DOI10.47051/TKDS5945

Published September 26, 2021. Updated August 24, 2026. Open access. Peer-reviewed.

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Coloma’s Lightbulb-Lizard (Riama colomaromani)

Reptiles of Ecuador | Sauria | Gymnophthalmidae | Riama colomaromani

English common name: Coloma’s Lightbulb-Lizard.

Spanish common name: Lagartija minadora de Coloma.

Recognition: ♂♂ 15.8 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=8.8 cm. ♀♀ 18.5 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=8.7 cm..1,2 Lightbulb-lizards (Riama) are easily distinguished from other sympatric lizards by their fossorial habits and extremely reduced extremities, where the fore- and hind limbs are too short to meet when adpressed against the body.1,2 Riama colomaromani differs from most other members of its genus by having a glossy black to bluish-brown dorsum with small white or yellow spots along the flanks, blackish ventral surfaces, and a reddish iris (Fig. 1).1,2 This species differs from R. unicolor by having a black tail underside, rather than red with thin black longitudinal lines.1 From the similar, but allopatric R. tarletonorum, it differs by having more longitudinal dorsal scale rows in males (24–27 vs. 21–25) and a black dorsal coloration in females.2 Adult males of R. colomaromani display low sexual dimorphism, resembling females in size, coloration, and number of femoral pores.2

Figure showing variation among individuals of Riama colomaromani

Figure 1: Individuals of Riama colomaromani from Sigchos, Cotopaxi province, Ecuador. j=juvenile.

Natural history: Riama colomaromani is a rarely encountered lizard that nevertheless can attain high local densities within specialized microhabitats of high-Andean ecosystems, ranging from pristine evergreen montane and cloud forests to pasture margins near forest borders.4,5 This species exhibits semi-fossorial habits, routinely found sheltered beneath rocks, shallowly buried in loose, dark organic soil, or concealed inside dirt banks among root systems and decaying logs.1,3 Individuals have been discovered in modified roadside habitats characterized by pastures and secondary growth, sometimes near drainage ditches, small waterfalls, and ponds, though standing water is not an essential microhabitat feature.1,3 When exposed, individuals rapidly attempt to retreat underground; if captured, they may bite or employ caudal autotomy to shed the tail. Like its congeners, Coloma’s Lightbulb-Lizard exhibits extreme stenothermy, rendering it exceptionally sensitive to thermal stress—rapidly succumbing to elevated temperatures if exposed to direct sunlight or handled continuously for more than a few seconds.3

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Conservation: Endangered Considered to be facing a high risk of extinction in the near future..6 Riama colomaromani is listed in this category because, at the time of the assessment in 2019,6 its distribution area was estimated to be under 2,500 km2 and the species was only known to occur in four localities, all of them heavily affected by habitat destruction due to agricultural expansion and active mining concessions.6 Although eight localities of occurrence are reported here (Appendix 1), none of these represent a major distribution extension, and the species’ estimated extent of occurrence (Fig. 2), though larger than previously thought, is still smaller than the 5,000 km2 threshold needed to qualify for a less threatened category. Fortunately, some R. colomaromani populations in Pichincha province are in protected areas: Bosque Protector Verdecocha, Reserva Biológica Yanacocha, and Bosque Protector el Cedral.

Distribution: Riama colomaromani is endemic to an area of approximately 3,630 km2 along the Pacific slopes of the Andes in northwestern Ecuador (Fig. 2).

Distribution of Riama colomaromani in Ecuador

Figure 2: Distribution of Riama colomaromani in Ecuador. The star corresponds to the type locality: Chillogallo–Guajalito road, Pichincha province. See Appendix 1 for a complete list of the presence localities included in the map.

Etymology: The generic name Riama does not appear to be a reference to any feature of this group of lizards, but a matter of personal taste. John Edward Gray usually selected girls’ names to use on reptiles.7–10 The specific epithet colomaromani honors Ecuadorian biologist Luis Coloma, in recognition of his innumerable contributions to the herpetology of Ecuador.1

Where to observe: Riama colomaromani is rarely recorded unless researchers actively sample suitable microhabitats by methodically digging into loose organic topsoil or overturning large rocks and decaying logs. However, in localized microhabitats featuring adequate moisture and native forest cover, population densities can be surprisingly high. Targeted sampling yields predictable encounter rates of approximately 3–12 individuals per day of field effort, with optimal search sites including the Bosque Protector Verdecocha and the Reserva Biológica Yanacocha.

Authors: Miguel Ángel Méndez-GaleanoaAffiliation: Grupo de Biodiversidad y Sistemática Molecular, Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Bogotá, Colombia. and Alejandro ArteagabAffiliation: Tropical Herping (TH), Quito, Ecuador.

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

Photographer: Jose VieiradAffiliation: Tropical Herping (TH), Quito, Ecuador.,eAffiliation: ExSitu, Quito, Ecuador.

How to cite? Méndez-Galeano MA, Arteaga A (2026) Coloma’s Lightbulb-Lizard (Riama colomaromani). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: www.reptilesofecuador.com. https://doi.org/10.47051/TKDS5945

Literature cited:

  1. Kizirian DA (1996) A review of Ecuadorian Proctoporus (Squamata: Gymnophthalmidae) with descriptions of nine new species. Herpetological Monographs 10: 85–155. https://doi.org/10.2307/1466981
  2. Arteaga A, Tovar-Ortiz A, Vieira J, Bringsøe H, Quezada A, Camper J, Harris K (2026) Six new species of lizards (Riama, Sauria, Gymnophthalmidae) from the high Andes of Ecuador. In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador. Second Edition. Khamai Foundation & Tropical Herping, Quito, 1082–1119. https://doi.org/10.47051/GZNM5526
  3. Field notes, Reptiles of Ecuador book project.
  4. MECN, JOCOTOCO, ECOMINGA (2013) Herpetofauna en áreas prioritarias para la conservación: el sistema de reservas Jocotoco y Ecominga. Museo Ecuatoriano de Ciencias Naturales, Quito, 408 pp.
  5. Yánez-Muñoz M, Meza-Ramos P, Ramírez S, Reyes-Puig J, Oyagata L (2009) Anfibios y reptiles del Distrito Metropolitano de Quito (DMQ). In: Yánez-Muñoz MH, Moreno-Cárdenas PA, Mena-Valenzuela P (Eds) Guía de campo de los pequeños vertebrados del Distrito Metropolitano de Quito (DMQ). Museo Ecuatoriano de Ciencias Naturales (MECN), Quito, 9–52.
  6. Cisneros-Heredia DF (2019) Riama colomaromani. The IUCN Red List of threatened species. Available from: www.iucnredlist.org. https://doi.org/10.2305/IUCN.UK.2019-3.RLTS.T50950484A50950493.en
  7. Gray JE (1831) Description of a new genus of ophisaurean animal, discovered by the late James Hunter in New Holland. Treuttel, Würtz & Co., London, 40 pp.
  8. Gray JE (1831) A synopsis of the species of the class Reptilia. In: Griffith E, Pidgeon E (Eds) The animal kingdom arranged in conformity with its organization. Whittaker, Treacher, & Co., London, 1–110.
  9. Gray JE (1838) Catalogue of the slender-tongued saurians, with descriptions of many new genera and species. Annals and Magazine of Natural History 1: 274–283.
  10. Gray JE (1845) Catalogue of the specimens of lizards in the collection of the British Museum. Trustees of the British Museum, London, 289 pp.

Appendix 1: Locality data used to create the distribution map of Riama colomaromani in Ecuador (Fig. 2). Asterisk (*) indicates type locality.

CountryProvinceLocalitySource
EcuadorCotopaxiSigchosPhoto by Luis Coloma
EcuadorCotopaxiSigchos, 10 km NW ofArteaga et al. 2026
EcuadorImbaburaLa DeliciaKizirian 1996
EcuadorImbaburaSanta RosaGalarza-Verkovitch 2020
EcuadorPichinchaBosque Protector El CedralPhoto by Luis Coloma
EcuadorPichinchaChillogallo, 19.8 km W of*Kizirian 1996
EcuadorPichinchaReserva Biológica YanacochaYánez-Muñoz et al. 2013
EcuadorPichinchaZurolomaArteaga et al. 2026