Montana Field Guide

Morphological Category – Symmetric biraphid

Valves linear-lanceolate with weakly triundulate margins and apiculate apices. Pseudoseptum present at each apex. Valves widest at the center. Axial Area very narrow. Central Area shaped like a bow tie or a butterfly’s wings. Raphe filiform with weakly expanded proximal ends. Areolae very fine, about 30 in 10 µm.

Size Range
Length 25-32 µm. Width 2.4-5.7 µm. Striae in 10 µm 28-32.

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

Stauroneis leguminopsis is distinguished from S. prominula by its triundulate margins and bow tie shaped central area.

Fens

Cold, circumneutral waters with low nutrients and conductivity (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.