Comprehensive DescriptionRead full entry
Ischnocnema guentheri is a small direct-developing frog (19-40mm SVL, belonging to the I. guentheri species series of Hedges et al. (2008) and closely related to I. parva (Heinicke et al. 2007). The snout is fairly long and acuminate in dorsal view. Nostrils lateral. Eyes large, fairly prominent, with the diameter about 1.5 times the snout length. The tympanum is distinct, with the diameter about 1/5 that of the eye. Single vocal sac weakly indicated, males with vocal slits. The first finger is about the same length as the second. Fingers free, without webbing, fairly long, all with dilated tips, a pronounced rounded tubercle at the base of the first finger; metacarpal tubercles well developed. Legs and toes long, with enlarged discs, fifth toe longest. Outer metatarsal tubercle rounded. Dorsal texture smooth or very finely granular. Ventral texture smooth.
Dorsal color can vary greatly from dark brown, uniform dark, brick red, green or pale cream. Posterior surface of the thigh almost uniform brown. Dark sacral spots present. Most individuals bear an interrupted or complete dark stripe in the anterior surface of the tibia. The belly is smooth and can vary from light yellow to golden yellow or cream, just like the inner side of the tibia. Heel with tubercles (Cochran 1955; Heyer 1984; Heyer et al. 1990). The species exhibits sexual size dimorphism, with males being smaller than females (Heyer 1984). Mean body mass is 1.77g (Rocha et al. 2007).
The species has a diploid chromosomal number of 2n = 22 (Beçak 1968; Siqueira et al. 2004).
The name of the genus comes from the Greek words ischnos, meaning slender or weak, and kneme, meaning calf of the leg (Hedges et al. 2008). The species is named for Albrecht Karl Ludwig Gotthilf Günther (October 3, 1830 - February 1, 1914), a German-born British zoologist. A photo of the holotype is available in Kwet and Solé (2005). A table with distinctive traits that can differentiate I. guentheri from other members of the group from southeastern Brazil is available from Heyer (1984: 21).
Kwet and Solé (2005) stated that there are at least three cryptic species under the name of I. guentheri, revealing the necessity of taxonomic clarification.