WWU Professor Emeritus Robin Matthews details newly described desmids

Under a microscope, desmids can appear as delicate and complex as snowflakes.

Microscope photo of Micrasterias radiosa var. elegantior, a desmid that has multiple spokes radiating from the center

Desmids are incredibly diverse and characterized by their intricate, symmetrical cell structure. 𝘔𝘪𝘤𝘳𝘢𝘴𝘵𝘦𝘳𝘪𝘢𝘴 𝘳𝘢𝘥𝘪𝘰𝘴𝘢 𝘷𝘢𝘳. 𝘦𝘭𝘦𝘨𝘢𝘯𝘵𝘪𝘰𝘳 has a lace or snowflake-like quality. © R. Matthews, used with permission.

These single-cell or filamentous green algae found in freshwater lakes, ponds and bogs are comprised of two mirror-image semicells. Desmids are extremely sensitive to changes in the environment, so are valuable indicators for water and habitat quality.

“In Europe, where desmids have been studied for several hundred years, they’ve found that about 90% of their desmid diversity has been lost due to habitat alteration and climate change,” said Professor Emeritus Robin Matthews, former professor of Environmental Sciences who served as the director of the Institute for Watershed Studies from 1994 to 2019.

There are an estimated 5-6,000 described desmids globally. Two recent papers co-authored by Matthews add seven more to those numbers. An article that came out in June details three previously undescribed desmids.

A microscope photo of Cosmarium methowense shows two mirror image semicells in bright green

𝘊𝘰𝘴𝘮𝘢𝘳𝘪𝘶𝘮 𝘮𝘦𝘵𝘩𝘰𝘸𝘦𝘯𝘴𝘦 was found in Big and Little Twin Lakes, two small kettle lakes in the Methow River watershed on the eastern side of the Cascades. © R. Matthews, used with permission.

One of them, Cosmarium methowense, was found in Big and Little Twin Lakes, small kettle lakes in the Methow River watershed on the eastern side of the Cascades.

Matthews worked with the Methow tribe and Syilx Nation to name Cosmarium methowense after the original placename (mətxʷu) used by the Methow tribe, whose historic lands include the region where this desmid was collected.

This is on the heels of a 2024 paper about four other desmids found near Mt. Adams in southwest Washington.

An interest in desmids has taken Matthews to some of the most remote lakes, ponds, and wetlands in the Pacific Northwest. They exist around the world, but conditions here provide an ideal habitat for the microscopic organisms.

“I’ve been interested in freshwater algae since my mom bought me a microscope in about 7th or 8th grade,” said Matthews. “I’m one of those weird people who just loves taxonomy.”

Taxonomy is the classification, description, and naming of things and studying how they are related within the scientific hierarchy.

Robin Matthews retrieves a sampling net from a pond with mountains in the background.

Robin Matthews uses a fine-mesh plankton net to collect samples at a pond on the trail to the Big Four Ice Caves in the Mt.Baker-Snoqualmie National Forest in May 2019. © G. Matthews, used with permission.

Retired from teaching, but not retired from working with students, Matthews still mentors Western students helping them get comfortable with identifying algae species.

Natalie Furness, a GIS specialist with WWU’s Spatial Institute created the map that’s in the 2025 article; IWS Director Angela Strecker, created the 2024 map. IWS analyzed water quality for all the locations. WWU’s SciTech (Scientific Technical Services) provided support for creating high-resolution scanning electron microscope (SEM) images of the desmids.

Photos and accompanying specimens of the newly described desmids will be archived in the United States Algal Collection at the Smithsonian Institution in Washington, D.C.

Interested in algae, desmids, and water quality? Learn more about the Institute for Watershed Studies and find degrees in Environmental Sciences.

Jennifer Nerad covers Western's College of the Environment and College of Business and Economics for the Office of University Communications. Have a great story idea? Reach out to her at neradj@wwu.edu.