The moss genus Codriophorus P. Beauv. is one of four segregates of the traditionally conceived genus Racomitrium Brid. which has proved to be an artiﬁcial and heterogeneous taxon. Codriophorus is easily distinguished, principally by the presence of large, flat papillae distributed over the longitudinal cell walls which cover the major part of the lumina. In this character it very much resembles the genus Racomitrium s. str. but differs in having a densely papillose calyptra, a costa often ending well below the leaf apex, epilose innermost perichaetial leaves, smooth setae that are twisted to the right on drying, lack of a hyaline hair-point in the vast majority of species, a capsule which is never ventricose and mostly shorter peristome teeth that are divided to the middle or base.
Codriophorus species have usually been classiﬁed in sect. Papillosa (Kindb.) Nog. or subg. Cataractarum Vilh. within Racomitrium. In total, 42 species, 25 varieties and 13 forms have been described which may be referred to the latter genus. The types or original material of 69 names (86%), including the types of all species names, have been located and taxonomically assessed. As a result of these critical taxonomic studies 15 species have been recognised within Codriophorus. They are deﬁned by a combination of gametophyte and sporophyte characters, the most important of which are to be found in the morphological and anatomical structure of the costa, leaf areolation, leaf apex, recurvature of the leaf margin, branching pattern and alar cells.
Codriophorus is here divided into two sections, sect. Codriophorus and sect. Fascicularia Bednarek-Ochyra. They are subsequently subdivided into four and three subsections respectively.
Aspects of the ecology and phytogeography of the Codriophorus species have been studied and global and regional distribution maps for each species are provided. Every species is illustrated with many line drawings, showing all morphological and anatomical details and SEM micrographs for some species are also included. The phytogeography of Codriophorus is analysed and its species are placed in generally recognised phytogeographical elements.