Published October 11, 2020. Open access.

Gallery ❯

Unicolored Lightbulb-Lizard (Riama unicolor)

Reptiles of Ecuador | Sauria | Gymnophthalmidae | Riama | 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.. Lightbulb-lizards are easily distinguishable from other lizards by their fossorial (living underground) habits and extremities so short that the front and hind limbs cannot reach each other.1,2 Adult males of Riama unicolor differ from females by having broader heads and more colorful lower flanks. Unicolored Lightbulb-Lizards differ from other Riama by having a reddish underside of the tail with thin black longitudinal lines. Other lightbulb lizards that occur nearby R. unicolor are R. colomaromani, R. simotera, and R. raneyi, but these other lizards have completely black ventral surfaces.2

Variation among individuals of Riama unicolor

Figure 1: Unicolored Lightbulb-Lizards (Riama unicolor) from La Libertad, Carchi province (), and Tabacundo–Mojanda, Pichincha province (), Ecuador. j=juvenile

Natural history: Locally commonRecorded weekly in densities above five individuals per locality.. Riama unicolor is a fossorial lizard that inhabits old-growth to heavily disturbed high evergreen montane forest and humid highland shrublands. It also occurs in areas containing a mixture of pastures, crops, and remnants of native vegetation,3,4 and even in gardens in heavily-populated urban areas such as Quito.3 Lizards of this species spend most of their lives in tunnels they excavate in areas of soft soil or under rocks, logs, debris, and flowerpots.2,3 On rare occasions, individuals have also be seen crossing roads.3 In captivity, their diet includes maggots and small insects.2 When threatened, Unicolored Lightbulb-Lizards flee into crevices. If captured, they may bite or readily shed the tail. These lizards are susceptible to high temperatures, dying if exposed to the sun or even if handled for longer than just a few seconds.2 Members of this species are preyed upon by frogs (Gastrotheca riobambae).2

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Conservation: Vulnerable Considered to be facing a high risk of extinction in the mid-term future..5 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.5 An estimated 64.3% of the habitat of R. unicolor has already been destroyed,6 mostly due to encroaching human activities such as urban development, agriculture, cattle grazing, and the replacement of native vegetation with eucalyptus and pine trees.3,5 Fortunately, Drab Lightbulb-Lizards persist in urban areas despite a considerable degree of habitat modification,4 and they are among the few reptiles able to survive in Ecuador’s capital city.4

Distribution: Riama unicolor is endemic to an estimated ~6,682 km2 area in the inter-Andean valleys of northern Ecuador. The species occurs at elevations between 2022 and 3405 m (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.710 The specific epithet unicolor is a Latin adjective that probably refers to the nearly unicolored dorsal pattern of lizards of this species.2

See it in the wild: Unicolored Lightbulb-Lizards are recorded rarely unless they are actively searched for by digging in areas of soft soil or by turning over rocks and logs. They can be found with ~20–40% certainty in humid areas having remnants of native vegetation.

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.

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

How to cite? Arteaga A (2020) Unicolored Lightbulb-Lizard (Riama unicolor). In: Arteaga A, Bustamante L, Vieira J, Guayasamin JM (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/PEFN1380

Literature cited:

  1. 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. DOI: 10.1111/j.1096-3642.2005.00145.x
  2. 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
  3. Field notes, Reptiles of Ecuador book project.
  4. Arteaga A, Bustamante L, Guayasamin JM (2013) The amphibians and reptiles of Mindo. Universidad Tecnológica Indoamérica, Quito, 257 pp.
  5. 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
  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 unicolor in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used.

EcuadorCarchi14 km W TulcánField notes of Luis Coloma
EcuadorCarchiGruta de la PazField notes of Giovanni Onore
EcuadorCarchiHuacaAguirre et al. 2014
EcuadorCarchiLa LibertadThis work
EcuadorCarchiMontúfarKizirian 1996
EcuadorCarchiMontúfar–AtalSánchez-Pacheco et al. 2012
EcuadorCarchiSan GabrielThis work
EcuadorCarchiSan Gabriel–El AngelThis work
EcuadorCarchiTulcánThis work
EcuadorCarchiVicinities of La LibertadThis work
EcuadorImbabura3 km SE San RafaelDoan 2003
EcuadorImbabura7 km W QuirogaKizirian 1996
EcuadorImbabura8 km NW OtavaloKizirian 1996
EcuadorImbaburaCahuasquí–UrcuquíDiego Piñán
EcuadorImbaburaChachimbiroKizirian 1996
EcuadorImbaburaCotacachi–Intag 1Aguirre et al. 2014
EcuadorImbaburaCotacachi–Intag 2Aguirre et al. 2014
EcuadorImbaburaCuicochaKizirian 1996
EcuadorImbaburaHacienda ZuletaPhoto by Anton Sorokin
EcuadorImbaburaHostería CusinField notes of Elicio Tapia
EcuadorImbaburaImbabura-Mariano AcostaThis work
EcuadorImbaburaIslote YeroviAlmendáriz & Orcés 2004
EcuadorImbaburaLaguna El CunrroField notes of Rafael Cárdenas
EcuadorImbaburaPerihuelaThis work
EcuadorImbaburaPimampiroKizirian 1996
EcuadorImbaburaTabacundo–MojandaKU 221766
EcuadorImbaburaTumbabiroAguirre et al. 2014
EcuadorImbaburaUrcusiquiKU 118101
EcuadorImbaburaVía Cotacachi–QuirogaiNaturalist
EcuadorPichincha12 km E PifoKizirian 1996
EcuadorPichincha2.5 km W TabacundoKizirian 1996
EcuadorPichincha3.8 km W TabacundoThis work
EcuadorPichincha40 SE QuitoSánchez-Pacheco et al. 2012
EcuadorPichincha5.9 km W TabacundoKizirian 1996
EcuadorPichinchaAloguinchoQCAZ 3060
EcuadorPichinchaBetween Quito and PapallactaKizirian 1996
EcuadorPichinchaBosque de PasochoaField notes of Felipe Campos
EcuadorPichinchaBrazil y ZamoraPhoto by Viviana Jaramillo
EcuadorPichinchaCalacalíThis work
EcuadorPichinchaCayambeKizirian 1996
EcuadorPichinchaColegio Fernandez MadridiNaturalist
EcuadorPichinchaEl IncaiNaturalist
EcuadorPichinchaHacienda GorzonKizirian 1996
EcuadorPichinchaHacienda OlallaKizirian 1996
EcuadorPichinchaHacienda PesilloAlmendáriz & Orcés 2004
EcuadorPichinchaHacienda PichinchaQCAZ 11660
EcuadorPichinchakm 10 Cayambe–OlmedoKizirian 1996
EcuadorPichinchaLa UnióniNaturalist
EcuadorPichinchaMachachiSánchez-Pacheco et al. 2012
EcuadorPichinchaMirador de GuápuloiNaturalist
EcuadorPichinchaNear El CrateriNaturalist
EcuadorPichinchaNonoMaría Jose Quiroz, pers. comm.
EcuadorPichinchaPaloguilloField notes of Juan Freile
EcuadorPichinchaParque MetropolitanoiNaturalist
EcuadorPichinchaParque RumipambaFinding Species
EcuadorPichinchaPasochoaKizirian 1996
EcuadorPichinchaPUCEThis work
EcuadorPichinchaQuitoKizirian 1996
EcuadorPichinchaQuito, Calle MurgeónDHMECN 332
EcuadorPichinchaRío MachángaraKizirian 1996
EcuadorPichinchaSan Antonio de PichinchaUSNM
EcuadorPichinchaSan Jorge EcolodgePhoto by Clint King
EcuadorPichinchaSE Slopes Guagua PichinchaKizirian 1996
EcuadorPichinchaTabacundoKizirian 1996
EcuadorPichinchaValle de los ChillosKizirian 1996