Stachylidium, Gonytrichum, Mesobotrys, Chaetopsis and Chaetopsella

Abstract

Stachylidium bicolor is chosen as the lectotype species of the genus Stachylidium and is illustrated and described from temperate and tropical collections. Gonytrichum caesium , the type species of Gonytrichum , has been shown by Mr E. W. Mason to be based on the conidiophores of Melanopsamella inaequalis ; the conidiophores are illustrated and described. The name Mesobotrys is based on the two species M. macroclada and M. fusca , which are here regarded as conspecific ; furthermore, they are considered to be congeneric with Gonytrichum caesium ; a new combination is proposed and the conidiophores and conidia described. The type or lectotype species of these three generic names produce slimy amerospores from phialides. Chaetopsis wauchii (= C. grisea ) is the type species of Chaetopsis , and contrary to previous descriptions it has been found to produce slimy didymospores from polyphialides, and not amerospores. Chaetopsella is regarded as a synonym of Chaetopsis , being based on C. grisea which is an earlier name for C. wauchii . An attempt has been made to trace all British records of these fungi to their source. Nomenclators of all species attributed to the four generic names are given with the original substratum and country of origin.