DOI10.47051/MXLB2904

Published September 9, 2020. Updated December 1, 2023. Open access. Peer-reviewed.

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Yumbo Lightbulb-Lizard (Riama yumborum)

Reptiles of Ecuador | Sauria | Gymnophthalmidae | Riama yumborum

English common name: Yumbo Lightbulb-Lizard.

Spanish common names: Lagartija minadora de los Yumbos, lagartija bombillo de los Yumbos.

Recognition: ♂♂ 13.3 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=6.2 cm. ♀♀ 13.1 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=5.4 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.3,4 Riama yumborum can be recognized from other small slender leaf-litter lizards by having a yellowish to orange-red belly with brown smears in each scale, short limbs, and no dorsolateral stripes (Fig. 1). This is one of two short-legged microteiids occurring in the Santa Lucía Cloud Forest Reserve. The other is Andinosaura oculata, a larger lizard having conspicuous dorsolateral lines and contrasting ocelli along the flanks.

Variation among individuals of Riama yumborum

Figure 1: Individuals of Riama yumborum from Santa Lucía Cloud Forest Reserve, Pichincha province, Ecuador. j=juvenile

Natural history: Riama yumborum is an extremely rare cryptozoic lizard adapted to moist, shaded microhabitats in pristine closed canopy evergreen montane forests.2,5 The species occurs also along borders between disturbed forest and pastures.5 Yumbo Lightbulb-Lizards occur in areas of dense leaf-litter within 100 m from streams and waterfalls.5 These reptiles are active at ground level during the daytime, either under leaf-litter, at the base of trees, or among shallow roots.2,5 When not active, they hide under leaf-litter, logs, soil, and rocks.2,5 When threatened, they dart into the leaf-litter, readily shedding the tail if captured.

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Conservation: Vulnerable Considered to be facing a high risk of extinction in the mid-term future.. Riama yumborum is listed in this category, instead of Data Deficient,6 because the species is known from a single population occupying an area estimated to be no larger than 4 km2. Currently, R. yumborum is the lizard species in Ecuador having the smallest known geographic range, which makes it especially prone to extinction from anthropogenic disturbances or natural stochastic events within a short time period.7 Fortunately, the species faces no obvious immediate extinction threats and its entire area of distribution is currently within the limits of the Santa Lucía Cloud Forest Reserve.

Distribution: Riama yumborum is endemic to an area of approximately 3.27 km2 in the Pacific slopes of the Andes in northwestern Ecuador. It has only been recorded in Santa Lucía Cloud Forest Reserve, but an unconfirmed photographic record from Manduriacu Reserve, Imbabura province, could represent the second known locality for the species (Fig. 2).

Distribution of Riama yumborum in Ecuador

Figure 2: Distribution of Riama yumborum in Ecuador. The star corresponds to the type locality: Santa Lucía Cloud Forest Reserve, Pichincha province.

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.8–11 The specific epithet yumborum means “of the Yumbos.” It honors the Yumbo culture (800–1660 AD), a pre-Incan civilization that inhabited the same region where R. yumborum occurs.3

See it in the wild: Given their secretive habits and extremely small geographic range, Yumbo Lightbulb-Lizards are not recorded accidentally. These lizards have only been captured using pitfall traps with drift fences or uncovered by raking leaf-litter or by turning over rocks and logs in moist, shaded microhabitats within Santa Lucía Reserve.

Acknowledgments: Special thanks to Connor Sullivan for providing locality and natural history data of Riama yumborum. Thanks to Holger Beck for granting access to Santa Lucía Cloud Forest Reserve. 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 reviewers: Simon MaddockbAffiliation: Faculty of Science and Engineering, University of Wolverhampton, Wolverhampton, United Kingdom. and 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? Arteaga A (2023) Yumbo Lightbulb-Lizard (Riama yumborum). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: www.reptilesofecuador.com. DOI: 10.47051/MXLB2904

Literature cited:

  1. Aguirre-Penafiel V, Torres-Carvajal O, Nunes PM, Peck MR, Maddock ST (2014) A new species of Riama Gray, 1858 (Squamata: Gymnophthalmidae) from the Tropical Andes. Zootaxa 3866: 246–260. DOI: 10.11646/zootaxa.3866.2.4
  2. Field notes, Reptiles of Ecuador book project.
  3. 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
  4. 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
  5. Connor Sullivan, pers. comm.
  6. Yánez-Muñoz M (2017) Riama yumborum. The IUCN Red List of threatened species. Available from: www.iucnredlist.org. DOI: 10.2305/IUCN.UK.2017-2.RLTS.T68049597A68049600.en
  7. Meiri S, Bauer AM, Allison A, Castro-Herrera F, Chirio L, Colli G, Das I, Doan TM, Glaw F, Grismer LL, Hoogmoed M, Kraus F, LeBreton M, Meirte D, Nagy ZT, Nogueira CdC, Oliver P, Pauwels OSG, Pincheira-Donoso D, Shea G, Sindaco R, Tallowin OJS, Torres-Carvajal O, Trape J-F, Uetz P, Wagner P, Wang Y, Ziegler T, Roll U (2018) Extinct, obscure or imaginary: the lizard species with the smallest ranges. Diversity and Distributions 24: 262–273. DOI: 10.1111/ddi.12678
  8. 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.
  9. 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.
  10. 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.
  11. Gray JE (1845) Catalogue of the specimens of lizards in the collection of the British Museum. Trustees of the British Museum, London, 289 pp.