New Lichen Species Allographa effusosoredica Discovered in Western Ghats

Allographa effusosoredica a. Thallus, b. soredia, c. ascus showing I+ blue ascospores, d. clear hymenium, e. ascospores.

In a significant scientific discovery from one of India’s most ecologically rich regions, researchers have identified a new species of lichen, Allographa effusosoredica, from the Western Ghats, a UNESCO World Heritage Site and biodiversity hotspot.

This discovery not only adds to India’s growing inventory of lichen species but also offers new insights into the ancient biological partnership known as symbiosis — where two or more different organisms live in close association, often to mutual benefit.

Lichens are remarkable in that they are not single organisms, but symbiotic partnerships — typically between a fungus (which provides structure and protection) and a photobiont, usually a green alga or cyanobacterium, that performs photosynthesis to produce food. Despite their modest appearance, lichens are ecosystem keystones: they contribute to soil formation, nourish insects, and serve as bioindicators — living signals of air quality and environmental change.

The newly discovered Allographa effusosoredica is a crustose lichen, meaning it forms a crust-like structure tightly attached to its substrate. It is distinguished by its striking effuse soredia — powdery reproductive structures that help in vegetative propagation — and by rare chemical traits, including the presence of norstictic acid, a compound seldom found in other morphologically similar species within the genus Allographa. These features make the species both taxonomically and chemically significant.

This study was conducted by scientists from the MACS-Agharkar Research Institute, Pune, an autonomous institute under the Department of Science & Technology (DST), Government of India. The team employed an integrative taxonomic approach, combining classical taxonomy (based on morphology and chemistry) with modern molecular tools — a method now seen as essential in resolving the often complex identities of lichen species.

Crucially, the research identified the algal partner of A. effusosoredica as a species of Trentepohlia — a genus of filamentous green algae known for its orange-red pigments and common presence in tropical regions. This finding adds to the limited but growing knowledge of photobiont diversity in tropical lichens and supports the idea of locally adapted symbionts — algal partners uniquely suited to their fungal hosts in specific regions.

To determine the evolutionary placement of the species, the team employed DNA sequencing across multiple genetic markers — mtSSU, LSU, and RPB2 for the fungal component, and ITS (Internal Transcribed Spacer) for the algal symbiont. This genetic analysis revealed that A. effusosoredica is phylogenetically closest to Allographa xanthospora.

Interestingly, its physical form closely resembles Graphis glaucescens, sparking evolutionary questions about generic boundaries within the Graphidaceae family, which encompasses many crustose lichen genera.

Notably, Allographa effusosoredica is the first Indian species of Allographa to be sequenced and supported by molecular data, making it a milestone for Indian lichenology. The researchers highlight the importance of such data-driven approaches in clarifying evolutionary relationships and refining classifications within this diverse and under-studied group of organisms.

The study was part of a research project funded by the Anusandhan National Research Foundation (ANRF) — formerly known as the Science and Engineering Research Board (SERB). The project, titled “Unravelling the symbiosis of algal and fungal partners in lichen family Graphidaceae and Parmeliaceae from the Western Ghats through polyphasic taxonomic approach and ecological studies”, aimed to uncover deeper ecological and evolutionary insights into lichens through a polyphasic approach — a method that integrates morphology, chemistry, genetics, and ecology.

With this addition, Allographa effusosoredica becomes the 53rd species from the genus Allographa reported from India and the 22nd species recorded specifically from the Western Ghats. The discovery underscores the urgent need for molecular research on Indian lichens, particularly in biodiversity hotspots like the Western Ghats, where many cryptic and endemic species remain scientifically undocumented.

In essence, this discovery is more than just the identification of a new species — it is a step forward in understanding the genetic complexity of symbiotic life forms, their evolutionary histories, and their vital role in the functioning of forest ecosystems.

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