HAUSTORIAL ULTRASTRUCTURE AND MORPHOLOGY OF MELAMPSORELLA AND THEKOPSORA-AREOLATA

The morphology and ultrastructure of dikaryotic haustoria (D-haustoria ) of Melampsorella caryophyllacearum and Melampsorella symphyti (Uredi nales, Pucciniastraceae) were found to be different. The haustorium of M. caryophyllacearum was branched apically and the haustorial neck wa s sheathed by a fold of the extrahaustorial membrane. A system of fila mentous structures was present in the matrix fold around the neck. In hi. symphyti, no such matrix fold was present and the haustorial body was unbranched. D-haustoria of Thekopsora areolata were bulbous and un branched. They differed from D-haustoria of other Thekopsora species b y the presence of a matrix fold at the haustorial neck. Melampsorella, Thekopsora and Pucciniastrum are the only pucciniastraceous genera, s o far that revealed different haustorial types. The systematic implica tions are discussed.