Axel O. Bachmann

Distributional patterns of Chacoan water bugs (Heteroptera: Belostomatidae, Corixidae, Micronectidae, and Gerridae)

Distributional patterns of South American species of aquatic and semiaquatic Heteroptera from the Chaco biogeographic province were analyzed. Based on a track analysis of 60 species of Belostomatidae, Corixidae, Micronectidae, and Gerridae, five generalized tracks were found:(1) Bolivia, and northwestern and central Argentina (Belostoma dallasi, Ectemnostega montana, E. quechua, E. stridulata, E. venturii, Sigara tucma, S. yala, Tenagobia pulchra, Eurygerris fuscinervis, and Trepobates taylori); (2) southern Brazil, eastern Bolivia, Paraguay, and northeastern Argentina (Belostoma bosqi, Heterocorixa brasiliensis, Tenagobia selecta tarahui, and T. schadei); (3) southeastern Brazil and northeastern Argentina, determined by Belostoma candidulum, B. testaceopallidum, Heterocorixa nigra, Sigara hungerfordi, Brachymetra furva,Halobatopsis spiniventris, Metrobates plaumanni plaumanni, and M. vigilis; (4) southeastern Brazil, Uruguay, and central western Argentina (Belostoma cummingsi, B. martini, Sigara argentiniensis, Tenagobia fuscata, and T. carapachay); and (5) southern (Trichocorixa milicorum, Sigara santiagiensis, and S. forciceps). Three panbiogeographic nodes have been determined:(1) northeastern Argentina, in the intersection of generalized tracks 2 and 3; (2) central Argentina, in the intersection of generalized tracks 1 and 4; and (3) central Argentina, in the intersection of generalized tracks 4 and 5. In spite of these complex patterns, these results show that the Chaco province appears to be a natural biogeographic area.

Seasonal Patterns of the Insect Community Structure in Urban Rain Pools of Temperate Argentina

Abstract Temporary aquatic environments are widespread in the world, and although there are considerable regional differences in their type and method of formation they have many physical, chemical and biological properties in common. With the aim to increase knowledge of urban temporary pool fauna, the objectives of this work were to assess the seasonal patterns of species composition, richness, and diversity of the aquatic insect community inhabiting rain pools in urban temperate Argentina, and to identify the environmental variables associated to these patterns. Four temporary pools of an urban green space in Buenos Aires City were studied throughout a 1-year period. Eleven flood cycles with very varied hydroperiods and dry periods, mainly associated with rainfall, were identified. Insect species richness in these temporary urban pools, 86 taxa were documented, was found to be within the range reported for wild temporary water bodies of other regions of the world. The present results provide evidence for the existence of a clear link between habitat and community variability. Hydroperiod and seasonality were the main environmental factors involved in structuring the insect communities of the studied water bodies. Urban pools in green spaces have the potential to act to its dwellers like corridors through the urban matrix. Taking into account these characteristics and their accessibility, urban temporary pools can be considered as promising habitats for the study of ecological processes involving the insect community.

A catalog of the types of Staphylinidae (Insecta, Coleoptera) deposited in the Museo Argentino de Ciencias Naturales, Buenos Aires (MACN)

The type specimens (all current categories) of Staphylinidae deposited in this Museum are listed; names are recorded, most of them represented by name-bearing types (primary types). The specific and subspecific names are alphabetically ordered in a single list, followed by the generic names (and subgeneric ones, if they were stated) spelled as they were published; later combinations and/ or current binomina are mentioned insofar these are known to the authors. Two lists are added: 2. Specimens labeled as types of names not found in the literature and probably never published, or published as nomina nuda; and 3. Specimens labeled as types, but not originally designated as such. An appendix provides a systematically arranged list of all names discussed, with indication of where they are discussed in the text.

Redescription and Taxonomic Status of Pleurhomus sahlbergi Sharp, 1883 (Coleoptera, Hydrophilidae)

The genus Pleurhomus and its sole species P. sahlbergi have been only poorly characterized, both in the original description and in subsequent treatments. A full redescription of the adults of both sexes is given; the larvae remain unknown. On the basis of the emargination in the last apparent urosternite, the untoothed claws in all pairs of legs, in both sexes, the short but evident series of punctures on the elytra, the minute notch at the distal end of the elytral commisure, and the depressed apical segment in the antenna, Pleurhomus clearly differs from Tropisternus. However, until the species of this genus, and especially those of the subgenus Homostethus, are better known, the subgeneric status of Pleurhomus within Tropisternus is here maintained, along with Homostethus, Strepitornus, Pristoternus and Tropisternus.