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 Helobdella 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 Helobdella are described based on specimens collected in Mexico, Helobdella papilloprocta sp. nov. and Helobdella gulloae sp. nov. These specimens were preliminarily identified as H. socimulcensis (Caballero, 1931), but detailed morphological and molecular analyses confirmed their status as separate species. In addition, a neotype for Helobdella socimulcensis is designated, and a redescription of the species is provided based on specimens from the type locality: Xochimilco, Mexico City, Mexico.

Finally, H. austinensis in Nuevo León and H. europaea in Morelos, Mexico are reported for the first time, representing new records for the country. In total, ten species of Helobdella are known from Mexico.