Emendations to tissue typology in discomycetes

Abstract

The term ‘textura oblita’,referring to a tissue type in ascomycetes with apothecial ascomata, has causedmuch confusion to ascomycologists. Originally it was defined as along-celled tissue type consisting of thick-walled hyphae with intercellularsubstance. However, this definition appeared not well, or not at all, applicableto the originally given examples like Phialea starbaeckii. This has resulted in two other definitions which are moreor less the opposite of each other, viz. as a thick-walled tissue with gelatinizedwalls and as a thin-walled tissue embedded in a gelatinous matrix. The main issueis the location of the gelatinous substance in the relevant tissue: in the cellwall, extracellular or both. Unfortunately all of the three tissues are called‘gelatinous tissue’, although the term ‘gelatinous tissue’ according to itsdefinition concerns only tissue with extrahyphal gel. This implies thatessential information about the location of the gel is ignored. In effect, allthree conceptions of textura oblita are reducible to versions of texturaporrecta that differ in the location of the gel. Similarly other tissue typescan occur in different versions.

To conclude, an emended tissuetypology is provided in which the distinguished versions of the six basictissue types are arranged according to the shape of their cells, thearrangement of their hyphae, the occurrence of thickened cell walls and theoccurrence of extracellular gel.

The species name Cyathicula starbaeckii, comb. nov., is validly published here.