Taxonomic assessment of Sorbus subgenus Aria in the Malé Karpaty Mountains

Abstract

In this paper we present a taxonomic assessment of Sorbus subgen. Aria in the Malé Karpaty Mts (western Slovakia and north-eastern Austria). Detailed field observations, morphological comparison, herbarium revisions, multivariate morphometric analyses, flow cytometry and molecular (nuclear microsatellite markers) analyses were used to assess the taxonomic diversity within this group. Diploids, triploids and tetraploids were detected. Diploids are represented by a single taxon, S. aria, which shows considerable morphological and genetic variability. Sorbus aria ranges from rare to locally abundant throughout the area studied. Triploids are confined to the central and southern parts of the region and include several single, presumably apomictic individuals and rare apomictic lineages, which are not treated as separate species here due to the very limited number of individuals recorded. Tetraploids show similar distribution patterns to those of triploids: S. danubialis and S. collina occur in the southern part of the mountains, while S. petraea, a new species described here, inhabits the central part of the mountain range. The entire population of S. petraea includes approximately one hundred individuals. It occurs mainly in the surroundings of Vysoká Mt. by the village of Kuchyňa, where it forms several small populations and approximately 30 individuals grow on Čierna skala hill by the village of Plavecký Mikuláš. In addition to these recent occurrences, there are two herbarium specimens from the 1960s documenting the species on Vápená Mt. The low genetic and morphological variability and flow cytometric seed screening indicate an apomictic mode of reproduction in this species and justify its recognition at the species level. Sorbus collina is reported here in Slovakia for the first time. We have not confirmed the occurrence of S. austriaca, S. buekkensis, S. carpatica, S. graeca, S. pannonica, S. thaiszii and S. zolyomii in the Malé Karpaty Mts and consider the previously published records to be erroneous. Lectotypes are designated for S. thaiszii and S. zolyomii. A determination key, detailed distribution maps and photographs of representative herbarium specimens of all taxa of S. subgen. Aria occurring in the Malé Karpaty Mts are provided. A line drawing and a photograph of the newly described species are also presented.