Anatomical studies of sibling species within neotropical lymnaeids, snail intermediate hosts of fascioliasis

Abstract

Several anatomical parameters of the reproductive system have been used to distinguish Key words: Neotropical lymnaeids -sibling species -Lymnaea cubensis -Lymnaea viatrixEleven species of lymnaeid snails have been described in the Caribbean area and South America. However, only six species are considered as valid by Hubendick (1951) and Paraense (1976Paraense ( , 1982aParaense ( , 1983Paraense ( , 1984Paraense ( , 1986Paraense ( , 1994Paraense ( , 1995: Paraense, 1982 and L. columella Say, 1817. This last species has now a very large distribution in all tropical countries particularly in the neotropical area (see Malek & Chrosciechowski 1964, Paraense 1982b, Gomez et al. 1986). Two other species may be added to that list (i) L. truncatula (Müller, 1774) from Europe which recently invaded several Andean countries (Oviedo et al. 1995, Jabbour-Zahab et al. 1997, Durand et al. 2002; (ii) L. plicata Hylton-Scott, 1953 from Chubut Province, Argentina which validity has not yet been confirmed.The morphology of the shell and reproductive system of five of those species has been well studied and allows a clear identification (Paraense 1982a, 1984, 1986, 1995, Samadi et al. 2000, Pointier et al. 2004 Moreover, an analysis of the genetic variability based on 12 enzyme loci revealed different fixed alleles at nine loci between two syntopic samples of L. viatrix var. elongata at the type locality in Lima, Peru (Durand et al. 2002). The absence of heterozygotes within this locality thus indicated the presence of isolated populations or cryptic species within the variety elongata. In the same study, Durand et al. (2002) also found significant genetic differences between the two taxa from Lima and another population sampled in Bahia Blanca, Argentina, located about 350 km to the north of the type locality for L. viatrix var. ventricosa. More recently, the use of several molecular markers (PCR-RLFP analysis of the ITS1 and ITS2 rDNA and 16S rDNAmt using 12 restriction enzymes) in a study of several populations morphologically identified as L. viatrix from Brazil, Uruguay, and Argentina showed a high level of genetic polymorphism between populations which was interpreted as an intra-specific variation (Carvalho et al. 2004).A morphological comparison of several populations of L. cubensis from the Caribbean area and several populations of the introduced L. truncatula from Bolivia was carried out by Samadi et al. (2000) using several conchological and anatomical characters of the reproductive system. The conchological study showed the presence of a large amount of variability within and between populations that did not allow distinction between taxa. The analysis of anatomical parameters of the reproductive system also showed a high variability, but all these characters clearly separated L. cubensis from L. truncatula independently from their geographical origin. In the present paper, we use these anatomical characters in the same way to see if it is possible to distinguish morphologically L. cubensis from L. viatrix. The materia...

New record forGalba neotropica(d'Orbigny, 1835) in Argentina, with a detailed analysis of its morphology and molecular characteristics

“…About 10% of the collected adults were relaxed overnight using menthol, killed by immersion in hot water (70°C) for 40 seconds and immediately submerged for 15 seconds in cold water to avoid tissue damage (Pointier et al 2006). The animal was removed from the shell.…”

“…Email: jpujadas@ege.fcen.uba.ar Until recently, the specific identification of lymnaeid snails has been based exclusively on morphological characteristics of the shell, radula, and renal and reproductive organs (Hubendick 1951;Paraense 1976;Pointier et al 2004). However, reliance on these features failed to distinguish species with similar morphology (cryptic species) or variants within a single species (Pointier et al 2006;Standley et al 2013).…”

“…Pujadas et al therefore, have been the most used in lymnaeid studies (Bargues and Mas-Coma 2005). Today, there is a general consensus that both molecular and morphological analyses are needed to correctly identify the members of the family Lymnaeidae (Samadi et al 2000;Pointier et al 2006;Correa et al 2011).…”

“…The four species are similar in size and shell morphology (Samadi et al 2000;Correa et al 2011), and only G. truncatula is distinguishable from the rest by the anatomy of the prostate and penial complex (Samadi et al 2000;Pointier et al 2006). Galba viatrix, G. cubensis and G. neotropica differ only by the DNA sequences of different molecular markers, such as ITS-1, ITS-2 and cytochrome oxidase subunit I (COI) (Pointier et al 2006;Bargues et al 2007;Standley et al 2013).…”

“…Galba viatrix, G. cubensis and G. neotropica differ only by the DNA sequences of different molecular markers, such as ITS-1, ITS-2 and cytochrome oxidase subunit I (COI) (Pointier et al 2006;Bargues et al 2007;Standley et al 2013).…”