ABSTRACT The exotic land gastropod Ovachlamys fulgens (Gude, 1900), aka the jumping snail, was registered in Eldorado city, Misiones province, constituting the first documented record of that species in Argentina-and for all of South America as well. Identities of the individuals were confirmed through morphological examination, and by a DNA sequencing of the cytochrome oxidase subunit I gene. DNA sequences for the mitochondrial 16S-rRNA and the nuclear 18S-rRNA genes were also obtained from the morphologically-confirmed specimens to gain insights into the genetic background of this species in Argentina, and as additional markers for enhancing the rapidity of identification by governmental authorities who are responsible for managing the presence of exotic species. Different size classes suggested that the species had successfully reproduced and become established in the locality. Ovachlamys fulgens is emphasized in the literature as being a serious pest to orchids. Misiones province harbors a high species richness of orchids, representing about one half of the known species in Argentina. Owing to the use of the orchid as an ornamental plant, the commercial trade could have facilitated the introduction of the species into Argentina. Control measures, preventive education, and surveillance are needed to prevent the further spread of this snail.

As espécies do gênero Drepanotrema, a maioria delas endêmicas da região Neotropical, pertencem ao Planorbidae. Das nove espécies desta família, seis são encontradas na Argentina. Este artigo analisa o crescimento individual de Drepanotrema cimex na lagoa de Arenalcito, Reserva Natural de Usos Múltiples Ilha Martín García, Buenos Aires, Argentina (34°11′ S - 58°15′ W). A amostragem foi realizada entre fevereiro de 2006 e junho de 2007. Durante o curso das campanhas foram obtidas 14 amostras (n = 1931). Cinco variáveis ambientais foram medidas: temperatura da água, oxigênio dissolvido (mg L–1), condutividade elétrica (uS cm–1), sólidos dissolvidos e pH. O crescimento individual das espécies foi analisada matematicamente por meio da equação de von Bertalanffy em que: Lt = 5,6 (1-e–2, 0592 (t–0, 293)). O paràmetro L∞ foi estimada pe lo método de Ford-Walford. A população de D.cimex foi caracterizada por uma estrutura complexa e dinâmica de tamanho ao longo do ciclo anual. A análise das curvas mostrou distribuições unimodais (2006) e polimodais (abril-junho 2007), identificando a existência de coortes na população estudada.

The species of the genus Drepanotrema, most of them endemic to the Neotropical region, belong to the Planorbidae. Of the nine species of this genus, six are found in Argentina. The present investigation analysed the individual growth of Drepanotrema cimex in Arenalcito pond (34°11′ S, 58°15′ W), Martín García Island Natural Reserve of Multiple Uses, Buenos Aires Province, Argentina. A total of 14 samples were collected (n = 1931) from February 2006 to June 2007. Five environmental variables were measured: water temperature, dissolved oxygen (mg L–1), electrical conductivity (µS cm–1), total dissolved solids, and pH. The individual growth of the species was analysed mathematically by means of the von Bertalanffy equation, where: Lt = 5,6(1-e–2,0592 (t–0,293)). The parameter L∞ was estimated by the Ford-Walford Method. The population of D. cimex was characterised by a complex and dynamic size structure throughout the annual cycle. The analysis of the curves revealed unimodal (2006) and polymodal (April to June 2007) distributions, which pattern served to identify the existence of cohorts within the population studied.