Geographic distribution of the Gerridae in Argentina (Insecta, Heteroptera)

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 C6rdoba Prov.), Brachymetraalbineruaalbinerua (herein first recordedfrom SaltaProv.), Rheumatobates(Rheumatobates) bonariensis, R. (R.)crassifemur crassifemur (herein first recorded from Santa Fe Prov.), Halobatopsisplatensis, H. spiniventris (herein first recorded from Entre Rios Prov.), Metrobatesplaumanniplaumanni, M. vigilis, Ovatametragualeguay (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. Introduction Only very scanty distributional data of South American Gerridae are available, and none about habitat preferences, commonness, and gregariousness. Records of some argentine species were stated by Pennington (1920-1921), Bachmann (1962a, 1962b,1963), Crespo (1984), Mazzucconi and Bachmann (1995); Bachmann (1966) presented the range of distribution for all the species known from Argentina. Distributional information for all the Gerridae known to occur in Argentina is updated. The range of distribution of some species is extended to provinces not previously recorded. Information on the preferential habitats, the degree of commonness in the area, and the degree of gregariousness for all species are here included for the first time. Materials and Methods The material examined belongs to the Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires (MACN), the Laboratorio de Entomologia of the Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, the Museo de Ciencias Naturales, La Plata (MLP), and the Instituto Miguel Lillo, Tucum6n (IML). ' The distributional information is given in lists of localities arranged by provinces, in a table of occurrences by provinces (table I), and in maps (figs. 14). Data were taken from the labels and the literature. Data of commonness and gregariousness came mostly from authors' field observations. Results Numerous new records are herein included. Eight of the fourteen species known to occur in Argentina have been found in Provinces not previously recorded, viz., Eurygerris fuscinervis for San Juan and San Luis, Limnogonus aduncus for Formosa, L. lubricus for Cbrdoba, Brachymetra albinerva for Salta, Rheumatobates crassifemur for Santa Fe, Halobatopsis spiniventris for Entre Rios, Ovatametra gualeguay for Buenos Aires, and Trepobates taylori for Jujuy. 364 Volume 9, nos. 3-4, September-December, 1995, INSECTA MUNDI The following records for Eurygerris fuscinervis are probably erroneous (mislabellings), and they were not included in the corresponding list and map: Buenos Aires, Corrientes and Misiones (specimens deposited in MACN), Santa Fe and Chaco (specimens deposited in IML) and Santiago del Estero (Pennington, 1920-1921). Most of these specimens are apterous, so they could not have reached those localities on flight or by wind. Aquarius chilensis, from central Chile, has not been recorded from Argentina, and it is very unlikely that it will ever be found here. Trepobatoides boliviensis from Bolivia, and Tachygerris adamsoni and T. quadrilineatus from Brasil, may eventually be found in northern Argentina. Gerrinae sensu Bianchi 1896 Gerrini sensu Matsuda 1960 Eurygerris fuscinervis (Berg 1898) Distribution. Northwestern, western, and central provinces, from the boundary with Bolivia southward to San Juan, central C6rdoba and central San Luis Provinces, in mountains and hills. northward to Venezuela. Localities recorded (fig. 1). Catamarca: Aconquija. Barranca Larga. Concepci6n. El Alamito. El Rodeo. Mutquin (2000 m). Quebrada del rio Pisuvil (1700-1850 m). Rio La Viiia, ruta 38. Singuil(1200 m). Cordoba: Achala, rio San Antonio. Agua de Oro. Alta Gracia. Alto de San Pedro. Athos Pampa. Capilla del Monte, rio Calabalumba. Copina. Cruz Chica. Huerta Grande. La Cumbre. La Falda. La Poblaci6n. Los Burritos. Los Cocos. Mina Clavero. Parque Provincial Chancani. Rio Pintos. Valle Hermoso. Villa El Sauce. Yacanto. Jujuy: Arroyo Las Lanzas, ruta 9. Palmas San Pedro. Parque Nacional Calilegua: Aguada del Tigre; arroyo El Negrito; Mesada de la Colmena (700 m). Reyes. Tiraxi. Yala. La Rioja: Embalse Los Sauces. Las Placetas. Los Talas. Salta: Aguaray. Chicoana. El Piquete. El Tala, ruta 9. Luna Muerta. Metbn. Pampa Grande. Parque Nacional BaritG. Parque Nacional El Rey. Pilotas. Pocitos. Quebrada de Escoipe. Quebrada de la Canaleta. Quebrada delrio Blanco. Rio Castaiias. Rio Quisto. Rosario de la Frontera. Salta, cerro San Lorenzo. San Lorenzo. Santa Victoria Este. Tacuil (2700 m). Tartagal. San Juan: Aguas Negras. Valle FQrtil. San Luis: El Volcbn. Embalse La Huertita. Lujbn, rio Lujbn. Merlo. Naschel. Potrero de 10s Funes. Rio Grande. Villa del Carmen. Tuc u d n : Aconquija. Amaicha del Valle. Cerro San Javier. Horco Molle. Naranjal. Quebrada de 10s Sosas. Quebrada del rio Blanco. Raco. Rio Las Tacanas. Rio Pueblo Viejo (1000 m). Rodeo Grande. San Javier, quebrada Cainzo. San Pedro de Colalao, rio Ceibalito. Tacanas, rio Ceibalito. Tafi del Valle. Tafi Viejo. Villa NouguBs. Biological features. Inhabiting mountain rivers and rivulets, mainly a t the margins, from 700 up to 2700 m above sea level. A very common, gregarious species; in most series apterous specimens are dominant over macropterous ones (micropterous specimens are rare). Limnogonus (Limnogonus) aduncus Drake and Harris 1933 Distribution. Northwestern and northeastern corners of Argentina; a single record from Formosa Province (dry area). Northward to Guiana and Trinidad. Localities recorded (fig. 3). Formosa: Palo Santo. Misiones: Parque NacionalIguazG. Salta: Orbn. Salta Forestal, Salta Sector 11, 50 km E of Las Lajitas. Tartagal. Urundel. Valle de Acambuco. Biological features. Inhabiting borders of rivulets in forested hilly areas (but Palo Santo lies in a dry, shrub and savannah dominated area in the Chacoan plain). An uncommon species; probably not gregarious (only very few specimens were collected each time). Limnogonus (Limnogonus) ignot us Drake and Harris 1934 Distribution. About the northern third of Argentina, but not in mountaineous areas; southward to Buenos Aires. Northward to Guiana. Localities recorded (fig. 2). Buenos Aires: Buenos Aires (city). ChascomGs. Flores. La Plata, arroyo El Gato. Pereyra, arroyo Pereyra. Salto. Chaco: Arroyo Ortega. Barranqueras. Pampa del Infierno. Resistencia. C6rdoba. Corrientes. Entre Rios: Lazo. Formosa: Arroyo He-He Chico. Arroyo HeHe Grande. Clorinda. Loma Ga. Parque Nacional Pilcomayo, laguna Blanca. Misiones: Arroyo Ram6n, ruta 14, North of OberA. Barra Bonita. INSECTA MUNDI, Vol. 9, No. 3-4, September December, 1995 365 Bernardo de Irigoyen. Loreto. Pindapoy. Posadas. Puerto Esperanza. Puerto Londero. Rio Alto Uruguai. Rio UruzG. San Javier. Santa Maria. Salta: Capiazuti. Pocitos. Santa Victoria Este. Tartagal. Santa Fe. Santiago del Estero: rio Salado. Tu-