Preliminary results of the taxonomic value of Tortula densa (Velen.) J.-P. Frahm inferred from the Internal Transcribed Spacer (ITS) of the nrDNA

The taxonomic concept of T. ruralis Hedw., T. calcicolens Kramer and T. densa (Velen.) J.-P. Frahm of various specialists varies much and was controversely discussed. The species were regarded as synonymous or distinct taxa, or T. densa was either placed into synonymy of T. ruralis or T. calcicolens. A molecular analysis using Internal Transcribed Spacer 1 and 2 (ITS) of selected Tortula specimens including specimens referred to T. ruralis, T. calcicolens and T. densa from the same locality, revealed that all three differed in their nuclear DNA sequences. This shows that these morphologically and anatomically distinct specimens are not modifications of T. ruralis and T. densa is not an intermediate between T. calcicolens and T. ruralis but a distinct genotype, as indicated by mixed tufts.