Fossil record of Meliolaceae from India sheds new insight into its taxonomy and life cycle

Abstract

The asexual morph of Meliolaceae has long been a focus of attention for mycologists because there has been a lack of research to establish the asexual morph cycle of Meliolaceae. Besides asexual morph, only a few research works have also been done on the setae (mainly ascomatal setae) of Meliolaceae. In this connection, the use of reliable fossil evidence in evolutionary studies is obligatory. The present study fills this lacuna by reporting the in-situ occurrence of a new enigmatic fossil-genus and species Palaeomeliola indica Kundu and Khan, gen. et sp. nov. with mycelial setae, ascomata, ascomatal setae, ascomatal conoid cells, 4-septate ascospores, phialides, and phialoconidia on the cuticle fragments of a compressed disease-symptomatic monocot leaf recovered from the middle Siwalik (Late Miocene; ca. 12–8 Mya) of Himachal Pradesh, western Himalaya. Palaeomeliola indica is the first fossil-species of Meliolaceae having all sexual and asexual morphs. From this point of view, our new fossil fungus is very distinctive and establishes the greatest preserved fossil record of Meliolaceae. The preserved sexual and asexual morph data sheds new insight into the systematics, life cycle, and evolutionary lineages of Meliolaceae. Furthermore, the findings of this study will form the basis for any future life cycle reconstruction and morphological character evolutionary study of Meliolaceae.