Slender salamander3/31/2023 ![]() The class Amphibia is comprised of three orders: Anura (Salientia), Caudata (Urodela), and Gymnophiona (Apoda). Hélène Dumond, in Hormones and Reproduction of Vertebrates: Amphibians, 2011 1 Introduction Taxonomic accounts provide information on generic content, distribution, characteristics, and biology of each family. An up-to-date phylogeny details approximate time periods during which divergences occurred during the evolutionary history of salamanders and shows evolutionary relationships among the families as we now know them. Conservation status of salamanders is summarized. Nearly 45% of known species belong to this subfamily. One group of plethodontids ( lungless salamanders), the bolitoglossines, has undergone a major radiation in the tropics of Mexico and Central America, with a few species occurring in the Amazon rainforest. Most salamanders live in moist habitats, frequently adjacent to or in streams, lakes, or swamps. About 619 species are known, distributed among 10 families. Salamanders are tailed amphibians with distinct heads and occur largely in the Northern Hemisphere (Holoarctic). Caldwell, in Herpetology (Fourth Edition), 2014 Abstract ![]() Larvae of these species often exploit habitats within the river channel that are relatively inaccessible to fish, such as interstitial spaces among the substrate of the streambed, or lateral seepages. In general, amphibians that occupy larger streams and rivers attain sizes that preclude fish predation, such as the hellbender ( Cryptobranchus alleganiensis) and mudpuppy ( Necturus maculosus). However, one contributing factor is likely to be the distribution of stream fishes, which prey on salamander larvae and tend to become more abundant in larger streams and rivers. The cause of these headwater associations is complex, involving both evolutionary and ecological processes. Plethodontid diversity is especially high in headwater streams of the southern Appalachian Mountains of eastern North America. Many species, particularly those in the family Plethodontidae, are restricted to low-order, headwater streams. Like many groups of lotic organisms, the distributions of amphibian species associated with these habitats can be characterized by position along the stream continuum, from headwater streams to large rivers. Other salamander families that include species associated with lotic habitats include the Cryptobranchidae (hellbenders and giant salamanders), Dicamptodontidae (Pacific giant salamanders), Proteidae (waterdogs and mudpuppies), and Rhyacotritonidae (torrent salamanders).įigure 5. During this period, the northern two-lined salamander can be found under rocks and logs during the day, and foraging on the forest floor and in understory vegetation at night. In contrast, adults of the northern two-lined salamander ( Eurycea bislineata Figure 5), another stream-breeding plethodontid, spends summer months in the riparian zone and adjacent uplands. Some species, like the northern spring salamander ( Gyrinophilus porphyriticus Figure 4), are highly aquatic and found under cover in the stream channel and along the wetted edge during the day, although they may move into the riparian zone on nighttime foraging bouts. 5.48C and D) and are covered with enamel rather than enameloid, so they should be looked upon as a variant of the normal bicuspid adult tooth rather than a reversion to the larval monocuspid tooth type ( Ehmcke and Clemen, 2000 Ehmcke et al., 2004).ĭespite their common reliance on moisture for cutaneous respiration, adult plethodontid salamanders exhibit a range of associations with streams and rivers. ![]() However, they often retain a vestigial labial cusp ( Fig. 5.48A and B), the enlarged anterior teeth superficially look monocuspid ( Fig. Although the maxillary teeth of both males and females, and the premaxillary teeth of females, have the usual bicuspid morphology ( Fig. ![]() Secretions from the chin glands of the male may then enter the circulatory system of the female and stimulate her to mate. These enlarged teeth seem to be used by the male to inflict small wounds on the dorsum of the female. This local change is under the control of androgens, but clearly does not affect all teeth ( Davit-Béal et al., 2007). Male plethodontids develop enlarged conical teeth at the front of the upper jaw (and sometimes lower jaw) during the reproductive season only. ![]()
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