The Oklahoma salamander is a small, dark, slender salamander that is generally yellowish tan to dark brown or gray. The stripe running along the back may be golden or yellowish tan to brown and is bordered by dark brown lines. Also along back, there may be a row of dark brown V-shapes corresponding to each of the 19–21 costal grooves (vertical grooves on the sides of the body). The sides and tail have small white flecks. The belly is gray but may be somewhat yellow.
Most commonly, however, this species is seen only in its gilled, aquatic larval stage or as neotenic adults (adults that retain gills). In these, the back and sides are cream or light tan and covered with extensive gray stippling, with two lines of small white spots along the sides, and a pale belly. Poorly developed dorsal and ventral fins are present on the tail.
Similar species: For the evolving relationship between this species and its closest relatives, see the Status section.
Adult length: 1¾–3¼ inches; occasionally to 4 inches.
Occurs in the central and southwestern portions of the Ozark Highlands. Overall range is limited to the eastern edge of Oklahoma, southwestern Missouri, and northern Arkansas.
Habitat and Conservation
Both larval and adult life stages are permanently aquatic, and most of Missouri's population lives in small, clear, cherty, gravel-bottom creeks, streams, and springs. When surface water is present, these salamanders live in the spaces among loose gravel or under rocks. During dry periods and presumably during the winter, these salamanders follow the water level down into the creek gravel bed; using this type of aquatic habitat allows them to remain active all year.
Although extremely rare in Missouri, transformed individuals (adults lacking external gills) hide under rocks and logs in or near cave springs or cold, clear streams. They are especially associated with the dimly lit areas beyond cave entrances and in leafy seepage areas of the Ozark Highlands. When outside caves, these salamanders are nocturnal and may venture away from streams on rainy nights.
The Oklahoma salamander has a restricted distribution in Missouri, Oklahoma, and Arkansas, but it appears to be relatively secure in Missouri. However, its requirements for clean creeks, springs, and an abundance of clean gravel make it vulnerable to water pollution and habitat loss. Siltation (the filling of spaces between gravel stones with sediments), followed by gravel removal, are the primary threats for this species.
Small arthropods are the primary food of both adults and larvae, especially ostracods (seed shrimp), isopods (such as aquatic pillbugs), dipterans (true flies, including their aquatic, wormlike larvae), and ephemeropterans (mayflies, including their aquatic larvae).
Populations appear to be relatively secure, despite the restricted distribution. This species requires clean, silt-free creeks and springs. Siltation, gravel removal, and water pollution are its primary threats.
Taxonomically, this species has a confusing history. It's closely related to the many-ribbed salamander (Eurycea multiplicata multiplicata), a species that occurs in the Ouachitas of Arkansas and Oklahoma, and what was called the gray-bellied salamander (E. multiplicata griseogaster), which occurred in the Missouri Ozarks. At one point, the Oklahoma salamander was considered separate from both of these. Then came evidence that the gray-bellied and Oklahoma salamanders were the same species, and for a time, the tentative name for both was "gray-bellied salamander." In 2004, researchers using genetic evidence proved the two were the same and declared the species the Oklahoma salamander (E. tynerensis), which is where we stand today.
Neoteny is common in this species; this means that adults retain the feathery external gills that generally characterize the larval stage; thus the adults remain permanently aquatic. It is very rare to find an adult of this species that has fully transformed into a gill-less form.
Fertilization is internal, and females attach their eggs to the undersurface of rocks or within spaces in the gravel substrate of springs and streams. Females lay 3–21 eggs. Incubation lasts about 30 days. Larvae are gilled. After 5–8 months, the larvae become sexually mature. Most adults will be neotenic (retaining the gilled, aquatic form), while a few may transform into the gill-less adult form more typical of this family. Neotenic adults generally attain larger sizes than those that undergo the full metamorphosis.
The reproductive season varies considerably within the range of this species due to temperature variation among breeding sites. Places where the temperature is fairly stable, such as in cave streams and springs, have prolonged reproductive seasons. Places where the temperature fluctuates widely, such as in surface streams, have briefer reproductive seasons. Generally, breeding may last from September into July, with many populations laying eggs during the fall to late spring.
To keep this salamander present in healthy populations in our state, people should take care to protect the habitats it requires. In particular, this means preventing siltation in streams, gravel removal, and groundwater pollution. Construction, plowing, and other soil disturbance on land can easily lead to erosion of sediments that wash into creeks, which can fill the spaces among gravel in and along streams. Maintaining vegetative buffer zones along streams and sinkholes, implementing erosion and sediment controls, and utilizing other habitat best-management practices will protect this and many other Ozark stream-dwelling animals, including a variety of fishes.
These small salamanders prey on a variety of small aquatic animals and in turn become food for other animals, including fish, herons, snakes, and other amphibians. The eggs and tiny larvae are most vulnerable to predation.
Animals that move in and out of caves play an important role in bringing nutrients, which are plentiful outside the cave, into the cave system where nutrients are more scarce. A salamander that eats insects outside a cave can move deeper into the cave; its excrement, and perhaps eventually its own dead body, may end up in the cave as food for cave-obligate species.
This is a member of the lungless salamander family (Plethodontidae). It’s a large family with 27 genera and about 443 species. The family probably originated in the southern Appalachian Mountains; its members now occur over the eastern half of North America, the West Coast, and into Mexico, Central America, and northern South America. A few species also occur in southern Europe and South Korea.
The lungless salamander family is named because the adults lack lungs and most (except for this species) lack gills. In most of the lungless salamanders, the oxygen they require is taken from their environment through the skin and mucous membrane of the mouth. In this species, however, most adults retain their external gills and continue an aquatic existence.