Yeast M. boundymillsiae grown on agar in a Petri plate has an unusual form. While most yeasts are white to cream colored and form smooth colonies, this yeast forms greenish, fuzzy colonies with a convoluted knob in the center. This yeast also secretes an unknown brown pigment into the agar. (Photo: M.-A. Lachance)
Yeast M. boundymillsiae grown on agar in a Petri plate has an unusual form. While most yeasts are white to cream colored and form smooth colonies, this yeast forms greenish, fuzzy colonies with a convoluted knob in the center. This yeast also secretes an unknown brown pigment into the agar. (Photo: M.-A. Lachance)

New Yeast Species Moniliella boundymillsiae Honors Kyria Boundy-Mills, Curator of the Phaff Yeast Culture Collection

  • by Kyria Boundy-Mills

The naming of a new species is one of the highest honors in biology. In 2026, researchers from Brazil, Australia, and Canada described a new yeast species, Moniliella boundymillsiae, naming it in honor of Dr. Kyria Boundy-Mills, longtime curator of the Phaff Yeast Culture Collection at the University of California, Davis. The species was described in the International Journal of Systematic and Evolutionary Microbiology, the preeminent journal for the publication of new microbial species.

The honor is especially meaningful because so few yeast species have been named. Scientists estimate that more than 90% of the world's yeast species remain undiscovered or undescribed. While only about 3,000 yeast species have been formally named, tens of thousands are thought to exist. Every newly described species represents years of exploration, careful laboratory study, and international collaboration.

The discovery of Moniliella boundymillsiae also highlights the vital role of biological collections. The Phaff Yeast Culture Collection preserves over 10,000 yeast strains representing more than 1,500 named species, making it one of the world's largest public collections of wild yeasts. Just as importantly, it also contains more than 200 yeast species that scientists know are new to science but have not yet been formally described and named. 

Many of these unique yeasts originated in the pioneering field studies of yeast ecologists and taxonomists Herman Phaff (UC Davis), Marc-André Lachance (U Western Ontario), William T. Starmer (Syracuse U), and Phil Ganter (Tennessee State U). Their field work collected thousands yeasts from flowers, insects, tree exudates, cacti, soils, foods and beverages, and other natural habitats across the globe. By rescuing these individual researcher’s collections, the Phaff collection now maintains the original isolates which include many strains unavailable from any other public collection. This represents an irreplaceable record of microbial biodiversity spanning over 80 years of yeast ecology research.

According to UC Davis alumnus and retired University of Western Ontario professor Dr. Marc-André Lachance, he collected all eleven strains of Moniliella boundy-millsiae in 1995 during studies of yeast diversity associated with flowers and flower-visiting insects across more than 700 kilometers of coastal Queensland in tropical Australia. Many of the nearly 800 yeast isolates recovered during that expedition, and thousands of other strains he isolated in his 40-year career, are now preserved in the Phaff collection. The eleven M. boundymillsiae isolates are an unusually pigmented species found in morning glory and Hibiscus flowers or their insects. Physiological studies at the time demonstrated that the isolates likely represented a previously unknown species. Thirty years later, supported by DNA analyses, Lachance and colleagues named the new species Moniliella boundymillsiae in recognition of Dr. Boundy-Mills' contributions to yeast biodiversity research and to the stewardship of culture collections.

In 2021, Boundy-Mills and Lachance packed up over 5,000 yeast strains to ship from the University of Western Ontario to the University of California Davis, to incorporate them into the Phaff collection. (Photo: K. Boundy-Mills)
In 2021, Boundy-Mills and Lachance packed up over 5,000 yeast strains to ship from the University of Western Ontario to the University of California Davis, to incorporate them into the Phaff collection. (Photo: K. Boundy-Mills)

Maintaining collections like the Phaff collection involves much more than storing samples in freezers. Before a strain can be released to researchers, curators must confirm that it is alive, free of contamination, correctly identified, and accompanied by complete information about where, when, and by whom it was collected. These quality-control and documentation steps require considerable time and expertise.

Like many scientific collections, the Phaff collection also has a backlog of thousands of valuable strains awaiting this work before they can be fully incorporated into the public collection. Many of these strains may represent new species or possess properties valuable for biotechnology, food production, agriculture, medicine, or environmental research. Completing this work transforms preserved samples into accessible scientific resources that can support discovery for decades to come.

Unfortunately, biological collections are especially vulnerable during times of economic uncertainty. Because their greatest value often lies decades into the future, institutions may view them as lower priorities than short-term research projects. Yet the long-term preservation of biological diversity is precisely what makes collections indispensable. Every newly described species, including Moniliella boundymillsiae, is a reminder that yesterday’s carefully preserved specimens, and today’s maintenance of their biodiversity, enable tomorrow's scientific breakthroughs.

The naming of Moniliella boundymillsiae honors one scientist, but it also celebrates the broader mission of the Phaff Yeast Culture Collection: preserving the world's yeast biodiversity so that future generations can continue discovering, understanding, and using these remarkable microorganisms.