Abstract
Here, we describe the new species Mallomonas decora that was first detected in two small ponds in the Czech Republic. The description is based on silica-scale morphology, employing both transmission (TEM) and scanning electron microscopy (SEM).
Possessing only apical bristles attached to the most anterior ring od collar scales, Mallomonas decora belongs to the section Torquatae. The shield of the collar scale is covered with ribs that are transversely oriented; towards the central part of the shield, the ribs are branched and/or form a reticulate honeycomb structure.
The anterior submarginal rib is flattened, supporting the anterior submarginal flange, that is covered with conspicuous ribs. The taxa that are the most similar to M. decora are M. dickii and M. ocalensis.
Mallomonas dickii differs from M. decora by the presence of large pores located between pairs of ribs on the anterior flange. The ribs on the shield of M. dickii are also spaced more closely.
Mallomonas ocalensis differs from M. decora by having the protruding anterior submarginal rib, ornamented with the small papillae and short struts connecting it to the base plate.