ABSTRACT

Watermold taxonomy has historically been based, at the species level, on sexual characters. However, the persistent and well-documented plasticity of these features makes identification difficult. This problem is compounded by the use of equivocal language in species descriptions. Our study, to our knowledge the first of its kind to be published, seeks to quantitatively assess the variability of sexual characters within a single Saprolegnia isolate. We have used strict observational guidelines to minimise observer bias, and have employed statistical analysis to determine what differences, if any, exist in the rate of occurrence of the various states of 4 sexual characters traditionally used in identification. A series of subcultures of both hyphal tip and single spore origin was used in our study. We will show that despite best possible methodology, the sexual features of Saprolegnia are too variable to be useful in taxonomic endeavours, and that this places all watermold classifications based on sexual characters in question.