Taxonomy, gamete morphology and mating types of Urospora (Ulotrichales, Chlorophyta) in North America

Abstract

L.A. Hanic. 2005. Taxonomy, gamete morphology and mating types of Urospora (Ulotrichales, Chlorophyta) in North America. Phycologia 44: 183–193.Filament and gamete morphology, mating tests and hybridizations reveal the presence of eight taxa of Urospora from the Pacific and Atlantic coasts of North America. Three are dioecious and anisogamous: U. penicilliformis, U. neglecta and U. wormskioldii (synonym: U. vancouveriana). A fourth, U. bangioides, is monoecious and isogamous. Two are unisexual female variants, one with biflagellate parthenogametes (both coasts) and the other with quadriflagellate parthenogametes (Atlantic coast only). Two others are unidentified monoecious, anisogamous variants: one on the Atlantic coast and one on the Pacific coast. Urospora penicilliformis, U. neglecta and U. wormskioldii from the Pacific formed viable hybrids with their Atlantic counterparts and are considered to be conspecific with them. Urospora penicilliformis from the Pacific coast also formed viable hybrid zygotes with U. penicilliformis from Helgoland and Japan, again indicating conspecificity. On the Pacific coast, U. penicilliformis is the most common Urospora in the upper littoral, ranging from southern California to Homer, Alaska, with U. neglecta being restricted to British Columbia and Alaska. On the Atlantic coast, U. neglecta is the dominant Urospora, with U. penicilliformis subdominant in the upper littoral. Urospora wormskioldii is the dominant Urospora in the lower littoral on both coasts. Sexuality is reported for the first time in U. wormskioldii and for the first time in North America in U. bangioides. Monoecy and isogamy are confirmed in the genus. Urospora penicilliformis, U. neglecta and U. wormskioldii, although usually dioecious, are occasionally monoecious, indicating that the dioecious condition in these three species is not fixed. Emended descriptions of the species and genus are provided.