Taxonomic implications of antheridial variability in forty-five watermold isolates: a statistical analysis

Morphological variability of sexual features used in watermold identification renders species identifications difficult and calls into question the taxonomic utility of these characters. Herein I have employed chi square statistical analysis to quantify antheridial character state distribution differences between replicate pairs of 38 isolates representing the saprolegniaceous genera Achlya, Saprolegnia, Thraustotheca, and 7 non-sporulating watermolds. Thirty-nine of 45 pairs differed at or below the P=.05 significance level, suggesting that current morphological species concepts are inadequate, at least for Achlya and Saprolegnia.