hear Fonozoo call

Description
The male Centrolene heloderma has a snout vent length is 26.8 - 31.5 mm while the female snout vent length is longer at around 32.3 mm. The head length of Centrolene heloderma is about a third of the snout vent length. The shape of the snout is relatively long and depressed. It is inclined anteriorly from the nostrils to the lip’s margin and is rounded in the dorsal view. The nostrils are found about three-fifths the distance down from the eye to the snout’s tip. The eyes of Centrolene heloderma are small relative to closely related species and are directed in a more lateral direction than an anterior direction. The internal nostrils are small and rounded. They are widely, medially separated. The tongue is broad, heart-shaped, and deeply notched posteriorly. Centrolene heloderma has vocal slits extending from the tongue’s midlateral base to the angles of its jaws. It has a single vocal sac that, when inflated extends laterally beyond its head. The humeral spine projects at a 45-degree angle from the humerus. It has a robust forearm with a scalloped dermal fold. Its first and second fingers are about the same size, and the fourth finger is larger than both, but no information is available on the third finger. The webbing between the first, second, and third fingers is very simple and almost nonexistent, and between the third and fourth finger there is moderate webbing. The hind limbs are relatively strong, with the average length of the tibia bone a bit over half of the snout-vent length. There is a row of tubercles on the outer edge of the tarsus. The metatarsal of the species is missing an inner fold and the tubercle of the inner metatarsal is low and elongate. The outer metatarsal tubercle is small and cone-shaped The skin of Centrolene heloderma is coarsely granular on the flanks, belly, and the posterior surfaces of the thighs, but it is smooth on the rest of the body. The cloacal opening is directed downwards at the upper level of the thighs. Below the cloaca there are two large and many small tubercles (Duellman 1981).

Centrolene heloderma has granular skin on its backside, which differentiates it from other Centrolene species. It is most similar to Centrolene buckleyi in appearance, but it can be diagnosed from the presence of small spines on its back, less webbing between its digits, lack of skin folds on its limbs, and only the lower half of its tympana is visible (Duellman 1981).

In life, the color of the back ranges from green to dark green to bluish green, and is covered in white to white-blue tubercles. The tubercles on the dorsal part of the frog have a stronger blue tint and the tubercles around the cloaca, heel, and skin over the ulna, which is the whitest. The limbs are the same color as the dorsal region. The margin of the lips and throat are yellow with the yellow coloration lighter around the mouth opening. The bones of the Centrolene heloderma are green. The color of the iris is yellow to pale gold with fine, black, connected lines (known as reticulations or crosslinks) running through it (Duellman 1981, Guayasamin and Frenkel 2014).

In preservative, the dorsal surfaces of the animal are a dull, greyish lavender, sometimes with tiny cream or white dots, and the other remaining surfaces are a dull, cream or white color (Guayasamin and Frenkel 2014, Duellman 1981).

The size difference is the most noticeable difference between the male and female. The males have snout vent lengths of 26.8 - 31.5 mm while the female snout vent lengths are longer at around 32.3 mm. The males also have humeral spines, which the females lack (Duellman 1981).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Colombia, Ecuador

View distribution map in BerkeleyMapper.

Centrolene heloderma is endemic to the Pacific slopes of the Andes – specifically the Western slopes of the Cordillera Occidental Mountains in Ecuador, Colombia’s Cauca, Valle del Cauca and Risaralda Departments, all the way south to the Tandayapa and Saloya Valleys in Ecuador’s Provincia de Pichincha. They are known to inhabit the canopies of mature cloud forests at 1960 – 2400 m above sea level (Duellman 1981, Coloma et al 2004, Arteaga 2013).

Life History, Abundance, Activity, and Special Behaviors
It is visibly elusive and is more often heard than seen. It is active during the night, and during the rainiest months of December through April, it tends to stay in areas of vegetation 1-7 m above ground, near cold-water streams and waterfalls in deep, mature cloud forests. It will occasionally stray from streams, most likely in order to migrate to other territories for habituation (Duellman 1981, Hutter and Guayasamin 2012).

Like many other Centrolenids, males fight while dangling upside-down, grasping onto vegetation by their hind limbs, and onto each other with their ventral sides facing each other (Guayasamin, J. M., et al. 2009).

Reproduction takes place during the rainy season. Males call while perched on the backsides of leaves. The call is loud and high in pitch, used to attract females and let other males know of its presence, which can be described as a harsh “peep”. Females have been documented to lay clutches of up to 29 eggs, which encase brownish embryos. They deposit their eggs on the backsides of leaves high above the water level, which the tadpoles drop into when they hatch (Duellman 1981, Guayasamin et al. 2014).

Larva
Tadpoles have a wormlike body shape with C-shaped eyes on its dorsal side (Cisneros-Heredia et al. 2006).

The tadpoles feed on external food sources and are fossorial, living buried within leaf packs in vegetation along flowing streams (Cisneros-Heredia 2006).

Trends and Threats
The most likely cause of decline is climate change, which has caused the cloud layer of its habitat to move up the mountainsides and thus reduce humidity within its altitudinal range. Other likely threats are deforestation for both legal and illegal agricultural development, fire, logging, and human settlement; the introduction of predatory fish species; and pollution from the spraying of illegal crops. Chytridiomycosis is another possible contribution to the decline (Guayasamin et al. 2014).

This species was last recorded in 1996 in Columbia, and appears to be quite rare. The overall abundance and population appear to have taken a sharp decline in the last three generations, with an 80% decrease in population size inferred from the apparent disappearance of most of its population (Coloma 2004).

It is currently protected in Ecuador at Las Gralarias, a 1063- acre wildlife sanctuary, which encompasses the cloud forests of its habitat, located in the parish of Mindo (Duellman 1981, Arteaga, et al. 2013).

Relation to Humans
The population decrease of this species has likely further accelerated due to an increase in farms of predatory fish that are thought to eat them. There are conservation efforts to increase the populations of these species from conservation areas in Columbia, and the IUCN Red List has made a call to action to create a captive population of these frogs (Coloma 2004).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Urbanization
Prolonged drought
Local pesticides, fertilizers, and pollutants
Predators (natural or introduced)
Disease
Climate change, increased UVB or increased sensitivity to it, etc.

Comments
There is still debate about the relatedness of Centrolene heloderma to other species. This debate is unsettled throughout the Centrolene genus. However, Centrolene heloderma shares morphological similarities to Centrolene condor, Centrolene leminiscatum, Centrolene altitudinale, and Centrolene buckleyi, suggesting that Centrolene heloderma is more closely related to these species than others within the genus. These morphological similarities include sloping snouts in lateral view, white labial stripes, and ulnar folds (Guayasamin 2009).

More recent studies have placed Centrolene heloderma in a clade with Centrolene altitudinale, Centrolene nostosticum, Centrolene buckleyi, Centrolene ballux, Centrolene lynchi, Centrolene muelleri, Centrolene sabini, Centrolene venezuelenze, Centrolene buckleyi, Centrolene hesperium, and Centrolene huilense, with an estimated divergence time for Centrolene heloderma of 5-10 million years (Hutter et al. 2013).

The aforementioned, synapomorphic fighting behavior of Centrolenids is considered to be derived given that it has been observed only within Centrolenidae (see section 3) (Guayasamin, J. M., et al. 2009).

The name Centrolene is probably derived from the Greek “kentron”, meaning “point” or “spur”, and “-olene” meaning “elbow” (McCranie & Wilson 2002), in reference to the humeral spine that is obvious in adult males of the type species Centrolene geckoideum. “Helo-” comes from the Greek “helos” meaning “wart”, and “-derma” comes from the latin “derma” meaning “skin”. Thus, heloderma is a reference to the texture of the species’ dorsal skin caused by the presence of tubercles, which are much more numerous in Centrolene heloderma than the other Centrolenids (Arteaga, et al. 2013).

This species was discovered by William E. Duellman on April 4th, 1975 in the Provincia De Pichincha in Ecuador. At most sites of Centrolene heloderma habitation, Nymphargus griffithsi and Nymphargus lasgralarias are found in much greater abundance (Duellman 1981, Arteaga, et al. 2013).

References

Arteaga, A., Bustamante, L., Guayasamin, J. M. (2013). The Amphibians and Reptiles of Mindo. Universidad Tecnológica Indoamérica, Quito. Imprenta Mariscal, Ecuador.

Cisneros-Heredia, D. F., McDiarmid, R. W. (2006). ''A new species of the genus Centrolene (Amphibia: Anura: Centrolenidae) from Ecuador with comments on the taxonomy and biogeography of glassfrogs.'' Zootaxa, 1244, 1-32.

Coloma, L. A., Santiago Ron, S., Cisneros-Heredia, D., Grant, T. (2004). Centrolene heloderma. The IUCN Red List of Threatened Species. Version 2015.2. www.iucnredlist.org. Downloaded in May 2015.

Duellman, W. E. (1981). ''Three New Species of Centrolenid Frogs from the Pacific Versant of Ecuador and Colombia.'' University of Kansas Occasional Papers of the Museum of Natural History, 88, 1-9.

Guayasamin, J. M., Castroviejo-Fisher, S., Trueb, L., Ayarzaguena, J., Rada, M., Vila, C. (2009). ''Phylogenetic systematics of glassfrogs (Amphibia: Centrolenidae) and their sister taxon Allophryne ruthveni.'' Zootaxa, 2100, 1-97.

Guayasamin, J. M., Mendoza, A. M., Longo, A. V., Zamudio, K. R., Bonaccorso, E. (2014). ''High Prevalence of Batrachochytrium dendrobatidis in an Andean frog Community (Reserva Las Gralarias, Ecuador).'' Amphibian and Reptile Conservation, 8(1), 33-44.

Guayasamin, J. M., Varela-Jaramillo, A., Frenkel, C. (2014). Centrolene heloderma. AmphibiaWebEcuador. Museum of Zoology, Pontificia Universidad Católica del Ecuador. Version 2014.0. http://zoologia.puce.edu.ec/Vertebrados/Vertebrata.aspx. Downloaded in May 2015.

Hutter, C. R., Guayasamin, J. M. (2012). "A New Cryptic Species of Glassfrog (Centrolenidae: Nymphargus) from Reserva Las Gralarias, Ecuador." Zootaxa, 3257, 1-21. [link]

Hutter, C. R., Guayasamin, J. M., Wiens, J. J. (2013). ''Explaining Andean Megadiversity: the Evolutionary and Ecological Causes of Glassfrog Elevational Richness Patterns.'' Ecology Letters, 16(9), 1135-1144.

Species Account Citation: AmphibiaWeb 2023 Centrolene heloderma: Bumpy Glassfrog <https://amphibiaweb.org/species/1725> University of California, Berkeley, CA, USA. Accessed Nov 16, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 16 Nov 2024.

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