Most authors throughout the 19th and 20th century disagreed with Fitzinger's assessment. The green frogs were included again with the brown frogs, in line with the tendency to place any frog similar in
habitus to the
common frog (
R. temporaria) in
Rana. That genus, in the loose circumscription, eventually became a sort of "
wastebin taxon". Around 2000, with
molecular phylogenetic studies becoming commonplace, it was discovered that Fitzinger's assessment was correct after all – not only is
Pelophylax an independent genus, but it does in fact belong to a lineage of
Raninae not particularly close to
Rana. But it also turned out that these Eurasian green frogs might not form a
monophyletic lineage. The sheer number of
species involved in the group of
Pelophylax and its closest relatives means that it will probably be some time until the definite circumscription of this genus is resolved. The
Pelophylax frogs belong to a group of moderately advanced Raninae – possibly a
clade – that also includes such genera as
Babina,
Glandirana,
Hylarana,
Pulchrana,
Sanguirana,
Sylvirana, as well as
Hydrophylax which like
Pelophylax is suspected of being not monophyletic. These genera were formerly also included in
Rana by most authors, and several of them have only been established in the 1990s. And as regards the possible
paraphyly of
Pelophylax, it seems that some species assigned there are very close to
Hylarana, and thus it might simply be a matter of moving them to that genus. But
hybridogenic
speciation is running rampant in the Old World green frogs, and this obfuscates the data gained from
DNA sequence analyses. Following the establishment of
Pelophylax in Europe, their diversification appears to have been based around the expansion and contraction of the
Paratethys Sea, which served as a geographic barrier to the dispersal of many taxa.
Species Including named
klepta (
hybridogenic species),
Pelophylax sensu lato contained 25 species. However, more recent lumps have reduced this to 13 species, subsuming many of the former small-range endemic species of eastern Europe and west Asia into
P. ridibundus. The following species have been variously suggested: • †
Pelophylax aquensis (Late Oligocene of France) • †
Pelophylax barani (Middle/Late Miocene of Turkey) • †
Pelophylax meriani (Early Miocene of Germany) • †
Pelophylax pueyoi (Late Miocene of Spain) • †
Pelophylax quellenbergi (Late Miocene of Spain) == Invasiveness ==