Montana Field Guide

Morphological Category – Symmetric biraphid

Valves lanceolate with gradually attenuated, subtly protracted and broadly rounded rostrate apices. Axial Area is narrow, widens slightly near the central area. Central Area a rectangular stauros with short striae sometimes present at the margins. Raphe lateral with straight proximal ends. Striae slightly radiate in the middle, becoming more radiate towards the apices. Areolae irregularly spaced, difficult to resolve in LM, 24-30 in 10 µm.

Size Range
Length 41-58 µm. Width 8.3-9.8 µm. Striae in 10 µm 27-30.

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

Stauroneis bryocola is distinguished from S. gracilior, S. kootenai, and S. pikuni by its rostrate, rather than capitate, apices and somewhat finer striae and areolae. Apices of S. schroederi are very narrowly rostrate, almost apiculate. Valves of S. neohyalina are linear-lanceolate with very narrow subcapitate apices.
Note: Stauroneis bryocola is not included in the Diatoms of Montana and Western North America catalog and atlas by Loren Bahls (2021, 2023).

Lakes and ponds in the mountains.

Stauroneis bryocola is known from lakes and shallow ponds in southwestern Montana.

Water Chemistry
The pH of these waters ranges from 6.5 to 7.8 and specific conductance ranges from 21 to 41 µS/cm. At the type locality on Heard Island it was found among wet mosses in some small tarns (Van de Vijver et al. 2004).

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.