Long sigmoid and twisted ascospores in the genus Harpidium: H. longisporum sp. nov., a synopsis of the genus and a key to the species

Abstract

Harpidium longisporum is proposed as a new species. It is characterized by an areolate, mainly black thallus with trebouxioid algae, K+ bluepurple pigmented parts, pycnoascocarps forming aspicilioid apothecia, with moniliform paraphyses, unitunicate-rostrate, thick-walled asci and long sigmoid, lunate to falcate or irregularly curved and twisted ascospores, growing on steps of a vertical, intermittently moist, gneiss rock face. The genus Harpidium now comprises four species worldwide and, based on the selected specimens, a genus synopsis, a comparative table and a key to the species are included.