RT Journal Article SR Electronic T1 Systematics and geographical distribution of Galba species, a group of cryptic and worldwide freshwater snails JF bioRxiv FD Cold Spring Harbor Laboratory SP 647867 DO 10.1101/647867 A1 Pilar Alda A1 Manon Lounnas A1 Antonio A. Vázquez A1 Rolando Ayaqui A1 Manuel Calvopiña A1 Maritza Celi-Erazo A1 Robert T. Dillon, Jr. A1 Luisa Carolina González Ramírez A1 Eric S. Loker A1 Jenny Muzzio-Aroca A1 Alberto Orlando Nárvaez A1 Oscar Noya A1 Andrés Esteban Pereira A1 Luiggi Martini Robles A1 Richar Rodríguez-Hidalgo A1 Nelson Uribe A1 Patrice David A1 Philippe Jarne A1 Jean-Pierre Pointier A1 Sylvie Hurtrez-Boussès YR 2019 UL http://biorxiv.org/content/early/2019/12/09/647867.abstract AB 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 phylogenetic relationships of these species with an integrative approach that includes morphology (shell and reproductive anatomy), 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 clusters of species. Four of these clusters (G. truncatula, G. cubensis/viator, G. humilis and G. schirazensis) are morphologically cryptic and constitute species or species complexes with wide variation in their genetic diversity, geographic distribution and invasiveness. The other two clusters constitute a single species or a species complex (Galba cousini/meridensis) that demonstrate more geographically restricted distributions and exhibit an alternative morphology more phylogenetically derived than the cryptic one. Further genetic studies are required to clarify the status of both G. cousini/meridensis and G. cubensis/viator. We emphasize that no Galba species should be identified without molecular markers and that additional sampling is required, especially in North America, Eurasia and Africa to clarify remaining questions in systematics and biogeography. We also discuss several hypotheses that can explain crypsis in Galba, such as convergence and morphological stasis, and hypothesize a role for stabilizing selection in amphibious (rather than strictly freshwater) habitats.