Hyalinobatrachium valerioi is a small frog, with adult males ranging from 19.5 to 24.0 mm, and adult females measuring from 22.5 to 26 mm (Savage 2002). It has large yellow round spots and small black dots on a green background, so that it mimics the appearance of an egg clutch (Leenders 2001). The upper surface is shagreened (with small, rounded bumps). As with other glass frogs, the venter is transparent; the heart is visible and red, but the digestive tract, pericardium, and liver are wrapped in a white guanine coat. This frog has a broad head and a snout that appears truncated both in profile and from above. The eyes have gold irises and are not protuberant. The tympanum is not distinct. Digital discs are present and truncate. The first finger is longer than the second, with webbing present between the outer fingers. Toes are extensively webbed. Males have a white nuptial pad consisting of a few separate glands on the outer margin of the thumb base (Savage 2002; Leenders 2001).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Colombia, Costa Rica, Ecuador, Panama
Hyalinobatrachium valerioi can be found from central Costa Rica to the Pacific slopes of Ecuador (Wild 2003). This frog occurs in lowland moist and wet forest as well as premontane wet forest and rainforest (Savage 2002). It inhabits vegetation along small, free-flowing streams (Guyer and Donnelly 2005).
Life History, Abundance, Activity, and Special Behaviors
The Reticulated Glass Frog is nocturnal (Guyer and Donnelly 2005). Males are highly territorial and call from under leaves, throughout the wet season (May to late October) (Savage 2002). The call consists of a single short "sheet" that is repeated after a pause (Wild 2003). Territoriality spacing is also maintained by calls (Savage 2002). If another male enters the territory, a call consisting of a squeak is made, sometimes by both the defending and the intruding male (Savage 2002). If the intruder fails to leave immediately, wrestling occurs and the defending resident male will pin the intruding male down (Savage 2002).
After mating, the female lays eggs in a sticky jelly mass consisting of a single layer of about 35 eggs, on the underside of a leaf above a stream. The egg deposition site may be up to 6 m above the water. Eggs are green, and measure about 2 mm in diameter, or 3-4 mm including their envelopes. The female leaves the breeding site soon after the eggs are fertilized. After fertilization, the male guards the eggs both at night and during the day. Other males that approach the eggs are aggressively attacked. Males continue to call, attracting more females, and have been observed to guard up to as many as seven clutches on the underside of a single leaf. During the day the guarding posture consists of facing the eggs while keeping one hand on the clutch. During nighttime, the male remains in close proximity to the eggs but adopts the guarding posture only sometimes. At night, in addition to remaining near the eggs, the male parent engages in hydric brooding. This involves wetting the eggs by settling the posterior ventral side of the body and thighs on top of the clutch and emptying the bladder
The male frog parent's diurnal guarding behavior may also serve to protect the clutch from predation by wasps, which have been observed to carry individual eggs and embryos away (McDiarmid 1978). McDiarmid (1978) hypothesized that the adult mimicry of the coloration of an egg mass might decoy a wasp to approach the guarding male parent rather than the actual clutch. This might result in the male parent's being able to drive off or consume the potential wasp predator (McDiarmid 1978).
The tadpole of the Reticulated Glass Frog is small, measuring 12 mm in total length at the time of hatching. As described by Savage (2002), the tadpole of this species has brown blotches dorsally and on the tail, with the fins being clear and the underside bright red. It has an elongated body and tail, with the body being relatively depressed. The tail fin is small and the tail tip is rounded. The spiracle is posterior and midlateral. The oral disc is complete, with beaks and 2/3 rows of denticles present. Fine serrations are present on the lower beak. The A2 row of denticles has a gap above the mouth. A single row of papillae is present on the lateral and ventral margins of the oral disc.
Trends and Threats
This species is not threatened but is also not commonly seen (Savage 2002). The Costa Rican populations appear to be stable; however, it is thought to be in decline in Panama and has disjunct distributions in Panama, Ecuador, and Colombia. It can be found in the Reserva Ecológica Los Illinizas in Ecuador and in other protected areas in Colombia, Panama, and Costa Rica (Solis et al. 2008).
Possible reasons for amphibian decline
General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Local pesticides, fertilizers, and pollutants
The color pattern of this frog mimics the egg mass that it guards (McDiarmid 1978). This species is likely to be part of a species complex in Ecuador (Solis et al. 2008).
This species was featured in News of the Week February 7, 2022:
Many types of predators assault frogs; an unusual group of micropredators are frog-biting midges (Diptera: Corethrellidae). These tiny flies home in on calling frogs from which they get a blood-meal. Although corethrellids have been studied in the context of their predation on single species, the broader interactions among predators and prey have not generally been examined. For example, does a midge species attack only a single frog species, and how many midge species are in a community? Virgo et al. (2021) examined a midge-frog community of 17 frog species in Costa Rica and found that although a single midge species may attack a variety of frog species, there is some degree of specialization, and certain frog species were targeted much more frequently. Although five different morphospecies of corethrellids were identified, DNA analysis detected several, up to 20, cryptic species. When the DNA-delimited candidate species were used as units instead of the morphospecies, the specificity of the mite-frog interactions increased. Much remains to be investigated in this fascinating system, such as whether there has been co-evolution of the flies and their prey, or what exactly attracts certain fly species to frog species. (Written by D. Cannatella)
Guyer, C., and Donnelly, M. A. (2005). Amphibians and Reptiles of La Selva, Costa Rica and the Caribbean Slope: A Comprehensive Guide. University of California Press, Berkeley.
Leenders, T. (2001). A Guide to Amphibians And Reptiles of Costa Rica. Zona Tropical, Miami.
McDiarmid, R. W. (1978). ''Evolution of parental care in frogs.'' The Development of Behavior: Comparative and Evolutionary Aspects. G. M. Burghardt and M. Bekoff, eds., Garland STPM Press, New York, USA.
Savage, J. M. (2002). The Amphibians and Reptiles of Costa Rica:a herpetofauna between two continents, between two seas. University of Chicago Press, Chicago, Illinois, USA and London.
Solís, F., Ibáñez, R., Chaves, G., Savage, J., Bolaños, F., Kubicki, B., Jaramillo, C., Fuenmayor, Q., Coloma, L.A., Ron, S.R., Cisneros-Heredia, D., Bolívar, W. & Almendáriz, A. (2008). Hyalinobatrachium valerioi. The IUCN Red List of Threatened Species 2008: e.T55036A11243874. http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T55036A11243874.en. Downloaded on 25 January 2017.
Wild, E. R. (2003). ''La Palma glass frog, Hyalinobatrachium valerioi.'' Grzimek's Animal Life Encyclopedia, Volume 6, Amphibians. 2nd edition. M. Hutchins, W. E. Duellman, and N. Schlager, eds., Gale Group, Farmington Hills, Michigan.
Originally submitted by: Peera Chantasirivisal (first posted 2005-10-25)
Edited by: Kellie Whittaker, David B. Wake (April 2016), Ann T. Chang (January 2017), Michelle S. Koo (2022-08-15)
Species Account Citation: AmphibiaWeb 2022 Hyalinobatrachium valerioi: Reticulated Glass Frog <https://amphibiaweb.org/species/1830> University of California, Berkeley, CA, USA. Accessed Dec 2, 2023.
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Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 2 Dec 2023.
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