Host Range and Phylogenetic Position of Acipenserobdella volgensis (Zykoff, 1904) (Hirudinea: Piscicolidae) with a Global Checklist of Bivalve-Associated Fish Leeches

Abstract

The fish leech Acipenserobdella volgensis (Hirudinea: Piscicolidae) is a rare and poorly known freshwater species, which is thought to be an obligate parasite of sturgeons. This leech has a disjunctive range in Europe and eastern Siberia. Here, we estimate the phylogenetic affinities and host range of A. volgensis using a set of DNA sequences (COI and 18S rRNA gene fragments), field observation data, and a review of the body of literature. Based on a time-calibrated Bayesian phylogeny, we show that the European and Siberian lineages of A. volgensis have been separated since the latest Pliocene (mean age = 2.7 Ma). The analysis of available host records indicates that this leech is characterized by a broader host range as it was collected from fish belonging to four families (Acipenseridae, Cyprinidae, Salmonidae, and Esocidae). Conversely, only a few suitable primary hosts (six sturgeons, one cyprinid, and one salmonid fish) were confirmed by earlier research. Moreover, this leech could be considered a facultative mussel-associated species that uses bivalves (duck mussel Anodonta anatina; Unionidae) as shelter. Globally, three other piscicolid leeches have been recorded from the mantle cavity of bivalve molluscs, that is, the freshwater taxa Caspiobdella fadejewi and Alexandrobdella makhrovi, and the marine species Austrobdella coliumicus.

Sturgeon Parasites: A Review of Their Diversity and Distribution

“…Additionally, leeches can transmit diseases or parasites to the fish, as they can carry a range of harmful pathogens [119]. Bolotov et al (2022) [60] identified the Hirudinea Acipenserobdella volgensis in the pectoral fin of Acipenseridae in the Volga river basin in Russia. This species was also found on Acipenser baerii, A. gueldenstaedtii, and A. nudiventris [120].…”