Description

Dendropsophus microcephalus is a small frog. Adult males have a snout vent length of up to 27 mm (McCranie and Wilson 2002). Honduran females measure up to 29 mm (McCranie and Wilson 2002), while Mexican and Costa Rican females may reach 30.6 mm (Duellman 2001).

The head is flat and the snout is round and short. Eyes have horizontally elliptical pupils. Nostrils are laterally directed and the area between nostrils is somewhat concave. No vertical rostral keel is present. The tympanum is located slightly below the eye at a distance of about its own length. The supratympanic fold is weak. The tongue is ovoid and free for about one-third of its length posteriorly. Maxillary teeth are conical. Vomerine teeth are present, with tooth patches on raised ridges between ovoid to elliptical choanae and separated by slightly less than their own length. The dorsal skin is generally smooth, while the ventral surfaces range from weakly granular on the throat to coarsely areolate on the belly. This species has a well-developed axillary membrane. The upper arm is slimmer than the forearm. A weak transverse dermal fold is present on the upper surface of the wrists but no vertical dermal fold is present on the elbow. A weakly defined inner tarsal fold is present, which spans the length of the tarsus, but no dermal ridge is present along the posterior ventrolateral edge of the tarsus. (McCranie and Wilson 2002).

Fingers are 1/3 webbed and the toes 3/4 webbed (Duellman 2001). Lateral keels are present on unwebbed sections of the fingers. Fingers and toes have discs expanded to a nearly ovoid shape with rounded disc covers. The discs on the toes are slightly smaller than the discs on the fingers. Subarticular tubercles are present on the fingers and are globular to conical and round. Supernumerary tubercles are not present on the fingers. The palmar tubercle is low, ovoid, and sometimes bifid to occasionally indistinct. The accessory palmar tubercles are round and slightly raised. The prepollex is round, enlarged and does not bear nuptial excrescences. On the toes, the subarticular tubercles are spherical in shape. Supernumerary tubercles are not present on the toes. The inner metatarsal tubercle is oval and raised, and the outer metatarsal tubercle is small, rounded and elevated. There is no vertical dermal fold on the heel. No nuptial pads are present (McCranie and Wilson 2002).

This species can undergo metachrosis, or color change. During the night, the dorsum is a light yellow color with various brown or tan markings. During the day, the dorsum is a tan-yellow color, or light brown with darker brown or red markings (Duellman 2001). The venter is white, and breeding males have a yellow vocal sac (Duellman 2001). This frog has uniformly yellow thighs with a brown line, often bordered with a narrow white line extending from the nostril to the vent (Leenders 2001). The dorsal pattern on this species is variable; many individuals have an "X" shape on their backs, or two longitudinal bars connected with a crossbar. Others have irregularly placed dark brown dashes. In specimens from Mexico and Guatemala, the lateral brown stripe only extends to the sacral region, but in Costa Rica, many specimens have a stripe that extends to the groin (Duellman 2001). The iris is bronze. (McCranie and Wilson 2002).

Dendropsophus microcephalus tadpoles collected east of Esparta, Costa Rica typically had a total length of 28 mm and a body length of 9.2 mm (Duellman 2001). Eyes are dorsolateral and the snout is pointed. The body is wider than it is deep. The mouth has finely serrated beaks and no teeth. The dorsal fin reaches onto the body. The spiracle is sinistral. Tadpoles have a yellow dorsum and a white venter, and the posterior half of the tail is orange. A brown stripe runs from the larval snout through the eye (Campbell 1998).

The diploid chromosome number is 30 (Duellman, 2001).

A Spanish-language species account can be found at the website of Instituto Nacional de Biodiversidad (INBio).