Subramanian’s concept of true and false chains of phialoconidia is rejected and replaced by a distinction between connected and disconnected chains. In connected conidial chains the primary conidial wall is strongly thickened at both ends and a connective is formed. This criterion allows the distinction between trichocomaceous or eurotiaceous (connected) and sphaeriaceous (disconnected) catenulate phialoconidia. The ultrastructure of conidiogenesis is described. On the basis of this criterion, the species of the Acremonium diversisporum series as well as the anamorph of Sagenoma viride Stolk & Orr with connected chains are transferred from Acremonium to the new genus Sagenomella to which four new species are added.