Neoichnological studies on Diphaglossinae (Hymenoptera, Colletidae): tracking the origin of fossil bent cells (Celliforma isp nov.)

SARZETTI, L. C.; GENISE, J. F.; SANCHEZ, M. V.; FARINA, J. L

Sao Leopoldo, Brasil

Simposio; Simposio Latinoamericano de Icnología; 2010

All the ichnospecies of Celliforma described until now show a straight longitudinal axis. However, a new ichnospecies of Celliforma, showing the upper part bent, was found in the Collón Curá Formation (Middle Miocene) at two localities in Argentina: El Petiso (Chubut province) and Pilcaniyeu (Río Negro province), Argentina. Strongly bent cells (more than 90º) are known from former studies on species of North American Diphaglossinae (Ptiloglossa), whereas the knowledge on South American representatives is scarce and doubtful. In any case bent cells could be considered a synapomorphy of Diphaglossinae, and different angles of inclination of the upper part of cells seem to be attributable to species of different genera. An optimization of this character on Diphaglossinae phylogeny cannot be accomplished because of the confusion involving previous unreliable observations on the South American species. Accordingly, new neoichnological studies of South American Diphaglossinae were undertaken to track the origin and evolution of this character and the phylogenetic importance of the curved Celliforma. The studies were conducted at different localities in Argentina and Chile: Vinchina and Anillaco in La Rioja Province (Zikanapis tucumana), PN Los Alerces in Chubut Province (Cadeguala albopilosa), Puente Río Negro and Futaleufú in Los Lagos Region (Diphaglossa gayi). The cells of these three species show upper parts curved less than 90 degrees, as the fossil ones, in contrast with those of the North American Ptiloglossa.The nests of Z. tucumana showed 1-2 cells, whose vertical part was 20 mm long and 10 mm wide. The ones of C. albopilosa showed 2-4 cells, 11 mm long and 7 mm wide. D. gayi construct 4-5 cells per nest, 25 mm long and 10 mm wide. Therefore, ichnologic evidence suggests that ancestors of these South American Diphaglossinae inhabited northern extrandean Patagonia about 15 million years ago.