River Frog (Lithobates heckscheri)
Description: The river frog is a very large species with adults commonly between 3 and 5 inches in length. The skin is rough and wrinkled but there are no dorso-lateral ridges as there are in the green frog (Lithobates clamitans). The back is some shade of dark green or blackish-green and the belly is dark grey, or blackish with pale wavy lines and specks. A distinctive characteristic is white spots on the lips, particularly on the lower lip, and this helps to distinguish this species from Bullfrogs (L. catesbeianus) and Pig Frogs (L. grylio). Another distinguishing feature is a pale band outlining the groin. Males have a yellowish throat and their tympani (eardrums) are larger than their eyes while those of females are smaller.
Habitat: Its typical habitat is marshes and other wet locations with emergent vegetation near streams, rivers, ponds and lakes.
Range: The river frog is endemic to the Atlantic and Gulf coastal plains of the southeastern United States. Its range at least formerly extended southwards from the southern part of North Carolina to southeastern Mississippi and northern Florida; it is now thought to have been extirpated from North Carolina due to habitat loss.
Diet: They are largely nocturnal and feed on insects and other invertebrates, as well as small vertebrates, including frogs.
Reproduction: Breeding takes place between April and August with males calling from the edge of ponds and swamps from April to July. The call has been described as "a deep, low-pitched, rolling snore". The eggs are laid in a floating layer among emergent vegetation, a clutch numbering several thousand eggs which hatch after about three days. The tadpoles are at first a dark color but become much paler over time with a dark edge to the tail fin. They congregate in the shallows in the daytime, sometimes in dense swarms, but move into deep water at night. They feed on both animal and vegetable matter. They remain as tadpoles for a long period, overwintering once or twice, and reaching a snout-to-vent length of 3.8 inches or more. After metamorphosis, the newly emerged juveniles are 1.2 to 2.0 inches long and move away from the margins of the water. The large number of juveniles compared to the relatively small number of adults indicates a high mortality rate for newly emerged young.
Status: The river frog has a wide range and is quite common in much of that range. The population appears to be large and reasonably stable and the main threat the frog faces is degradation of its habitat; it has declined in portions of its range due to this, and is thought to have been extirpated from the northernmost extremity of its range in southern North Carolina by 1975. However, it is present in a number of protected areas and the IUCN considers its conservation status to be of "least concern".
Taxonomy: This species was placed in the genus Lithobates by Frost et al. (2006). However, Yuan et al. (2016, Systematic Biology, doi: 10.1093/sysbio/syw055) showed that this action created problems of paraphyly in other genera. Yuan et al. (2016) recognized subgenera within Rana for the major traditional species groups, with Lithobates used as the subgenus for the Rana palmipes group. AmphibiaWeb recommends the optional use of these subgenera to refer to these major species groups, with names written as Rana (Aquarana) catesbeiana, for example.
»» Kingdom: Animalia - Animals
»» Phylum: Chordata - Chordates
»» Subphylum: Vertebrata - Vertebrates
»» Class: Amphibia - Amphibians
»» Order: Anura - Frogs & Toads
»» Family: Ranidae - True Frogs
»» Genus: Lithobates
»» Species: Lithobates heckscheri - River Frog
»» Subspecies: None
This article uses material from the Wikipedia article "Lithobates heckscheri", which is released under the Creative Commons Attribution-Share-Alike License 3.0. Content may have been omitted from the original, but no content has been changed or extended.
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