A NEW SPECIES OF GENUS ALICHOVIA GORJANSKY FROM THE PONÓN TREHUÉ FORMATION, MENDOZA PROVINCE, ARGENTINA

LAVIÉ, FERNANDO J.

Congreso; Reunión de Comunicaciones de la Asociación Paleontológica Argentina; 2018

The Ponón Trehué Formation is a sedimentary succession recognized in the San Rafael Block in Mendoza Province. It is composed entirely bycarbonate rocks such as sparitic dolomites, microbialitic limestones and nodular limestones at the base and middle part of the unit, while levels ofpackstone/grainstone intercalated with mudstone/wackestone characterize the upper part. Recently, a high diverse fauna of linguliform brachiopods ofthe orders Lingulida, Acrotretida, Paterinida and Siphonotretida was described by Holmer, Popov, Lehnert and Ghodabi Pour. The last order mainlycharacterized by valves with different arrangement of hollow spines and larval and postlarval shell lacking pitted microornamentation. The onlymaterial described by these authors that belongs to the siphonotertids was assigned with doubts to Multispinula Rowell. Besides finding a similarfauna in new samples analyzed, a new species of Alichovia is here proposed, being its diagnostic character the presence of bifurcated(ramispinose) spines. Alichovia n. sp. is characterized by a concave shell with spaced concentric lamellae, bearing fine spines in the edges,alternating with thicker multibifurcated spines. Originally, this genus was reported from Baltica (Lower Ordovician of Poland and Middle Ordovicianof Estonia and Czech Republic) and later in the eastern margin of Gondwana (Middle Ordovician of Iran). This new species represents the firstrecord of this striking genus in the western margin of Gondwana in the Middle Ordovician