Studies of British species of Endogone: I. Morphology and taxonomy

Abstract

Chlamydosporic species . Material of Endogone macrocarpa from a number of localities fell into four fairly distinct types; golden-spored, yellow-spored, orange-spored and brown-spored. There was no evidence that these were geographical races or that the variation was due to environmental factors. The species is considered to be a variable one. Variation in E. microcarpa was less marked but relatively large-spored and small-spored variants occurred. E. fuegiana Speg. is a new record for Britain. The spores of this species are borne in groups at the ends of inflated hyphae. A single fruit-body of an unusual type, in which chlamydospores and sterile vesicles were borne in groups at the ends of a complex system of branched hyphae, was provisionally assigned to the E. fasciculata—E. vesiculifera group. Fruit-bodies of a species associated with mycorrhizal strawberry roots were considered to be chlamydosporic. A detailed examination of wall-structure in chlamydospores of these species showed that both exospore and endospore are continuous with the corresponding layers of the wall of the subtending hypha. Zygosporic species . It was confirmed that the size of the zygospores of E. lactiflua is correlated with the density of their distribution within the fruit-body. E. pisiformis , from the New Forest, is described as the first authentic record of this species in Britain. A fruit-body of E. microcarpa contained both typical chlamydospores and zygospores, some of which were of an unusual type. This is the first record of a zygosporic form of this species and only the second record of a mixed zygosporic and chlamydosporic fruit-body in Endogone . Certain problems of the morphology and taxonomy of Endogone are discussed and a key to the British species is given.