Rana palustris Leconte, 1825:282. Type locality not stated. Designated as vicinity of Philadelphia, Pennsylvania, by Schmidt, 1953:83. No type specimen known to exist.
Rana pardalis Harlan, 1826:59 (nomen nudum, name intended by Harlan for the new species described by Leconte).
Rana palustris mansuetti Hardy, 1964:91. Type-locality: "Maxton Pond, approximately one mile southwest of Maxton, Robeson County, North Carolina." Holotype, U.S. Natl. Mus. 150535, a female, collected 26 February 1961 by Jerry D. Hardy Jr.
*All taxonomic information taken from Zweifel, Richard G., Ed. Catalogue of American Amphibians and Reptiles. 1971. Society for the Study of Amphibians and Reptiles. 117.1.
Now, in layman's terms, the above scientific jargon means the following:
The Pickerel Frog is in the family Ranidae, which consists of 45 genera and 586 species (Nova Scotia Museum of Natural History website). Ranids are found all over the world.
Rana palustris was first described by John LeConte in 1825. Exactly where he found this new specimen (or the type-locality, as it is called) is unknown (Leconte p. 282). However, in 1953 Karl P. Schmidt designated the type locality as the area around Philadelphia, Pennsylvania. No specimens (or type-specimens, as they are termed) from Leconte's work are known to exist (Schmidt p. 83). Then, in 1826 Richard Harlan named LeConte's new species Rana pardalis (Harlan p. 59).
Years went by, until on February 26th, 1961, Jerry D. Hardy collected another specimen of this frog. The type-locality was Maxton Pond, North Carolina. Unlike the Leconte study, we do have specimens from Hardy's work. Indeed, his female holotype (the single specimen used by the author to describe a species) resides at the U.S. National Museum. And so, in 1964, the Pickerel Frog's name changed again when Hardy published his find as Rana palustris mansuetti (Hardy p. 91).
Finally, in 1971, Raymond Schaaf and Philip Smith named the species Rana palustris, and so it remains.
Some museums that have Pickerel Frog specimens...
the Cleveland Museum of Natural History