1,374 research outputs found
Variation, Systematics, and Relationships of the \u3cem\u3eLeptodactylus Bolivianus\u3c/em\u3eComplex (Amphibia: Anura: Leptodactylidae)
A cluster of morphologically similar frogs of the genus Leptodactylus having a pair of distinct dorsolateral folds on the dorsum and well-developed lateral fringes on the toes has never been systematically evaluated by examining materials from throughout its geographic range. The species involved are herein referred to as members of the Leptodactylus bolivianus complex. There have been three names proposed for members of this complex: Leptodactylus bolivianus Boulenger, 1898; Leptodactylus insularum Barbour, 1906; and Leptodactylus romani Melin, 1941. The collective range for the L. bolivianus complex is from Costa Rica southward through Panama, extending across northern South America (east of the Andes) in the river valleys draining to the Caribbean, and throughout much of the Amazon basin with southernmost limits in the Bolivian departments of La Paz, Cochabamba, and Santa Cruz.
We analyze variation in this complex of frogs throughout its geographic range to understand inherent patterns of differentiation and to interpret those patterns in terms of species-level recognition, distributions, and relationships
Diffraction and an infrared finite gluon propagator
We discuss some phenomenological applications of an infrared finite gluon
propagator characterized by a dynamically generated gluon mass. In particular
we compute the effect of the dynamical gluon mass on and
diffractive scattering. We also show how the data on photoproduction
and hadronic reactions can be derived from the and
forward scattering amplitudes by assuming vector meson dominance and
the additive quark model.Comment: 4 pages, 7 figures, added references and figures, changed structure.
Contribution to Proceedings of XVIIIth Reuniao de Trabalho sobre Interacoes
Hadronicas, Sao Paulo, Brazil, 22-24 May, 200
Are \u3cem\u3eLeptodactylus didymus\u3c/em\u3e and \u3cem\u3eL. mystaceus\u3c/em\u3e Phylogenetically Sibling Species (Amphibia, Anura, Leptodactylidae)?
The Leptodactylus fuscus species group consists of 25 currently recognized species; within this species group and distributed throughout the Amazon Basin, Atlantic Forests, Gran Chaco, and cerrados is the L. mystaceus species complex. This species complex consists of L. didymus, L. elenae, L. mystaceus, L. notoaktites, and L. spixi. Adult morphologies have been used to distinguish these species from each other except for L. didymus and L. mystaceus (Heyer, 1978; Heyer et al., 1996). Leptodactylus didymus and L. mystaceus are morphologically indistinguishable; the species are recognizable only by the characteristics of their advertisement calls: non-pulsed in L. didymus and pulsed in L. mystaceus (Heyer et al., 1996).
Traditionally, L. mystaceus and L. didymus have been considered sibling species. The concept of sibling species was originally introduced by Mayr (1942: 151) to describe pairs or groups of morphologically identical or nearly identical species; however, in subsequent work Mayr (1976) interchangeably used the terms sibling and cryptic species to describe morphologically similar species. Mayr (1942: 151) considered sibling species to be important in understanding the full complexity of animal speciation. In order to differentiate these two terms, herein we take a narrow cladistic methodological approach (i.e., dichotomous speciation) by which we restrict the term sibling species to two taxa that share a most recent common ancestor; whereas, the term cryptic (derived from the Greek Kruptos, meaning \u27hidden\u27; Allaby, 1991) species refers to hidden diversity and does not necessarily imply close phylogenetic relationship. Thus, the sibling species pair of L. didymus and L. mystaceus assumes two postulates: (1) the taxa shared a most recent common ancestor not shared with other species in the L. mystaceus species complex and (2) the two taxa could represent a recent speciation event (i.e., not enough time has passed to reach morphological differentiation, although this is not a requisite).
Herein, we analyze the genetic diversity among taxa in this species complex to determine if the sibling species L. didymus and L. mystaceus are sister taxa. If the assumptions about sibling species are correct, then we would expect that the two taxa involved would be genetically closer between themselves than with any other closely related species
ARE Leptodactylus didymus AND L. mystaceus PHYLOGENETICALLY SIBLING SPECIES (AMPHIBIA, ANURA, LEPTODACTYLIDAE)?
The Leptodactylus fuscus species group consists of 25 currently recognized species; within this species group and distributed throughout the Amazon Basin, Atlantic Forests, Gran Chaco, and cerrados is the L. mystaceus species complex. This species complex consists of L. didymus, L. elenae, L. mystaceus, L. notoaktites, and L. spixi. Adult morphologies have been used to distinguish these species from each other except for L. didymus and L. mystaceus (Heyer, 1978; Heyer et al., 1996). Leptodactylus didymus and L. mystaceus are morphologically indistinguishable; the species are recognizable only by the characteristics of their advertisement calls: non-pulsed in L. didymus and pulsed in L. mystaceus (Heyer et al., 1996).
Traditionally, L. mystaceus and L. didymus have been considered sibling species. The concept of sibling species was originally introduced by Mayr (1942: 151) to describe pairs or groups of morphologically identical or nearly identical species; however, in subsequent work Mayr (1976) interchangeably used the terms sibling and cryptic species to describe morphologically similar species. Mayr (1942: 151) considered sibling species to be important in understanding the full complexity of animal speciation. In order to differentiate these two terms, herein we take a narrow cladistic methodological approach (i.e., dichotomous speciation) by which we restrict the term sibling species to two taxa that share a most recent common ancestor; whereas, the term cryptic (derived from the Greek Kruptos, meaning \u27hidden\u27; Allaby, 1991) species refers to hidden diversity and does not necessarily imply close phylogenetic relationship. Thus, the sibling species pair of L. didymus and L. mystaceus assumes two postulates: (1) the taxa shared a most recent common ancestor not shared with other species in the L. mystaceus species complex and (2) the two taxa could represent a recent speciation event (i.e., not enough time has passed to reach morphological differentiation, although this is not a requisite).
Herein, we analyze the genetic diversity among taxa in this species complex to determine if the sibling species L. didymus and L. mystaceus are sister taxa. If the assumptions about sibling species are correct, then we would expect that the two taxa involved would be genetically closer between themselves than with any other closely related species
On the Engimatic Distribution of The Honduran Endemic \u3cem\u3eLeptodactylus Silvanimbus\u3c/em\u3e (Amphibia: Anura: Leptodactylidae)
Most species of the frog genus Leptodactylus occur in South America, and all authors who have treated the zoogeography of the genus have concluded that it originated somewhere in South America (e.g., Savage 1982). Savage (1982, 518) summarized the historical herpetofaunal units of the Neotropics as follows: All evidence points to an ancient contiguity and essential similarity of a generalized tropical herpetofauna that ranged over tropical North, Middle, and most of South America in Cretaceous-Paleocene times. Descendents of this fauna are represented today by the South and Middle American tracks (Elements). To the north of this fauna ranged a subtropical-temperate Laurasian derived unit, today represented by the Old Northern Element (track). By Eocene, northern and southern fragments of the generalized tropical units had become isolated in Middle and South America, respectively. Differentiation in situ until Pliocene produced the distinctive herpetofaunas that became intermixed with the establishment of the Isthmian Link
\u3cem\u3eLeptodactylus silvanimbus\u3c/em\u3e
Adult Leptodactylus silvanimhus are of moderate sized, the head is about as wide as long, and the hind limbs are moderate in length (see Table; also see Heyer and Thompson 2000 for definitions of adult size and leg length categories for Leptodacrylus). The male vocal sac is single and internal. Male forearms are hypertrophied in larger individuals. Adult males have two black thumb spines on each hand and lack chest spines. Individuals lack dorsolateral folds. The toe tips are narrow, not expanded. Females have weakly developed lateral toe fringes and males either have lateral toe ridges or weakly developed fringes. The upper shank surface is shagreened with several dark coni apicales. The outer tarsus has white-tipped tubercles and small dark coni apicales. The sole of the foot is mostly smooth with a few tiny dark coni apicales. The upper lip is gray, paler below and behind the eye. The dorsal pattern is grayish-brown with slightly darker interorbital and middorsal blotches. The species lacks light middorsal stripes. The belly pattern is almost uniform cream. The posterior thigh surfaces are mottled; no individuals have distinct light horizontal stripes on the lower portion of the posterior thigh. The dorsal shank surfaces have irregular dark crossbands
Genetic Resolution of the Enigmatic Lesser Antillean Distribution of the Frog \u3cem\u3eLeptodactylus Validus\u3c/em\u3e (Anura, Leptodactylidae)
Leptodactylus validus has an unusual distribution, inhabiting Trinidad, Tobago, and the Lesser Antilles, but not the mainland of South America. This distribution is inconsistent with other distribution patterns observed for these islands. Although slight variation in adult morphology has been observed among the different island populations of L. validus, call data suggest the presence of a single species. Calls of L. pallidirostris from Venezuela and Brazil suggested that this taxon might be conspecific with L. validus. Sequence data from the 12S and 16S mt rDNA genes indicate that L. validus represents a single species throughout its distribution and is conspecific with L. pallidirostris. Dispersal of L. validus from Trinidad and Tobago to the Lesser Antilles was likely mediated by human activities
Leptodactylus cunicularius Sazima and Bokermann Rabbit-burrow Frog
Adult Leptodactylus cunicularius are moderately small. The head is longer than wide and the hind limbs are long (Table 1; Heyer and Thompson 2000 provided definitions of adult size and leg length categories for Leptodactylus). Male vocal sacs are internal, not externally expanded. The snout is protruding, not sexually dimorphic. Male forearms are not hypertrophied and males lack asperities on the thumbs and chest. The dorsum is variegated with small, often confluent, spots and blotches. There is a very thin interrupted mid-dorsal light stripe (pinstripe). Usually, there is a noticeable light, irregular, elongate, mid-dorsal blotch in the scapular region. The supratympanic fold is not marked differently from the surrounding region. A weak to distinct pair of interrupted (partial or along entire length) dorsolateral folds extends from the posterior portion of the eye, passing just lateral to the sacral bones and ending in the upper groin region of the leg; the folds are usually subtly highlighted with marginally lighter stripes than the surrounding dorsal region
\u3cem\u3eLeptodactylus pentadactylus\u3c/em\u3e
Adult Leptodactylus pentadactylus (Figure 1) are large, the head is about as wide as long, and the hind limbs are moderately long (Table 1; Heyer and Thompson [2000] provided definitions of adult size and leg length categories for Leptodactylus). Male vocal sacs are not visible externally or are moderately expanded as a single sac. Sexually active males usually do not have hypertrophied forearms (the largest male examined, 195 mm SVL, has very weakly hypertrophied forearms), only the largest males have a single small to moderate size black spine on each thumb. No males have chest spines. Dorsolateral folds are usually entire from the eye to at least the sacrum. Flank folds (diverging from the supratympanic fold at the uppermost portion of the tympanum) are variable, either continuous or interrupted, often extending from the tympanum to the lower flank, or only to the shoulder. The toe tips are rounded, just wider than the adjacent phalanges. The toes have prominent lateral ridges. A trace of basal webbing occurs among all toes, or toes I–II–III–IV or II–III–IV. The upper shank and outer tarsal surfaces are smooth, shagreened, or have several white or black tubercles. The sole of the foot texture is usually smooth, a few individuals have no more than a few black or white tubercles
- …