New records of the chaetiferous leech-like annelid Paracanthobdella livanowi (Epshtein, 1966) (Annelida: Clitellata: Acanthobdellida) from Kamchatka, Russia

Abstract

Acanthobdellidans are unique in their organisation and phylogenetic relationships due to having transitional characters that combine features of oligochaetous and achaetous annelids. Alongside the relatively well-studied Acanthobdella peledina Grube, 1851, there is another member of the group, Paracanthobdella livanowi (Epshtein, 1966), with five rows of chaetae and an anterior sucker. It appears that the anterior sucker is weakly developed in small juveniles but acquires a deep cavity in adults. Smaller individuals of P. livanowi can be distinguished from A. peledina, which does not possess an anterior sucker, by the varying breadth of their chaetae. The mid-body segment consists of two doubled annuli in juveniles and is quadri-annulate in large individuals. In Kamchatka freshwaters, hosts of P. livanowi mostly include Salvelinus spp. and more rarely Gasterosteus aculeatus, Oncorhynchus mykiss and O. kisutch. New information on the distribution and the biology of P. livanowi is presented.

New data about the functional morphology of the chaetiferous leech‐like annelids Acanthobdella peledina (Grube, 1851) and Paracanthobdella livanowi (Epshtein, 1966) (Clitellata, Acanthobdellida)

“…Acanthobdellida live in freshwater habitats in cold regions of the northern hemisphere, and they parasitize fish inhabiting local ecosystems, in particular Salmonidae and Thymalidae fishes. Acanthobdella peledina is widespread in the boreal region of Scandinavia (Dahm, ; Andersson, ; Borgström and Halvorsen, 1972; Sawyer, ) northern regions of the Scandinavian Peninsula (Dahm, ; Andersson, ), Finland (Poppius, ), the boreal region of Siberia, Russia (Lukin, ; Pronin, ) and Alaska (Holmquist, ; Hauck et al, ; Kaygorodova et al, ; Utevsky et al, ).…”

“…A. peledina primarily parasitizes fish salmonid: Salmo trutta Linnaeus, 1758, and Salavelinus sp., Coregonidae: Stenodus nelma (Pallas, 1773) and Coregonus tugun (Pallas, 1814), as well as Thymalidae: Thymallus arcticus (Pallas, 1776) (Livanow, ; Epshtein, ; Sawyer, ; Kaygorodova et al, ; Utevsky et al, ). A. peledina parasitizes on the surface of the host's body where it resides permanently, leaving the host only during the reproductive season (Sawyer, ; Epshtein, ; Świątek et al, ; Kaygorodova et al, ; Utevsky et al, ).…”

“…Paracanthobdella livanowi inhabits the Kamchatka Peninsula (Epshtein, ; Sawyer, ; Utevsky et al, ) and the waters of the Chukchi Peninsula (Epshtein, ). P. livanowi is a parasite of Savelis sp., and it has been observed on the fry of Oncorhynchus kisutch , Suckley, 1861 and Oncorhynchus kidney , Walbaum, 1792 (Epshtein, ; Utevsky et al, ). P. livanowi shows a strong preference for the base of the dorsal fin, but it has also been noted on the pectoral fins, occasionally on the ventral or anal fins, and on the surface of the body.…”

“…P. livanowi shows a strong preference for the base of the dorsal fin, but it has also been noted on the pectoral fins, occasionally on the ventral or anal fins, and on the surface of the body. It is frequently found in a free‐living state (Sawyer, ; Epshtein, ; Utevsky et al, ). Choice of the host is probably dictated by the territorial behavior and feeding habits of fish (Sawyer, ).…”

“…The anterior sucker is well developed and distinctly separated from the first body segment. The posterior sucker is formed of four somites which are relatively small and poorly developed (Livanow, ; Andersson, ; Epshtein, ; Sawyer, ; Epshtein, ; Utevsky et al, ). The full mid‐body somite in both leech‐like species is composed of four annuli (Sawyer, ).…”