Guillermo H. Omad

A new species of Bezzia Kieffer from Argentinean Patagonia (Diptera: Ceratopogonidae)

Abstract. Bezzia, galesa Spinelli, a new Patagonian species, is described in all stages and illustrated by using binocular, phase-contrast and scanning electron microscopy. Immatures were collected associated to submerged filamentous algae in an unnamed pond in western Chubut province, Argentina, and reared to adults in the laboratory. Adults and immatures of this new species are compared with the most similar species Bezzia ventanensis Spinelli, Bezzia, roldani Spinelli et Wirth and Bezzia blantoni Spinelli et Wirth. Details on the rearing process and feeding behavior in laboratory are given.

Descriptions of Pupae of Three Psychodinae Species (Diptera: Psychodidae) from Argentina

Abstract. The pupae of Alepia montana Bravo, Alepia truncata Bravo, Lago et Castro and Psychoda simillima Tonnoir, belonging to the subfamily Psychodinae, are described and illustrated. The pupae of A. montana and A. truncata were collected in tree holes in the city of San Ramón de la Nueva Orán, Province of Salta and the pupa of P. simillima in small pool on the nameless stream near El Hoyo city, Province of Chubut, Argentina. The pupa of P. simillima is similar to other pupae of the genus Psychoda Latreille, being distinguished by some features in the last segment and by respiratory trumpet. These are the first pupae described of any species of the genus Alepia Enderlein.

Biotic diversity of benthic macroinvertebrates at contrasting glacier-fed systems in Patagonia Mountains: The role of environmental heterogeneity facing global warming

Patagonia is by far the largest glacierized area in South America. However, little is known about ecology, functioning and biodiversity of glacier-fed streams facing global warming. We investigated changes in environmental features and macroinvertebrate communities along a longitudinal gradient of glacier influence of two Patagonian systems that differ in glacier cover magnitude and the spatial sequence of lotic and lentic phases. Both glaciers, Torrecillas (~5.5km2, Torrecillas system) and Cónico (~0.44km2, Baggilt system), are retreating. Longitudinal distribution of benthic invertebrates partially fitted to predictions for glacierized temperate systems, with Diamesinae spp. dominating at closest sites to the Cónico, and Orthocladiinae increasing downstream, but patterns were unclear at Torrecillas. Generalized Linear Model identified chlorophyll a and conductivity as having significant effect on richness and density respectively at Torrecillas; detritus biomass and gravel influenced species richness, and boulder percentage and water temperature affected density, at Baggilt. Canonical Correspondence Analyses integrating benthic biota and environmental variables revealed that a higher environmental heterogeneity at Baggilt, related with spatial dimension (unshaded/shaded reaches, wetland reaches), local resources (detritus, bryophytes) and temperature, probably explained the unexpected high richness in benthic assemblages (67 taxa). Environmental conditions imposed by the lake outlet (proglacial) at Torrecillas resulted in a less diverse community (31 taxa). Finally our results suggest that these isolated, small glacier-fed streams typical of the Patagonian landscape appear highly vulnerable to global warming. Endemic elements could disappear at upper segments being replaced by other species common at rhithral environments, which might increase local diversity (alfa diversity) but decrease regional diversity (gamma diversity). From an ecosystem perspective stream functioning can result altered. Glacier retreating or disappearing threatens major ecosystem services for Patagonian inhabitants such as water supply, hydrological regulation, recreation and tourism.

Selective Foraging by Non-native Rainbow Trout on Invertebrates in Patagonian Streams in Argentina

BackgroundIt is well known that fish predation alters ecosystem processes by top-down effects. Salmonids are described as aggressive, visually and size-selective predators. Thus, prey selection by the non-native rainbow trout was examined on a seasonal basis at two streams: Nant y Fall (NyF) and Cabeza de Vaca (CVA) at Patagonia, a region where this kind of information is lacking.ResultsThe benthos density at NyF was higher than that at CVA, and at both streams, riffles supported higher macroinvertebrate densities than pools. The diet of trouts from both streams was dominated by aquatic macroinvertebrates, was diverse, and was varied seasonally. The individuals represented in the stomach contents were among the largest available at the streams. Diet diversity peaked during spring at NyF and during summer at CVA, whereas at both streams, the niche width peaked during spring.Prey selectivity varied seasonally. The selected preys included both aquatic (Gasteropoda, Crustacea, Plecoptera, Trichoptera, Ephemeroptera, Coleoptera, Diptera, and Odonata) and terrestrial organisms (adult dipterans, Oligochaeta, Araneae, Homoptera, Hymenoptera, Orthoptera, and Hemiptera). Some infaunal invertebrates like oligochaetes and some small Coleoptera and Diptera larvae (mainly Chironomidae) were not selected by trouts.ConclusionsDespite of the overall dominance of trichopteran species, the composition of the diet of the rainbow trout varied seasonally. This fish positively selected both aquatic and terrestrial organisms. We observed that in both streams, trouts consumed the larger individuals available in those environments.

A new species of Mycomya Rondani (Diptera, Mycetophilidae, Mycomyinae) from Argentinean Patagonia

Mycomya bowiei n. sp. is described based on male and female specimens from Argentinean Patagonia. Additionally, we provide a redescription of Mycomya bifida Freman (1951) and new records of three species of Mycomya previously unrecorded from either Chubut Province or Argentina.

New genus of Psychodinae (Diptera, Psychodidae) from Argentina

Adults (male and female) and pupae of Chuspilepia saltenia gen. nov., sp. nov. were collected in tree holes in the Yungas rainforest, near San Ramon de la Nueva Oran city, Salta province, Argentina. It was not possible to place this new species in any known genera using the available keys and published descriptions, thus a new genus is proposed for the Neotropical region of Argentina.