Revised classification and evolution of leucotrichiine microcaddisflies (Trichoptera: Hydroptilidae) based on morphological and molecular data

Hydroptilidae constitute the most diverse caddisfly family, with over 2000 species known from every habitable continent. Leucotrichiinae are exclusively New World microcaddisflies, currently including over 200 species and 17 genera. Phylogenetic analyses of Leucotrichiinae relationships based on 114 morphological characters and 2451 molecular characters from DNA sequences were conducted. DNA sequences analysed were from one mitochondrial gene, cytochrome oxidase I (653 bp), and four nuclear genes, carbamoylphosphate synthase (802 bp), elongation factor 1α (352 bp), histone 3 (308 bp) and 28S rDNA (336 bp). The morphological matrix included 94 taxa (with representatives of all included genera) and the molecular matrix included 62 taxa. Individual and combined datasets were analysed under parsimony and Bayesian inference. In addition, a relaxed molecular clock divergence time estimate was conducted to determine the age of the subfamily and major lineages. All Bayesian inference analyses strongly suggest a monophyletic Leucotrichiinae, which initially diverged at approximately 124 Ma into two monophyletic groups of genera. These groups are herein elevated to tribal status, Alisotrichiini trib.n. and Leucotrichiini Flint sensu n. Several genera of Leucotrichiini were not recovered as monophyletic clades and some nomenclatural changes are proposed to reflect their phylogenetic history. These include the synonymy of Abtrichia with Peltopsyche; transfer of Betrichia hamulifera to Costatrichia; transfer of Betrichia alibrachia and Costatrichia falsa to Leucotrichia; and transfer of Costatrichia fluminensis to Acostatrichia. Additionally, Tupiniquintrichia gen.n. is described to include Peltopsyche maclachlani and Leucotrichia procera. According to our results, crown diversifications of both Alisotrichiini trib.n. (～80 Ma) and Leucotrichiini sensu n. (～103 Ma) occurred after complete separation of South America from Africa. Current distributions of most leucotrichiine genera are probably a result of migration from South America towards the north using the proto‐Caribbean archipelago (100 to 49 Ma). This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:FB6A3385-323D-41AF-B4BE-E19A393A493C .     

Sap salinity effects on xylem conductivity in two mangrove species

Xylem sap salinity and conductivity were examined in two mangrove ecosystem tree species . For Avicennia germinans , extracted xylem sap osmotic potentials ranged from −0.24 to −1.36 MPa versus −0.14 to −0.56 MPa for Conocarpus erectus. Xylem sap of Conocarpus did not vary in osmotic potential between sites nor between predawn and midday. In Avicennia , values were more negative at midday than predawn, and also more negative at hypersaline than hyposaline sites. After removing embolisms, specific conductivity ( K _s) was measured as a function of salinity of the artificial xylem sap perfusion. For both species the lowest K _s values, about 70% of the maximum K _s, were obtained when stems were perfused with deionized water (0 m m ; 0.0 MPa) or with a 557-m m saline solution (−2.4 MPa). Higher K _s values were obtained in the range from −0.3 to −1.2 MPa, with a peak at −0.82 ± 0.08 MPa for Avicennia and −0.75 ± 0.08 MPa for Conocarpus . The variations in K _s values with minima both at very low and very high salt concentrations were consistent with published results for swelling and shrinking of synthetic hydrogels, suggesting native hydrogels in pit membranes of vessels could help regulate conductivity.     

Effect of Phosphatidylcholine on Acrosome Breakdown and Fertilizing Capacity of Amphibian Spermatozoa

The effect of vesicles of purified egg yolk phosphatidylcholine on the fertilizing capacity and acrosome breakdown of amphibian spermatozoa was studied. When Bufo arenarum spermatozoa were incubated with either small unilamellar vesicles (prepared by sonication) or with large unilamellar vesicles (prepared by reverse-phase evaporation) a decrease in the fertilizing capacity of spermatozoa was found. At the same phosphatidylcholine concentration, large unilamellar vesicles were more inhibitory than small unilamellar vesicles. The inhibition was dependent upon the phospholipid concentration and the length of the incubation period. Small unilamellar vesicles did not modify the time course of acrosome breakdown in Leptodactylus chaquensis , while large unilamellar vesicles markedly accelerated the rate of acrosome breakdown. In both biossays, the charge of the vesicles (made either positive or negative by the addition of 5% stearylamine or 5% phosphatidic acid) did not influence their biological effect. Multilamellar vesicles did not alter the fertilizing capacity nor the acrosome breakdown. We conclude that the size and the structure of the vesicles are important parameters in determining the inhibitory capacity of phosphatidyl choline on amphibian fertilization.     

A NEW WIDE-GAUGE SAUROPOD TRACK SITE FROM THE LATE CRETACEOUS OF MENDOZA, NEUQUÉN BASIN, ARGENTINA

Abstract:  Agua del Choique is a new Late Cretaceous sauropod track site from Mendoza Province, Neuquén Basin, Argentina. It is situated in the Loncoche Formation, late Campanian – early Maastrichthian in age, and is one of the youngest sauropod tracks site recorded in the world. Agua del Choique represents a lake setting and river-dominated delta deposits, and comprises at least 160 well-preserved tracks, located on a calcareous sandstone bed. A new ichnotaxon, Titanopodus  mendozensis ichnogen. et ichnosp. nov., is erected for the footprints of this track site. Titanopodus  mendozensis exhibits the following association of features: (1) wide-gauge trackway (manus and pes trackway ratios of 18–22 and 26–31 per cent respectively), (2) pronounced heteropody (manus-pes area ratio of 1:3), (3) outer limits of trackway defined, in some cases, by the manus tracks, and (4) manus impression with an asymmetrical crescent contour and acuminate external border. Titanopodus  mendozensis is an excellent case study of the wide-gauge style of locomotion produced by Late Cretaceous derived titanosaurs that have no impression of manual phalanges. These features, and the fossil record from the Loncoche Formation, suggest that the trackmakers were, probably, middle size saltasaurine or aeolosaurine titanosaurs (14–16 m long).     

Ecohydrological effects of grazing‐induced degradation in the Patagonian Monte,Argentina

Water‐limited ecosystems have undergone rapid change as a consequence of changing land use and climate. The consequences of these changes on soil quality and vegetation dynamics have been documented in different regions of the world. In contrast, their effects on soil water, the most limiting resource in these environments, have received less attention, although in recent years increasing efforts have been made to relate grazing, soil water and vegetation functioning. In this paper, we present the results of field observations of plant phenology and soil water content carried out during two successive years at four sites along a degradation gradient caused by grazing in the Patagonian Monte, Argentina. We also developed a simplified soil water balance model to evaluate how changes in plant cover could affect water balance. Our field observations showed that the soil water content in the soil layer where roots of grasses are abundant (0–25 cm) was higher and the growing cycles were longer in degraded than in preserved sites. Similarly, our modelling approach showed that the deep soil (depth > 10 cm) was wetter in the degraded than in the preserved situation. Simulation also suggested a switch from transpiration to a direct evaporation dominance of water losses with degradation. Although reductions in plant cover related to grazing degradation were associated with a decrease in annual transpiration, the simulated soil water loss by transpiration was higher during summer in the degraded than in the well preserved situation. Thus, our field observations seem to be a consequence of ecohydrological changes causing an accumulation of water in the soil profile during the cold season and its transpiration during summer. In conclusion, our results showed that changes in plant cover caused by grazing disturbance can alter the soil water balance, which in turn can affect vegetation function.     

What causes changes in plant litter quality and quantity as consequence of grazing in the Patagonian Monte: Plant cover reduction or changes in species composition?

In Patagonian Monte, as in other arid ecosystems, grazing has triggered changes in vegetation and soil such as plant cover reduction, changes in species composition and soil nutrient losses. Several mechanisms were proposed interconnecting these changes, but evidence supporting them is very scarce. On the basis of published data concerning plant cover by species along grazing gradients and leaf litter production of dominant species, we estimated the effects of grazing on a – quality (N, soluble phenolics and lignin concentrations) and b – quantity (leaf litterfall (LLF) and inputs of nitrogen, soluble phenolics and lignin to the soil) of leaf litter in the Patagonian Monte, discriminating the effect of plant cover reduction from that of species composition. We also evaluated the relationship between senesced leaves traits and the response of species to grazing (i.e. their relative change in plant cover). Grazing causes a reduction in LLF and in the inputs of nitrogen, soluble phenolics and lignin to the soil. In the case of LLF, this reduction was not only a result of the decrease in plant cover but also due to changes in species composition. In contrast, our results showed that the reduction in nitrogen, soluble phenolics and lignin inputs to the soil by LLF is only a consequence of plant cover reduction. Additionally, litter quality was affected through increasing concentration of N and secondary compounds (soluble phenolics and lignin). N and soluble phenolics concentration on senesced leaves were positively related to the response of species to grazing, suggesting that other factors instead of N are relevant to sheep foraging decisions.     

Petenaeaceae,a new angiosperm family in Huerteales with a distant relationship to Gerrardina (Gerrardinaceae)

Petenaea cordata (from northern Central America) was first described in Elaeocarpaceae and later placed in Tiliaceae, but most authors have been uncertain about its familial affinities. It was considered a taxon incertae sedis in the Angiosperm Phylogeny Group classification (APG III). A recent collection was made in Guatemala, and analysis of both rbcL and atpB in the large Soltis et al. angiosperm matrix, the most completely sampled study published to date, indicated a moderately supported relationship to Tapiscia (Tapisciaceae, the only member of the newly recognized order Huerteales in this matrix; 81% bootstrap support). We then conducted a more restricted analysis using the Bayer et al. rbcL/atpB matrix for Malvales supplemented with the other genera of Huerteales from published studies. Our results indicate a distant, weakly supported sister‐group relationship to the African genus Gerrardina (Gerrardinaceae; Huerteales). After comparison of the characters cited in the literature and an examination of herbarium material of both genera, we could find no obvious synapomorphies for Gerrardina and Petenaea or any other relationship of the latter, and we therefore propose the new monogeneric family, Petenaeaceae. The polymorphic order Huerteales now comprises four small families: Dipentodontaceae, Gerrardinaceae, Petenaeaceae and Tapisciaceae. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 16–25.