Molecular phylogeny reveals high diversity of broad tapeworm (Diphyllobothriidae) in fish and marine mammals from the Southern Hemisphere

JESÚS S. HERNÁNDEZ-ORTS; TOMÁ SCHOLZ; INGA N. MARTINEK; TETIANA A. KUZMINA; ELENA B. EDER; ANALÍA A. SAN MARTÍN; ROMAN KUCHTA

Vysočina

Congreso; XIV Czech and Slovak Parazitological Days; 2022

Institute of Parasitology, CAS

Tapeworms of the family Diphyllobothriidae, also known as broad tapeworms (BT), are common parasites of phocids and otariids. While molecular phylogenetic relationships of the BT from pinnipeds from the Northern Hemisphere has been under detailed revision since the last decades, the diversity and systematics of these parasites from the Southern Hemisphere remain poorly studied. In the last years, we performed a large-scale host sampling and phylogenetic analysis of marine BT from the Atlantic coast of Argentina and Antarctic waters. Plerocercoids of BT were collected from eight species of marine fishes (second intermediate hosts) off Galindez Island (Argentine Islands, West Antarctica) and from common dolphins Delphinus delphis (euparatenic transit hosts) off central Patagonia, Argentina. Gravid BT were collected from Crabeater seal Lobodon carcinophaga from Galindez Island, and South American sea lions Otaria flavescens or South American fur seals Arctocephalus australis from central Patagonia and Tierra del Fuego, Argentina. Moreover, faecal samples of southern elephant seal Mirounga leonina from Patagonia were screened for BT infections using standard diphyllobothrid specific protocols and Sanger sequencing. Partial sequences of the large subunits nuclear ribosomal RNA gene (LSU) and the complete mitochondrial cytochrome c oxidase subunit 1 (cox1) were generated. Novel sequences were provided for Adenocephalus pacificus, Diphyllobothrium sprakeri, and for the first time, for Baylisia baylisi. In addition, our molecular analyses revealed three genetically distinct linages of “Diphyllobotrium” in Antarctic fishes and marine mammals from Argentine and Antarctic waters. The obtained results represent an important step to increase the knowledge on the diversity, distribution, life-cycles and interrelationships of BT from marine mammals in the Southern hemisphere.