Salamanders (Caudata)
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Abstract:
Abstract Salamanders form a monophyletic group, constituting one of the three orders of modern amphibians (Lissamphibia), together with frogs and caecilians. Salamanders comprise the second most species-rich order of amphibians (1) and are typically classified in 10 families, with ca. 68% of the species belonging to the Family Plethodontidae. thebody plan has remained relatively stable since the Jurassic (2, 3) (Fig. 1), displaying several features that in combination distinguish it from the body plan of other amphibians: presence of a tail both in larval and adult phases, two pairs of limbs of equal size (when present) set perpendicular to the body, presence of teeth on both jaws, presence of ribs on most trunk vertebrae, and absence of several skull bones (4). Here we review the phylogenetic relationships and the divergence times of salamander families. thefamilies are grouped into Ave suborders: Cryptobranchoidea (Cryptobranchidae and Hynobiidae), Sirenoidea (Sirenidae), Salamandroidea (Salamandridae, Ambystomatidae, Dicamptodontidae), Proteoidea (Proteidae), and Plethodontoidea (Plethodontidae, Rhyacotritonidae, and Amphiumidae). Despite the increasing number of studies and data addressing the phylogeny of salamander families, their relationships are di1cult to resolve. Several relationships are consistently recovered with diBerent data sets, while the positions of others, in particular the sirenids and proteids, have remained contentious.Keywords:
Salamandridae
Monophyly
Body plan
Neoteny
Salamandridae
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SUMMARY The authors provide a detailed description of the skull in neotenic Triturus vulgaris meridionalis (Boulenger) (Amphibia Caudata Salamandridae) and compare it with the morphology of normal adults. The finds are also compared with published data concerning other urodeles. Though some interesting differences are found between the skull of normal and neotenic individuals, these do not plead in favour of the general hypothesis that neoteny has had a general role in the evolution of urodeles. The authors suggest that at an early stage of urodele evolution, telescoping of developmental phases occurred as an adaptation to short seasons favourable to larval development. The cranial kinesis of Triturus vulgaris is described in detail and this supports the contention by IORDANSKY (1982), contrary to current belief, that cranial kinesis is widespread among urodeles. Some features of cranial changes at metamorphosis appear to be linked with functional requirements.
Neoteny
Salamandridae
Triturus
Morphology
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The skull of neotenic individuals of the Alpine Newt Triturus alpestris from the locality Drakolimni (Greece) is described on the basis of models made from magnified serial frontal sections. In order to recognize features associated with neoteny and paedomorphosis, the results were compared with normal development of contemporary Triturus and of other Caudata. The neotenic larvae from Greece correspond to advanced stages of metamorphosis in normal development of Triturus alpestris. Comparison with salamandrids from the Tertiary of Europe in which the hyobranchial skeleton was preserved, namely Brachycormus noachicus, Chelotriton paradoxus, and Palaeopleurodeles hauffi, revealed that both latter taxa were completely metamorphosed adults anatomically similar to their contemporary relatives Tylototriton, Echinotriton, and Pleurodeles, whereas Brachycormus, though apparently related to Chelotriton, was a neotenic amphibian. This is suggested by its incompletely metamorphosed but ossified hyobranchial skeleton. © 1996 Wiley-Liss, Inc.
Neoteny
Salamandridae
Triturus
Pleurodeles
Heterochrony
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Comparison of metamorphosis of skull and hyobranchial system in two species of neotenic salamanders reveals two different types of neoteny. Ambystoma talpoideum is completely neotenic owing to delayed metamorphosis. Notophthalmus viridescens exhibits limited neoteny as a result of incomplete metamorphosis. Morphological details of neoteny are compared to life history in both species in order to discuss the ecological morphology of the two neotenic strategies. Comparisons to Taricha granulosa, Triturus vulgaris, and Ambystoma gracile indicate that these two strategies are widely employed and may represent familial patterns.
Neoteny
Salamandridae
Notophthalmus viridescens
Morphology
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Citations (57)
Species with truncated developmental patterns may go undetected if they resemble the juveniles of their close relatives. Herein we present an example of this phenomenon with the description of a highly divergent, relict species of stream-dwelling plethodontid salamander from the Ouachita Mountains of North America. Both mitochondrial and nuclear sequence data show that this new species is most closely related to its syntopic relative, Eurycea multiplicata. Interestingly, E. multiplicata exhibits the ancestral biphasic (metamorphic) life cycle, whereas the new species maintains an aquatic larval form throughout life (paedomorphic) and superficially resembles larval E. multiplicata. The new species is the first known paedomorphic plethodontid from the Ouachita Mountains, and the most divergent paedomorphic salamander discovered in over seventy years. This species represents an independent instance of the evolution of paedomorphosis associated with a porous streambed, which may facilitate vertical seasonal movements. This new species currently has an extremely limited known distribution and is of immediate conservation concern.
Neoteny
Salamandridae
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Citations (42)
Abstract The ontogenetic sequence of cranial osteogenesis through adulthood is described in samples of newts from completely metamorphosing and partially neotenic populations. Cranial ossification proceeds in the same sequence in both samples. Seven stages of cranial development are described on the basis of conspicuous events that occur during ontogeny. These include four larval stages, metamorphs, efts, and adults. Neotenic adults have skulls that are metamorphosed completely and indistinguishable from the skulls of non‐neotenic adults. Neoteny in these newts does not involve the skull and is limited to the postmetamorphic retention of some gill structures and, thus, is termed “limited neoteny.” The evolution of limited neoteny in newts as a correlated response to the inhibition of land‐drive behavior is discussed.
Neoteny
Salamandridae
Notophthalmus viridescens
Heterochrony
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The morphology and probable evolution of the depressor muscles of the lower jaw, innervated by the seventh cranial nerve (VII;M. Ceratomandibularis, M. Depressor Mandibulae), in larval, neotenic, and metamorphosed Urodela were investigated. Observations on innervation and skeletal connections of the muscles were included, especially the relations of form and extension of the squamosal to proximal attachments of the M. Depressor Mandibulae. The M. Ceratomandibularis is purely premetamorphic, but present in the Amphiumidae. Concerning the M. Depressor Mandibulae, homologies of pre- and postmetamorphic muscles were evaluated, including the "M. Levator Hyoidei" of Dipnoi, Sirenidae, and other Tetrapoda, which is the homologue of the posterior M. Depressor Mandibulae of salamanders. The concept of "M. Depressor Mandibulae Anterior" and "M. Depressor Mandibulae Posterior" (Baird ['51] Univ. Kansas Sci. Bull. 34:221-265) was extended to nonbolitoglossine salamanders. The probable ancestral state of the M. Depressor Mandibulae for urodeles and possible plesiomorphic and apomorphic conditions obtaining in various taxa of different ranks were determined. In an attempt to reconcile results with previously published hypotheses of certain sister-group relationships by various authors, holophyly of (Dicamptodontidae + Ambystomatidae), Proteidae, and Bolitoglossini is supported. No synapomorphies for the taxa (Sirenidae + Salamandridae) or (Amphiumidae + Plethodontidae) emerge from the present study. J Morphol 233:77-97, 1997. © 1997 Wiley-Liss, Inc.
Salamandridae
Neoteny
Synapomorphy
Sister group
Morphology
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Sexual dimorphism, phenotypic difference between males and females of the same species, has been demonstrated in many invertebrates and vertebrates. In many of these studies, which were especially conducted on amphibians, female individuals were reported to be larger than males. However, this does not necessarily mean that this also applies to body shapes. Therefore, in this study, a total of 31 characters of body size and body shape were measured and analyzed in the Near Eastern fire salamander, in order to understand whether these characters differ between female and male individuals. The results suggest that there is a significant difference between the sexes in terms of both body size and some body shapes (e.g. arm and leg length, arm diameter, cloacal proportions) in this fire salamander. I conclude that both sexual size and shape dimorphism need to be taken into account to help understand an organism’s life-history traits, ecology, population dynamics and behavior.
Sexual dimorphism
Salamandra
Salamandridae
Evolvability
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The endangered Caucasian salamander, Mertensiella caucasica (Waga, 1876), is endemic to the western Lesser Caucasus. Here, we used N-mixed models to analyse repeated count data of Caucasian salamanders from the eastern Black Sea region of Turkey. We estimated a mean detection probability of 0.29, a population size of 21 individuals, and a range of 9 to 36 individuals per 20 × 10 m plot. Our results provide preliminary data on the population status of the Caucasian salamander in northeastern Anatolia. These results would contribute to the effective management and conservation of the species.
Salamandridae
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