Published May 2, 2021. Updated December 1, 2023. Open access. Peer-reviewed.

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Spotted Lightbulb-Lizard (Riama stigmatoral)

Reptiles of Ecuador | Sauria | Gymnophthalmidae | Riama stigmatoral

English common name: Spotted Lightbulb-Lizard.

Spanish common name: Lagartija minadora de puntos amarillos.

Recognition: ♂♂ 15.8 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=7.2 cm. ♀♀ 17.4 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=7.9 cm..1,2 Lightbulb-lizards are easily distinguishable from other lizards by their fossorial habits and extremities so short that the front and hind limbs cannot reach each other.1 Riama stigmatoral is the only member of its genus in its area of distribution. Individuals from the eastern part of the range have a brown dorsum with cream or yellow ventrolateral spots,1 but these spots are absent in western populations.2 Another lightbulb lizard that occurs in Morona Santiago province is R. anatoloros, but this species can be identified by its small size and complete series of supraciliary scales.1 Adult males of R. stigmatoral differ from females by having a broader head and more conspicuous spots along the flanks (Fig. 1).

Figure showing variation among individuals of Riama stigmatoral

Figure 1: Individuals of Riama stigmatoral from Santa Ana () and Guachapala (), Azuay province, Ecuador. j=juvenile.

Natural history: Riama stigmatoral is a rarely seen fossorial lizard that nevertheless occurs in high densities in select microhabitats within high evergreen montane forests.1,2 The species also occurs in pastures, plantations, and rural gardens adjacent to these forests.1,2 These lizards are usually found hidden under dirt cloths, logs, and rocks in bush fences at the border of pastures.2 Females lay clutches of two eggs under rocks.2 When dug up or otherwise exposed, these shy reptiles will quickly flee underground.2 If captured, they may bite or readily shed the tail. Spotted Lightbulb-Lizards are susceptible to high temperatures, dying if exposed to the sun or even if handled for longer than just a few seconds.2

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Conservation: Endangered Considered to be facing a high risk of extinction in the near future..3 Riama stigmatoral is listed in this category, instead of Vulnerable,4,5 because the species is known from only eight populations and is restricted to an area smaller than 5000 km2 that has lost ~77% of its natural vegetation cover.6 The habitat of R. stigmatoral is severely fragmented and continues to decline in extent and quality due to encroaching human activities such as agriculture and urban development.

Distribution: Riama stigmatoral is endemic to an area of approximately 1,362 km2 in the headwaters of the Paute river in southeastern Ecuador. The species occurs along the Amazonian versant of the Andes as well as in the inter-Andean valley of Cuenca (Fig. 2).

Distribution of Riama stigmatoral in Ecuador

Figure 2: Distribution of Riama stigmatoral in Ecuador. The star corresponds to the type locality: Pailas, Morona Santiago 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 girl’s names to use on reptiles.710 The specific epithet stigmatoral comes from the Greek word stigma (=spot) and the Latin noun toral (=valance), and refers to the ventrolaterally positioned spots of males of this species.1

See it in the wild: Spotted Lightbulb-Lizards are recorded rarely unless actively searched for by digging in areas of soft soil or by turning over rocks and logs in pastures near remnants of native forest. These lizards can be found with almost complete certainty in rural areas near the towns Guachapala and Sevilla de Oro, Azuay province.

Acknowledgments: Special thanks to Amanda Quezada for finding some of the specimens of Riama stigmatoral pictured in this account.

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 (2023) Spotted Lightbulb-Lizard (Riama stigmatoral). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/HKXV6456

Literature cited:

  1. Kizirian DA (1996) A review of Ecuadorian Proctoporus (Squamata: Gymnophthalmidae) with descriptions of nine new species. Herpetological Monographs 10: 85–155. DOI: 10.2307/1466981
  2. Field notes, Reptiles of Ecuador book project.
  3. Carrillo E, Aldás A, Altamirano M, Ayala F, Cisneros-Heredia DF, Endara A, Márquez C, Morales M, Nogales F, Salvador P, Torres ML, Valencia J, Villamarín F, Yánez-Muñoz M, Zárate P (2005) Lista roja de los reptiles del Ecuador. Fundación Novum Millenium, Quito, 46 pp.
  4. Cisneros-Heredia DF (2019) Riama stigmatoral. The IUCN Red List of threatened species. Available from: DOI: 10.2305/IUCN.UK.2019-3.RLTS.T178237A54446205.en
  5. IUCN (2001) IUCN Red List categories and criteria: Version 3.1. IUCN Species Survival Commission, Gland and Cambridge, 30 pp.
  6. MAE (2012) Línea base de deforestación del Ecuador continental. Ministerio del Ambiente del Ecuador, Quito, 30 pp.
  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 stigmatoral in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used. Asterisk (*) indicates type locality.

EcuadorAzuayCerro NegroKizirian 1996
EcuadorAzuayCruz y AntenasSánchez-Pacheco et al. 2017
EcuadorAzuayGuachapala, 1 km S ofThis work; Fig. 1
EcuadorAzuaySan Vicente, camino a las antenasSánchez-Pacheco et al. 2017
EcuadorAzuaySevilla de OroSánchez-Pacheco et al. 2012
EcuadorAzuayVía Auquilula–Santa AnaThis work; Fig. 1
EcuadorCañarIglesia de BibliánSánchez-Pacheco et al. 2017
EcuadorCañarJatumpambaiNaturalist; photo examined
EcuadorMorona SantiagoBetween Pailas and MiradorKizirian 1996
EcuadorMorona SantiagoPailas*Kizirian 1996