Recent evolution of ancient Arctic leech relatives: systematics of Acanthobdellida

Abstract

Acanthobdellida gnaw into the sides of salmonid fishes in frigid Arctic lakes and rivers, latching on with fearsome facial hooks. Sister to leeches, they are an ancient lineage with two described species. Unfortunately, Acanthobdellida are rarely collected, leading to a paucity of literature despite their unique morphology. Populations range from Eurasia to Alaska (USA), but few specimens of Acanthobdella peledina are represented in molecular studies, and no molecular data exist for Paracanthobdella livanowi, making their taxonomic position difficult to assess. We use phylogenetics and morphology to determine whether allopatric populations of A. peledina are distinct species and assess the current classification scheme used for Acanthobdellida. We produce a new suborder, Acanthobdelliformes, to match the taxonomy within Hirudinea. Scanning electron micrographs indicate species-level differences in the anterior sucker and facial hooks; molecular phylogenetics mirrors this divergence between species. We assign both species to the family Acanthobdellidae and abandon the family Paracanthobdellidae. Alaskan and European A. peledina populations are morphologically similar, but appear phylogenetically divergent. Our data strongly suggest that members of the order Acanthobdellida diverged relatively recently in their ancient history, but based on genetic distance, this divergence appears to pre-date the most recent cycles of glaciation.

Cryptic taxonomic diversity and high-latitude melanism in the glossiphoniid leech assemblage from the Eurasian Arctic

“…Both the Kolguev Island and the Putorana Plateau are hard-to-reach areas, and none of freshwater leeches was collected from there before our sampling efforts. At first glance, this taxon may represent a high-latitude relict, as do two Acanthobdellidae species 27 , 30 , 31 , 97 . From an evolutionary point of view, the new genus may be a sister lineage to the Nearctic Actinobdella , having a similar sexannulate condition 36 , although external traits such as a specific annulation can arise independently in different clades of the glossiphoniid leeches 3 , 33 (see Supplementary Table S3 for detail).…”

Distribution of the invasive polychaete Hypania invalida (Grube, 1860) against the background of the benthic fauna in the upper Oder River catchment (Poland)

“…For COI amplification, the LCO1490 and HCO2198 primer set was used (Folmer et al, 1994). Initially, we attempted to amplify 18S as two partially overlapping segments using primer A combined with Rev1044a18S for "segment A" and Frw921b18S combined with primer B for "segment B" (Apakupakul et al, 1999;de Carle et al, 2022). However, this approach, usually successful for other annelids, produced low-quality reads for H. invalida.…”