Paracanthobdella livanowi

• Main Authors: Carle, Danielle Božena De, Gajda, Łukasz, Bielecki, Aleksander, Cios, Stanisław, Cichocka, Joanna M., Golden, Heidi E., Gryska, Andrew D., Sokolov, Sergey, Shedko, Marina Borisowna, Knudsen, Rune, Utevsky, Serge, Świątek, Piotr, Tessler, Michael
• Format: Other/Unknown Material
• Language: unknown
• Published: 2022
• Subjects: Biodiversity; Taxonomy; Animalia; Annelida; Acanthobdellida; Acanthobdellidae; Paracanthobdella; Paracanthobdella livanowi; Arctic
• Online Access: https://zenodo.org/record/7044002; https://doi.org/10.5281/zenodo.7044002

Species: Paracanthobdella livanowi (Epstein, 1966) NOTES ON OUR TAXONOMIC SCHEME Here, we present a taxonomic scheme for hookfaced fish worms (Acanthobdellida). Despite its historical significance, we do not retain the family Paracanthobdellidae for P. livanowi, because both morphological and molecular analyses suggest that the two acanthobdellidan species share many characteristics. Initially, Acanthobdellidae and Paracanthobdellidae were differentiated based on a few morphological differences that were viewed as taxonomically important (Epstein, 1987). Specifically, members of Paracanthobdellidae were said to possess a primitive prostomium and well-developed anterior sucker. Although the two-family system seemed well supported at the time, we have found that the prostomium of P. livanowi is not more conspicuous or developed than the anterior region of A. peledina. Moreover, the area between rows of chaetae in the cephalic extremity of the latter can be deepened such that it resembles a shallow sucker. It should also be noted that juvenile individuals of P. livanowi do not bear well-developed anterior suckers; this character is only common to large-bodied individuals of the species. The sum of this evidence suggests that the morphological differences between the two acanthobdellidan species, although pronounced, are not sufficient to warrant two families. We therefore classify both Acanthobdella and Paracanthobdella under the single family Acanthobdellidae. We establish a new suborder Acanthobdelliformes to match better the taxonomy erected for Hirudinea in prior work (Tessler et al., 2018a), which divided Hirudinida (leeches) into five suborders (Americobdelliformes, Erpobdelliformes, Hirudiniformes, Glossiphoniiformes and Oceanobdelliformes). Acanthobdelliformes is defined by the presence of chaetae on each of five contiguous segments in the anterior body region, and 31 segments (mid-body ones are quadrannulate with annulus a3 being subdivided) (Sawyer, 1986; Purschke et al., 1993; Bielecki et al., 2014). ...