Abstract

HERBST, Rafael  and  CRISAFULLI, Alexandra. Buckya austroamericana nov. gen. et sp. (Bennettitales) from the Upper Triassic Laguna Colorada Formation (El Tranquilo Group), Santa Cruz province, Argentina. Ser. correl. geol. [online]. 2016, vol.32, n.2, pp.1-10. ISSN 1666-9479.

A new genus and species of a bennettitalean trunk from the Upper Triassic of Santa Cruz pro-vince, Argentina, is described. Buckya austroamericana is based on a specimen with its internal anatomy: monoxylic trunk including pith with secretory, sclerenchymatic and mucilaginous cells; primary xylem endarch with scalariform thickened tracheids; secondary xylem with circular bordered pits, uni- and biseriate rays. Poorly preserved secondary phloem. Cortex with parenchyma cells, abundant secretory cells, mucilagenous sacs and isolated sclerenchyma bands. Externally, leaf bases and/or foliar scars correspond to those of Bucklandia Presl (in Sternberg). The validity of this generic name is analyzed for specimens with preserved anatomy, as it was erected for trunks showing only external morphology (branch traces and/or foliar bases). It is concluded that the name should be conserved for the last type of fossils; as a consequence, a new genus is necessary for specimens preserving internal anatomy. For this purpose, the new genus Buckya is proposed and several species are transferred to it. Buckya nov. gen. is a worldwide known cosmopolitan genus from the Jurassic and Cretaceous but species of Bucklandia (sensu this work) are also known from the Triassic; fronds usually ascribed to bennettites such as Pterophyllum Brongniart, Pseudoctenis Seward, Anomozamites Schimper, among others are also frequent in the Gondwana Triassic. The closest species to B. austroamericana are Bucklandia kerae Saiki and Yoshida from the Cretaceous of Japan and Bucklandia indica Seward from the Jurassic of India (both here transferred to Buckya) but they differ in several aspects, some of them showing primitive features.

Keywords : Bennettitales. Trunks. Anatomy. Upper Triassic. Argentina..

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