Description
Boana alfaroi is a treefrog with a snout-vent length range of 27.91 – 36.27 mm in males and 39.68 – 49.21 mm in females. The head width is larger than the head length. The snout is rounded in lateral view and truncated in dorsal view. The canthus rostralis is indistinct and rounded. The loreal region is concave and the internarial area is convex. The nostrils are not protuberant and they are directed laterally. The eyes are very protuberant, and the eye diameter is larger than the tympanum diameter and the distance to the nostrils. The tympanum is concealed beneath skin and the tympanum annulus is evident, ovoid, longer dorsoventrally, and is dorsally concealed by the supratympanic fold. The supratympanic fold reaches the anterior border of the arm insertion. The skin on the dorsum, head, flanks, and dorsal limb surfaces is smooth, and the skin on the ventral surfaces is coarsely granular. There is a cloacal sheath covering the cloacal opening and there are round tubercles on either side of the vent. The arms are slender, there is no axillary membrane, and there are indistinct low tubercles along the ventrolateral edge of the forearm. The relative lengths of the fingers are I < II < IV < III, and they have large, oval discs. The subarticular tubercles are prominent, round to ovoid in shape, and singular. There are also supernumerary tubercles and a small and elongated palmar tubercle. The finger webbing is basal. There are scattered tubercles along the ventrolateral edges of the feet and the tarsus, and the toes have discs that are slightly wider than long that are smaller than the singer discs. The relative length of the toes is I < II < V < III < IV. The inner metatarsal tubercle is large, elongated, and elliptical, and the outer metatarsal tubercle is ill defined. The subarticular tubercles are round, single, and flat, and the supernumerary tubercles are only on the soles. The webbing formula for the toes is I 2 – 2 II 2 – 3 III 2 – 3 IV 3 – 1 ¾ V. The males have a prepollical spine (Caminer and Ron 2014).

Boana alfaroi can be differentiated from its most similar species, B. tetete, by having a an advertisement call consisting of multiple notes where B. tetete’s advertisement call only consists of one. Boana alfaroi also has a smaller tympanum. It also differs from B. fasciatus, B. almendarizae, B. calcarata, and B. maculateralis by its advertisement call and by having a small tubercle on its heel instead of a large calcar. Lastly, it differs from B. fasciatus, B. almendarizae, and B. calcarata by the dark brown dots on its flanks (Caminer and Ron 2014).

In life, the dorsal coloration is a creamy white, yellowish tan, reddish brown, or brown. Individuals sometimes have pale brown dorsal markings of broad transversal bands and narrow longitudinal lines, the latter of which are sometimes on the dorsal surfaces of the limbs as well. A faint brown middorsal line is often present. Occasionally there are scattered minute black dots on the dorsum as well. The flanks are blue in females and light blue or white in males with dark brown dots or blotches. These blotches can also be present on the hidden surfaces of the shanks and the dorsal surfaces of the feet. The ventral coloration is a creamy white or yellowish white. There are brown flecks present on the ventral side of the head, neck, and chest. The ventral surfaces of the limbs are translucent white or yellowish. The discs and webbing are brown, yellowish, or pale cream color. There can be a narrow to wide brown stripe on the outer edge of the hands, forearms, thighs, feet, and tarsal folds. The iris is either yellowish, bronze, or cream with a yellow tone on the upper quarter (Caminer and Ron 2014).

In preservative, the dorsum is a grayish brown with five to six broad diffuse brown transversal bands. The brown middorsal line and the scattered minute black dots are present. The flanks are creamy white with dark brown dots, and the dorsal surfaces of the limbs are grayish brown with narrow transversal brown bars. The hidden surfaces of the thighs are grayish white with dark brown dots. The ventral coloration is creamy white with brown flecks on the ventral side of the head, neck, and chest. The ventral surfaces of the limbs are yellowish white with a narrow to wide brown stripe on the outer edge of the hands, forearms, thighs, feet, and tarsal folds (Caminer and Ron 2014).

There is sexual size dimorphism in B. alfaroi with the females being larger. There is also coloration variation between individuals. In life, the dorsal coloration varies from creamy white to pale grayish brown, grayish brown, pale brown, or brown. The dorsal marks vary in number and they can be irregular or absent. The middorsal line generally extends from the tip of the snout to the middorsum, but can be isolated to just the head, the middorsum, or the sacral region. The transversal bands vary from five to seven and are sometimes connected. The presence of longitudinal lines on the dorsum varies, and the scattered dots on the dorsal surfaces can be either black or white. The flank coloration varies from blue to light blue or white depending on whether it’s male or female. The presence of dark blotches on the hidden surfaces of the thighs, shanks, ventral surfaces of the forelimbs, and dorsal surfaces of the feet varies (Caminer and Ron 2014).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Ecuador

View distribution map in BerkeleyMapper.

Boana alfaroi occurs in the Northwest Amazon and has been found in Assis, State of Acre, Brazil; Valle del Guamez, Putamayo Department, Colombia; Municipio Solano, Caquetá Department, Colombia; Loreto, Peru; central-eastern Peru; and northern Amazon regions in Ecuador (Carvalho et al. 2017; Meza-Joya et al. 2019; Medina-Rangel et al. 2019; Gagliardi-Urrutia et al. 2022; Crnobrna et al. 2023; Caminar and Ron 2014). The elevation range of the Ecuadorian localities is from 176 m to 350 m asl (Caminer and Ron 2014).

Their habitat is mainly Amazon Lowland Evergreen Forest, Floodplain Lowlands, and Lowland Forest of Palms, all of which have canopies of about 30 m. Individuals are found in flooded areas, swamps, near streams and ponds, or in forest away from bodies of water (Caminer and Ron 2014).

Life History, Abundance, Activity, and Special Behaviors

The advertisement call consists of four to five trill-like notes with a mean duration of 0.20 s and a mean rise time of 0.07 s (Caminer and Ron 2014).

Most individuals have been found at night perched on vegetation approximately 50 to 180 cm above the ground in flooded areas (Caminer and Ron 2014).

Larva

A B. calcarata larval specimen from Santa Cecilia, Ecuador was described in 2005, however the B. calcarata species complex has been further examined since then, and the locality of the specimen now also falls into the range of B. alfaroi. It has become unclear which species the larval specimen is (Duellman 2005; Caminer and Ron 2014).

In Gosner stage 38, the larva have a body length of about 10.8 mm and a total length of about 31.8 mm (Gosner 1960; Duellman 2005). The body is elongate ovoid in dorsal view, with the widest section at the midlength and it’s much wider than high. The highest point of the larva is at about three-fourths the length of the body. The snout is rounded in the dorsal view and in profile it inclines from the nares to a rounded tip. The nares are situated dorsally, directed anterolaterally, ovoid, and are midway between the snout tip and the orbits. The median narial papillae are present. The eyes are moderately large, directed and situated dorsolaterally, and they are not visible from below. The interorbital space is narrow. The spiracle is sinistral and long and the distal third of the spiracular tube is not attached to the body wall. The spiracular aperture is round and directed posterodorsally at the two-thirds length of the body. The ventral tube is short, dextral, and incorporated into the ventral fin. The caudal musculature is moderately slender and it is highest at the junction with the body. It tapers into a slight tip. The dorsal fin starts on the proximal caudal musculature and gradually increases its height until about two-thirds the length of the tail. It then abruptly decreases to a narrow fringe. The ventral fin starts on the caudal musculature and doesn’t increase in height. The caudal musculature has a greater height than either fin at the midpoint of the tail. The oral disc is moderately large and is directed anteroventrally. It is incomplete and has lateral folds. There is a single row of small, blunt, marginal papillae present laterally and ventrally. The submarginal papillae are absent. The jaw sheaths are slender and serrate, and the anterior sheath is broadly V-shaped. All the rows of teeth are equal in length except for P-3, which is slightly shorter (Duellman 2005).

In life, the dorsum is dark brown with a faint tan mottling and a tan interorbital bar. The tail is yellowish tan and it has vertical brown bars (Duellman 2005).

In preservative, the dorsum and sides of the body are brown. The posteromedial part and sides of the body are cream. The fins and the belly are transparent. There are faint vertical brown marks present on the proximal two-thirds of the tail, which are more prominent on the fins and caudal musculature posteriorly (Duellman 2005).

Trends and Threats

A small amount of B. alfaroi’s habitat has been degraded by agriculture and cattle raising, but because its range is relatively large, the threats are of low concern (Caminer and Ron 2014).

Comments

In a 2014 Maximum Likelihood analysis of 12S and 16S mtDNA, B. alfaroi was placed as sister to B. tetete. In this same study, the researchers also looked at nucDNA of two genes, which led to a B. tetete specimen being included in the B. alfaroi lineage. However the number of specimens used and the amount of data for the nucDNA analysis was much less than for the mtDNA analysis, so it is difficult to draw conclusions from the nucDNA analysis (Caminer and Ron 2014).

References

Caminer, M. A. and Santiago, R. R. (2014). Systematic of treefrogs of the Hypisboas calcaratus and Hypsiboas fasciatus species complex (Anura, Hylidae) with the description of four new species. ZooKeys 370, 1 - 68. [link]

Carvalho, T. R. de, D. L. Bang, B. F. V. Teixeira, and A. A. Giaretta. (2017). First record of Boana alfaroi (Caminer & Ron, 2014) (Anura: Hylidae) in Brazil. Check List. The Journal of Biodiversity Data 13(4): 135–139. [link]

Crnobrna, B., R. Santa-Cruz Farfan, C. Gallegos, J. J. López-Rojas, I. B. Llanqui, G. Panduro Pisco, and A. Kelsen Arbaiza. 2023. Herpetological records from the Abujao basin, central Peruvian Amazon. Check List. The Journal of Biodiversity Data 19: 433–465 [link]

Duellman, W. E. (2005). Cusco Amazonico: The lives of amphibians and reptiles in an Amazonian rainforest. New York: Comstock Publishing Associates, Cornell University.

Gagliardi-Urrutia, L. A. G., C. R. García Dávila, A. F. Jaramillo-Martinez, O. Rojas-Padilla, E. J. Rios-Alva, R. Aguilar-Manihuari, P. E. Pérez-Peña, S. Castroviejo-Fisher, P. I. Simões, G. Estivals, J. Guillen Huaman, D. Castro Ruiz, C. Angulo Chávez, C. Mariac, F. Duponchelle, and J.-F. Renno. (2022). Afibios de Loreto. Lima, Peru: Ministerio del Ambiente and Instituto de Investigaciones de la Amazonía Peruana.

Medina-Rangel, G. F., M. E. Thompson, D. H. Ruiz-Valderrama, W. Fajardo Muñoz, J. Lombana Lugo, C. A. Londoño-Guarnizo, C. Moquena Carbajal, H. D. Ríos Rosero, J. E. Sánchez Pamo, and E. Sánchez. (2019). Anfibios y reptiles. Pitman, N., A. Salazar Molano, Samper Samper, C. Vriesendorp, A. Vásquez Cerón, A. del Campo, T. L. Miller, E. A. Matapi Yucuna, M. E. Thompson, L. de Souza, D. Alvira Reyes, D. F. Stotz, N. Kotlinski, T. Wachter, E. Woodward, and R. Botero García eds., Colombia: Bajo Caguán–Caquetá. Rapid Biological and Social Inventories 30: 111–454. Chicago, Illinois, Field Museum.

Meza-Joya, F. L., E. Ramos-Pallares, and C. Hernández-Jaimes. (2019). Hidden diversity in frogs within Boana calcarata–fasciata and Boana geographica species complexes from Colombia. Herpetology Notes 12: 391–400.

Species Account Citation: AmphibiaWeb 2024 Boana alfaroi: Alfaro's Treefrog <https://amphibiaweb.org/species/8121> University of California, Berkeley, CA, USA. Accessed Feb 1, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 1 Feb 2025.

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