Telford et al . (Brevia, 19 May 2006, p. 1015) reported that freshwater diatoms exhibit regional-scale richness-pH relationships that depend substantially on regional habitat availability. On this basis, the authors argued that, despite their microscopic size, diatoms are not ubiquitously dispersed. Here, I describe my demonstration that their primary evidence against the ubiquitous dispersal hypothesis is spurious.