Loginova O.A.1*, Belokobylskiy I.F.2, Spiridonov S.E.1 2026. First molecular characteristics and additional morphological data for Priapocephalus eschrichtii (Cestoda: Tetrabothriidae) from a gray whale (Eschrichtius robustus) // Invert. Zool. Vol.23. No.2: 244–257 [in English].
1 A.N. Severtsov Institute of Ecology and Evolution, 33 Leninskij prosp., Moscow 119071 Russia.
2 Russian Federal Research Institute of Fisheries and Oceanography, 19 Okruzhnoy proezd, Moscow 105187 Russia.
* Corresponding author
Olga Loginova: loginova_spb@bk.ru ORCID https://orcid.org/0000-0002-9846-0800
Ivan Belokobylskiy: iwan09101985@mail.ru ORCID https://orcid.org/0000-0001-9826-2225
Sergei Spiridonov: s_e_spiridonov@rambler.ru ORCID https://orcid.org/0000-0001-6657-0418
doi: 10.15298/invertzool.23.2.03
ABSTRACT: Tapeworm Priapocephalus eschrichtii is one of the only two known cestode species parasitizing the gray whale (Eschrichtius robustus) as adults. It was described in 1970 and still lacks molecular characteristics and detailed morphology depictions. The main issue in further studies of such a parasite lies in its sampling, as whaling is currently strictly prohibited. Live specimens of P. eschrichtii were found during the governmental monitoring of legal aboriginal gray whale hunting in 2024 in Chukotka, Russia. We took this opportunity to study these helminths via DNA analysis, histology, and microscopy. The sequences for cox1 mtDNA, 18S, 28S, and ITS2 of P. eschrichtii are reported here for the first time. Histological analysis showed that adults of P. eschrichtii can cause inflammation of the mucosa in the small intestine of a gray whale. Light microscopy revealed clustered structures containing eggs in P. eschrichtii for the first time. Molecular and morphological analyses support a close relationship between Priapocephalus and Tetrabothrius genera. Data on scanning electron microscopy and histology support the idea about presence of pseudoscolex in P. eschrichtii. Eggs released in clusters contribute to multiple infections of the definitive host.
KEY WORDS: Priapocephalus eschrichtii, gray whale, cestode, DNA.