Published October 11, 2020. Updated December 1, 2023. Open access. Peer-reviewed.

Gallery ❯

Unicolored Lightbulb-Lizard (Riama unicolor)

Reptiles of Ecuador | Sauria | Gymnophthalmidae | Riama unicolor

English common names: Unicolored Lightbulb-Lizard, Drab Lightbulb-Lizard.

Spanish common names: Lagartija minadora de vientre rojo.

Recognition: ♂♂ 14.5 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=6.8 cm. ♀♀ 14.5 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=6.5 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 Unicolored Lightbulb-Lizards differ from other members of the genus by having a reddish tail underside adorned with black longitudinal lines (Fig. 1). In contrast, other lightbulb lizard species potentially coexisting with R. unicolor, namely R. colomaromani, R. simotera, and R. raneyi, exhibit entirely black ventral surfaces.1 Adult males of R. unicolor can be differentiated from females by their broader heads and more vibrant lower flanks.

Variation among individuals of Riama unicolor

Figure 1: Individuals of Riama unicolor from Ecuador: La Libertad, Carchi province (); Tabacundo, Pichincha province (). j=juvenile.

Natural history: Riama unicolor is a locally common fossorial lizard that inhabits old-growth to heavily disturbed montane forests and highland shrublands. The species also occupies areas containing a mixture of pastures, crops, and remnants of native vegetation, and surprisingly, even gardens within densely populated urban zones.2,3 Lizards of this species predominantly reside in tunnels they excavate in soft soil or beneath rocks, logs, debris, and flowerpots.1,2 On rare occasions, they have been observed crossing roads during broad daylight.2 In captivity, individuals consume maggots and small insects.1 When threatened, Unicolored Lightbulb-Lizards flee into crevices. If captured, they may bite or readily shed the tail. These lizards are particularly vulnerable to high temperatures, succumbing to the sun or even brief handling for just a few seconds.1 There are records of frogs (Gastrotheca riobambae) preying upon individuals of R. unicolor.1

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Conservation: Vulnerable Considered to be facing a high risk of extinction in the mid-term future..4 Riama unicolor is listed in this category because the species has a relatively small (~6,682 km2) extent of occurrence, its habitat is severely fragmented, and it has undergone widespread observed population declines.4 An estimated 64.3% of the habitat of R. unicolor has already been destroyed5 by encroaching human activities such as urban development, agriculture, cattle grazing, and the replacement of native vegetation with eucalyptus and pine trees.2,4 Fortunately, the species persist in urban areas despite a considerable degree of habitat modification,3 being one of the few reptiles able to survive in Ecuador’s capital city.3

Distribution: Riama unicolor is endemic to an area of approximately 6,682 km2 in the inter-Andean valleys of northern Ecuador (Fig. 2).

Distribution of Riama unicolor in Ecuador

Figure 2: Distribution of Riama unicolor in Ecuador. 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.69 The specific epithet unicolor is a Latin adjective that probably refers to the nearly unicolored dorsal pattern.1

See it in the wild: Unicolored Lightbulb-Lizards are recorded rarely unless actively searched for by digging in areas of soft soil or by turning over rocks and logs in suitable habitats. Prime locations for encountering the species include Refugio Pasochoa and Reserve Pulhulahua.

Special thanks to Walter Jennings for symbolically adopting the Unicolored Lightbulb-Lizard and helping bring the Reptiles of Ecuador book project to life.

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Acknowledgments: Special thanks to Amanda Quezada, Frank Pichardo, Harry Turner, and Jorge Castillo for their help and companionship during the search of specimens of Riama unicolor in the field. Thanks to Diego Piñán and María Jose Quiroz for providing locality data of R. unicolor. Thanks to Andres Pérez for the post-processing of images. 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.

Photographers: Jose VieiracAffiliation: Tropical Herping (TH), Quito, Ecuador.,dAffiliation: ExSitu, Quito, Ecuador. and Alejandro ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador.

How to cite? Arteaga A (2023) Unicolored Lightbulb-Lizard (Riama unicolor). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/PEFN1380

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. Arteaga A, Bustamante L, Guayasamin JM (2013) The amphibians and reptiles of Mindo. Universidad Tecnológica Indoamérica, Quito, 257 pp.
  4. Cisneros-Heredia DF, Brito J, Yánez-Muñoz M, Almendáriz A (2019) Riama unicolor. The IUCN Red List of threatened species. Available from: DOI: 10.2305/IUCN.UK.2019-3.RLTS.T50950566A50950573.en
  5. MAE (2012) Línea base de deforestación del Ecuador continental. Ministerio del Ambiente del Ecuador, Quito, 30 pp.
  6. 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.
  7. 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.
  8. 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.
  9. 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 unicolor in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used.

EcuadorCarchiGruta de la PazGalarza-Verkovitch 2020
EcuadorCarchiHuacaAguirre et al. 2014
EcuadorCarchiLa LibertadThis work; Fig. 1
EcuadorCarchiMontúfarKizirian 1996
EcuadorCarchiMontúfar–AtalSánchez-Pacheco et al. 2012
EcuadorCarchiSan GabrielReptiles of Ecuador book database
EcuadorCarchiSan Gabriel–El AngelReptiles of Ecuador book database
EcuadorCarchiTulcánReptiles of Ecuador book database
EcuadorCarchiTulcán, 14 km W ofPhoto by Luis Coloma
EcuadorCarchiVicinities of La LibertadReptiles of Ecuador book database
EcuadorImbaburaCahuasquí–UrcuquíPhoto by Diego Piñán
EcuadorImbaburaChachimbiroKizirian 1996
EcuadorImbaburaCotacachi–Intag 1Aguirre et al. 2014
EcuadorImbaburaCotacachi–Intag 2Aguirre et al. 2014
EcuadorImbaburaCuicochaKizirian 1996
EcuadorImbaburaHacienda ZuletaPhoto by Anton Sorokin
EcuadorImbaburaImbabura-Mariano AcostaReptiles of Ecuador book database
EcuadorImbaburaIslote YeroviAlmendáriz & Orcés 2004
EcuadorImbaburaOtavalo, 8 km NW ofKizirian 1996
EcuadorImbaburaPerihuelaReptiles of Ecuador book database
EcuadorImbaburaPimampiroKizirian 1996
EcuadorImbaburaQuiroga, 7 km W ofKizirian 1996
EcuadorImbaburaSan PabloKizirian 1996
EcuadorImbaburaSan Rafael, 3 km SE ofDoan 2003
EcuadorImbaburaSigsipambaiNaturalist; photo examined
EcuadorImbaburaTabacundo–MojandaKU 221766; VertNet
EcuadorImbaburaTumbabiroAguirre et al. 2014
EcuadorImbaburaUrcusiquiKizirian 1996
EcuadorImbaburaVía Cotacachi–QuirogaiNaturalist; photo examined
EcuadorImbaburaYaguachiGalarza-Verkovitch 2020
EcuadorPichinchaAloguinchoGalarza-Verkovitch 2020
EcuadorPichinchaBetween Quito and PapallactaKizirian 1996
EcuadorPichinchaBosque de PasochoaField notes of Felipe Campos
EcuadorPichinchaBrazil y ZamoraPhoto by Viviana Jaramillo
EcuadorPichinchaCalacalíReptiles of Ecuador book database
EcuadorPichinchaCayambeKizirian 1996
EcuadorPichinchaCayambe, 10 km N ofKizirian 1996
EcuadorPichinchaChillogalloKizirian 1996
EcuadorPichinchaColegio Fernandez MadridiNaturalist; photo examined
EcuadorPichinchaEl IncaiNaturalist; photo examined
EcuadorPichinchaHacienda GorzonKizirian 1996
EcuadorPichinchaHacienda OlallaKizirian 1996
EcuadorPichinchaHacienda PesilloAlmendáriz & Orcés 2004
EcuadorPichinchaLa JosefinaiNaturalist; photo examined
EcuadorPichinchaLa PlayitaiNaturalist; photo examined
EcuadorPichinchaLa UnióniNaturalist; photo examined
EcuadorPichinchaMachachiSánchez-Pacheco et al. 2012
EcuadorPichinchaMirador de GuápuloiNaturalist; photo examined
EcuadorPichinchaNear El CrateriNaturalist; photo examined
EcuadorPichinchaNonoMaría Jose Quiroz, pers. comm.
EcuadorPichinchaPaloguilloField notes of Juan Freile
EcuadorPichinchaPan-American highway at EquatorUSNM 196250; VertNet
EcuadorPichinchaParque MetropolitanoiNaturalist; photo examined
EcuadorPichinchaParque RumipambaPhoto by Finding Species
EcuadorPichinchaPasochoaKizirian 1996
EcuadorPichinchaPifo, 12 km E ofKizirian 1996
EcuadorPichinchaPUCEReptiles of Ecuador book database
EcuadorPichinchaQuitoKizirian 1996
EcuadorPichinchaQuito, 40 SE ofSánchez-Pacheco et al. 2012
EcuadorPichinchaRío MachángaraKizirian 1996
EcuadorPichinchaSan Jorge EcolodgePhoto by Clint King
EcuadorPichinchaSE Slopes Guagua PichinchaKizirian 1996
EcuadorPichinchaTabacundoKizirian 1996
EcuadorPichinchaTabacundo, 2.5 km W ofKizirian 1996
EcuadorPichinchaTabacundo, 3.8 km W ofReptiles of Ecuador book database
EcuadorPichinchaTabacundo, 5.9 km W ofKizirian 1996
EcuadorPichinchaTabacundo, 7 km N ofThis work; Fig. 1
EcuadorPichinchaValle de los ChillosKizirian 1996
EcuadorPichinchaVía a MolinucoGalarza-Verkovitch 2020