found: Frank, N. Comp. guide to sci. and common names of reptiles and amphibians of the world, 1995:p. 107 (Rana esculenta, edible frog)
found: Wikipedia, July 15, 2010(The Edible Frog (Pelophylax kl. esculentus) is a name for a common European frog, also known as the common water frog or green frog (however, this latter term is also used for the North American species Lithobates clamitans). Pelophylax esculentus is the fertile hybrid of the Pool Frog (Pelophylax lessonae) and the Marsh Frog (Pelophylax ridibundus), hence the addition of the "kl." (for klepton or synklepton) in the species name. When edible frogs mate with each other, their offspring are often misformed, so there are no pure populations of edible frogs. The hybrid populations are propagated by female edible frogs mating with males of one of the parental species)
found: Amphibian species of the world 5.4, an online reference, July 15, 2010(Because each individual of "Rana esculenta" is a hybrid with a genome of Pelophylax lessonae and a genome of Pelophylax ridibundus, "Pelophylax esculentus" or Pelophylax kl. esculentus must be regarded as a kind of frog, not a species, a pattern-class in the Pelophylax ridibundus-Rana lessonae hybridogenetic complex. "Pelophylax esculentus" had a hybrid origin from Pelophylax lessonae and Pelophylax ridibundus)
