Systematics and geographical distribution of Galba species, a group of cryptic and worldwide freshwater snails

Pilar Alda (1, 2, 3) , Manon Lounnas (2) , Antonio A Vázquez (2, 4) , Rolando Ayaqui (5) , Manuel Calvopiña (6) , Maritza Celi-Erazo (7) , Robert T Dillon , Luisa Carolina González Ramírez (8) , Eric Loker (9) , Jenny Muzzio-Aroca , Alberto Orlando Nárvaez , Oscar Noya , Andrés Esteban Pereira , Luiggi Martini Robles , Richar Rodríguez-Hidalgo , Nelson Uribe , Patrice David (10) , Philippe Jarne (10) , Jean-Pierre Pointier (11) , Sylvie Hurtrez-Boussès (2)

1 UNS - Universidad Nacional del Sur [Argentina]
2 MIVEGEC - Maladies infectieuses et vecteurs : écologie, génétique, évolution et contrôle
3 CONICET - Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires]
4 Pedro Kouri Institute of Tropical Medicine
5 Universidad La Salle [Arequipa, Perú]
6 UDLA - Universidad de Las Américas [Ecuador]
7 UCE - Universidad Central del Ecuador
8 Universidad Nacional de Chimborazo
9 The University of New Mexico [Albuquerque]
10 CEFE - Centre d’Ecologie Fonctionnelle et Evolutive
11 CRIOBE - Centre de recherches insulaires et observatoire de l'environnement

Cryptic species can present a significant challenge to the application of systematic and biogeographic principles, especially if they are invasive or transmit parasites or pathogens. Detecting cryptic species requires a pluralistic approach in which molecular markers facilitate the detection of coherent taxonomic units that can then be analyzed using various traits (e.g., internal morphology) and crosses. In asexual or self-fertilizing species, the latter criteria are of limited use. We studied a group of cryptic freshwater snails (genus Galba) from the family Lymnaeidae that have invaded almost all continents, reproducing mainly by self-fertilization and transmitting liver flukes to humans and livestock. We aim to clarify the systematics, distribution, and phylogeny of these species with an integrative approach that includes morphology, molecular markers, wide-scale sampling across America, and data retrieved from GenBank (to include Old World samples). Our phylogenetic analysis suggests that the genus Galba originated ca. 22 Myr ago and today comprises six species or species complexes. Four of them show an elongated-shell cryptic phenotype and exhibit wide variation in their genetic diversity, geographic distribution, and invasiveness. The remaining two species have more geographically restricted distributions and exhibit a globose-shell cryptic phenotype, most likely phylogenetically derived from the elongated one. We emphasize that no Galba species should be identified without molecular markers. We also discuss several hypotheses that can explain the origin of cryptic species in Galba, such as convergence and morphological stasis.

Keywords: Self-fertilization; Biological invasions; Vector snails; Lymnaeidae; America; Phylogenetics; Self-fertilization

Domains: Systematics, Phylogenetics and taxonomy; Invertebrate Zoology

Pilar Alda, Manon Lounnas, Antonio A Vázquez, Rolando Ayaqui, Manuel Calvopiña, et al.. Systematics and geographical distribution of Galba species, a group of cryptic and worldwide freshwater snails. Molecular Phylogenetics and Evolution, 2020, 157, pp.107035. ⟨10.1016/j.ympev.2020.107035⟩. ⟨hal-03174525⟩