Abstract
Helicascus presently comprises two marine species, H. kanaloanus and H. nypae. During investigations of freshwater ascomycetes in Egypt, Malaysia and northern Thailand, we collected two new species of Helicascus from freshwater, which is a new habitat for the genus. Helicascus aegyptiacus sp. nov. is characterised by its smaller asci and ascospores with verruculose walls. Helicascus aquaticus sp. nov. is distinct in having 1-3-septate ascospores and producing a Pleurophomopsis-like anamorph when grown in water agar with sterilized pine needles. During this study we also collected Massarina thalassioidea from freshwater and molecular data confirm this as a species of Helicascus. Thus, we combine this species under Helicascus. All Helicascus species, Massarina thalassioidea and Morosphaeria elaterascus form a strongly supported monophyletic clade and the latter species is also transferred to Helicascus. A key to Helicascus species is provided.