Photo 952321, (c) Joseph Sánchez, some rights reserved (CC BY-NC)

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Associated observations

Photos / Sounds


Lowland Burrowing Treefrog Smilisca fodiens




June 27, 2014


Smilisca fodiens is a frog that can reach sizes of 54 - 63 mm. Females do not differ significantly from males in proportions. The relatively small head is slightly wider than long. The skin of the head is partly co-ossified with underlying cranial bones. The snout when dorsally viewed is acutely rounded and bluntly rounded from the lateral view. The canthal ridges are distinct, where they meet forms a bony internasal ridge. The ridge extends anteriorly to the tip of the snout. The pupil is horizontal and the iris is dull bronze. The hind limbs are short and robust. The fingers are long and have small discs. The fingers are slender and have no webbing. The toes have small amount of webbing. The terminal discs are smaller than the finger discs. The inner metatarsal tubercle is large, elliptical, and spade-like. The skin is granular on the belly, dorsum, and parts of the thighs but otherwise smooth. The vocal sac is subgular and bilobate, and the halves are narrowly separated. The tadpoles have short tails, are pelagic type, have a anteroventral mouth with a large beak, have large papillae both laterally and ventrally, and have two-thirds tooth rows (Trueb 1969).

Smilisca fodiens's closest relative is Smilisca dentata, from which it can be differentiated by S. fodiens having a bony ridge extending from a point between the nostrils to the tip of the acutely rounded snout, digits expanded into small discs, and vocal sacs connected medially in breeding males (Trueb 1969).

In life, the dorsum coloration ranges from tan, pale olive-brown, grey-brown, and pink-brown. There are longitudinal stripes and small spots with dark brown or red-brown coloration and dark brown or black outline. In preservative, the dorsal ground color varies from pale grey-tan to creamy/pink-tan (Trueb 1969).

There is variation in the pattern of stripe/spot arrangement, as well as slight coloration differences (Trueb 1969).

Smilisca fodiens occurs from south-central Arizona in the USA, southward along the Pacific coast through to western Sonora, Sinaloa, Nayarit and Colima in Mexico. Inland it is found from central Jalisco to northern Michoacán and adjacent Guanajuato, Mexico. It occurs from near sea level to about 1,490m (Santos-Barrera et al. 2010).

Its natural habitats are subtropical or tropical dry forests, subtropical or tropical moist lowland forests, subtropical or tropical dry shrubland, subtropical or tropical dry lowland grassland, intermittent freshwater marshes, and temperate desert.

Similar to spadefoots, this species spends the majority of the year underground and emerges with the first, substantial summer rains. While dormant underground, it forms a cocoon of multiple layers of stratum corneum (the outermost layer of the epidermis) that is perforated only at the nostrils. This cocoon prevents desiccation. Firschein (1951) described the unken reflex in this species, which consists of flexing the head downward and elevating the limbs so as to rest on the belly. The purpose of this behavior may be to close burrows in the ground. Lowland burrowing treefrogs are typically found on the ground, but they can climb short distances into trees and shrubs.

Breeding occurs “explosively” during the summer rains from late June into September. After the first substantial storm, Lowland burrowing treefrogs gather around temporary pools that form in washes, cattle tanks, or other impoundments. The advertisement calls, given at night by males, are low-pitched notes resembling the quack of a duck. Males also give what may be a territorial call, similar to the advertisement call of the Western chorus frog. Males call from secluded places, often out of water, but near breeding pools. Clutch size and larval developmental times are unknown.

Unknown, but presumably Lowland burrowing treefrogs eat a variety of arthropods.

Until recently, this species was considered in the genus Pternohyla. The Lowland burrowing treefrog is a tropical or subtropical species that reaches its northern limit in southern Arizona.
Brennan,T.C.(2008).LOWLAND BURROWING TREEFROG Smilisca fodiens [reptilesofaz.orgl] de:

AmphibiaWeb: Information on amphibian biology and conservation. [web application]. 2014. Berkeley, California: AmphibiaWeb. Available: (Accessed: Jun 28, 2014).

Associated taxa
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