Morphological re-evaluation of Callumispora Bharadwaj & Srivastava 1969 and Punctatisporites Ibrahim 1933 emend. Potonié & Kremp 1954 and their taxonomic implications

Abstract

The taxonomic status of the late Paleozoic morphogenus Callumispora Bharadwaj & Srivastava is reviewed to validate the long pending debate regarding its congeneric link to Punctatisporites Ibrahim, emend. Potonié & Kremp. As on record, 25 species of both Punctatisporites (13) and Callumispora (12) were described by Indian workers. In this study, available holotypes and paratypes, along with original illustrations and diagnoses, were re-examined, and images were captured both under an optical light microscope and a Confocal Laser Scanning Microscope. New material collected from the Damodar Basin (east India) and Wardha Basin (central India) were macerated and specimens illustrated with a Scanning Electron Microscope and compared with images of Punctatisporites documented in South America and Callumispora specimens from India. The five main morphological features which formed the main criteria to distinguish the two genera were re-evaluated viz., amb, size, haptotypic structure, exine thickness and exine structure. The critical re-analysis revealed that Punctatisporites and Callumsipora both possess circular to subcircular amb, their exine varies from laevigate to infrapunctate, their size ranges from 24 to 140 µm, the length of the trilete ray ranges from ½ to ¾ th the spore radius or more, the thickness of the exine also ranges from 1 to 6 µm. Based on all morphological similarities, it is evident that Punctatisporites and Callumispora are congeneric, Callumispora being junior synonym of Punctatisporites by taxonomic rule of priority. This synonymization avoids the superfluous proliferation of taxon names that prevent biostratigraphic correlations and paleobiogeographic analyses.