NE Amphibian Species
The Class Amphibia contains over 6,433 described living species worldwide, with 276 amphibian species found in the continental United States (Crother 2000, American Museum of Natural History). Currently, 90 amphibian species are recognized in the Northeast, including 59 species in the Order Caudata (salamanders) and 31 species in the Order Anura (frogs and toads). Almost half of the amphibians in the Northeast are salamanders within the family Plethodontidae. Amphibian species richness and conservation status by state is presented in the Table of NE Amphibian Species along with the distributional overlap of Northeast species with other US ARMI regions.
Amphibians are found in all physiographic regions of the Northeast, from sea level to the heights of the Appalachian, Adirondack, and White Mountains. The biome that encompasses the entire Northeast is Temperate Forest. Centers of species richness occur: 1) along the West Virginia/Virginia border in association with the Blue Ridge, Allegheny and Appalachian Mountains (particularly species in the family Plethodontidae), and 2) in the Atlantic Coastal Plain, especially in southeastern Virginia (particularly species in the family Hylidae).
Table of NE Amphibian Species
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I. Order Caudata (Salamanders)Seven families in the Order Caudata are found in the Northeast (Petranka 1998). The family Plethodontidae (lungless salamanders) is the most species-rich family in the region, with 43 species. Plethodontids are more diverse in the Southeast region, and reach their greatest diversity further south in southern Mexico and Central America. The second most species-rich family in the Northeast region is the family Ambystomatidae (mole salamanders), with 9 species. The other families (Cryptobranchidae, Sirenidae, Amphiumidae, Proteidae, and Salamandridae) are represented in the Northeast by only one or two species each. Members of two families, Sirenidae and Amphiumidae, are only found in one state within the Northeast (Virginia). Nine salamander species, all within the family Plethodontidae (Gyrinophilus subterraneus, Plethodon hoffmani, P. hubrichti, P. nettingi, P. punctatus, P. shenandoah, P. virginia, Pseudotriton montanus diastictus, Pseudotriton ruber nitidus), are endemic to the Northeast. These species typically have limited distributions, sometimes isolated to only a few mountaintops or caves, and most are found in Virginia and West Virginia. The longevity of salamanders varies from 1 to 30 years (Flower 1925).
A. Aquatic Salamanders1. River and Stream (Lotic) Salamanders
Large fully aquatic salamanders (Cryptobranchus, Necturus) are found in large streams and rivers. Eggs are deposited in vegetation, debris, or under rocks in the water. Young pass through a larval stage, and adults remain aquatic. Some adults even retain larval features (e.g., exposed gills in Necturus). Small aquatic salamanders (Desmognathus, Eurycea, Gyrinophilus, Pseudotriton) frequent smaller streams and seeps. In this group, larval development occurs within streams, but after metamorphosis, adults spend part of their life history in the leaf litter and rocky substrate alongside streams.
2. Pond-breeding (Lentic) Salamanders
Siren species are entirely aquatic and inhabit various types of vegetated ponds and mucky swamps. Amphiuma species generally are aquatic, although eggs are deposited on land near water. Notophthalmus and most Ambystoma species may use temporary ponds to complete metamorphosis. After metamorphosis, these species spend a considerable amount of time in terrestrial habitats. Ambystoma talpoideum and Notophthalmus viridescens have individuals or populations that are facultative paedomorphs, retaining larval features as adults and not metamorphosing in some areas as long as permanent water remains.
B. Terrestrial Salamanders
In the family Plethodontidae, all members of the Tribe Plethodontinii and several salamanders in the subfamily Desmognathinae are entirely terrestrial and do not use standing water for reproduction. These salamanders deposit their eggs in moist areas and the young develop within the eggs and hatch as miniature adults. For most salamanders in this group, eggs are laid in underground retreats, under rocks, or beneath or within rotting logs. For some Northeast species, nests in the wild have never been found (e.g., Plethodon hubrichti, P. punctatus). During favorable moist conditions, terrestrial salamanders actively forage on the surface of the forest floor, in leaf litter, arboreally, or under surface debris such as rocks and logs. During dry periods, these salamanders retreat underground to moist areas. Their survival depends on maintaining a moist skin surface to allow cutaneous respiration.
II. Order Anura (Frogs and Toads)
Five families of anurans are found in the Northeast (Bufonidae, Hylidae, Pelobatidae, Ranidae, and Microhylidae). The highest diversity of anurans in the Northeast occurs within the family Hylidae (17 species), followed by the Ranidae (8 species), and the Bufonidae (4 species). The only endemic frog in the Northeast is the New Jersey chorus frog (Pseudacris feriarum kalmi). (Note: the taxonomy of this group is under revision). Pelobatidae and Microhylidae are represented by only one species each, Scaphiopus holbrookii and Gastrophryne carolinensis, respectively. Frogs and toads in the Northeast exhibit a biphasic life cycle consisting of aquatic egg and larval stages followed by metamorphosis into a terrestrial juvenile. Once mature, adults remigrate back to water to reproduce. Most anurans breed in lentic waters, but some also use lotic waters. The time between metamorphosis and first breeding ranges from 1-4 years (Duellman and Trueb 1994). The longevity of anurans varies from 1 to 15 or more years (Flower, 1925). Most anurans reproduce in temporary or permanent pond or wetland systems, where males call to attract females. Fewer species use streams or rivers (e.g., Rana catesbeiana, R. clamitans melanota, R. palustris). Some anurans require fishless temporary ponds for successful reproduction (e.g., Scaphiopus holbrookii, Rana sylvatica), whereas others can use a wide range of temporary or permanent ponds (e.g., many species within the Bufonidae, Hylidae and Ranidae). After metamorphosis, anurans can range widely (up to 6 km) from aquatic sites using a variety of terrestrial habitats (Dodd 1996). Anurans use various terrestrial refugia including caves, underground burrows and other subterranean habitats, tree roots, rock crevices, and can be found under surface debris such as fallen logs and rocks. Tree frogs use arboreal retreats.
Crother, B.I. (ed.) 2000. Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confidence in Our Understanding. SSAR Herpetological Circular No. 29. 82 pp.
Dodd, C.K., Jr. 1996. Use of terrestrial habitats by amphibians in the sandhill uplands of north-central Florida. Alytes 14:42-52.
Duellman, W.E., and L. Trueb. 1994. Biology of Amphibians. The Johns Hopkins University Press, Baltimore, MD. 670pp.
Flower, S. 1925. Contributions to our knowledge of the duration of life in vertebrate animals. - II. Batrachians. Proceedings of the Zoological Society of London, 1925 (pt I): 269-289.
Petranka, J.W. 1998. Salamanders of the United States and Canada. Smithsonian Institution Press, Washington, D.C.