A revision ofTaraxacum sect.Piesis (Compositae)

On the basis of allozyme and cultivation data, and of additional herbarium material, a taxonomic and nomenclatural revision ofTaraxacum sect.Piesis A.J. Richards exKirschner et?těpánek is provided. The section is made up of halophilous, sexually reproducing taxa. InT. stenocephalum Boiss. etKotschy,T. pindicum Kirschner et?těpánek, sp. nov., andT. perenne Kirschner et?těpánek, sp. nov., a tetraploid chromosome number has been recorded, representing the only known case of sexuality at the tetraploid level in the genus. The complex ofT. stenocephalum, includes some geographically and morphologically extreme populations treated as subspecies: subsp.gumusanicum (Soest)Kirschner et?těpánek, comb. nov., subsp.magnum Kirschner et?těpánek, subsp. nov., and subsp.daralagesicum (Schischk.)Kirschner et?těpánek, comb. nov. In addition toT. bessarabicum (Hornem.)Hand.-Mazz., a widely distributed Eurasian species,T. stenocephalum, a complex centred in Transcaucasia and Anatolia, andT. pachypodum H. Lindb., a North African endemic, four new species are described:T. salsum Kirschner et?těpánek, sp. nov., a diploid endemic confined to E Crimea,T. perenne Kirschner et?těpánek, sp. nov., a tetraploid sexual species known only from SW Crimea,T. pindicum Kirschner et?těpánek, sp. nov., a remarkable tetraploid endemic to the Pindos Mts., Greece, andT. salsitatis Kirschner, ?těpänek etYirdirimli, sp. nov., an Anatolian diploid species. Furthermore, a hybrid betweenT. salsum andT. bessarabicum from Crimea (documented on the basis of allozyme data elsewhere) is given a binomial,T. xmesohalobium Kirschner et?těpánek, nothosp. nov.