Pseudostilbella euphorbiae, a new sporodochial hyphomycete, isolated from Euphorbia resinifera

Abstract

Pseudostilbella anam. gen.nov. and Pseudostilbella euphorbiae anam. sp.nov. are proposed to accommodate a fungus isolated from lesions on living stems of Euphorbia resinifera Berg. collected in Morocco. The conidioma is a sporodochium borne on a rudimentary, brownish to greyish-brown, diffuse, KOH− stroma that is an extreme development of prosenchyma. The sparingly branched conidiophores develop from underlying pseudoparenchymatous cells. Conidiogenous cells form palisades and produce filiform, straight, or sinuous conidia. The conidiogenous system is holoblastic. Orange, slimy conidial masses accumulate on the colony surface or at the apex of synnema-like aggregations according to the location of the sporodochia. Sporodochia are sessile when colonies are grown under intense light, whereas they form at the apex of white stalks under diffuse light. Cultures grown in continuous darkness produce mycelial, synnema-like aggregations but do not sporulate. Light is thus needed for sporulation. Key words: Hyphomycetes, Euphorbia, fungal taxonomy, photomorphogenesis, sporodochial fungi.