Eleutherodactylus iberia is the smallest frog in the Northern Hemisphere, and is tied for the world's smallest tetrapod with another frog, Brachycephalus didactylus (a Brazilian brachycephalid). Both reach only about 10 mm in adult SVL. It is currently the only species of Eleutherodactylus known to reach such a small size.
Dorsal skin is weakly rugose without dorsolateral folds. Head as wide as body and is as long as is wide. Snout subacuminate in dorsal and lateral view. Canthus rostralis is rounded and slightly concave when viewed dorsally. Loreal region is flat and sloping abruptly. Supratympanic fold is weakly defined and covers upper edge of tympanum (which is round and larger in males, higher than wide and smaller in females). Tympanum is separated from eye by a distance less than its own diameter. Vomerine teeth absent. Finger and toe tips are rounded and very thin.
This small frog has a dorsal coloration of dark brown with a vivid coppery stripe on the canthal region which gradually changes to orange over the eyelids, becoming golden yellow and white behind the eyes, then continuing posteriorly and becoming a discontinuous dorsolateral stripe near the vent. The loreal region is dark brown along with the flanks. The flanks also have a discontinuous white line which separates the flank coloration from vthe entral coloration. Forelimbs have an orange bar on them. Thighs have diagonal white lines crossing from the vent to the knee. Ventral coloration is a deep purple
(Estrada and Hedges 1996).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Cuba
Endemic to eastern Cuba. Known only from Holguin Province, including near Nibujon at sea level (Gomez and Alonso 2000) and the type locality at Arroyo Sucio (Anacleto) Arriba, on the western slope of Monte Iberia at 600 m elevation (Estrada and Hedges 1996). It has been collected during the day and night under leaf litter and among the roots of ferns in a secondary hardwood forest on the western slope of Monte Iberia (Estrada and Hedges 1996). This region receives considerable rainfall (> 1600 mm/year) and has high humidity year-round (Estrada and Hedges 1996).
Life History, Abundance, Activity, and Special Behaviors
This species is toxic. E. iberia and another Cuban species, Eleutherodactylus orientalis, are the only eleutherodactylid anurans known to have skin toxins. These toxins are lipid-soluble alkaloids (pumiliotoxins and indolizidines), and are thought to be derived from dietary sources. Stomach contents for E. iberia and E. orientalis were found to have a high proportion of mites (an average of 71% of prey items in four specimens of E. iberia, and 66% in three specimens of E. orientalis), including oribatid mites. The coloration is thus thought to be aposematic (warning of toxicity); the yellow-white dorsolateral stripes on a dark background are reminiscent of several members of the genus Phyllobates (highly toxic dendrobatid frogs). This species is probably diurnal but detailed studies have not yet been carried out. Other anuran lineages known to have lipid-soluble skin toxins include those in the family Dendrobatidae, one genus of mantelline frogs (Mantella), one genus of bufonids (Melanophryniscus),and one genus of myobatrachids (Pseudophryne) (Rodríguez et al. 2010).
The clutch size appears to be one, as is also true for the related species E. limbatus, E. cubanus, and E. orientalis. A female was collected a few centimeters from her single egg
(Estrada and Hedges 1996). This species is thought to have direct development (Stuart et al. 2008).
Eleutherodactylus iberia has a low frequency call which consists of a series of irregular "chirps" similar to those of E. limbatus and E. orientalis The dominant frequency of E. iberia's call is 5.78 +/- .07 kHz.
(Estrada and Hedges 1996).
Trends and Threats
This species is considered Critically Endangered due to its very restricted range (Stuart et al. 2008). Deforestation, due to subsistence farming and wood collection, presents the single greatest threat (Stuart et al. 2008). E. iberia requires closed canopy rainforest and high humidity (Stuart et al. 2008). Mining also presents a threat as there are large mineral deposits in the areas where the species is known to occur, and pesticides may be contributing to the decline of this species as well (Gomez and Alonso 2000). Although it occurs in at least one nominally protected area (Parque Nacional Alejandro de Humboldt), this area is also subject to some deforestation (Stuart et al. 2008).
Possible reasons for amphibian decline
Local pesticides, fertilizers, and pollutants
Long-distance pesticides, toxins, and pollutants
Predators (natural or introduced)
This is thought to be the smallest frog in the Northern Hemisphere (Gomez and Alonso 2000). Miniaturization has occurred across five families of frogs (Brachycephalidae, Eleutherodactylidae, Leptodactylidae, Microhylidae, and Sooglossidae), and with it come constraints in morphological development, including digital reduction and loss of vomerine teeth. Miniaturized frog species also tend to have high-frequency calls (>5 kHz) and to have clutches with very small numbers of eggs (sometimes only one egg). The eggs are direct-developing, hatching directly into froglets and bypassing the tadpole stage (Estrada and Hedges 1996). Miniaturization, along with dietary specialization in tiny prey (ants and mites), is also thought to have preceded the evolution of alkaloid sequestration, aposematic (warning) coloration, and diurnality (Rodríguez et al. 2010).
Estrada, A. R., and Hedges, S.B. (1996). ''At the lower size limit in tetrapods: a new diminutive frog from Cuba (Leptodactylidae: Eleutherodactylus).'' Copeia, 1996(4), 853-859.
Gomez, A. R., and Alonso, R. (2000). ''Threatened amphibians of Cuba.'' Froglog, 2000(37), 5-6.
Rodríguez, A., Poth, D., Schulz, S., and Vences, M. (2010). ''Discovery of skin alkaloids in a miniaturized eleutherodactylid frog from Cuba.'' Biology Letters, published online 3 November 2010 ahead of print, doi: 10.1098/rsbl.2010.0844.
Stuart, S., Hoffmann, M., Chanson, J., Cox, N., Berridge, R., Ramani, P., Young, B. (eds) (2008). Threatened Amphibians of the World. Lynx Edicions, IUCN, and Conservation International, Barcelona, Spain; Gland, Switzerland; and Arlington, Virginia, USA.
Written by Vance Vredenburg and Raul E. Diaz (vancev AT sfsu.edu, lissamphibia AT gmail.com), San Francisco State University, University of Kansas
First submitted 2000-10-11
Edited by Kellie Whittaker (2010-11-29)
Species Account Citation: AmphibiaWeb 2010 Eleutherodactylus iberia: Monte Iberia Dwarf Frog <http://amphibiaweb.org/species/2972> University of California, Berkeley, CA, USA. Accessed Feb 18, 2020.
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Citation: AmphibiaWeb. 2020. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 18 Feb 2020.
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