Description

DESCRIPTION:

Vitreorana baliomma is a small, slender, neotropical glass frog with a snout-vent length range of 16.4 - 21.2 mm (Pontes et al. 2014). In a study of six individuals from both sexes, females were larger, having an average snout-vent length of 20.55 ± 0.8 mm in comparison to 18.18 ± 0.6 mm in males (Gouveia et al. 2012). In the dorsal view the snout is truncated, and in the profile view it is rounded. The head width is larger than the head length, and it has a single subgular vocal sac. The pupil is horizontal. Only the round outline of the tympanum can be seen. A flap surrounded by uniform tubercles is found above the cloaca. Finger Ⅲ is the longest, followed by Finger Ⅳ, Ⅰ, and Ⅱ, and fingers have slightly rounded and extended adhesive disks. In males, a poorly developed nuptial pad is formed by clustered non-keratinized glands on Finger Ⅰ. Accessory glands border and extend to the bottom side of this finger (Pontes et al. 2014).

DIAGNOSIS:

Vitreorana baliomma is differentiated from other Altantic Forest Vitreorana species by the presence of a layer of white iridophores that cover the stomach and intestines. Additionally, while V. eurygnatha, V. parvula, and V. uranoscopa have nuptial pads with a large concentration of glands at the base of the thumb, V. baliomma has nuptial pads formed with surface and accessory glands at the edge of Finger Ⅰ. In preservation, V. baliomma has lavender dotted melanophores on the iris, whereas V. eurygnatha, V. parvula, and V. uranoscopa have a black or lavender net-like pattern on their iris. Vitreorana baliomma is differentiated from the related V. gorzulae by geography and its more translucent parietal peritoneum that lacks iridophores. Additionally, in V. baliomma finger Ⅰ is longer than Ⅱ, and in V. gorzulae the opposite is true (Pontes et al. 2014).

COLORATION:

In life, the dorsal surface is leaf green in color and has small white speckles dispersed across its smooth skin. The outer eye of V. baliomma has a white fibrous tunic, and the iris is speckled with golden melanophores and has a tan edge. The pupil is horizontal. Like other glass frogs, V. baliomma has a transparent light green ventrum that allows for its white internal organs to be viewed. These organs are white because of a layer of iridophores (Pontes et al. 2014), however the urinary bladder peritoneum is translucent instead of white (Zucchetti et al. 2021). The hands and feet are yellow-green, and melanophores are mostly absent from digits (Pontes et al. 2014).

In preservative, the frog is a cloudy cream-color, and its dorsal side has small, star-shaped lavender melanophores. The iris edge and outer eye are cream, the iris has densely packed lavender melanophores, and a thin cream ring surrounds the horizontal pupil (Pontes et al. 2014).

VARIATION:

Besides sexual dimorphism in size (females being larger), there is not much data on differences within the species, however, two individuals analyzed in preservative showed gray melanophores on iris and dorsum instead of lavender melanophores, which has been attributed to differential and/or excessive sun exposure (Pontes et al. 2014).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Brazil

View distribution map in BerkeleyMapper.

Vitreorana baliomma inhabits the Northern Atlantic Forest of Brazil (Pontes et al. 2014). The species has been documented in 10 different localities across the States of Bahia, Minas Gerais, Sergipe, and Alagoas (Zucchetti et al. 2021). During the breeding season it is found in marginal vegetation near streams between 98 to 620 meters above sea level (Pontes et al. 2014, Lisboa et al. 2019). Vitreorana baliomma tolerates disturbed habitats, and has been recorded in fragmented secondary forest and cacao plantations that retained fragments of native vegetation (Pontes et al. 2014).

Life History, Abundance, Activity, and Special Behaviors

Vitreorana baliomma appears to be primarily nocturnal (Zucchetti et al. 2021).

In the right habitat, V. baliomma seems to be reasonably common (Zucchetti et al. 2021).

Breeding behavior, including calling, is linked to rainfall and humidity and therefore more common during the rainier season, from May to August (Gouveia et al. 2012, Zucchetti et al. 2021). All occurrences have been in marginal vegetation along small forest streams, where males congregate to call (Zucchetti et al. 2021).

Male V. baliomma perform calls from the topsides of leaves between 0.3 to 4 m above forested streams (Pontes et al. 2014). Calls have been observed from solitary males or a chorus of up to six frogs, in which frogs respond to a call from the first individual that vocalizes (Gouveia et al. 2012).

Two distinct calls are performed by V. baliomma. The more common call, Call A, is usually preformed in sequence, but can also be delivered independently. Call A increases in amplitude slightly over time, and has a dominant frequency of 4694 - 5081 Hz. The call always has seven repeated segments (pulses, specifically amplitude modulations) delivered at a rate of 35.3 - 37.8 pulses per second, and lasts for 185 - 198 ms. If it is emitted, the less common, Call B follows Call A by 217 - 249 ms. Call B has 4 or 5 pulses delivered at a rate similar to Call A. It lasts 98 - 116 ms at a dominant frequency of 4694 - 5038 Hz (Bang et al. 2020).

Mating behavior includes female V. baliomma circling the vegetation around a calling male. The female leaps close to the male, and the two begin axillary amplexus. The female leaps between leaves while the pair continue amplexus, switching between the under and upper-side of the leaves, which may be an indication that the female selects the optimal location for the egg clutch. The pair also frequently rotate 180 or 360° when on a leaf (Zucchetti et al. 2021).

After amplexus, gelatinous clutches, ranging from 13.1 - 43.2 mm in diameter, are deposited on leaves above water and contain 7 - 22 eggs. Recently laid eggs are cream colored or have a green tint to them (Zuccetti et al. 2021), and individual eggs are 2.18 ± 0.23 mm in diameter (Gouvia et al. 2012).

Immediately after egg deposition, female V. baliomma may perform parental care in the form of brooding behavior. In one study, female frogs were observed raising their posterior end repeatedly after positioning themselves above a recently deposited clutch, and they continued this behavior for an average of 110 minutes. This behavior may help with fertilization or add humidity to the clutch (Zuccetti et al. 2021).

Tadpoles are fossorial and tend to burrow beneath substrate in water bodies (Lisboa et al. 2019).

Trends and Threats
Vitreorana baliomma’s conservation status has not been evaluated. While the majority of the Brazilian Atlantic Forest, where it is found, has been heavily deforested and fragmented (Ribeiro et al. 2009), V. baliomma appears to be tolerant to anthropogenic habitat modification, as the type specimen was found in a cacao plantation with sporadically retained forest trees for shade (Pontes et al. 2014).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Habitat fragmentation
Local pesticides, fertilizers, and pollutants
Disease
Climate change, increased UVB or increased sensitivity to it, etc.

Comments

PHYLOGENETIC RELATIONSHIPS:

Maximum Likelihood phylogenetic analyses of 12S, 16S, and COI mtDNA sequences and POMC nDNA place V. baliomma as sister to V. gorzulae, a species found in the Guiana Shield. Vitreorana baliomma’s closer relationship to a geographically distant species rather than to other Vitreorana species in the Atlantic Forest is unusual, but is also supported by its unique morphology. Vitreorana baliomma is the only Atlantic Forest Vitreorana without white pigmentation on its urinary bladder peritoneum. The other Atlantic Forest Vitreorana analyzed form a monophyletic clade (Zucchetti et al. 2021).

ETYMOLOGY:

The species epithet, “baliomma” is a reference to the unique pattern on its iris derived from the Greek words “balios”, meaning “spotted” and “omma'' meaning “eye” (Pontes et al. 2014).

Vitreorana baliomma was previously thought to be Vitreorana eurygnatha (Freitas et al. 2004, Carvalho et al. 2005, Gouveia et al. 2012).

References

Bang, D., Lisboa, B., Teixeira, B., Giaretta, A., Carvalho, T. De. (2020). "A comparative acoustic analysis of species of Vitreorana (Anura: Centrolenidae) from the Brazilian Atlantic Forest and Cerrado, with a description of the call of V. baliomma and insights into the taxonomic status of Cerrado populations." Phyllomedusa 19(1), 35–47. [link]

Freitas, M. A., Silva, T. F. S., and Argôlo, A. J. S. (2004). ''Geographic distribution. Hyalinobatrachium eurygnathum (Rio Glass Frog).'' Herpetological Review, 35, 281.

Gouveia, S. F., Faria, R. G., Rocha, A. D. (2012). "Local distribution and notes on reproduction of Vitreorana aff. eurygnatha (Anura: Centrolenidae) from Sergipe, Northeastern Brazil" 120, 16 - 21 [link]

Lisboa, B., dos Santos,W. F. S., Torquato, S., Guarnieri, M. C., Mott T. (2019). "A new state record of the glassfrog Vitreorana baliomma (Anura: Centrolenidae), with notes on its reproductive biology." Herpetology Notes 12, 957–960. [link]

Pontes, R., Caramaschi, U., Pombal, J. P. (2014). "A remarkable new glass frog (Centrolenidae: Vitreorana) from the Northeast Atlantic Forest, Brazil." Herpetologica 70(3), 298–308. [link]

Ribeiro, M. C., Metzger, J. P., Martensen, A. C., Ponzoni, F. J., Hirota, M. M. (2009). "The Brazilian Atlantic Forest: How much is left, and how is the remaining forest distributed? Implications for conservation." Biological Conservation 142, 1141–1153. [link]

Zucchetti, V. M., Rojas-Padilla, O., Ribeiro Dias, I.,Solé, M., Castroviejo-Fisher, S. (2021). "Reproductive biology and phylogenetic relationships of Vitreorana baliomma (Anura: Centrolenidae)." Salamandra 57(3), 353–370. [link]

Species Account Citation: AmphibiaWeb 2022 Vitreorana baliomma <https://amphibiaweb.org/species/8226> University of California, Berkeley, CA, USA. Accessed Aug 9, 2022.

Citation: AmphibiaWeb. 2022. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 9 Aug 2022.

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