Fossils can reveal a long-vanished combination of character states: Evidence from a mysterious foliicolous anamorphic fungus from the Middle Siwalik (Late Miocene) of Himachal Pradesh, India

ABSTRACT

Fossils can unveil a long-vanished combination of character states that inform inferences about the timing and patterns of diversification of modern fungi. By examining the well-preserved stacked chained vesicular conidiophores developed in clusters from the basal stroma, we describe a new taxon of fossil Zygosporiaceae with a combination of characters unknown among extant taxa on compressed serrated-margined dicot leaf (cf. Fagaceae) recovered from the Siwalik sediments (Late Miocene; ca. 12–8 Ma) of Himachal Pradesh, western Himalaya. Based upon conidiophore morphology, our Siwalik fungal remains, similar to Zygosporium Mont. (Zygosporiaceae: Xylariales: Sordariomycetes), are recognized as a new fossil species, Z. stromaticum Kundu & Khan, sp. nov. Zygosporium stromaticum is the only known fossil anamorphic fungus that occurs on plant cuticles and has a cluster of stacked chained vesicular conidiophores arising from a poorly preserved basal stroma formed by irregular, thick-walled cells. Its combination of morphological characteristics is unknown in extant fungal taxa, so Z. stromaticum likely represents a new anamorphic foliicolous fungus that may now be extinct. This unique evidence may be essential for the calibration of divergence time estimations of fungal lineages.

KEYWORDS:

• Compressed leaf
• Himachal Himalaya
• stacked chained vesicular conidiophores
• Siwalik
• taxonomy
• Zygosporium stromaticum
• 1 new fossil taxon

ACKNOWLEDGMENTS

The authors gratefully acknowledge the Department of Botany, Sidho-Kanho-Birsha University, Purulia, India, for providing infrastructural facilities to accomplish this work.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Funding for this research was provided by DST-SERB, GOI (Department of Science and Technology-Science and Engineering Research Board, Government Of India), New Delhi, India (file no. CRG/2020/001303), to M.A.K.