Resumen

BELTRAN, Marisol; BODNAR, Josefina  y  COTUREL, Eliana Paula. Lycopodites (Lycopodiidae, Lycopodiales): un nuevo integrante de las floras triásicas de la Argentina. Rev. Mus. Argent. Cienc. Nat. [online]. 2018, vol.20, n.2, pp.205-216. ISSN 1853-0400.

The record of Mesozoic lycophytes from Argentina is scarce, for this reason the finding of new samples is significant for the knowledge of the fossil biodiversity. In this contribution, stems of herbaceous lycophytes coming from Barreal Formation (Anisian, Middle Triassic, San Juan Province) and Potrerillos Formation (Carnian, Upper Triassic, Mendoza Province) are described. The fossil from Barreal is a fragment of a delicate dichotomous stem, covered by helically arranged microphylls, of which only the basal zone was preserved. The microphyll bases are rhomboidal, with straight to slightly concave margins, of uniform size, and have a central leaf scar of circular to ovate shape, inside of which the vascular bundle scar is observed. The Potrerillos specimen corresponds to a delicate dichotomous stem covered by isophyllous microphylls, elliptical, adpressed, helically arranged. Both samples are assigned to the genus Lycopodites due to their size, the type of phyllotaxis, the absence of ligule and the microphyll morphology, but they are not related to a species entity as a consequence of the scarce preserved material. Within the herbaceous lycophytes, the studied fossils show greater affinity to the Lycopodiales, since they exhibit isophyllous axes. This work constitutes the first description of the genus Lycopodites in Argentina and the first record for the Triassic of South America. Their occurrence would indicate high moisture local conditions, and would coincide with the regional paleoclimatic interpretations which propose a humidity increase in the lapses Anisian-early Ladinian and Carnian.

Palabras clave : Herbaceous lycophytes; Mesozoic; Barreal Formation; Potrerillos Formation.