Valvidistemon E. M. FRIIS, P. R. CRANE, K. R. PEDERSEN, M. M. MENDES et J. KVACEK 2022, gen. nov

Genus Valvidistemon E.M.FRIIS, P.R.CRANE, K.R.PEDERSEN, M.M.MENDES et J.KVAČEK gen. nov. T y p e. Valvidistemon globiferus E.M.FRIIS, P.R.CRANE, K.R.PEDERSEN, M.M.MENDES et J.KVAČEK gen. et sp. nov. P l a n t F o s s i l N a m e s R e g i s t r y N u m b e r. PFN0002794 (for new genus). E t y m o l o g y. From Greek valvida for valve and stemon for stamen. G e n e r i c d i a g n o s i s. Stamen small with a poorly differentiated base. Anther tetrasporangiate, dithecate. Dehiscence valvate by two laterally hinged vales over each theca. Connective between thecae massive. Apical extension of the connective prominent, only slightly shorter than the anther, globose, overhanging the thecae. Pollen small, semitectate-reticulate. C o m m e n t s o n t h e g e n u s. Similarstamenswith valvate dehiscence,laterally hinged valves, poor differentiation between stamen base and anther, and a prominent globose apical extension of the connective, are characteristic of several extant members of Annonaceae (e.g., Endress and Hufford 1989, Van Heusden 1992). Comparable stamens also occur in extinct and extant members of Platanaceae (Friis et al. 1988, Endress and Hufford 1989), but in Platanaceae the stamens have a distinct filament, and the pollen is tricolpate. The stamen is assigned here to a new genus. We are not aware of similar stamens that have been described in the fossil record and because information on other floral parts are missing detailed comparison with extant angiosperms is currently not possible.
Published as part of Friis, Else Marie, Crane, Peter R., Pedersen, Kaj Raunsgaard, Mendes, Mário Miguel & Kvaček, Jiří, 2022, The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms, pp. 341-424 in Fossil Imprint 78 (2) on page 379, DOI: 10.37520/fi.2022.016, http://zenodo.org/record/7522801
{"references":["Endress, P. K., Hufford, L. D. (1989): The diversity of stamen structures and dehiscence patterns among Magnoliidae. - Botanical Journal of the Linnean Society, 100: 45 - 85. https: // doi. org / 10.1111 / j. 1095 - 8339.1989. tb 01709. x","Van Heusden, E. C. H. (1992): Flowers of Annonaceae: morphology, classification, and evolution. - Blumea, Supplement, 7: 1 - 218.","Friis, E. M., Crane, P. R., Pedersen, K. R. (1988): Reproductive structure of Cretaceous Platanaceae. - Biologiske Skrifter, det Kongelige Danske Videnskabernes Selskab, 31: 1 - 56."]}