Hemidictyum

Christenhusz, Maarten J. M. & Schneider, Harald, 2011, Corrections to Phytotaxa 19: Linear sequence of lycophytes and ferns, Phytotaxa 28 (1), pp. 50-52 : 51

Placement of Hemidictyum in Hemidictyaceae , sister to Aspleniaceae

Recent analysis including the members of our newly described Diplaziopsidaceae made us conclude that this family should consist of Diplaziopsis C.Chr. and Homalosorus Small ex Pic.Serm. only. The third genus Hemidictyum C.Presl , was tentatively included in Diplaziopsidaceae , but has since been found to be sister to Aspleniaceae ( Lehtonen 2011) . It should therefore either be treated as an independent family [ Hemidictyaeae , fam. nov., frondes herbaceae, compositae, pinnis oppositis lanceolatis serratis; fasciculus vasorum in stipite unicus; venae pinnatae, simplices; sori lineares, elongati, dorso venae simplicis; indusium lineare, elongatum, planum. Type: Hemidictyum C. Presl (1836: 110) ], or be included in Aspleniaceae (as suggested by Lehtonen 2011), although the latter is unwarranted because synapomorphies of such a broadly defined Aspleniaceae are not yet known. Moreover the separation of Hemidictyum and Aspleniaceae dates back to the Cretaceous according to current estimates of divergence times of derived ferns ( Schuettpelz & Pryer 2009), and the recognition of two families will therefore be helpful for future classification of Cretaceous and early Tertiary ferns.