Calongia gibelluloides gen. sp. nov., a remarkable minute new lichenicolous conidial fungus from northern Spain

The new conidial lichenicolous fungus Calongia gibelluloides gen. sp. nov. is described from discoloured soredial patches on thalli of Flavoparmelia caperata and discoloured squamules of a Cladonia species collected in northern Spain. It is especially unusual in its minute size, the solitary conidiophores reaching at most 45 μm and bearing a cluster of conidiogenous cells that are at first enclosed by a membranous sheath, and produce 1-septate narrowly ellipsoid to elongate-reniform or elongate-soleiform fuscous conidia. The fungus has some features that recall the entomogenous hypocrealean genus Gibellula, but species of that genus have synnematous conidiomata, ornamented conidiophores, phialidic conidiogenous cells, no membranous vesicle, and non-septate conidia produced in chains. The phylogenetic placement remains uncertain in the absence of a teleomorph or molecular evidence.