I studied the evolutionary relationships and parental care behaviors of an assemblage of 19 species of microhylid frogs from a mid-elevation site in Papua New Guinea. The microhylid frogs of New Guinea are an exceptionally diverse radiation of frogs (\u3e150 species in \u3e20 Genera) on the largest tropical island. Two novel parental care behaviors for male frogs (froglet attendance and froglet transport) are described and quantified and six ecological guilds are defined to better understand variation in parental care behaviors across species. Patterns of parental care behaviors found in ecological guilds of the assemblage were studied in the field with experiments and observations. I discuss the functions and importance of parental care in adaptive suites at the guild level. Results from adult removal experiments for clutches of two species (one terrestrial and one arboreal breeder) confirm that attendance significantly increases offspring survivorship. I show how the proximate causes of mortality in unattended clutches most likely reflect diverse selective pressures acting on species in different microhabitats. Desiccation appears to be a major selective force molding the parental care behaviors of the arboreal frog, Oreophryne sp. rattler whereas predation appears to be the major selective pressure accounting for the parental care behaviors exhibited by the terrestrial frog, Hylophorbus rufescens .I sequenced DNA (1381 base pairs from the 18S and 16S rRNA genes) and coded 36 behavioral characters to hypothesize the phylogeny of Papuan microhylid frogs. Results of phylogenetic analyses suggest that (1) both of the currently recognized Papuan subfamilies, the Genyophryninae and the Asterophryinae are artificial taxa and should be combined into the Asterophryinae (Gunther, 1858), (2) currently recognized genera Austrochaperina, Cophixalus , and Oreophryne are polyphyletic, (3) the previously proposed phylogenetic hypotheses of Wu (1994), the monophyly of both the subfamilies and genera of these microhylid frogs are refuted. I discuss how specific parental care behaviors evolved in these frogs relative to ecological guilds in my preferred hypothesis of phylogeny
