Leptodactylidae Research Articles

A NEW, CRYPTIC SPECIES OF PHYSALAEMUS (ANURA: LEPTODACTYLIDAE) FROM WESTERN ECUADOR WITH COMMENTS ON THE CALL STRUCTURE OF THE P. PUSTULOSUS SPECIES GROUP

We describe a new species of leptodactylid frog of the genus Physalaemus from the lowlands of western Ecuador. It belongs to the P. pustulosus species group and differs from other group members in its smaller size, skin texture, tadpole characters, and advertisement call. The new species has wide variation in size and color pattern both at the intra- and inter-population levels. This variation matches that observed in P. montubio and P. randi, and render difficult its diagnosis on the basis of morphological features. A phylogenetic analysis of morphological characters shows that the new species belongs to a clade distributed west of the Andes in Ecuador and northern Peru, sister to (P. petersi P. pustulosus). A phylogeny based on mtDNA shows that P. montubio and P. randi form a clade sister to (P. coloradorum P. sp. nov.). The calls of these three species have two components with different acoustic features that arguably match the frequency sensitivity of the ear of conspecific females, in a manner similar to the complex calls of P. pustulosus. The new species occurs in two predominantly dry regions, the Lowland Deciduous Costa Forest, and the Lowland Semideciduous Costa Forest.

Protamines in the internally fertilizing neobatrachian frog Eleutherodactylus coqui

The internally fertilizing primitive frog Ascaphus truei (family Ascaphidae) from the Pacific Northwest is the only frog with an intromittent organ. The more advanced neobatrachian frog Eleutherodactylus coqui (family Leptodactylidae) from Puerto Rico has secondarily acquired internal fertilization but mates by cloacal apposition. Nonetheless, both frogs have introsperm with an elongated head containing highly condensed chromatin. Characterization of sperm nuclear basic proteins (SNBPs) in E. coqui by acid-urea polyacrylamide gel electrophoresis indicates that, as in A. truei, testes from a single animal contain several protamines. Amino acid analysis indicates a composition for the most rapidly moving protamine of each species as follows: in E. coqui, ARG (35.6 mol %) + LYS (3.8 mol %) + HIS (7.6 mol %) = 47 mol % total basic residues and in A. truei, ARG (42.1 mol %) + LYS (11.1 mol %) = 53.2 mol % total basic residues. Transmission electron microscopy shows that E. coqui introsperm, like those in A. truei, are elongate with highly condensed chromatin. However, E. coqui introsperm lacks an axial perforatorium that extends into an endonuclear canal. These morphological features are plesiomorphic (primitive) and shared by A. truei with urodeles and basal amniotes (Jamieson et al. (1993) Herpetologica 49:52-65). In E. coqui introsperm, the nucleoprotein complex has a cross-sectional axis of 420 + 20 angstroms and shows a knobby chromatin structural organization in TEM. The presence of arginine-enriched protamines in both a basal anuran like the ascaphid A. truei and a more advanced neobatrachian like the leptodactylid E. coqui supports the hypothesis that internal fertilization acts as a constraint on the range of SNBP diversity in animals.

TWO NEW SPECIES OF PHYSALAEMUS (ANURA: LEPTODACTYLIDAE) FROM WESTERN ECUADOR

We describe two new species of the leptodactylid frog genus Physalaemus from the lowlands of western Ecuador. Both species belong to the P. pustulosus species group. They differ from other group members, except P. coloradorum, in their smaller size. They can be distinguished from P. coloradorum by their less tuberculate dorsal skin and a more depressed loreal region. The new species differ from each other markedly in advertisement call. Although the ranges overlap, body size, flank gland length, and parotoid gland length (relative to snout-vent length) are also significantly different. Overall the new species are similar in color patterns and body shape; they are difficult to diagnose from each other with morphological characters.

The ultimate expanding earth hypothesis

The ultimate expanding earth hypothesis

A new species of Physalaemus (Amphibia; Leptodactylidae) from the Atlantic forest in southeastern Brazil

A new species of leptodactylid frog, Physalaemus atlanticus, is described from Ubatuba, northern coast of S o Paulo in southeastern Brazil. The new species belongs to the Physalaemus signifer species group and is characterized by the following set of characters: small size (males 20.1 22.1 mm SVL, females 21.0 23.9 mm SVL); canthus rostralis distinct; dorsal skin texture smooth to slightly rugose; belly orange in life; advertisement call with duration of 0.6 0.84 s and frequency between 0.9 1.8 kHz. Descriptions of the advertisement call and tadpole are provided, as well as information on natural history.

Habitat use and Spatial Structure of a Barking Frog (Eleutherodactylus augusti) Population in Southeastern Arizona

Barking Frogs (Eleutherodactylus augusti) are the northernmost ranging member of the large tropical family Leptodactylidae. We investigated the ecology of this saxicolous species at the northern edge of its range in a canyon in southern Arizona. We captured 54 frogs on discontinuous rock outcrops; eight of nine females and 39 of 45 males were on limestone outcrops. The remaining frogs were closer to limestone outcrops by more than 200 m than would be expected if they were distributed randomly with respect to limestone formations. Seven of 10 frogs radio-tracked had core home ranges (50% fixed kernel) from 94 to 100% on limestone; the other three frogs did not have any part of their home range on limestone outcrops. During five years of mark-recapture efforts, no frogs were found on a different outcrop from the one where they were originally captured; no radio-tracked frogs moved between outcrops during the breeding season. We estimated that four to 20 Barking Frogs occupied each outcrop; these groups probably are connected primarily by juvenile dispersal. As an organism living at the edge of its range, Barking Frogs in Arizona may rely heavily on extensive underground areas such as those found in limestone to protect them from a physiologically challenging environment. To manage for the persistence of Barking Frogs in southern Arizona, we must identify and protect habitat patches and movement pathways among them.

Ultrastructure of poison glands of South American frogs: A comparison betweenPhysalaemus albonotatus andLeptodactylus chaquensis (Anura: Leptodactylidae)

Serous (poison) cutaneous glands of the leptodactylid species Physalaemus albonotatus and Leptodactylus chaquensis were compared using light and transmission electron microscopy. Glands in the two species share structural traits common in anurans, including the peripheral contractile sheath (myoepithelium) and the syncytial secretory unit that produces, stores, and modifies the poison. At the ultrastructural level, early steps of poison production are also similar and fit the usual path of proteosynthesis, involving rough endoplasmic reticulum (RER) and Golgi stacks (dictyosomes) in the peripheral syncytial cytoplasm. However, several differences are obvious during the maturational processes that lead post-Golgian products to their ultimate ultrastructural traits. In P. albonotatus, the dense product released from the dictyosomes acquires a thick repeating substructure, which, however, becomes looser in the inner portion of the syncytium. In L. chaquensis, serous maturation involves gradual condensation, and opaque, somewhat "vacuolized" granules are formed. These different maturational paths expressed during poison manufacturing in the two species agree with the polyphyletic origin of the family Leptodactylidae. On the other hand, data collected for P. albonotatus fit previous findings from P. biligonigerus and stress the view that poisons produced by congeneric species share similar (or identical) ultrastructural features.

A New Species of Giant Torrent Frog, Genus Megaelosia, from the Atlantic Rain Forest of Espírito Santo, Brazil (Amphibia: Leptodactylidae)

Herein is described a new species of leptodactylid frog from Pedra Azul, Municipality of Domingos Martins, State of Espírito Santo, southeastern Brazil. The new species is a member of the genus Megaelosia, and is characterized by large size; fold of fifth toe not reaching outer metatarsal tubercle; snout rounded in dorsal view and slightly protruding in lateral view; tympanum moderately small; finger tips with scutes fused to the subunguis and toe tips with a pair of scutes free of the subunguis; dorsal skin texture smooth; skin of the flanks without large granules; belly and throat predominantly gray with many, small yellow blotches; and distinct bilateral vocal sacs in males. The tadpole is described. The new species is the northern limit for the genus Megaelosia, and reinforces the high endemism and richness of the anuran fauna from Santa Teresa region, State of Espírito Santo, Brazil.

Testes Size in Leptodactylid Frogs and Occurrence of Multimale Spawning in the Genus Leptodactylus in Brazil

Although rare, some anurans show multimale spawning. Herein we present data on testes mass relative to body mass for 11 leptodactylids and report multimale spawning in Leptodactylus chaquensis and Leptodactylus podicipinus. Testes mass averaged 4.13% of body mass for L. chaquensis and 0.75% for L. podicipinus. Testes size of both leptodactylid species with multimale spawning show that they are large and close to values recorded for rhacophorid frogs with multimale breeding (0.71-7.79%). Large testes size in frogs with multimale spawning supports the sperm competition hypothesis.

Karyotypic Variation in the Genus Megaelosia (Anura, Hylodinae) with the First Description of a B-Chromosome in a Leptodactylid Frog

Three species of the genus Megaelosia (Megaelosia massarti, Megaelosia boticariana, and Megaelosia lutzae) were studied karyotypically using conventional Giemsa staining, C-banding, and NOR techniques. Megaelosia lutzae had 2n = 32 chromosomes, a new diploid number for this genus and for the subfamily Hylodinae. Two morphotypes of B-chromosomes were found in two specimens of M. massarti. C-banding patterns and NOR location varied among the species. Nevertheless, some chromosome pairs, as well as the NOR-bearing secondary constriction and the large pericentromeric C-block on the short arm of chromosome 10, were consistent among the three species. Megaelosia differs markedly from other Hylodinae and Dendrobatidae in terms of karyotype.

Chromosome banding in Amphibia

Extensive cytogenetic analyses on a population of the leptodactylid frog Eleutherodactylus riveroi in northern Venezuela revealed the existence of multiple XXAA♂/XYAA♀/XAA^Y♀ sex chromosomes. The XAA^Y karyotype originated by a centric (Robertsonian) fusion between the original, free Y chromosome and an autosome. 46.2% of the male individuals in this population are carriers of this Y-autosome fusion. In male meiosis the XAA^Y sex chromosomes pair in the expected trivalent configuration. In the same population 53.8% of the male animals still possess the original, free XY sex chromosomes. E. riveroi is only the second vertebrate species discovered in which a derived Y-autosome fusion coexists with the ancestral free XY sex chromosomes. The free XY sex chromosomes, as well as the multiple XA^Y sex chromosomes are still in a very primitive (homomorphic) stage of differentiation. With no banding technique applied it is possible to distinguish the Y from the X. Various banding techniques and in situ hybridizations have been carried out to characterize the karyotypes. DNA flow cytometric measurements show that the genome size of E. riveroi resembles that of other Eleutherodactylus species. The cytogenetic data obtained in E. riveroi are compared with those of the sole other vertebrate known to possess the extremely rare, multiple XXAA♂/XYAA♀/XAA^Y♀ sex chromosomes. Surprisingly enough, this vertebrate again is a frog belonging to the genus Eleutherodactylus [E. (maussi) biporcatus] which lives exactly in the same habitat in northern Venezuela as does E. riveroi.

Isoforms of soluble alpha-tubulin in oocytes and brain of the frog (genus Rana): changes during oocyte maturation.

Rana oocytes have previously been shown to contain much more soluble tubulin than does the brain, suggesting different assembly and disassembly dynamics of frog oocyte tubulin compared to that in brain. By using centrifugation, SDS-PAGE, two-dimensional gel electrophoresis and Western blots, probed with anti-alpha-tubulin monoclonal antibodies, polymorphic alpha-tubulins (isoforms) were compared in brains and follicle-enclosed oocytes of northern (Rana pipiens) and southern (R. berlandieri) frogs. Oocyte tubulin in both species had isoforms with greater ranges of isoelectric point (pI) than those of brain tubulins; in particular, the oocyte tubulin pIs ranged further into the acidic region of the isoelectric-focusing gels than corresponding brain tubulin. This difference may, in part, be responsible for the previously reported assembly differences between oocyte tubulin (undetectable assembly) and brain tubulin (high assembly). Isoforms of alpha-tubulin with relatively acidic pI were more abundant in northern frog brain and oocyte soluble extracts than in analogous extracts from southern frogs. Furthermore, additional acidic alpha-tubulin isoforms were found in progesterone-treated oocytes (i.e., eggs), indicating increased heterogeneity of acidic alpha-tubulin isoforms during oocyte meiotic maturation. Among northern frog oocyte soluble components fractionated on Superose-6b columns, tubulin complexes with apparent molecular mass of about 1800 kDa were found to contain acidic alpha-tubulin isoforms while the putative oligomeric tubulins with an apparent molecular mass of about 250 kDa contained an additional relatively basic alpha-tubulin isoform. The acidic alpha-tubulin isoforms, therefore, are proposed to be associated with cold-adaptable cells of brain and oocytes, and may also be involved in stabilization of large soluble tubulin complexes in oocytes of the northern frog.

Pedal luring in the leaf-frog Phyllomedusa burmeisteri (Anura, Hylidae, Phyllomedusinae)

93 Luring behavior as a strategy of prey capture has evolved independently in several squamate lineages, including pygopodid lizards (Murray et al. 1991), and boid (Murphy et al. 1978, Radcliffe et al. 1980), viperid (Greene and Campbell 1972, Heatwole and Dawson 1976, Henderson 1970, Sazima 1991), elapid (Carpenter et al. 1978), and colubrid snakes (Sazima and Puorto 1993). Bavetz (1994) reported pedal luring related to predation in ambystomatid salamanders. In anurans, this feeding behavior has been described only for the terrestrial leptodactylid frogs Ceratophrys calcarata (Murphy 1976) and C. ornata (Radcliffe et al. 1986). Pedal luring apparently does not occur in the terrestrial leptodactylids Caudiverbera caudiverbera and Odontophrynus americanus tested by Radcliffe et al. (1986). Hodl and Amezquita (2001) reviewed visual signaling in anuran amphibians including signals addressed toward potential prey. Here I describe for the first time pedal luring behavior in a hylid frog, the highly arboreal leaf-frog Phyllomedusa burmeisteri. Observations were made of a captive adult female (82 mm snout-vent length) collected on 03 November, 2001 in the Serra do Caraca, an Atlantic forest reserve of Southeastern Brazil; Pedal luring in the leaf-frog Phyllomedusa burmeisteri (Anura, Hylidae, Phyllomedusinae)

Environmental influences on anuran sound communication

Studies of anuran vocal behavior in the South American temperate forest may represent the southernmost influence of Robert Capranicas comparative approach to sound communication. Vocalizations of leptodactylid frogs in this region exhibit patterns of propagation characteristic for different microhabitats. Calls containing frequencies above about 1 kHz experience higher attenuations in bogs as compared to marshes, irrespective of the species native environment. A similar lack of optimal relationships between signal structure and habitat properties for call propagation occurs in sound environments other than the temperate austral forest, as indicated by joint studies with colleagues from Cuba in Caribbean tropical forests and from Spain in European Mediterranean habitats. Anurans from southern Chile calling in bogs have peculiar acoustic adaptations: males call from burrows inside which the calls of neighboring cospecifics are amplified considerably. This effect potentially counteracts the constraints for signal propagation of sound-attenuating environments. The evidence presented indicates that anuran calls have not been subjected to environmental selection pressures, to the extent vocalizations of other vertebrates have. Dispersion of anurans is limited by availability of water sources, but males can choose locations favoring signal broadcast and reception in their relatively restricted breeding areas. [Work supported by FONDECYT Grant No. 1010569.]

Speciation by polyploidy in Odontophrynus americanus

AbstractDiploid and tetraploid populations of the leptodactylid frog Odontophrynus americanus were studied in the Cordoba province (central Argentine) to evaluate whether they represent a cryptic species pair rather than forms of the same species as they are considered at present. We examined three independent character complexes (external morphology, advertisement calls, allozymes) and quantified the character‐specific state of differentiation between diploids and tetraploids in comparison to that of the congeneric and widely sympatric O. occidentalis. Multivariate analysis of 15 morphometric characters indicated a remarkable degree of differention between both forms, but did not permit an unequivocal identification of individuals (rate of erroneous classification: 25%), whereas all O. occidentalis were classified correctly. In contrast, the temporal structure of the advertisement call permitted a distinction of diploids, tetraploids and O. occidentalis even based on a single call. The latter differed from the other by producing a call consisting of several pulse trains. The pulse rate of the O. americanus call, which consists of a single pulse train, was significantly lower in tetraploids than in diploids. The allozyme pattern and the corresponding allele frequencies indicated a close relationship among the three Odontophrynus taxa, but genetic distances obtained suggested a differentiation of gene pools at the level of species. Considering the degree of differentiation demonstrated in this study, the ploidy and the different geographical distribution, we conclude that diploids and tetraploids represent two species, similar to its North American counterpart Hyla chrysoscelis/H. versicolor. As the name O. americanus refers to tetraploids collected near Buenos Aires (Argentina), we describe the diploids as the new species Odontophrynus cordobae sp. nov.

Microhabitat Use and Orientation to Water Flow Direction by Tadpoles of the Leptodactylid Frog Thoropa miliaris in Southeastern Brazil

Frog larvae develop in a wide array of microhabitats including permanent and nonpermanent ponds, rivers, lakes, tank bromeliads, and other water reservoirs (Duellman and Trueb, 1994). A unique form of development and microhabitat specialization occurs in tadpoles of leptodactylid frogs of the genus Thoropa: tadpoles live in the film of water on rock surfaces at the wet borders of waterfalls in rain-forest areas, and in rocky fields of mountain ranges of southeastern Brazil (Bokermann, 1965; Caramaschi and Sazima 1984; Cocroft and Heyer, 1988). The tadpoles of this genus have an elongated, dorsoventrally compressed body, reduced fins, an expanded and flattened abdomen with an adherent ventral disk, and a long muscular tail, which, together with the labium, are used for movement and adhesion to the substrate (Bokermann, 1965; Wassersug and Heyer, 1983). Thoropa miliaris (Spix, 1824) occurs near freshwater bodies along the Atlantic rain forest of the states of Rio de Janeiro, Sao Paulo, Minas Gerais, and Espirito Santo in southeastern Brazil (Cocroft and Heyer, 1988) and also on rocky marine shores (Abe and Bicudo, 1991). Information available on microhabitat use by tadpoles of this species is restricted to general notes reporting the use of a very shallow film of current water on rock surfaces at the side of waterfalls with varying slopes, including vertical. These reports suggest that the tadpoles tend to remain with the head oriented against the water flow when adhered to the rock surface (Bokermann, 1965; Abe and Bicudo, 1991). However, there is no quantitative description of microhabitat use by this species. In this study, we analyze microhabitat use by T miliaris tadpoles to address the following questions. Do tadpoles orient randomly or selectively in relation to water flow? Do tadpoles tend to remain at the shallowest sites or use the available film of water indiscriminately? Do tadpoles occupy some slopes available on the waterfall surface more than others? Does water temperature where tadpoles occur differ from that of the main drainage of the waterfalls nearby?

Microhabitat Use and Orientation to Water Flow Direction by Tadpoles of the Leptodactylid Frog Thoropa miliaris in Southeastern Brazil

Microhabitat Use and Orientation to Water Flow Direction by Tadpoles of the Leptodactylid Frog Thoropa miliaris in Southeastern Brazil

Chromosome banding in Amphibia

Highly differentiated, heteromorphic ZZ♀/ZW♂ sex chromosomes were found in the karyotypes of the neotropical leptodactylid frogs Eleutherodactylus euphronides and E. shrevei. The W chromosomes are the largest heterochromatic, female-specific chromosomes so far discovered in the class Amphibia. The analyses of the banding patterns with AT- and GC base-pair specific fluorochromes show that the constitutive heterochromatin in the giant W chromosomes consists of various categories of repetitive DNA sequences. The W chromosomes of both species are similar in size, morphology and banding patterns, whereas their Z chromosomes exhibit conspicuous differences. In the cell nuclei of female animals, the W chromosomes form very prominent chromatin bodies (W chromatin). DNA flow cytometric measurements demonstrate clear differences in the DNA content of male and female erythrocytes caused by the giant W chromosome, and also shows that these Eleutherodactylus genomes are among the smallest of all amphibian genomes. The importance of the heteromorphic ZW sex chromosomes for the study of Z-linked genes, the similarities and differences of the two karyotypes, and the significance of the exceptionally small genomes are discussed.

Chromosome banding in Amphibia

A 15-year cytogenetic survey on one population of the leaf litter frog Eleutherodactylus maussi in northern Venezuela confirmed the existence of multiple XXAA♂/XAA^Y♀ sex chromosomes which originated by a centric (Robertsonian) fusion between the original Y chromosome and an autosome. 95% of the male individuals in this population are carriers of this Y-autosome fusion. In male meiosis the XAA^Y sex chromosomes pair in the expected trivalent configuration. In the same population, 5% of the male animals still possess the original, free XY sex chromosomes. In a second population of E. maussi analyzed, all male specimens are characterized by these ancestral XY chromosomes which form normal bivalents in meiosis. E. maussi apparently represents the first vertebrate species discovered in which a derived Y-autosome fusion still coexists with the ancestral free XY sex chromosomes. The free XY sex chromosomes, as well as the multiple XA^Y sex chromosomes are still in a very primitive (homomorphic) stage of differentiation. With no banding technique applied it is possible to distinguish the Y from the X. DNA flow cytometric measurements show that the genome of E. maussi is among the largest in the anuran family Leptodactylidae. The present study also supplies further data on differential chromosome banding and fluorescence in situ hybridization experiments in this amphibian species.

Temporal selectivity by single neurons in the torus semicircularis of Batrachyla antartandica (Amphibia: Leptodactylidae).

We investigated the response selectivities of single auditory neurons in the torus semicircularis of Batrachyla antartandica (a leptodactylid from southern Chile) to synthetic stimuli having diverse temporal structures. The advertisement call for this species is characterized by a long sequence of brief sound pulses having a dominant frequency of about 2000 Hz. We constructed five different series of synthetic stimuli in which the following acoustic parameters were systematically modified, one at a time: pulse rate, pulse duration, pulse rise time, pulse fall time, and train duration. The carrier frequency of these stimuli was fixed at the characteristic frequency of the units under study (n=44). Response patterns of TS units to these synthetic call variants revealed different degrees of selectivity for each of the temporal variables. A substantial number of neurons showed preference for pulse rates below 2 pulses s(-1), approximating the values found in natural advertisement calls. Tonic neurons generally showed preferences for long pulse durations, long rise and fall times, and long train durations. In contrast, phasic and phasic-burst neurons preferred stimuli with short duration, short rise and fall times and short train durations.