Taxonomic diversity and sympatry among water frogs from Southern France: evidence for new assemblages

European water frogs can be found to form several hybridogenetic complexes.The most widespread complex occurs in Central and Eastern Europe (Graf and Polls-Pelaz, 1989).In this complex, the hybridogen Rana kl.esculenta (genome RL) originated from "primary" hybridization between R. ridibunda (genome RR) and R. lessonae (genome LL).The hybridogens usually coexist only with the sexual parental host species R. lessonae.Matings between the hybridogen R. kl.esculenta and R. lessonae (as "secondary" hybridizations) maintain hybridogenetic lineages as R. kl.esculenta transmits only its ridibunda genome to haploid gametes (L-E system, Uzzell and Berger, 1975).Such host-hybridogen populations constitute persisting reproductive systems.However, in natural populations, other taxa may coexist without forming hybridogenetic systems.Pagano et al. (1997) termed these coexisting taxa "assemblages" in contrast to the "systems" which represent host-hybridogen persisting populations.Parental species or hybridogens can also constitute "pure" populations (Günther et al., 1979;Graf and Polls-Pelaz, 1989).Another hybridogenetic complex occurs in Southern France and Northern Spain (Graf et al., 1977;Graf and Polls-Pelaz, 1989; Pagano et al., 2001a; b).In this complex, the origin of the hybridogen (R. kl.grafi, genome RP) remains speculative because hybridogens may originate from a "primary" hybridization be-