Gastrotheca williamsoni Gaige, 1922 *

Holotype: UMMZ 55559.

Type locality: San Esteban, Carabobo, Venezuela.

Distribution: Region 2. Known only from type locality.

Remarks: Not collected since original description. Either extremely rare, or extinct, or Gastrotheca walkeri could be a junior synonym. A review of this species is needed to clarify its taxonomy and conservation status. Duellman (2015) distinguished G. williamsoni from G. walkeri based on four morphological characters (absence of supraciliary processes ― vs present in walkeri ―, fingers ½ webbed ― vs ¼ webbed in walkeri ―, first finger longer than second ― shorter in walkeri ―, and granular tympanic annulus ― smooth in walkeri . The only known locality of G. williamsoni lies within the distribution of G. walkeri, and no additional specimen obtained for almost a century. As both species share a unique character among marsupial frogs (paired retroperitoneal brood pouches), have overlapping geographic distributions, and only differ in morphological traits prone to preservation artifacts, makes us doubt the validity of G. walkeri; assessing their taxonomic status requires further investigation. Included in subgenus Cryptotheca by Duellman (2015) or in Gastrotheca longipes species group sensu Castroviejo-Fisher et al. (2015).

Selected references: Gaige (1922); Lutz (1927); Ginés (1959); Rohl (1959); Rivero (1961, 1964a); Duellman (1980, 2015); Duellman et al. (1988); Barrio-Amorós (2013).