A survey of freshwater gastropods in the Microrregião Serrana of the state of Rio de Janeiro, Brazil.

Abstract

In 1984 we received samples of freshwater gas-tropods from many localities of the State of Rio deJaneiro, sent by Fundacao Nacional de Saude foridentification. In the past three years, aiming toelaborate a chart of planorbids of the State of Riode Janeiro additional collecting was done by theauthors in the area corresponding to theMicrorregiao Serrana of the state: Petropolis,Teresopolis and Sao Jose do Vale do Rio Preto.The survey was extended to the neighbour towns,Guapimirim and Mage, in order to improve theknowledge of that poorly studied area.The molluscs were collected from differentsuitable snail habitats: streams, rivers and marshareas in the Atlantic forest as well as drainage andsewage ditches, wells, flood areas, ponds and irri-gation canals.Live snails were kept at the laboratory for amonth in aquaria containing dechlorinated tapwater and, at the bottom, a thin layer of a 2:1 mix-ture of screened reddish soil and ground oystershells as a source of mineral nutrients. Snails werefed on fresh lettuce leaves. In the meantime speci-mens of Biomphalaria were exposed to artificiallight in intervals of five days to determine possibleinfection with trematode larvae, mainly Schisto-soma mansoni cercariae. The ten larger snails ofeach sample were preserved in Railliet-Henry’sfluid after relaxation in a 0.05% nembutal solutionand two of them were dissected under stereomi-croscope for identification. Technical details weredescribed elsewhere (SC Thiengo 1995 TecnicasMalacologicas, p. 255-265. In FS Barbosa, Topicosem Malacologia Medica , Fiocruz, Rio de Janeiro).Samples of taxonomic importance were depositedat the Malacological Collection of InstitutoOswaldo Cruz/Fiocruz.In all, 7 species of planorbids and 10 speciesof other freshwater gastropods were found in 15localities at the studied area (Table): Antillorbisnordestensis (Lucena, 1954); Biomphalariaperegrina (Orbigny, 1835); Biomphalaria stra-minea (Dunker, 1848); Biomphalaria tenagophila(Orbigny, 1835); Drepanotrema anatinum(Orbigny, 1835); Drepanotrema cimex (Moricand,1839); Drepanotrema lucidum (Pfeiffer, 1839);Ferrissia sp.; Gundlachia moricandi (Orbigny,1837); Heleobia davisi Silva & Thome, 1985; Lym-naea columella (Say, 1817); Lymnaea sp.;Melanoides tuberculata (Muller, 1774); Physacubensis Pfeiffer, 1839; Physa marmorataGuilding, 1828; Pomacea canaliculata (Lamarck,1801); Pomacea sordida (Swainson, 1823).Among the planorbid species B. tenagophilawas the most frequent, occurring in 13 out of the15 localities surveyed. According to WL Paraense(1986 Distribuicao dos caramujos no Brasil, p. 117-128. In FA Reis, I Faria & N Katz (eds), ModernosConhecimentos sobre Esquistossomose Man-sonica, Biblioteca da Academia Mineira deMedicina, Belo Horizonte) it ranges from Caravelas(17