Hawaiian Forest Fungi. IV. Rusts on Endemic Acacia Species

Four rusts, Uromyces digitatus, U. koae, Endoraecium acaciae, and E. hawaiiense, occur on endemic Acacia spp. in Hawaii. Endoraecium is a new genus erected to accommodate endocyclic species with pediceliate aecial teliospores. Uromyces koae, the only rust species previously reported from Acacia spp. in Hawaii, is shown to be demicyclic instead of macrocyclic as formerly believed. Uromyces digitatus, originally described from Australia as a demicyclic species, is shown to be macrocyclic in Hawaii. A microcyclic form of this species with teliospores indistinguishable from the macrocyclic form, also occurs in Hawaii. The symptomatology, biology, and host ranges of these rusts are described, and their possible taxonomic relationships are discussed.