Pseudospiropes sp., a fungal epiphyte on living stems of striped maple (Acer pensylvanicum)

Abstract

The living stems of striped maple (Acer pensylvanicum L.) at two sites in Nova Scotia were found to be covered by a striking pattern of fungal hyphae belonging to Pseudospiropes sp. The fungus colonizes branches or seedlings during their first season, and the density of its coverage increases every year thereafter. The fungus was absent from striped maple at a site near Lake Placid, NY, and there is some evidence that its frequency of occurrence has declined elsewhere in the last few years. A pure culture of the fungus was unable to hydrolyze several plant cell wall polymers. It was able to use simple lipids, however, and its presence increased the erosion of the cutinized layer of striped maple stems. The fungus does not penetrate the stem surface, and its occurrence is not correlated with twig length or volume. It was absent from three sympatric maple species.