Description of two new species of freshwater leeches of the genus Helobdella (Hirudinea, Glossiphoniidae) from Mexico, with a redescription of Helobdella socimulcensis (Caballero, 1931)

Freshwater leeches of the genus <i>Helobdella</i> Blanchard, 1896 (Annelida: Clitellata) are widely distributed in the New World, with most of the species occurring in the neotropics and a single species native to Europe. Species of the genus are characterized by the presence of an eversible proboscis, dorsoventrally flattened body, presence of a single pair of eyespots, and a preference for feeding on the hemolymph of aquatic invertebrates. In this study, two new species of <i>Helobdella</i> are described based on specimens collected in Mexico, <i>Helobdella papilloprocta</i> <b>sp. nov.</b> and <i>Helobdella gulloae</i> <b>sp. nov.</b> These specimens were preliminarily identified as <i>H. socimulcensis</i> (Caballero, 1931), but detailed morphological and molecular analyses confirmed their status as separate species. In addition, a neotype for <i>Helobdella socimulcensis</i> is designated, and a redescription of the species is provided based on specimens from the type locality: Xochimilco, Mexico City, Mexico. Finally, <i>H. austinensis</i> in Nuevo León and <i>H. europaea</i> in Morelos, Mexico are reported for the first time, representing new records for the country. In total, ten species of <i>Helobdella</i> are known from Mexico.