Guide to Denticula

The raphe system of each valve is positioned diagonally opposite to one another, demonstrating nitzschiod symmetry. The raphe system is located within a wide, low keel. The raphe may or may not have proximal raphe ends or be continuous across the valve, a feature difficult to see without SEM. Thick internal bars of silica (fibulae) are present and parallel to the striae. The fibulae widen near the valve margins to form a 'tooth-like' appearance, hence the genus name Denticula.

According to AlgaeBase (2025), Denticula includes 26 accepted species names. Originally, the genus included only freshwater taxa, however there are also marine and brackish water species. Some taxa were transferred to fossil genera Crucidenticula and Neodenticula (Akiba and Yanagisawa 1985). Others are considered within Denticulopsis (Simonsen 1979), Nagumoea (Witkowski et al. 2011) and Tetralunata (Hamsher et al. 2014). Phylogenetic relationshps within the Bacillariaceae are being pointed out, including the sister relationship between Denticula kuetzingii and Nitzschia amphibia (Mann et al. 2021).

Denticula species are often characteristic of carbonate rich waters of springs. The genus also contains species from large, oligotrophic lakes.