In current days there is still an astounding number of new species of animals being discovered and described (unfortunately, some are first described to be straight classified as threatned but, certainly, others just simply vanish from the face of the earth without even being known to science). A fair share of these new species are amphibians, usually being seen for the first time in some tropical forest in South America, Africa or Southeast Asia. Not so common is to find a whole new vertebrate species in Europe, while being in plain sight for a long time. In fact, it isn’t so obvious as that and molecular tools have proven extremely useful to find new species, when there isn’t obvious morphological differences between them.
One of these cryptid species is the recently described and proposed as nova taxa, portuguese parsley frog (Pelodytes atlanticus). Until recently, only three species of Pelodytes were described: P. caucasicus, as properly named, living in the Caucasus mountains; P. punctatus, occupying a range between Italy and Northeastern Spain and P. ibericus, in Iberian Peninsula. Mithocondrial DNA analysis as well as nuclear DNA markers found that in Iberia, three different species were actually present: P. atlanticus, only found in the Atlantic coast of Portugal; P. hespericus, in Central and Eastern Spain and P. ibericus, which in fact is only present in Southern Spain and Portugal (Díaz-Rodríguez 2017).
Pelodytes antlanticus (from Díaz-Martínez et al. 2017).
These new species, although being well geographically demarcated and obviously separated by genetics, are all very similar in terms of morphology and mating calls, not being quite clear how to differentiate them. They are not fully isolated as well, since there are minor hybrid zones, where geographic ranges overlap and genes flow between species.
This blurry speciation actually indicates that the western european parsley frogs have recently split from the rest of the lineage, leading to slightly different species. P. ibericus seems to have been the first one to split, around 3.6 million years ago, then P. atlanticus diverged 3.2 million years ago and, 0.2 million years after, P. hespericus and P. punctatus, diverged from one another (Díaz-Rodríguez 2014). This pattern of speciation was quite common in iberian herpetofauna during the last ice age, when it was considered a refugia for various animals. As the ice caps advanced or retracted along the peninsula, populations of amphibians or reptiles were isolated, eventally evolving into different species.
Phylogeny of Iberian Pelodytes species (from Díaz-Martínez et al. 2017).
Pelodytes is the only extant Genus of the Family Pelodytidae, now comprising 5 different species. There is one fossil species described, P. arevacus, from various Miocene sites of Spain. Other described extinct Genera are Miopelodytes (with M. gillmorei from the Miocene Elko formation, Nevada USA), Propelodytes (with P. wagneri from the Eocene Messel formation, Germany) and Aerugoamnis (A. paulus from the Eocene Green river formation, USA) (Garcia-Paris 2003). All Pelodytidae are small, nocturnal and mostly terrestrial frogs, sharing some common morphological characters (3 tarsal bones on food, vertebrae I and II fused, hyoid aparatus with parahyoid bone and astragalus fused to calcaneum).
Parsley frogs are sister to a clade including Megophrydae (Southeastern Asian horned toads) and Pelobatidae (Eurasian spadefoot toads). The North American spadefoot toads (Scaphiopidae) are sister to these three Families. In the great Anuran phylogenetic tree, these four groups, along Pipoidea (African clawed frogs and Surinam toad) form the Mesobatrachia. Archeobatrachia include very ancient lineages (Ascaphids, Leopelmatids and Discoglossids) and Neobatrachia include some more recent lineages (true toads, Ranid frogs, Hyliids and so on).
Pelodytes atlanticus, being the first portuguese endemic vertebrate, suggests that other cryptid species might be lurking in plain sight.