Taraxacum nigricans, T. alpestre and allies in the Taraxacum sect. Alpestria: taxonomy, geography and conservation status.

A long-standing problem with the taxonomic status and synonymy of the names Taraxacum nigricans (Kit.) Reichenb. and T. alpestre (Tausch) DC. is resolved. These two names, the oldest ones referable to high mountain dandelions in Central Europe, are typified, and a detailed comparison of these species’ morphology, genotype make-up, karyotypes and distribution is provided, together with a discussion of other cases of similar and probably closely related agamospermous taxa of Taraxacum and Hieracium. Taraxacum nigricans (2n = 32) and T. alpestre (2n = 32) are endemic to the Nízke Tatry Mts, Slovakia, and the Krkonoše/Karkonosze Mts, Czech Republic/ Poland, respectively. These are shown to differ in a series of minor but constant morphological, allozyme and karyotype features, and their treatment as separate agamospermous species is supported. A detailed analysis of cultivated and wild material from the Carpathians revealed the existence of a sexual taxon very close to the above two species and endemic to the region of the Bucegi Mts, Romania. It is described as a new species, T. carpaticum Štěpánek et Kirschner. Two new agamospermous species, apparently allied to T. nigricans, are described: T. rupicaprae Štěpánek et Kirschner, a species characterized by orange-ochraceous achenes and confined to the High Tatra Mts, and T. elegantissimum Štěpánek et Kirschner (2n = 24), which has substantially broader outer bracts and is known from the Rodna, Retezat and Fagaras Mts, Romania. Another three species are described that are morphological similar to T. carpaticum: T. pastorum (the Fagaras Mts, Romania), T. iucundum (the Retezat Mts, Romania) and T. pseudoalpestre (the Fagaras Mts, Romania).