IUCN threat status:

Least Concern (LC)

Comprehensive Description

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Description

Rana vaillanti is a large frog with males reaching 67-94 mm and females 76-125 mm in snout-vent length (Savage 2002). The head is longer than wide, with a pointed snout. The tympanum is large, and exceeds or is equal to the eye diameter. Fingers are unwebbed but have a lateral ridge, and also have slightly swollen tips. Finger I is longer than finger II. Subarticular tubercles are present under fingers but no supernumerary, plantar, or accessory palmar tubercles are present. The thenar tubercle is elongated and the palmar tubercle is cordate to bifid. On the hindlimb, a weak tarsal ridge is present. Toes have expanded tips and are fully webbed, with oblong subarticular tubercles. The inner metatarsal tubercle is present and elongate, but the outer metatarsal tubercle is lacking. Dorsal surfaces on this frog are covered with white-tipped denticles, particularly between the two prominent dorsolateral folds. The shank bears longitudinal rows of white-tipped denticles on the dorsal surface. Ventrally most surfaces are smooth, but the underside of the tarsus is denticulate. Males have paired rounded vocal slits and paired internal subgular vocal sacs, as well as yellowish nuptial excrescences on the dorsolateral surface of the thumb and forearm (Savage 2002).

This frog has a tannish brown dorsum with an anterior greenish cast, often containing small, black punctations that border the outside of the paired dorsolateral ridges (Savage 2002). Sexual dichromatism is present; males have a brighter green dorsum while females have a gray-brown dorsal coloration with green only along the edges (Ramirez et al. 1998). Scattered brown markings may be present posteriorly (Savage 2002). The top of the head and the sides of the face are green (Guyer and Donnelly 2005). The upper lip is a uniform grayish green color while the lower lip is either white or gray, extending as a strip to the anterior portion of the upper arm (Guyer and Donnelly 2005). The dorsal quarter of the iris is yellow, which stands out against the green color of the face (Guyer and Donnelly 2005). The venter may be a lighter yellow or even white, with much of the ventral side mottled with light and dark gray (Guyer and Donnelly 2005). Legs have transverse dark bars (Savage 2002), and the posterior thighs are dark gray with yellow reticula (Guyer and Donnelly 2005).

Sexual dimorphism is present as well; the female is larger than the male, and males have larger tympana, while females have tympanic diameters that are equal to or smaller than the orbit diameter (Ramirez et al. 1998). Breeding males also have a thickened, darker nuptial pad along the inside of each thumb and thicker forearms than the female (Guyer and Donnelly 2005).

Juvenile coloration tends to be of a brighter shade of green than the adult, so that the body is dark green with a wide, tan strip between the dorsolateral ridges, which contain small, black punctations. The sides of the juvenile body are brownish gray with yellow lips. The side of the face is green, bordered dorsally by a distinct black line that runs from the naris to the eye (Guyer and Donnelly 2005).

This species has very large larvae, reaching 80 mm in total length. The larval body is ovoid. The eyes and nostrils are dorsal. The mouth is ventral, with a moderate, emarginate oral disc having finely serrated beaks and 4/4 rows of denticles. Denticle rows A2-A4 are interrupted, either medially above the mouth or by the mouth, while row P1 is interrupted medially below the mouth. Papillae are present in three lateral rows on each side. The spiracle is sinistral and low, located near the level of the eye, and the vent is dextral. The tail is of moderate length with deep tail fins and a rounded tail tip. Dorsally and laterally, the body is dark, with irregular dark blotches; the tail musculature and fins also have large dark blotches (Savage 2002).

Previous species lists may refer to this frog as Rana palmipes (Guyer and Donnelly 2005). Savage (2002) and Guyer and Donnelly (2005) follow the systematic treatment of Hillis and de Sá (1988), in separating the two species based on morphology.

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

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