Diversity in fossil fungal spores

Abstract

Diverse types of fungal spores, exhibiting a variety of morphological variations, have been added to the fossil records from time to time. These may be unicellate (unicellular), dicellate, tricellate, tetracellate, multicellate, muriform, filiform, spirally coiled and star-like. Similarly, these may be inaperturate, monoaperturate, diaperturate, triaperturate and multiaperturate. The present paper documents all published fossil fungal spore genera and species. Assignment of fossil fungal spores to extant fungal taxa is seldom possible. These are therefore placed into artificial supra-generic taxa based on morphological characters, e.g. number and nature of cells and characters associated with size, symmetry, apertures, septa and spore wall. These supra-generic taxa are: Amerosporae (unicellate spores; 61 genera), Didymosporae (dicellate spores; 21 genera), Phragmosporae (tri- or pluricellate, transversely septate spores; 41 genera), Dictyosporae (muriform spores divided by intersecting longitudinal and transverse or diagonal septa; 18 genera), Helicosporae (one to many celled, spirally coiled spores with curved axis; 9 genera) and Staurosporae (pluricellate, stellate spores, with more than one axis; 9 genera). In addition, a number of species of fossil fungal spores, described under 26 modern fungal genera, have also been included. Genera are arranged in alphabetical order under each of the above groups. Similarly, species are also arranged under each genus in alphabetical order. Five new species, viz. Dicellaesporites vermae, Dyadosporites singhii, Fusiformisporites sahii, Diporicellaesporites tiruchirappalliensis and Multicellites tamilensis, and four new combinations, viz. Hypoxylonites disciformis (Sheffy & Dilcher), Hypoxylonites lanceolatus (Debi Mukh.), Melanospora primigenia (Casp.) and Thecaphora mohgaoensis (Chitaley & Yawale) are proposed here. The dominant genera, both in number and variety, are: Brachysporisporites R.T. Lange & P.H. Sm., Dicellaesporites Elsik, Diporicellaesporites Elsik, Diporisporites Hammen, Dyadosporites R.T. Clarke, Fusiformisporites Rouse, Hypoxylonites Elsik, Inapertisporites Hammen, Multicellaesporites Elsik, Multicellites Kalgutkar & Janson., Pluricellaesporites Hammen and Staphlosporonites Sheffy & Dilcher. Fossil fungal spores are known from all parts of the globe and in the sediments ranging from the Precambrian era to most recent age. Their distribution in time and space is presented. A comparison of the fossil fungal spores with extant taxa is also made and affinity of a good number of fossil genera and species could be traced with the extant genera or higher taxa. Palaeoenvironmental and stratigraphie implications of fungal spores are also discussed.