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Sarzetti L.C.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Genise J.F.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Sanchez M.V.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Farina J.L.,Museo Municipal de Ciencias Naturales Lorenzo Scaglia | Molina M.A.,CONICET
Journal of Hymenoptera Research

The nests of Cadeguala albopilosa (Spinola, 1851), Diphaglossa gayi Spinola, 1851, Ptiloglossa tarsata (Friese, 1900), Ptiloglossa matutina (Schrottky, 1904) and Zikanapis tucumana (Moure, 1945) (Colletidae, Diphaglossinae) from Argentina and Chile are described herein. They show similar features to those of other Diphaglossinae: they consist of a main tunnel, cells disposed radially, isolated or in pairs, and connected to the main tunnel by laterals ones. Main tunnels are mostly vertical in species nesting in soil surface but horizontal to inclined in D. gayi, which nests in banks. Cells are vertical with curved necks. The cells of C. albopilosa show less curved necks (less than 90°), whereas in the remaining four species the cell neck is highly curved (90° or more). Cells of P. tarsata have a spiral earthen closure and a wad cottonlike material, whereas in P. matutina only had the last one. In the remaining studied species any type of closure were found. Cocoons of C. albopilosa and P. tarsata are coriaceous showing a closure composed of three disks. Zikanapis tucumana and possibly P. matutina showed dim-light foraging. The remaining species are diurnal. The climate in their nesting sites is highly diverse, ranging from 8°C to 20°C in mean annual temperature, and from 250 mm to 3000 mm in mean annual precipitation. Only C. albopilosa and, to a lesser extent, Z. tucumana nested gregariously. Zikanapis tucumana and P. tarsata were observed visiting flowers of Solanum. Copyright Laura C. Sarzetti et al. Source

Genise J.F.,CONICET | Farina J.L.,Museo Municipal de Ciencias Naturales Lorenzo Scaglia

Quaternary (Ensenadan stage-age) deposits of the Miramar Formation from the Buenos Aires sea coast near Mar del Plata (Argentina) are well known for bearing long horizontal tunnels produced by xenarthrans, either ground sloths or armadillos. Little known is that, in some cases, these palaeocaves cross-cut social insect nests. Nests of two studied palaeocaves can be attributed to ants based on the presence of abundant ant remains, filling of chambers and organic-rich linings. Insect remains show part of a food web composed of army ants (Neivamyrmex) preying on leaf-cutting ants (Acromyrmex), Pheidole and other soil invertebrates. The other main component of this web is represented by the xenarthrans feeding on these ants. The facultative foraging function of xenarthran palaeocaves is supported by the common record of these extended horizontal tunnel systems similar to other subterranean foraging mammals, the presence of insect nests cross-cut by them and the extended myrmecophagy among xenarthrans. Xenarthran foraging burrows, despite their high-energy cost, would have been favoured by abundance of underground ant nests during Quaternary times and harsh climate. This climate would have produced the scarcity of insects on surface and longest periods of underground activity by xenarthrans, involving the extension of shelter burrows for adult and possibly juvenile feeding. □Ant fossil nests, Argentina, Buenos Aires, food web, Quaternary, xenarthran palaeocaves. © 2012 The Authors, Lethaia © 2012 The Lethaia Foundation. Source

Rodriguez C.S.,CONICET | Pujol M.G.,Museo Municipal de Ciencias Naturales Lorenzo Scaglia | Mianzan H.W.,CONICET | Mianzan H.W.,Instituto Nacional Of Investigacion Y Desarrollo Pesquero Inidep | Genzano G.N.,CONICET
Latin American Journal of Aquatic Research

In this paper we report the first finding of the hydromedusa Gonionemus vertens Agassiz, 1862 in the southern hemisphere. About 30 newly released medusae were found within an aquarium on September 2008. The aquarium contained benthic samples collected in intertidal and subtidal rocky fringe off Mar del Plata, near a commercially important harbor in Argentina. Medusae were fed with Artemia salina until sexual maturation. Possible way of species introduction is discussed. Source

Luzzatto D.C.,Institute Biologia Marina y Pesquera Almirante Storni | Luzzatto D.C.,CONICET | Sieira R.,CONICET | Pujol M.G.,Museo Municipal de Ciencias Naturales Lorenzo Scaglia | De Diaz Astarloa J.M.,CONICET

This study aimed at sequencing the mitochondrial cytochrome b gene (cyt b) of seahorses morphologically identified as Hippocampuspatagonicus Piacentino & Luzzatto, 2004 from the two known localities where the species occur in the Argentine Sea (San Antonio Oeste and Mar del Plata). Based on the lack of substitutions within cyt b found between the individuals of both localities, the geographical range of H. patagonicus was extended up to the Northern limit of the Argentine Sea. A phylogenetic analysis comparing the cyt b sequences of Hippocampus species revealed that H. patagonicus together with H. hippocampus and H. erectus belong to a monophyletic group of species. The comparison of the cyt b sequence of Hippocampus cf. erectus from Southern Brazil with that one of H- patagonicus resulted in scarce differences. This could suggest the presence of H, patagonicus in southern Brazil, although further investigation is needed to resolve the taxonomie status of H, erectus in the South Western Atlantic. Source

The coastal cliffs of Mar del Plata are of the more complete localities of the Southamerican Quaternary, with significant differences in the stratigraphy between the northern and southern flanks. The Plio-Pleistocene record is composed by an almost uniform sequence of coarse silt and very fine sand transported to the area by eolian processes although the last imprint denotes very characteristic fluvial processes. Chapadmalal Formation is located at the toe of these cliffs and is overlapped by an extended caliche level that is the base of the fluvial deposit recognized as Barranca de Los Lobos, Punta Vorohué and Punta San Andrés units. To the top, Miramar Formation shows an increase in the gravity-dominated phenomena and transport of caliche pebbles. During the upper Pleistocene, the accommodation space had diminished towards the southern flank while to the north there was plenty of accommodation space for the aggradation of meandering rivers and the infilling of shallow lakes. © 2015, Asociacion Geologica Argentina. All rights reserved. Source

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