The Palaearctic Titmouse Species (Aves: Paridae: Parus sensu lato) — A current survey*

Abstract

Within the Palaearctic taxa belonging to the genus Parus s.l. there are sympatric species at all levels of similarity. However, during the entire 20th Century no other sympatric cryptospecies were discovered, despite the progressive refinement of comparative methods. All the taxonomic changes introduced were related to determining the status of allopatric and parapatric taxa, in particular with respect to either 1. the subspecies or species status or, more rarely, 2. direct systematic relationships in the cases of Parus superciliosus, P. lugubris hyrcanus and P. davidi. This taxonomic survey of Palaearctic titmouse species aims at a synthesis of the results of both classical morphological methods on the one hand and the more recent bioacoustic and molecular studies on the other. Under the assumptions of the biospecies concept 22 Palaearctic titmouse species are distinguished, which at a higher taxonomic level belong to fourteen geospecies. Most species embrace different “population groups”, which represent the smallest bundling of taxa on a morphological-geographical basis. Within Palaearctic Paridae each of the 44 population groups presented in this paper is distinguished by a distinct morphological character set. Mean values of several morphometric measurements, such as wing length, tail length and relative tail length are provided for each population group in the species list (Section VI).