TL;DR: The development of oral structures in egg‐brooding hylids provides insight into the phylogenetic significance of these charactes in other groups of anurans, and reinforces the idea that microhylids evolved from ranoidlike ancestors.
Abstract: Among egg-brooding hylid frogs there is much interspecific variation in the degree of development of the young at hatching. In certain species of Gastrotheca the eggs hatch into free-living tadpoles, whereas in others (and in the genera Amphignathodon, Cryptobatrachus, Stefania and Hemiphractus) the eggs hatch directly into frogs. We examined the oral anatomy of tadpoles and embryos of 22 species of egg-brooding hylids in order to determine the morphological differences between free-living larvae and embryos of species having direct development. All free-living Gastrotheca larvae are morphologically similar and have a large array of oral structures directly associated with a suspension feeding way of life. Among those egg-brooding hylids without free-living larvae there is a complete gradation from those with all of the free-living tadpole oral structures to those with none. Different lineages retain different vestiges of free-living larval morphology, suggesting that direct development has evolved multiple times among these frogs. All of the morphological patterns in the direct-developing embryos can be accounted for by simple truncation or acceleration of the normal tadpole developmental program. We explore the possibility that certain Gastrotheca species with tadpoles may have evolved from species that lack larval stages. The development of oral structures in egg-brooding hylids provides insight into the phylogenetic significance of these charactes in other groups of anurans. Most significantly they reinforce the idea that microhylids evolved from ranoidlike ancestors.
TL;DR: The results support the most recent common ancestor of hemiphractids as a direct-developer, and propose a revised taxonomy concordant with the optimal topologies.
Abstract: Egg-brooding frogs (Hemiphractidae) are a group of 105 currently recognized Neotropical species, with a remarkable diversity of developmental modes, from direct development to free-living and exotrophic tadpoles. Females carry their eggs on the back and embryos have unique bell-shaped gills. We inferred the evolutionary relationships of these frogs and used the resulting phylogeny to review their taxonomy and test hypotheses on the evolution of developmental modes and bell-shaped gills. Our inferences relied on a total evidence parsimony analysis of DNA sequences of up to 20 mitochondrial and nuclear genes (analyzed under tree-alignment), and 51 phenotypic characters sampled for 83% of currently valid hemiphractid species. Our analyses rendered a well-resolved phylogeny, with both Hemiphractidae (sister of Athesphatanura) and its six recognized genera being monophyletic. We also inferred novel intergeneric relationships [((Cryptobatrachus, Flectonotus), (Stefania, (Fritziana, (Hemiphractus, Gastrotheca))))], the non-monophyly of all species groups previously proposed within Gastrotheca and Stefania, and the existence of several putative new species within Fritziana and Hemiphractus. Contrary to previous hypotheses, our results support the most recent common ancestor of hemiphractids as a direct-developer. Free-living aquatic tadpoles apparently evolved from direct-developing ancestors three to eight times. Embryos of the sister taxa Cryptobatrachus and Flectonotus share a pair of single gills derived from branchial arch I, while embryos of the clade including the other four genera have two pairs of gills derived from branchial arches I and II respectively. Furthermore, in Gastrotheca the fusion of the two pairs of gills is a putative synapomorphy. We propose a revised taxonomy concordant with our optimal topologies.
TL;DR: The phylogenetic relationships of genera of hemiphractine hylid frogs (Marsupial Treefrogs) are reassessed and the evolution of several distinctive characters within this group is discussed using parsimony analysis.
TL;DR: The taxonomic status of populations of frogs in the genus Hemiphractus in Panama has been reviewed by as mentioned in this paper, who identified distinctive features of the skulls of frogs representing these three allopatric populations and herein revalidate H. panamensis.
Abstract: We reviewed the taxonomic status of populations of frogs in the genus Hemiphractus in Panama, which have all been referred to Hemiphractus fasciatus Peters, 1862 for over 40 years. Although relatively few specimens have been collected, mostly juveniles, it is clear that these frogs inhabit three separate upland regions of the country: The Cordillera de Talamanca in western Panama, the Chagres Highlands and Cordillera de San Blas in central Panama, and the Serrania de Pirre in the far eastern portion of the country. In accordance with previously published molecular data, we identified distinctive features of the skulls of frogs representing these three allopatric populations and herein revalidate H. panamensis (Stejneger, 1917), describe the new species Hemiphractus elioti sp. nov. from the Cordillera de Talamanca, and the new species Hemiphractus kaylockae sp. nov. from the Serrania de Pirre. We also propose that the taxon H. fasciatus is a South American species not occurring in Panama.