part of fungal structure conidiophore sterigma A small hyphal branch or structure which supports a sporangium, a conidium, or a basidiospore. In species with biseriate (two-layered) sterigmata such as A. nidulans, the first layer comprises primary sterigmata (metulae) and the second layer secondary sterigmata (phialides). Some species, e.g. A. fumigatus, A. oryzae, and others, have only phialides. FAO:0000044 fungal_anatomy_ontology sterigmata (plural)