Published July 25, 2023. Updated November 29, 2023. Open access. Peer-reviewed.

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Hotspring Lightbulb-Lizard (Riama balneator)

Reptiles of Ecuador | Sauria | Gymnophthalmidae | Riama balneator

English common name: Hotspring Lightbulb-Lizard.

Spanish common name: Lagartija minadora del balneario.

Recognition: ♂♂ 16.8 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=6.4 cm. ♀♀ 15.5 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 (living underground) habits and extremities so short that the front and hind limbs cannot reach each other.2,3 The Hotspring Lightbulb-Lizard (Riama balneator) is one of two members of its genus known to occur along the slopes of Tungurahua Volcano. The other one is R. meleagris, a lizard having smooth dorsal scales, a glossy blackish dorsal coloration with white spots, and no dorsolateral lines.2 In R. balneator, the dorsal scales are wrinkled and the coloration is brownish and less uniform (Fig. 1).1,2 The dorsal color pattern consists primarily of brown peppered with minute blackish spots. There is a distinct dorsolateral dark-bordered pale stripe on the head and neck, becoming less distinct at mid-body, and is barely visible on the anterior portion of the tail. Approximately 12–14 faintly defined ocelli are present laterally from the neck to just before the hind limb. The ventral surfaces of the body are dark brown, with iridescent tones present throughout. Males exhibit a darker hue compared to females. Females also display reddish shades on the posterior half of the body and cream shades on the edges of ventral scales.

Illustration of an adult female of Riama balneator

Figure 1: Illustration of an adult male of Riama balneator.

Natural history: Riama baleator is an extremely rare fossorial lizard found in pristine cloud forests as well as in pastures adjacent to these forests.1,2 Hotspring Lightbulb-Lizards and their eggs have been found under rotten logs in pastures near forest border.1 Nothing is know about the diet of this species, but lightbulb lizards in general are insectivorous.2,4

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Conservation: Endangered Considered to be facing a high risk of extinction in the near future..5 Riama balneator is included in this category because the species is known from only four localities (Appendix 1) and is restricted to an extremely small (approximately 286 km2) area.5 The habitat of R. balneator is severely fragmented and continues to decline in extent and quality due to encroaching human activities such as agriculture. Volcanic eruptions may also pose a threat to the long-term survival of the species.

Distribution: Riama balneator is endemic to an estimated area of 286 km2 along the eastern slopes of Tungurahua Volcano, east-central Ecuador (Fig. 2).

Distribution of Riama balneator in Ecuador

Figure 2: Distribution of Riama balneator in Ecuador. The star corresponds to the type locality: Puela River valley, Chimborazo 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.69 The specific epithet balneator is a Latin noun meaning “caretaker of the baths.” It refers to the town Baños (Spanish for “baths”), nearby the type locality, known for its geothermal springs.2

See it in the wild: Riama balneator is one Ecuador’s rarest lizards. Less than 10 individuals of this species have ever been reported. The locality having the greatest number of observations (=4) is Montañas de San Antonio, on the Eastern slopes of Tungurahua Volcano. However, there have not been recent observations despite targeted sampling in the area. Searching under rotten logs in pastures seems the best way to find these shy reptiles.

Author: Alejandro ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador.

Academic reviewer: Jeffrey D CamperbAffiliation: Department of Biology, Francis Marion University, Florence, USA.

Illustrator: Valentina Nieto Fernández

How to cite? Arteaga A (2023) Hotspring Lightbulb-Lizard (Riama balneator). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/PXHK3062

Literature cited:

  1. Reyes-Puig JP, Altamirano M, Yánez-Muñóz MH (2008) Reptilia, Squamata, Gymnophthalmidae, Riama balneator and Riama vespertina: distribution extension, Ecuador. Check List 4: 366–372. DOI: 10.15560/4.3.366
  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. 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
  4. Kizirian DA, Coloma LA (1991) A new species of Proctoporus (Squamata: Gymnophthalmidae) from Ecuador. Herpetologica 47: 420–429.
  5. Cisneros-Heredia DF (2017) Riama balneator. The IUCN Red List of threatened species. Available from: DOI: 10.2305/IUCN.UK.2017-2.RLTS.T178630A54446765.en
  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 (1945) 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 balneator in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used. Asterisk (*) indicates type locality.

EcuadorChimborazoPuela River valley*Kizirian 1996
EcuadorTungurahuaLa CandelariaReyes-Puig et al. 2013
EcuadorTungurahuaReserva Olivier CurratJuan Pablo Reyes, pers. comm.
EcuadorTungurahuaSan Antonio mountainsReyes-Puig et al. 2008