Tortella mediterranea (Pottiaceae), a new species from southern Europe, its molecular affinities, and taxonomic notes on T. nitida

Abstract

Tortella mediterranea is described as a new species from the Mediterranean Basin of southern Europe. It is mainly characterized by (1) absence of a stem central strand, (2) lanceolate leaf shape, (3) rather gradual limb-sheath transition, (4) partial presence of elongate marginal cells in the upper half of leaf and (5) ventral costal stereid band usually stronger than the dorsal. Chloroplast rps4 and nuclear ITS sequences were invariable within the studied specimens of the species, suggesting a low genetic variability, and the phylogenetic position is rather isolated with only obscure affinities to the group of closely related taxa around T. tortuosa and to T. fasciculata. The new species, seemingly a rather rare plant, was collected from dry and sunny to shaded limestone rocks. In addition, new molecular data for T. nitida s.str. and putative var. irrigata are provided and taxonomic problems within this variable species are discussed.