More Malpighiales: Woods of Achariaceae and/or Salicaceae from the Deccan Intertrappean beds, India

Abstract

The families Achariaceae and Salicaceae (Malpighiales) are characterized by wood anatomical ranges that partly overlap. Formerly these families were treated together in the polyphyletic Flacourtiaceae and a much more narrowly circumscribed Salicaceae. Here we attribute two recently collected fossil woods from the Deccan Intertrappean Beds to the clade that contain these two families, i.e., the Parietal Clade of the Malpighiales. The new genus Elioxylon shares features with several extant genera of Achariaceae and Salicaceae, but does not completely match with any of them. A new record of Hydnocarpoxylon indicum Bande & Khatri is a good match for extant Hydnocarpus Gaertn. (Achariaceae). Elioxylon and Hydnocarpoxylon share an absence of parenchyma, the presence of septate fibres and 1–3 seriate heterocellular rays with long uniseriate margins consistent with Achariaceae and Salicaceae. Elioxylon has mixed simple and scalariform perforations, whereas Hydnocarpxylon has exclusively scalariform perforations. Other Deccan fossils formerly attributed to “Flacourtiaceae” in the literature are critically discussed and mostly excluded from Achariaceae and Salicaceae. Elioxylon and Hydnocarpoxylon from the Maastrichtian ‐ Danian of India are the oldest fossil records of the Parietal Clade of the Malpighiales. With their occurrence on the Indian plate during its northward journey from Gondwana to Laurasia, these fossils provide further support for an ‘out‐of‐India’ hypothesis for Achariaceae and/or Salicaceae. “Baileyan trends” in vessel perforation plate and vessel grouping evolution are apparent in the phylogeny of the Parietal Clade.

First fossil woods and palm stems from the mid‐Paleocene of Myanmar and implications for biogeography and wood anatomy

“…There are other fossil woods that partly share some features with our fossil: (1) the Upper Cretaceous Big Bend Ericalean Wood Type I (Wheeler and Lehman, 2009), (2) the Eocene Nut Beds Xylotype IB-3 (Wheeler and Manchester, 2002), (3) the Eocene Nut Beds Xylotype IA-1, (4) one specimen of Page's classification Group IIIB3 (Page, 1979). Only three fossils with scalariform perforation plates are described from the Deccan intertraps (Wheeler et al, 2017), but they do not resemble our fossil because of opposite pitting, narrow rays, and rare parenchyma (Bande and Khatri, 1980;Srivastava et al, 2019). Overall, the combination of few bars per scalariform perforation plates and alternate intervessel pits features rarely occurs.…”

Ecological and Biogeographic Implications of Asian Cenozoic Fossil Floras

“…This finding is significant for understanding of the post-Neogene diversification of angiosperms in northwestern Yunnan mainly driven by environmental changes associated with uplift extension of the Tibetan Plateau. Srivastava et al (2019) augment their earlier review of numerous latest Cretaceous to Paleocene dicotyledonous woods of the Deccan Intertrappean beds of India (Wheeler et al, 2017) with renewed attention to representatives of the Parietal Clade of the Malpighiales. Based on wood anatomical characters, they recognize two new representatives: Elioxylon of uncertain modern affinities, and Hydnocarpoxylon indicum Bande & Khatri resembling modern Hydnocarpus Gaertn.…”

“…Srivastava et al () augment their earlier review of numerous latest Cretaceous to Paleocene dicotyledonous woods of the Deccan Intertrappean beds of India (Wheeler et al, ) with renewed attention to representatives of the Parietal Clade of the Malpighiales. Based on wood anatomical characters, they recognize two new representatives: Elioxylon of uncertain modern affinities, and Hydnocarpoxylon indicum Bande & Khatri resembling modern Hydnocarpus Gaertn.…”