Montana Field Guide

Morphological Category – Symmetric biraphid

Valves lanceolate with acute, narrowly rounded apices. Axial Area narrow and linear. Raphe branches simple, with unilaterally hooked distal raphe ends. Proximal raphe ends linear, not inflated. Striae slightly radiate throughout. Areolae arranged into longitudinal rows, separated by hyaline ribs on the external side of the valve, 10-12 in 10 µm. Areolae coarse, appear rectangular in LM. Stauros rectangular, extends to the valve margins, not transected by longitudinal ribs.

Size Range
Length 83-97 µm. Width 16-20 µm. Striae in 10 µm 16-17.

Useful Link:
Diatom Glossary [Diatoms of North America website]

Stauroneis staurolineata is very similar in appearance and also appears in lakes of the northeast U.S. Stauroneis staurolineata, however, has ribs that transect the stauros.

Low elevation mountain lake surrounded by forest (Bahls 2021).

Cool, circumneutral water with low nutrients and conductance (Bahls 2021).

Diatoms typically reproduce by cell division (mitosis) and occasionally by meiosis—sexual reproduction in which female and male gametes combine to form a specialized zygote called an auxospore. Repeated divisions result in cells of a population becoming progressively smaller and smaller. When cells reach a critically small size, sexual reproduction is initiated, resulting in an auxospore and initial cells that are the largest attainable for the species, after which cell division and size reduction resume (Amato 2010).

Climate change and regional warming.