Neotypification of Difflugia biwae (Amoebozoa: Tubulinea: Arcellinida) from the Lake Biwa, Japan

Difflugia biwae Kawamura, 1918 has been redescribed. Here, the neotype of D. biwae, which was newly collected from its type locality, Lake Biwa, is designated to the species to clarify its taxonomic status. Morphometric characterization of D. biwae was performed. A statistically significant correlation between body length and shell collar diameter was identified in the population of the Lake Biwa, but this correlation was not significant in the population from the Mulan Lake. The PCA scatterplot indicates that the Mulan Lake population could be a separate taxon identified by shorter protuberance length and body length.