EONOTOSPERMA ARRONDOI CÉSARI GEN. ET SP. NOV., A PTERIDOSPERM FROM THE EARLY CARBONIFEROUS OF ARGENTINA

Abstract

A new genus and species of fertile organ in organic connection with foliage from Early Carboniferous sediments of Argentina is described. The specimen displays single preovule-like structures borne tennina!ly on a forked branch system in the place of a normal pinnule, with both sterile and fertile pinnules produced on the same pinna. The ovules are 0.7 cm long and consist of a whorl of 5-6 sterile lobes that are fused only at the base. Dista!ly, the lobes flare outward or remain straight. While the ovules are externally similar to Genomosperma Long, the rachial fragment resembles the form genus Diplothmema Stur. Although the sterile foliage in Argentina has been described as D. bodenbenderi (Kurtz) Césari, a similar foliage type occurs in the early Late Carboniferous of Peru, but in association with a different type of preovule. As this suggests D. bodenbenderi-type foliage bore different ovules and possibly represents a number of different taxa. Eonotosperma arrondoi gen. et sp. nov. is proposed here for the fertile material from the Lower Carboniferous of Argentina and its frond is described. Eonotosperma arrondoi now represents the oldest and southemmost occurrence of early seed plant fertile remains in westem Gondwana, and adds to our knowledge of ovule attachment in early pteridosperms.