INSECT GALLS ON TRIASSIC PTERIDOSPERMS FROM THE QUEBRADA DE LOS FÓSILES FORMATION (PUESTO VIEJO GROUP, MENDOZA, ARGENTINA) AND THEIR PALEOENVIRONMENTAL IMPLICATIONS

CARIGLINO, BÁRBARA; ZAVATTIERI, ANA MARÍA; LARA, MARÍA BELÉN

Buenos Aires

Otro; I Reunión Virtual de Comunicaciones de la Asociación Paleontológica Argentina; 2020

Asociación Paleontológica Argentina

Galls are abnormal outgrowths of the plant?s tissue in reaction to an external stimulus, usually caused by viruses, fungi, parasites, mites or insects, among others. Most commonly, galls found on leaves are induced by the activity of an insect to provide food and/or shelter for their offspring. Here, we present evidence of galling on the leaves of the pteridosperm Ptilozamites longifolia from the Middle Triassic Quebrada de los Fósiles Formation, lower unit of the Puesto Viejo Group (Mendoza). The galls consist of slightly bulging structures placed one per leaf, ellipsoidal to circular in shape, sometimes with a thick, hardened outer wall surrounding the inner tissue, or completely fusinized. Functioning as a protective micro-habitat for the insects, galls are frequently found in ecologically disturbed environments. The Quebrada de los Fósiles Formation flora grew and deposited under intense volcanic activity. The ash-fall probably created stressful conditions for the biota, therefore favoring the inducement of galls by some insect clades. Despite galls from Triassic units have been extensively documented worldwide (e.g., Brazil, South Africa, Australia, India, Italy), these are the first evidences from this Period in Argentinean outcrops, emphasizing the need of new analyses of the paleofloras with a focus on plant-arthropod interactions.