Latitudinal distribution of the Lithothrix aspergillum (Corallinales, Rhodophyta) of the Mexican Pacific coast

Abstract

Population of Lithothrix aspergillum J. E. Gray (Corallinales, Rhodophyta) was collected at several sites on the west coast of Baja California during 1996 to 2002 and a through revision was made of specimens deposited in herbaria in Mexico and California in order to determine the occurrence and latitudinal distribution of the reproductive phases of L. aspergillum on the Mexican Pacific coast. Analysis of the information reveled that tetrasporangial thalli are present along the all range of distribution know for L. aspergillum in the west coast of the Baja California peninsula; the bisporangial thalli are confined in the northwest part of the peninsula; meanwhile the scarce gametangial thalli (male and female) are commons in the south part of the peninsula. In general, bisporangial thalli are arborescent and large, with a mean size of 9.4 ± 1.4 cm; tetrasporangial thalli are more compact and branched, and lower in size than tetrasporangial thalli with a mean size of 4.4 ± 1.2 cm; meanwhile, gametangial thalli are characterized by the small size, with a mean size of 3.5 ± 0.8 cm. The morphology and reproductive characters of each reproductive phases are described.