Fossil Tetraploa redefinition and potential contribution of dark pigments for the preservation of its spores in the fossil record

The establishment of affinities of fossil fungal spores with extant fungal taxa based mainly on the detailed analysis of morphological traits is difficult. Thus, it is necessary to use mycological terms to properly describe fossil fungi. In this work, we transfer five species of Frasnacritetrus Taugourd. (1968) to Tetraploa Berk. & Broome (1850) because the spores of the fossil and extant species share the same morphological traits. Here, we also discuss how dark pigments of extant spores of Tetraploa are synthesized to assess their potential contribution to the preservation of these diaspores in the fossil record, including their role in the fossilization process. In this work, we conclude that Frasnacritetrus should be considered a synonym of Tetraploa. Our results also shed light on how melanins have played a role in the preservation of fungal spores and other remains in the fossil record to thus, 1) understand how different burial histories and thermal maturation influenced long-term melanin survival, 2) to study the evolution of fungi lineages such as Tetraploa, and 3) to assess how fungal melanins can be used as biomarkers for palaeoecological purposes.

Automated summary

The establishment of affinities between fossil and extant fungal spores based on morphological traits is challenging, requiring the usage of mycological terms. In this study, we transferred five species of Frasnacritetrus to Tetraploa due to their shared morphological traits. Additionally, we discussed the synthesis of dark pigments in extant Tetraploa spores and their contribution to the preservation of these diaspores in the fossil record. Our findings shed light on the role of melanins in preserving fungal spores and other remains, providing insights into burial histories, thermal maturation effects, fungal lineage evolution, and the use of fungal melanins as biomarkers for paleoecological purposes.