An overlooked synonym of the African moss Pogonatum capense (Hampe) A.Jaeger

During revision of Polytrichum commune Hedw. and related taxa worldwide as part of an investigation undertaken during work for a Ph.D. thesis by the first author, a large number of historic and type specimens of taxa described under the genus Polytrichum were borrowed from various herbaria to help clarify the correct application of names. This process permitted the study of many potential and known type specimens that had not previously been critically examined. Numerous names were assigned to taxa now recognised within the recently revised Polytrichum commune complex (Kariyawasam 2021). However, one Polytrichum binomial for which original material, preserved in the Berlin herbarium (B), had apparently not previously been recognised or studied is that of P. transvaaliense Müll.Hal. At first sight this specimen clearly did not belong in Polytrichum as now recognised, but looked much more likely to be a member of Pogonatum, as was quickly confirmed. This binomial has not been dealt with in the revisions of De Sloover (1986) or Hyvönen (1989). It is listed under Polytrichum in the checklist of O’Shea (2006), but without any further comments. Using Hyvönen’s key to Pogonatum worldwide, the type specimen clearly falls within the circumscription of Pogonatum capense (Hampe) A.Jaeger, a relatively widespread species in South Africa and also reported from Angola, Zimbabwe, Madagascar and Mauritius (De Sloover 1986). As a later name, Polytrichum transvaaliense Müll.Hal. can now be lectotypifiied and relegated to the synonymy of that species, as detailed below. This adds to the five synonyms of Pognatum capense already listed by Hyvönen (1989).