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Winged Fruits of Linnaeeae (Caprifoliaceae) in the Tertiary of Western North America: Diplodipelta gen. nov.

1995; University of Chicago Press; Volume: 156; Issue: 5 Linguagem: Inglês

10.1086/297293

1537-5315

Steven R. Manchester, Michael J. Donoghue,

Plant and Fungal Species Descriptions

Recent phylogenetic analyses of the Caprifoliaceae and related families have paved the way for critical study and interpretation of the fossil record. A new extinct genus, Diplodipelta, is established on the basis of winged fruits from the Eocene, Oligocene, and Miocene of western North America, with two species: Diplodipelta reniptera (Becker) comb. nov. and D. miocenica (Berry) comb. nov. Although formerly attributed to Ptelea and Dodonaea, detailed comparative studies demonstrate that the fossils actually represent the Caprifoliaceae, tribe Linnaeeae, on the basis of elongate, indehiscent, longitudinally ribbed fruits with a sterile apical neck and persistent, epigynous calyces, and "supernumerary bracts." The samaroid dispersal units resemble those of extant Dipelta because the bracts are enlarged into wings that function in wind dispersal. However, Diplodipelta differs from Dipelta by the presence of a pair of fruits, rather than just one fruit, per dispersal unit, by the adnation of lateral wings to the peduncle, and by a peculiar transverse folding of the median wing. On the basis of available characters, Diplodipelta appears to be the sister group to Dipelta The stratigraphic record of Diplodipelta, together with the occurrence of genuine Dipelta fruits in the late Eocene of England, indicates that the divergence of these genera occurred during or prior to the late Eocene. The fossil record of Caprifoliaceae is reviewed, and previous reports of fossil Abelia fruits are discounted.