Revision of the subfamily Pitarinae Stewart, 1930 (Eucallista Dall, 1902; Austrocallista Erdmann & Morra, 1985; Proteopitar gen. nov.) from Cenozoic southern South America: systematic and phylogenetic analyses

posted on 22.07.2019 by Maximiliano Jorge Alvarez, Claudia Julia del Río, Sergio Martínez

Systematic and phylogenetic analyses of fossil and extant Pitarinae of the South-Western Atlantic Ocean and Chile have been performed. The group is represented by Eucallista Dall, 1902 (early Miocene–Recent), Austrocallista Erdmann & Morra, 1985 (Eocene–Pliocene) and Proteopitar gen. nov. (middle Miocene–Recent). Eucallista and Austrocallista have sculptured nymphs and include species previously assigned to Amiantis Carpenter, 1864. Eucallista is represented by three species: the extant E. purpurata (Lamarck, 1818) (Pleistocene–Recent, South-Western Atlantic Ocean from Golfo San Matías [Argentina] to Espirito Santo [Brazil]) and two fossil taxa, E. laziarina (Ihering, 1907) from the Miocene and Pliocene of Chile, Argentina and Uruguay, and E. domeykoana (Philippi, 1887) from the Miocene and Pliocene of Chile and Peru. Austrocallista has four taxa: Austrocallista sp. from the Eocene of Santa Cruz Province, A. iheringi (Cossmann, 1898) from the late Oligocene–middle Miocene of Patagonia, A. australis (Feruglio, 1935) (lectotype MGGC 607) from the early Miocene of Santa Cruz Province, and A. boliviana (Philippi, 1887) from the Miocene and Pliocene of Chile and Peru. Proteopitar gen. nov. is erected to incorporate two species previously assigned to Pitar Römer, 1857: Proteopitar mutabilis (del Río & Martínez, 1998) from the middle Miocene–late Miocene of Argentina and the Pleistocene–Recent species Proteopitar patagonicus (d’Orbigny, 1835–1847) (from Rio de Janeiro [Brazil] to Bahía Vera [Chubut, Argentina]). These systematic hypotheses are corroborated by the phylogenetic analysis performed, which is the first one of the subfamily that includes fossil and extant taxa based on morphological characters of the shell. In addition, a new site on the coast of Río Negro Province which contains shells of the extant species is dated as 830 Ka BP (MIS21), being the oldest record of both extant species.