Glass frog

An unidentified Glass frog (Centrolenidae) from an unknown locality. I suppose it could be a Reticulated Glass Frog, Hyalinobatrachium valerioi, but perhaps you, expert zoologists and herpetologists in Tumblr, could help with the ID of this frog. 

Photo credit: ©Nicolas Reusens | Locality: unknown

Glass frogs hold no secrets
Mother Nature Network

Photographer Andrew Snyder writes,

This glass frog (Hyalinobatrachium cf. cappellei) is a very small juvenile that was found on a small riverside branch along the Essequibo River on afternoon.

Currently Guyana has six species of glass frogs recorded for the country, and many of those look quite similar to each other. This image shows clearly why glass frogs get their name, but is also a way to make species identification possible.

The underside gives a clear view as to what color the bones are (typically either white or green) and whether certain organs such the heart are visible, all important diagnostic characteristics.

Reticulated Glass Frog - Hyalinobatrachium valerioi

In the Reticulated Glass Frog, Hyalinobatrachium valerioi (Centrolenidae), a species with well studied parental care, males perform nocturnal brooding by adopting a posture in which ventral surface and thighs are in close contact with the clutch. It is thought that this behavior has a moistening function.

Reference: [1]

Photo credit: ©Michele Monari | Location: not indicated (2010)

Conheçam as incríveis pererecas de vidro
São pererecas da família Centrolenidae em que as espécies são caracterizadas por apresentar a cor verde claro e a pele é quase totalmente transparente, principalmente na região ventral. Os órgãos internos, como intestinos, coração e fígado podem ser vistos através da pele por isso elas são chamadas de pererecas de vidro.

São pererecas geralmente pequenas variando de 3 a 7,5 cm de comprimento. São geralmente espécies de hábitos noturnos e se alimentam de invertebrados, principalmente insetos, e tem como predadores as aranhas e serpentes. Na época de reprodução, os machos saem para vocalizar como ritual de acasalamento. As fêmeas sempre colocam os ovos sobre folhas acima da água.

Em média, as fêmeas depositam cerca de 20 ovos nas folhas no período chuvoso e se desenvolvem ali por alguns dias. Depois, os girinos rompem a cápsula do ovo, caem na água e continuam até completarem o desenvolvimento. Alguns pesquisadores dizem que em muitas espécies de pererecas de vidro, em algumas circunstancias, ocorre canibalismo por parte da mãe que acaba comendo seus próprios ovos. Um dos gêneros mais conhecidos de pererecas de vidro é o Hyalinobatrachium em que várias espécies ocorrem no Brasil.

Veja também: Rãs e sapos coloridos e venenosos
Fonte: diário de biologia

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Glassy Fathers Do Matter: Egg Attendance Enhances Embryonic Survivorship in the Glass Frog Hyalinobatrachium valerioi

Hyalinobatrachium valerioi (Centrolenidae) is better known by names such as Reticulated Glass Frog, Valerio’s Glass Frog, La Palma Glass Frog, or Ranita de Vidrio [1].

This species ranges from central Costa Rica, through Panama and the Pacific lowlands of western Colombia, south to Mata Real in Azuay Province in Ecuador. It has also been reported from the Department of Caldas in the middle Magdalena Valley, Colombia [2]. 

Hyalinobatrachium valerioi is a tiny frog, with adult males ranging from 19.5 to 24.0 mm, and adult females measuring from 22.5 to 26 mm. 

The Reticulated Glass Frog is nocturnal. Males are highly territorial, maintaining territorial spacing by calls. If another male enters the territory, a call consisting of a squeak is made, sometimes by both the defending and the intruding male. If the intruder fails to leave immediately, wrestling occurs and the defending resident male will pin the intruding male down.

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 [1].

Males of the glass frog Hyalinobatrachium valerioi engage in diurnal and nocturnal attendance of egg clutches. The main cause of mortality in eggs is due to arthropod predation and desiccation of clutches [3].

To study the effect of parental care on embryonic survivorship, Vockenhuber et al. (2009) conducted a male removal experiment and measured embryonic survival rates on day 4, 8, and 12 after oviposition in attended and unattended clutches. With this study, they found that:

  • Clutch attendance was exclusively performed by males. During the night, attending males commonly engaged in brooding behavior by placing the ventral part of the body and thighs in close contact with the clutch. 
  • Embryonic survivorship was significantly higher in attended control clutches than in male-deprived clutches. Desiccation of clutches only occurred in unattended clutches, and arthropod predation was high in both groups.

Such results show that egg attendance in the glass frog H. valerioi enhances clutch survival to late prehatching stages and, therefore, can be considered as parental care, by deterring egg predators and preventing desiccation.

Although parental care yields benefits to male fitness via a lowered embryonic mortality, costs may be incurred in the form of lost mating opportunities, higher risk of adult predation, or energetic costs resulting from reduced feeding. However, males of H. valerioi, as with males of other frog species, continue to call during egg attendance and often accumulate multiple clutches.

[Download here the complete study]

 Photo credit: ©Brian Kubicki | Hyalinobatrachium valerioi from Costa Rica.


Hatching plasticity in the Fleischmann’s Glass Frog 

In the glass frog Hyalinobatrachium fleischmanni (Centrolenidae), commonly known as Fleischmann’s Glass Frog, both males and females attend their eggs clutches by sitting on them during the night and sleeping near but not on the eggs during the day.

The males sit on the egg mass and practice hydric brooding, which consists of occasionally excreting bladder water on the eggs to prevent desiccation.

Research has found that parents can alter hatching time owing to a direct effect of care on embryogenesis or via forms of care that cue the hatching process. 

Male-removal experiments in a wild population of Hyalinobatrachium fleischmanni found that embryos hatched early when abandoned, but extended development in the egg stage when fathers continued care. 

Reference: [1]

Photo credit: ©Josiah Townsend | Locality: San José de Texiguat, 250m elevation, Honduras (2010) | [Top] - [Bottom]