Tentamen Pteridophytorum genera in taxonomicum ordinem redigendi

Summary The main object of this paper is that of presenting a classification of all genera of the extant Pteridophytes, based on the phylogeny. First, a new scheme of classification of the higher groups of the extant Pteridophytes to the family level is proposed. It is followed by the taxonomical enumeration of all genera, which amount to 443 and are subdivided into 64 families. Altogether, the extant Pteridophytes are classified from the taxonomic level of division to that of genus. In the enumeration the genera are numbered according an arithmetical progression with a common difference of ten, i.e. the basic number for each genus is a decimal number, with the exception of the genera of uncertain taxonomic value and the intergeneric hybrids. In the enumeration, the generic name, the author, the bibliographical reference and the type species, whether a type (T.) or a lectotype (LT.), with its basionym, are given. The taxonomical enumeration of genera is accompanied by some comments in which the origin, the phylogeny and the relationship of the various groups are discussed; also the taxonomical position and rank assigned to the various families and genera in the proposed classification is justified. These comments are as far as possible concise and are limited to dealing with particular problems on the phylogeny and taxonomy of some groups of Pteridophytes. Some of them are integrated by phyletic schemes which are intended to show the degree of affinity between the various families and genera. The paper is completed by two appendices: a conspectus of all families and genera adopted in the proposed classification (Appendix I), and an alphabetical index of all generic names of the extant Pteridophytes which are validly published, whether legitimate or illegitimate, and whether adopted in this paper or treated as synonyms (Appendix II). The generic names of this index, including the orthographic variants, amonut to 923. The bibliographical references are limited to the papers quoted in the text.