Frogs of the subgenus Syrrhophus are among the most ubiquitous and abundant of amphibians throughout their range, yet also some of the least well known. Like other members of the Terrarana (Hedges et al. 2008), these frogs reproduce on land and have direct development. They inhabit a mosaic of different habitats along elevational gradients from sea level to about 2,000 meters, and are characterized by exceptional microendemism, with many species known only from the type locality. These frogs are ideal for addressing a range of fundamental evolutionary and ecological questions, owing to their high species diversity (>26 species), ample opportunities for species interactions, and unusual reproductive mode. This potential has not been realized however, due to a lack of understanding of phylogenetic relationships and an inaccurate taxonomy.
In part, this taxonomic confusion stems from overall morphological conservatism among Syrrhophus species, and a history of delimiting species using evolutionarily plastic characters such as color pattern, skin texture, relative digit length, and size of digital discs (Dixon 1957; Lynch 1970; Hedges et al. 2008). Members of this group were previously placed in two separate genera, Syrrhophus and Tomodactylus (Smith and Taylor 1948). Lynch (1968, 1970, 1971) maintained these genera as distinct, and discussed differences separating them from Eleutherodactylus. Hedges (1989) proposed that species previously placed in the genera Syrrhophus and Tomodactylus be placed in the subgenus Syrrhophus based on osteological similarities (Lynch 1971). Heinicke et al. (2007) found that two species from western Cuba formerly assigned to the subgenus Euhyas, E. symingtoni and E. zeus, grouped with the mainland Eleutherodactylus (Syrrhophus) marnockii in their phylogenetic analysis, and as a result, transferred them to the subgenus Syrrhophus. Their presence in Cuba suggests mainland Syrrhophus arose through dispersal from Cuba (Hedges 1989; Hass and Hedges 1991; Heinicke et al. 2007). Hedges et al. (2008) conducted a major monographic revision of New World direct developing frogs using DNA sequences, but included only three (of 24) mainland species of Syrrhophus in their phylogeny. Eleutherodactylus nitidus (a member of the former “Tomodactylus”) was found in a position nested within species of the former genus “Syrrhophus” (Hedges et al. 2008). Hedges et al. (2008) recognized the mainland and Cuban clades as informal “species series”, the E. longipes series (24 species) and E. symingtoni series (2 species), respectively. Within the E. longipes series, species were placed into six species groups defined by Lynch (1970): the E. leprus, longipes, marnockii, modestus, nitidus, and pipilans species groups (Hedges et al. 2008)