William E. Duellman

Major Caribbean and Central American frog faunas originated by ancient oceanic dispersal

Approximately one-half of all species of amphibians occur in the New World tropics, which includes South America, Middle America, and the West Indies. Of those, 27% (801 species) belong to a large assemblage, the eleutherodactyline frogs, which breed out of water and lay eggs that undergo direct development on land. Their wide distribution and mode of reproduction offer potential for resolving questions in evolution, ecology, and conservation. However, progress in all of these fields has been hindered by a poor understanding of their evolutionary relationships. As a result, most of the species have been placed in a single genus, Eleutherodactylus, which is the largest among vertebrates. Our DNA sequence analysis of a major fraction of eleutherodactyline diversity revealed three large radiations of species with unexpected geographic isolation: a South American Clade (393 sp.), a Caribbean Clade (171 sp.), and a Middle American Clade (111 sp.). Molecular clock analyses reject the prevailing hypothesis that these frogs arose from land connections with North and South America and their subsequent fragmentation in the Late Cretaceous (80–70 Mya). Origin by dispersal, probably over water from South America in the early Cenozoic (47–29 million years ago, Mya), is more likely.

Acoustic Resource Partitioning in Anuran Communities

WILBUR, H. M. 1971. The ecological relationship of the salamander Ambystoma laterale to its all-female, gynogenetic associate. Evolution 25:168-179. -. 1972. Competition, predation, and the structure of the Ambystoma-Rana sylvatica community. Ecology 53:3-21. . 1976. Density-dependent aspects of metamorphosis in Ambystoma and Rana sylvatica. Ecology 57:1289-1296. .. 1977. Propagule size, number, and dispersion pattern in Ambystoma and Asclepias. Amer. Natur. 111:43-68.

Population Decline of the Jambato Toad Atelopus ignescens (Anura: Bufonidae) in the Andes of Ecuador

Abstract The Jambato Toad, Atelopus ignescens, is endemic to montane forests, inter-Andean valleys, and paramos in Ecuador. Although formerly abundant and widely distributed, the species has not been recorded in nature since 1988. To determine its population status, data from intensive surveys in 1999–2001 are compared with those from 1967 and 1981. Presence-absence data from several localities also are reported. Temperature and precipitation between 1891 and 1999 were analyzed to determine whether these correlate with population trends. Atelopus ignescens was abundant in 1967 at Paramo de Guamaní (47 individuals recorded in 120 pers/min) and in 1981 at Paramo del Antisana (up to 0.75 individuals/m2). In the 1999–2001 surveys, A. ignescens was absent despite considerably higher survey efforts. The presence-absence data at several localities also indicate a dramatic decline. Before 1988, A. ignescens was present during 64% of the visits to sites throughout its range. After 1988, A. ignescens was absent at all sites. The results strongly suggest that A. ignescens is extinct. Climatic data show that 1987, the year previous to the last record of A. ignescens, was particularly warm and dry. The reasons for the decline in pristine areas remain unclear, although the available information suggests that a combination of factors such as pathogens and unusual weather conditions may have played an important role.

Loss and re-evolution of complex life cycles in marsupial frogs: does ancestral trait reconstruction mislead?

Abstract Using phylogeny-based methods to identify evolutionary transitions has become an integral part of evolutionary biology. Here, we demonstrate the potential for these methods to give statistically well-supported but misleading inferences about character evolution. We also show how inferences of character evolution can be informed using GIS-based methods to reconstruct ancestral environmental regimes. We reconstruct a phylogeny for marsupial frogs (Hemiphractidae) using nuclear and mitochondrial DNA sequences and estimate patterns of life-history evolution across the resulting tree. We find that Gastrotheca species with complex life cycles (i.e., egg, tadpole, and adult stages) are phylogenetically nested among species and genera with direct development (i.e., egg and adult stages only). Assuming a single rate for gains and losses in likelihood reconstructions, there is strong statistical support for the hypothesis that the tadpole stage was lost early in the phylogeny but reappeared within Gastrotheca. Assuming different rates of gain and loss, the model with significantly higher statistical support, the tadpole stage seems to have been lost multiple times but never regained. Given that both hypotheses cannot be correct, at least one reconstruction model must be giving well-supported but misleading results. Several lines of evidence (including GIS-based reconstructions of the ancestral climatic regime) suggest that the former hypothesis is correct, and that the tadpole stage has evolved from direct development within Gastrotheca, the only known case of such a reversal in frogs.

Phylogenetics, classification, and biogeography of the treefrogs (Amphibia: Anura: Arboranae)

A phylogenetic analysis of sequences from 503 species of hylid frogs and four outgroup taxa resulted in 16,128 aligned sites of 19 genes. The molecular data were subjected to a maximum likelihood analysis that resulted in a new phylogenetic tree of treefrogs. A conservative new classification based on the tree has (1) three families composing an unranked taxon, Arboranae, (2) nine subfamilies (five resurrected, one new), and (3) six resurrected generic names and five new generic names. Using the results of a maximum likelihood timetree, times of divergence were determined. For the most part these times of divergence correlated well with historical geologic events. The arboranan frogs originated in South America in the Late Mesozoic or Early Cenozoic. The family Pelodryadidae diverged from its South American relative, Phyllomedusidae, in the Eocene and invaded Australia via Antarctica. There were two dispersals from South America to North America in the Paleogene. One lineage was the ancestral stock of Acris and its relatives, whereas the other lineage, subfamily Hylinae, differentiated into a myriad of genera in Middle America.

A new frog family (Anura: Terrarana) from South America and an expanded direct-developing clade revealed by molecular phylogeny

Three frogs of a new species found in cloud forests on two nearby mountains in Guyana were included in a molecular phylogeny of 17 nuclear and mitochondrial genes (10,739 aligned sites) that revealed that their closest relative is Terrarana (Brachycephalidae, Craugastoridae, Eleutherodactylidae, and Strabomantidae) and their next-closest relative is Hemiphractidae (marsupial frogs). We place these frogs in a new family, genus, and species which is strongly supported as the basal clade within Terrarana: Ceuthomantidae n. fam., Ceuthomantis smaragdinus n. gen, n. sp. Morphological evidence supports the placement of two other species from the Guiana Highlands, Pristimantis aracamuni (BarrioAmoros & Molina) and P. cavernibardus (Myers & Donnelly), in the new family and genus. This close phylogenetic relationship of terraranans and marsupial frogs, nearly all of which have direct development, supports an hypothesis that direct development evolved early in the evolution of this huge clade (~1000 species), for which we propose the unranked taxonomic epithet Orthobatrachia.

Oral structures and their development in egg-brooding hylid frog embryos and larvae: evolutionary and ecological implications

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.

Description of a New Species of Bufo from Northern Peru with Comments on Phenetic Groups of South American Toads (Anura: Bufonidae)

A new species of arboreal toad, Bufo arborescandens, is from the forested slopes of the Cordillera Central in northern Peru. It lacks cranial crests, tympana, and tarsal folds; an adult male has a cluster of keratinous spines on the thumb. This small toad is placed in the Bufo veraguensis group, for which a key to the species and summary of distributions are provided. Of the 51 species of Bufo recognized in South America, 45 are allocated to eight phenetically defined groups.

Leptodactylid frogs of the Physalaemus pustulosus group

Within the leptodactylid frog genus Physalaemus, four species comprise a monophyletic group: P. petersi (with P.freibergi designated as a junior synonym), P. pustulatus, P. pustulosus and P. coloradorum, a new species from the Pacific lowlands of Ecuador. Physalaemus petersi and P. pustulosus seem to be sister- species, as do P. pustulatus and P. coloradorum. The monophyly of the genus Physalaemus is questionable. THE 33 nominal species of small toad-like leptodactylids of the genus Physalaemus were placed in four species groups by Lynch (1970). Four species were recognized in the Physalaemus pustulosus group-P. freibergi in Bo- livia, P. petersi in the Amazon basin, P. pustulatus on the Pacific lowlands of Ecuador and P. pus- tulosus in Mexico, Central America, and north- ern South America. Lynch (1970) suggested that the nominal species P. paraensis and P. schereri were synonyms of P. petersi and that P. stentor was a synonym of P. pustulosus, although he pro- vided no evidence to support these conclusions. While studying specimens of Physalaemus that we collected on the Pacific lowlands of Peru and Ecuador, we discovered that two distinct taxa occurred in that region. Comparisons of the trans-Andean specimens with members of the P. pustulosus group from elsewhere in the range of the group resulted in this review. Our pur- poses are to: 1) define the Physalaemus pustulosus THE 33 nominal species of small toad-like leptodactylids of the genus Physalaemus were placed in four species groups by Lynch (1970). Four species were recognized in the Physalaemus pustulosus group-P. freibergi in Bo- livia, P. petersi in the Amazon basin, P. pustulatus on the Pacific lowlands of Ecuador and P. pus- tulosus in Mexico, Central America, and north- ern South America. Lynch (1970) suggested that the nominal species P. paraensis and P. schereri were synonyms of P. petersi and that P. stentor was a synonym of P. pustulosus, although he pro- vided no evidence to support these conclusions. While studying specimens of Physalaemus that we collected on the Pacific lowlands of Peru and Ecuador, we discovered that two distinct taxa occurred in that region. Comparisons of the trans-Andean specimens with members of the P. pustulosus group from elsewhere in the range of the group resulted in this review. Our pur- poses are to: 1) define the Physalaemus pustulosus

The Central American Herpetofauna: An Ecological Perspective

Six major herpetological habitats (biociations) are recognized in Central America; these are based principally on the physiognomic characteristics of the vegetation. There are three tropical habitats (evergreen forest, scrub forest, and savanna) and three montane habitats (cloud forest and low montane wet forest, oak-pine forest, and alpine and subalpine habitats including fir forest, pine-cypress forest, and montane meadows). Temperature and moisture are the principal environmental factors affecting the distributions of amphibians and reptiles in Central America. Secondarily, cover in the form of shade or mulch, and suitable breeding sites are significant factors determining the distribution of species. Five major ecological assemblages are defined in the Central American herpetofauna; characteristic species are noted in each, and the geographical distribution of each assemblage is described. The humid tropical and arid tropical assemblages contain the largest numbers of species and are widespread in the lowlands. The humid montane assemblage is characterized by a high degree of local endemism and inhabits cloud forest and low wet forest in the mountainous regions. The arid montane assemblage consists of an impoverished fauna inhabiting oak-pine forests, and the high montane assemblage is made up of a few species living in the alpine and subalpine habitats. A geographical analysis shows that a greater continuity exists in the lowland than in the montane assemblages; the latter often more closely resemble assemblages in the adjacent lowlands than in geographically remote highlands and characteristically exhibit a higher degree of local endemism than the lowland faunas. Climatic fluctuations in the Pleis-