” because surveys failed to record it from 1959 until the first live specimen was photographed nearby Santa Isabel on July 2nd, 2017 (almost 60 years after its original description!).^3,5 As of 2020, there is only one confirmed population surviving in a small (~2.7 km²) habitat fragment under continuing pressure from human development, predation by exotic species (including cats, dogs, and chickens), and poaching.³ There is evidence that local people have collected this species for the international pet trade.³ Fortunately, in July 2020, the Orcés’ Blue Whiptail Conservation Project was launched. The project seeks to ensure the future of H. orcesi by reinforcing the single remaining wild population through a head-starting program in which young lizards are raised in captivity and subsequently released into the wild. The project also seeks to inspire local people to become guardians of the species and to eradicate exotic feral predators.

Distribution: Holcosus orcesi is endemic to an area of approximately 204 km² along the headwaters of the Río Jubones in the southwestern slopes of the Andes in Ecuador (Fig. 2).

Figure 2: Distribution of Holcosus orcesi in Ecuador. The star corresponds to the type locality: Abdón Calderón, Azuay province. See Appendix 1 for a complete list of the presence localities included in the map.

Etymology: The generic name Holcosus is probably derived from the Greek word holkos (a kind of grain).⁷ It may refer to the many grain-like keeled scales on the frontal region of the head in lizards of this genus.⁷ The specific epithet orcesi honors Gustavo Orcés, in recognition of his many contributions to the herpetology of Ecuador.¹

See it in the wild: There is only one locality where Orcés’ Blue Whiptails can still be encountered in the wild. This locality is not disclosed here to prevent poaching.

Special thanks to Suzana Lightman for symbolically adopting the Orcés’ Blue Whiptail and helping bring the Reptiles of Ecuador book project to life.

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Acknowledgments: Special thanks to Ernesto Arbeláez and Jose Manuel Falcón for providing locality data and natural history information for Holcosus orcesi. The Zoological Society for the Conservation of Species and Populations (ZGAP) provided the funding for the 2020 rescue mission that resulted in the establishment of a captive breeding conservation project for the species. We thank Frank Pichardo, Carlos Durán, and Amanda Quezada for their help and companionship during the fieldwork that resulted in the rediscovery of H. orcesi. 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).

Authors: Alejandro Arteaga^aAffiliation: Khamai Foundation, Quito, Ecuador. and Jose Vieira^aAffiliation: Tropical Herping (TH), Quito, Ecuador.^,^bAffiliation: ExSitu, Quito, Ecuador.

Photographer: Jose Vieira^aAffiliation: Tropical Herping (TH), Quito, Ecuador.^,^bAffiliation: ExSitu, Quito, Ecuador.

How to cite? Arteaga A, Vieira J (2024) Orcés’ Blue Whiptail (Holcosus orcesi). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: www.reptilesofecuador.com. DOI: 10.47051/WDQG2410

Literature cited:

Peters JA (1964) The lizard genus Ameiva in Ecuador. Bulletin of the Southern California Academy of Sciences 63: 113–127.
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.
Field notes, Reptiles of Ecuador book project.
José Manuel Falcón, pers. comm.
Cisneros-Heredia D, Yánez-Muñoz M, Brito J, Sánchez J (2017) Holcosus orcesi. The IUCN Red List of threatened species. Available from: www.iucnredlist.org. DOI: 10.2305/IUCN.UK.2017-2.RLTS.T49981813A49981970.en
MAE (2012) Línea base de deforestación del Ecuador continental. Ministerio del Ambiente del Ecuador, Quito, 30 pp.
Harvey MB, Ugueto GN, Gutberlet Jr RL (2012) Review of teiid morphology with a revised taxonomy and phylogeny of the Teiidae (Lepidosauria: Squamata). Zootaxa 3459: 1–156. DOI: 10.11646/zootaxa.3459.1.1

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

Country	Province	Locality	Source
Ecuador	Azuay	Abdón Calderón, 0.5 km NW of*	Peters 1964
Ecuador	Azuay	Abdón Calderón, 4 km SW of	Peters 1964
Ecuador	Azuay	Hostería Sol y Agua	Ernesto Arbeláez, pers. comm.
Ecuador	Azuay	Malapamba	Reptiles of Ecuador book database
Ecuador	Azuay	Parque Extremo Yunguilla	Ernesto Arbeláez, pers. comm.
Ecuador	Azuay	Río Minas	Peters 1964
Ecuador	Azuay	Río Rircay	Jose Manuel Falcón, pers. comm.