Fig. 2 DIC photographs of Troglomyces bilabiatus (a–e), T. botryandrus (f) and T. manfrediae (g). a–b Fully mature thalli where arrows point to the collar-like structure under the perithecial apex. c Although ascospores are seen inside the perithecium, this is not still open because its apex appears blocked with a plug (arrow). Some cells are labelled: I basal cell, II suprabasal cell, III upper cell of receptacle, VI perithecial stalk cell, a primary septum. d Immature thallus showing the trichogyne (tr), the antheridium (an) and the remains of the ascospore apex (sx). e Paired mature thalli showing the antheridia (an). f Perithecial apex detail with trichogyne stump (arrow). g Perithecial apex detail showing the collar-like structure (arrows). All scale bars 20 μm, except for e and f: 25 μm