Open Access

Silvia A. Mazzucconi, Axel O. Bachmann

• Distributional data for the fourteen species of Gerridae known to occur in Argentina are given: Eurygerris fuscinervis (herein first recorded from San Juan and San Luis Provinces), Limnogonus (Limnogonus) aduncus (herein first recorded from Formosa Prov.), L. (L.) ignotus, L. (L.)profugus, L. (Neogerris) lubricus (herein first recorded from Cordoba Prov.), Brachymetra albinerva albinerva (herein first recorded from Salta Prov.), Rheumatobates (Rheumatobates) bonariensis, R. (R.)crassifemur crassifemur (herein first recorded from Santa Fe Prov.), Halobatopsis platensis, H. spiniventris (herein first recorded from Entre Rios Prov.), Metrobates plaumanni plaumanni, M. vigilis, Ovatametra gualeguay (herein first recorded from Buenos Aires Prov.), and Trepobates taylori (herein first recorded from Jujuy Prov.). In addition distributional maps are provided. The species characteristic for each main geographic area of Argentina are: E. fuscineruis and T. taylori for the Northwestern mountainous area; L. ignotus, L. lubricus, and R. crassifemur for the Chacoan plain; L. ignotus and H. platensis for the Bonarian plain; L. ignotus, R. bonariensis, H. platensis and 0 . gualeguay for the Mesopotamian plain. E. fuscinervis and T. taylori are restricted to mountain rivers and rivulets, whereas the remaining species seem to be genuine inhabitants of either rivulets in forested hilly areas (L. aduncus, L. profugus, B. albinerva, H. spiniventris, M. plaumanni and M. vigilis), or rivers, rivulets and ponds in plains (L. ignotus, L. lubricus, R. bonariensis, R. crassifemur, H. platensis, and 0 . gualeguay). L. ignotus is a pioneer species in lowlands, readily colonizing new pools. Excepting L. aduncus, L. profugus, and 0. gualeguay which are rare, the remaining species are common in Argentina (no enough data are available for B. albinerva, M. plaumanni, and M. vigilis). Gregariousness is high in E. fuscinervis, R. bonariensis, R. crassifemur, and H. platensis, and probably also in B. albinerva. The other species mentioned seem not to be gregarious, but 0 . gualeguay appears sometimes in the dense aggregations of H. platensis, suggesting some gregarious tendency.