DOI10.47051/MBHS2870

Published June 10, 2026. Updated August 31, 2026. Open access.

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Konstant’s Lightbulb-Lizard (Riama konstanti)

Reptiles of Ecuador | Sauria | Gymnophthalmidae | Riama konstanti

English common name: Konstant’s Lightbulb-Lizard.

Spanish common name: Lagartija minadora de Konstant.

Recognition: ♂♂ 15.4 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=6.2 cm. ♀♀ 14.0 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=5.7 cm..1 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.2,3 The Konstant’s Lightbulb-Lizard (R. konstanti) co-occurs with R. labionis, from which it differs by having a uniformly black belly, and R. colomaromani, from which it differs by being smaller in body size and by having a brown (instead of glossy black) dorsal coloration (Fig. 1). From the similar, but allopatric R. unicolor, it differs by having a higher number of supraoculars (4 vs. 2–3).1 Riama konstanti exhibits little sexual dimorphism, with males differing from females primarily by having a reddish tint on the lower flanks and underside of tail.1

Figure showing variation among individuals of Riama konstanti

Figure 1: Individuals of Riama konstanti from Cotopaxi province, Ecuador: Otonga Reserve (); 9 km south of Las Pampas (). j=juvenile.

Natural history: Riama konstanti is a rarely encountered, semi-fossorial lizard that occurs in pristine montane cloud forests as well as along forest-edge clearings and dirt roads.1 Konstant’s Lightbulb-Lizards spend the vast majority of their lives within crevices, self-excavated tunnel networks in friable soils, or concealed beneath decomposing logs, root systems, and deep leaf-litter matrices.1,4 When unearthed or exposed, individuals rapidly attempt to retreat underground; if handled, they may bite or employ caudal autotomy to shed the tail.4 Like its congeners, R. konstanti exhibits extreme stenothermy, rendering it exceptionally vulnerable to thermal stress—rapidly succumbing to elevated temperatures if exposed to direct sunlight or handled continuously for more than a few seconds.4

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Conservation: Critically Endangered Considered to be facing imminent risk of extinction..1 Riama konstanti is recommended for this category because the species is known only from an extremely small (around 5 km2) cloud forest area that continues to decline in extent and quality due to deforestation. Only two localities are known (Appendix 1); they lack connectivity between them, and one is under immediate threat of disappearance due to the expansion of the cattle grazing frontier.1

Distribution: Riama konstanti is known from just two localities along the western foothills of the Ecuadorian Andes in Cotopaxi province (Fig. 2). The species occurs over an area of approximately 5 km2.

Distribution of Riama konstanti in Ecuador

Figure 2: Distribution of Riama konstanti in Ecuador. The star corresponds to the type locality: Otonga Reserve, Cotopaxi 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.5–8 The species is named after William “Bill” Konstant, in recognition of his more than four decades of contributions to wildlife conservation. Since 1980, Bill has helped safeguard populations of threatened species and their habitats in Latin America, Africa, and Asia.1

Where to observe: Riama konstanti is rarely encountered unless researchers actively target its microhabitat by methodically digging in areas of friable soil or by searching under thick accumulations of leaf-litter. At the Otonga Reserve, intensive sampling efforts yield a predictable encounter rate of approximately 2–3 individuals per day of dedicated fieldwork.

Author: Alejandro ArteagaaAffiliation: Fundación Khamai, Reserva Arlequín, Ecoruta Paseo del Quinde km 56, Santa Rosa de Mindo, Pichincha 171202, Ecuador.

Photographer: Jose VieirabAffiliation: Tropical Herping (TH), Quito, Ecuador.,cAffiliation: ExSitu, Quito, Ecuador.

How to cite? Arteaga A (2026) Konstant’s Lightbulb-Lizard (Riama konstanti). 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/MBHS2870

Literature cited:

  1. 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
  2. Doan TM, Castoe TA (2005) Phylogenetic taxonomy of the Cercosaurini (Squamata: Gymnophthalmidae), with new genera for species of Neusticurus and Proctoporus. Zoological Journal of the Linnean Society 143: 405–416. https://doi.org/10.1111/j.1096-3642.2005.00145.x
  3. 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
  4. Field notes, Reptiles of Ecuador book project.
  5. 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.
  6. 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.
  7. 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.
  8. 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 konstanti in Ecuador (Fig. 2). Asterisk (*) indicates type locality.

CountryProvinceLocalitySource
EcuadorCotopaxiLas Pampas, 9 km S ofArteaga et al. 2026
EcuadorCotopaxiReserva Otonga*Arteaga et al. 2026