Lithobates sphenocephalus (Cope 1886)

This frog is generally slim, with a narrow head and long legs. Its distinguishing features are its lack of digital pads, and an upper jaw with teeth. Its dorsolateral folds extend nearly to the hips. The head of the frog is narrow and pointed, and longer than it is broad. The tympanum is about the size of its eye. The body is slender, with its widest region around the bellow, which is smooth and white. There is a dorsolateral fold that originates behind each eye and continues posteriorly to the hips, with smaller, less extensive, longitudinal folds between the dorsolateral folds. The fore limbs are moderately slender, with fingers at the base that do not end in digital pads. The hind limbs are long and moderately slender. Two and a half joints of the longest toe are free of the web, the one join of the other toes if free of the web. The toes do not terminate in digital pads. The male vocal pouches are sausage-shaped sacs at the angles of the jaw. The usually cannot be seen unless they are calling to other individuals. There are two rounded patches of vomerine teeth between the internal nares and the maxillary teeth are found along the upper jaw. The back and sides are green or brown, with distinct round white spots. There is usually a rounded white dot in the center of each tympanum (Carr and Goin 1955). .See another account at californiaherps.com (http://www.californiaherps.com/frogs/pages/r.s.utricularia.html).

The R. sphenocephala is found state-wide in Florida, in all kinds of wet areas (Carr and Goin 1955).

One decline of this species is currently being researched on Long Island (NY). Southern leopard frogs were historically abundant in many locations throughout the island despite being on the northern terminus of their range. However the frogs appear to have suffered rapid and steady declines throughout the island over the past 15-30 years and may now be extirpated entirely. Intensive efforts are currently underway to investigate the status of this species on Long Island as well as possible decline causes and future conservation potential. This species occurs in a few other locales in New York State but its status is largely unknown. The southern leopard frog is listed as a Species of Special Concern in New York State. (Contributed by Jeremy Feinberg [Jerfein AT eden.rutgers.edu].)

Usually, breeding is initiated by the rain, prompting the males to call out to the females. R. sphenocephala , however, can be heard calling during any month of the year, except July and August (Sunquist et al 2002). Breeding calls are harsh, guttaral croaks (Carr and Goin 1955).

Southern leopard frogs are found from New Jersey in the north and south through the Coastal Plain to Florida. The range extends westward through Kentucky, southern Indiana, southern Illinois, eastern Iowa, eastern Oklahoma, and eastern Texas.

Biogeographic Regions: nearctic (Native )

In addition to being a staple in the diet of many aquatic predators (great blue herons, river otters, grackles, southern water snakes, brown water snakes, northern black snakes, peninsular ribbon snakes, and water moccasins), humans also eat southern leopard frogs (particularly the legs). Lithobates sphenocephalus sphenocephalus is captured in large numbers to be used for fishing bait, scientific research, and classroom teaching.

Known Predators:

• great blue herons (Ardea herodias)
• grackles (Quiscalus)
• water moccasins Agkistrodon piscivorous
• southern water snakes (Nerodia fasciata)
• peninsular ribbon snakes (Thamnophis sauritus sackenii)
• brown water snakes (Nerodia taxispilota)
• northern black snakes (Coluber constrictor constrictor)
• river otters (Lontra canadensis)
• humans (Homo sapiens)

Anti-predator Adaptations: cryptic

Southern leopard frogs are slender frogs, with long legs and sharply pointed heads. They have prominent dorsolateral folds that extend from behind the eye to the hips. The tympanum is about the size of the eye and occasionally has a small white dot in the middle. The distinguishing feature of southern leopard frogs is the lack of digital pads on its toes. The back and sides are green and brown with distinct round spots. Average adult length is 80 mm. This species is sexually dimorphic: males tend to be smaller than females. Males also possess paired vocal sacs and enlarged thumbs and forearms to increase chances of successful reproduction.

Range length: 20 to 130 mm.

Average length: 80 mm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: female larger; sexes shaped differently

Life expectancy in the wild remains unknown. The majority of southern leopard frogs probably do not survive their first year. Adults known to hibernate in northern parts of their range, suggest they can live at least 2 to 3 years. Other species of leopard frog average 6 to 9 years of age.

Southern leopard frogs are found near freshwater habitats in their range. During summer they disperse from the water and settle in moist vegetation. These frogs can be found anywhere from 1 to 5 km from their aquatic habitats. Eggs and larvae develop in still, shallow water, occasionally in brackish water.

Habitat Regions: temperate ; freshwater

Terrestrial Biomes: forest

Aquatic Biomes: lakes and ponds; rivers and streams; temporary pools

Wetlands: marsh ; swamp ; bog

Other Habitat Features: suburban ; riparian

Mature southern leopard frogs are primarily invertivores, feeding on terrestrial arthropods. Immature larvae are herbivorous, feeding on algae, plant tissue, and organic debris. Larger individuals will occasionally eat small vertebrates, although this is rare.

Animal Foods: mammals; amphibians; insects; terrestrial non-insect arthropods; terrestrial worms

Plant Foods: wood, bark, or stems; algae

Other Foods: detritus

Primary Diet: carnivore (Insectivore , Eats non-insect arthropods); herbivore (Folivore , Algivore)

Southern leopard frogs play a valuable role in the food chain. Birds, river otters, large fish, and many snake species prey on them. In turn, southern leopard frogs prey on smaller frogs, insects, and larvae.

The respiratory tracts of some ranid frogs are susceptible to infection by a group of lung worms.

Southern leopard frogs are raised and eaten by humans, particularly their large rear legs. Lithobates sphenocephalus sphenocephalus is also a common frog to be used for dissection by many science classes. These frogs eat large amounts of pest insects, such as mosquitoes.

Positive Impacts: food ; research and education; controls pest population

After heavy rains many frogs are killed on busy roads and highways. Also, a large chorus of frogs can be loud and sometimes be a disturbance at night in suburban areas.

Newly-hatched tadpoles are between 20 and 25 mm long. They eventually reach a length of 65 to 70 mm before transformation. The entire tadpole stage of life is usually around 90 days. The tadpole's tail bears dark spots when metamorphosis is imminent. Once fully transformed, the young frog will be approximately 20 mm long.

Development - Life Cycle: metamorphosis

Listed as "Least Concern" in view of its wide distribution, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

Southern leopard frogs use a short, guttural trill at rate of 10 to 12 per second. This sound is compared to chicken clucks or the sound made by rubbing your fingers across as balloon. They have paired vocal sacs that are spherical when inflated. This species uses a variety of calls in the breeding season. The call travels farther than those of related species. Males are also likely to use visual cues when competing for mates and tactile cues are used during mating.

Communication Channels: visual ; tactile ; acoustic

Other Communication Modes: choruses

Perception Channels: visual ; tactile ; acoustic ; chemical

This species was known by the name Rana utricularia until the late 1990s.

Breeding is typically initiated by rain, prompting males to call to females. However, southern leopard frogs call during any month of the year, except July and August. Breeding calls are harsh, guttural croaks.

Mating System: polygynous

Breeding occurs in fall, winter, and early spring. Eggs are laid just below the water's surface in a firm cluster about 90 mm wide and 40 mm thick and containing several hundred eggs per cluster. Often breeding frogs will congregate and lay numerous clusters of eggs in a small area.

Breeding interval: Southern leopard frogs breed once annually.

Breeding season: Breeding occurs from November to March in the southern portion of their range and March to June in the northern parts of their range.

Range time to hatching: 53 to 60 days.

Range age at sexual or reproductive maturity (female): 2 to 3 years.

Range age at sexual or reproductive maturity (male): 4 to 6 months.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous

Rana spenochephala shows little to no parental investment in their offspring after laying an egg cluster. Once the eggs are laid, they are left to survive on their own.

Parental Investment: no parental involvement

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Lithobates sphenocephalus Lithobates generoko animalia da. Anfibioen barruko Ranidae familian sailkatuta dago, Anura ordenan.