The genus Talaromyces Benjamin, being a heterogeneous genus is divided into two genera: Talaromyces, based on T. vermiculatus, characterized by asci developing in chains and Hamigera gen. nov., based on T. avellaneus, characterized by asci formed singly from croziers. Talaromyces striatus is also included in Hamigera. Descriptions and drawings are presented of the two species of Hamigera and the three species of the closely related genus Byssochlamys. A new series of Penicillium, the P. avellaneum series, is erected to accomodate P. avellaneum and P. ingelheimense.