Anamorph-Teleomorph Relationships

Abstract

About 300 species of Ingoldian hyphomycetes are now known (Descals et al. 1993). They grow mostly on leaves and twigs in rapidly flowing freshwater streams, but some are found in lakes, in stagnant water and some in terrestrial habitats but dispersed in water (see Chap. 2). It is probably best to regard some of them as amphibious fungi. Their amphibious nature is illustrated by the fact that although most of them develop conidia freely underwater, some will continue to sporulate in air on twigs or leaves removed from water, and some will also sporulate in culture on agar without free water. Some can survive for months on air-dried leaves removed from streams (Sanders and Webster 1978) (see Chaps. 2, 10). Tree trunks, branches, twigs and leaf petioles exposed to air by receding water levels or stranded on river banks and held in a humid environment frequently bear ascocarps and occasionally basidiocarps. A small proportion of these have been shown to be teleomorphs of Ingoldian fungi. They do not need to be submerged in water in order to discharge their spores, but (with the exception of Camptobasidium) do so freely in air. These air-borne spores permit dispersal over large distances and this may explain the paradox of the worldwide distribution of freshwater fungi with passively dispersed conidia. It may also help to explain why such fungi are to be found near the sources of freshwater streams. The opportunities which sexual reproduction provide for gene recombination and selection must also be important for the evolutionary success of fungi with teleomorphs.