COS 63-6 - Recent evolution of ancient Arctic leech relatives: systematics of the hook-faced fish worms

Tuesday, August 16, 2022

11:15 AM – 11:30 AM EDT

Location: 513C

Presenting Author(s)

Dd

Danielle de Carle

PhD Candidate
University of Toronto
Toronto, Ontario, Canada

Coauthor(s)

�G

Łukasz Gajda

University of Silesia in Katowice, Poland
AB

Aleksander Bielecki

University of Warmia and Mazury in Olsztyn, Poland
SC

Stanisław Cios, n/a

Ministry of Foreign Affairs of Poland, Poland
JC

Joanna Cichocka

University of Warmia and Mazury in Olsztyn, Poland
HG

Heidi Golden

University of Connecticut, United States
AG

Andrew Gryska

Alaska Department of Fish and Game, United States
SS

Sergey Sokolov

A.N. Severtsov Institute of Ecology and Evolution, Russia
MS

Marina Shedko

Far Eastern Branch of the Russian Academy of Sciences, Russia
RK

Rune Knudsen

The Arctic University of Norway, Norway
SU

Serge Utevsky

V.N. Karazin Kharkiv National University, Ukraine
P�

Piotr Świątek

University of Silesia in Katowice, Poland
MT

Michael Tessler

St. Francis College & American Museum of Natural History, United States

Background/Question/Methods

Acanthobdellida, an elusive group of worms that parasitizes freshwater Arctic fishes, is sister to the decidedly-flashier true leeches. Their unique morphology and phylogenetic relationships have inspired much speculation; however, they are seldom collected, and their biology is not well understood. One of the two species, Paracanthobdella livanowi, has never been sequenced or included in any phylogenetic analysis. While it was initially thought that the range of Acanthobdella peledina was restricted to northern Eurasia, two reports from the 1970s recovered specimens from Alaska, but these populations have not been characterized morphologically or molecularly. In this study, we detailed the morphology of Acanthobdellida – including specimens of A. peledina from Alaska – accounting for ontogenetic variation and trajectory. We also examine the phylogenetic relationships of the order as a whole.

Results/Conclusions

We review existing literature on the natural history and systematics of the enigmatic hook-faced fish worms, Acanthobdellida. We characterize the differences between acanthobdellidan species, and revise their classification accordingly: whereas each species was previously placed within its own family, we opt to classify both in the family Acanthobdellidae on the basis that the phylogenetic and morphological differences are not sufficient to require more than one family. Finally, we find preliminary evidence suggesting that the Alaskan and Nordic populations of Acanthobdella peledina are genetically – but not morphologically – distinct, and discuss the evolutionary implications of these findings.