A new addition to the Patagonian Ceratopetalum five-winged fossil fruit family

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Museomic approaches are employed in order to establish an evolutionary, palaeoecological, and biogeographic context for radially symmetrical, five-winged fossil fruits from the highly diverse early Eocene Laguna del Hunco flora of Chubut Province. Gandolfo and Hermsen draw comparisons with other fossil and modern fruits and describe the new species Ceratopetalum edgardo-romeroi (Cunoniaceae).

Ceratopetalum edgardoromeroi Gandolfo and Hermsen, sp. nov.
Ceratopetalum edgardoromeroi Gandolfo and Hermsen, sp. nov. (A) Overall view of the holotype showing the five wings and the circular central region with nectary and semi-inferior ovary. MPEF-Pb 5085a. Scale bar = 10 mm. (B) Detail of the central region showing the nectary and radiating veins (arrows show examples). MPEF-Pb 5085a. Scale bar = 2 mm. (C) Overall view of the specimen showing three complete or nearly complete wings and two wing bases, prominent nectary, central styles marking the position of the ovary and inter-wing veins (IWV). MPEF-Pb 5086b. Scale bar = 5 mm. (D) Detail of fruit wing showing three primary veins emerging from the central region and branching distally to form a reticulum of minor veins. MPEF-Pb 5086a. Scale bar = 5 mm. (E) Detail of the circular central region showing ends of radiating veins (RV), inter-wing veins (IWV), intersections of the inter-wing and radiating veins (I) and well-preserved encircling vein (EV) crossing beneath a wing. Styles (ST) are visible in the centre of the nectary. MPEF-Pb 5086b. Scale bar = 5 mm.

In addition to sharing several characteristics, such as symmetry, number of fruit wings and presence of a conspicuous floral nectary, which unequivocally place this new fossil species within the genus Ceratopetalum, the venation pattern of the minor fruit wings (sepals) is unique within the genus and diagnostically heralds the new species. C. edgardo-romeroi is the oldest known and only record of Ceratopetalum outside Australasia, and the discovery of this species further documents the biogeographic connection between Patagonia and Australasia.

Reference

Gandolfo, M. A., & Hermsen, E. J. (2017). Ceratopetalum (Cunoniaceae) fruits of Australasian affinity from the early Eocene Laguna del Hunco flora, Patagonia, Argentina. Annals of Botany, mcw283. https://doi.org/10.1093/aob/mcw283


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