Lichen Hunting in California

When people think about discovering new species, they often imagine expeditions to uncharted rainforests or deep ocean trenches. Yet, some of the most exciting discoveries in biology are happening much closer to home—in the mountain ranges of California—where scientists are finding previously unknown species of lichens right in our backyard. Over 1,000 published species that are largely heterogeneous in morphology were formerly grouped in the lichen genus Caloplaca s. lat. (Ascomycota, Teloschistaceae) ¹ . These fascinating organisms are most easily recognized by their bright orange or yellow coloration that dots rocks and tree bark across California's landscapes.

Bright orange Caloplaca lichens growing on rocks in California's mountains.

California's diverse mountain ranges provide ideal habitats for lichen diversification.

What makes this discovery journey particularly compelling is that despite the considerable scientific attention these lichens have received, many complicated groups within the genus should probably be split into more species ¹ . Each expedition to California's mountains continues to reveal specimens that are new to science, highlighting just how much we have yet to learn about the natural world around us.

The understanding of Caloplaca lichens has undergone a revolutionary transformation in recent years, driven largely by advances in molecular phylogeny. The taxonomy of the Teloschistaceae family (to which Caloplaca belongs) has developed rapidly since 2012, with a large number of new genera being proposed based on molecular investigations ² .

This dramatic reorganization reflects how DNA sequencing has revealed evolutionary relationships that weren't apparent from physical characteristics alone. The family is now divided into three or four subfamilies: Caloplacoideae, Teloschistoideae, and Xanthorioideae ² .

This reclassification matters because it helps scientists understand how these organisms have evolved and spread across different environments. What appeared similar to the human eye might be distantly related, while seemingly different lichens might share a close common ancestor.

The Research Mission

The compelling story of California's lichen diversity unfolded through dedicated fieldwork and molecular detective work. The project began when scientist Ulf Arup took a short trip to California and found several lichens that appeared to represent new species ¹ . This prompted a formal research mission to locate additional specimens of these undescribed species.

From Field to Laboratory: The Scientific Process

Remarkable Findings

The California mountain expedition yielded significant discoveries. In total, six new species were described through this project: two in the genus Xanthocarpia and four in the genus Rufoplaca ¹ . Interestingly, instead of primarily finding additional samples of the species initially spotted by Arup, many of the collected specimens were "totally new and only further complicated the situation" ¹ —highlighting the surprising depth of undiscovered diversity.

The research revealed that the majority of the samples belonged to two genera: Xanthocarpia and Rufoplaca ¹ . Particularly, Rufoplaca emerged as a complicated group requiring further research with more samples to clarify all the relationships between species.

Modern lichen research employs a diverse array of tools and techniques to uncover the secrets of these symbiotic organisms.

Key Chemical Analysis Methods

The chemical profiling of lichens provides crucial data for classification:

California's diverse topography and climate create ideal conditions for lichen diversification. The state's mountain ranges offer varied microhabitats with different exposures, elevations, and substrates that have allowed numerous lichen species to evolve and thrive.

Factors Contributing to Diversity

• Varied topography and elevation gradients
• Diverse microclimates and exposures
• Multiple substrate types (rocks, bark, soil)
• Mediterranean climate with seasonal variation
• Geographic isolation in mountain "islands"

California's diverse mountain ecosystems create numerous niches for lichen specialization.

The discovery of so many new species in relatively accessible areas suggests that previous underdocumentation, rather than actual rarity, may explain why these lichens remained unknown for so long. As one researcher noted, "With each short visit to the mountains of California an abundance of new Caloplaca s. lat. species are discovered" ¹ . Even a few days of focused collecting can yield specimens that are "new and exciting" to science.

The story of Caloplaca lichens in California represents a powerful reminder that scientific discovery isn't confined to remote wildernesses or high-tech laboratories alone. The mountain ranges of North America continue to yield biological treasures that reshape our understanding of biodiversity.

As researchers combine traditional field biology with cutting-edge genetic tools, our knowledge of these complex organisms grows exponentially. Each newly described lichen species adds another piece to the puzzle of how life diversifies and adapts to different environments—a puzzle that scientists are still assembling right in the hills and mountains of California.