INSTITUTO DE LIMNOLOGIA "DR. RAUL A. RINGUELET"
Unidad Ejecutora - UE
ODONATAN ENDOPHYTIC OVIPOSITION FROM THE EOCENE OF PATAGONIA: THE ICHNOGENUS PALEOOVOIDUS AND IMPLICATIONS FOR BEHAVIORAL STASIS
LAURA C. SARZETTI; CONRAD C. LABANDEIRA; JAVIER MUZON; PETER WILF; RUBEN CUNEO; KIRK R. JOHNSON; JORGE F. GENISE
JOURNAL OF PALEONTOLOGY
PALEONTOLOGICAL SOC INC
Año: 2009 vol. 83 p. 431 - 431
ABSTRACTWe document evidence of endophytic oviposition on fossil compression/impression leaves from the early Eocene Laguna del Hunco and middle Eocene Rı´o Pichileufu´ floras of Patagonia, Argentina. Based on distinctive morphologies and damage patterns of elongate, ovoid, lens-, or teardrop-shaped scars in the leaves, we assign this insect damage to the ichnogenus Paleoovoidus, consisting of an existing ichnospecies, P. rectus, and two new ichnospecies, P. arcuatum and P. bifurcatus. In P. rectus, the scars are characteristically arranged in linear rows along the midvein; in P. bifurcatus, scars are distributed in double rows along the midvein and parallel to secondary veins; and in P. arcuatum, scars are deployed in rectilinear and arcuate rows. In some cases, the narrow, angulate end of individual scars bear a darkened region ncompassing a circular hole or similar feature indicating ovipositor tissue penetration. A comparison to the structure and surface pattern of modern ovipositional damage on dicotyledonous leaves suggests considerable similarity to certain zygopteran Odonata. Specifically, members of the Lestidae probably produced P. rectus and P. bifurcatus, whereas species of Coenagrionidae were responsible for P. arcuatum. Both Patagonian localities represent an elevated diversity of potential fern, gymnosperm, and especially angiosperm hosts, the targets of all observed oviposition. However, we did not detect targeting of particular plant families. Our results indicate behavioral stasis for the three ovipositional patterns for at least 50 million years. Nevertheless, synonymy of these oviposition patterns with mid- Mesozoic ichnospecies indicates older origins for these distinctive modes of oviposition.