TY - JOUR

T1 - First elucidation of the life cycle in the family Brachycladiidae (Digenea), parasites of marine mammals

AU - Kremnev, Georgii

AU - Gonchar, Anna

AU - Krapivin, Vladimir

AU - Knyazeva, Olga

AU - Krupenko, Darya

N1 - Publisher Copyright: © 2020 Australian Society for Parasitology

PY - 2020/10

Y1 - 2020/10

N2 - Digeneans of the family Brachycladiidae are cosmopolitan parasites restricted to marine mammals. Their life cycles are unknown. Phylogenetically, Brachycladiidae are enclosed within Acanthocolpidae, parasites of marine teleost fishes. Acanthocolpidae typically possess three-host life cycles with gastropods of the superfamily Buccinoidea acting as the first intermediate hosts for most species, and either fishes or bivalves acting as the second intermediate hosts. A few species previously identified as Neophasis differ from other Acanthocolpidae in having naticid gastropods as first intermediate hosts, and both fishes and bivalves as second ones. We assumed that this may indicate incorrect life cycle description and revised previous data on rediae and cercariae of Neophasis spp. from Cryptonatica affinis (Naticidae) and metacercariae from cardiid bivalves at the White Sea using molecular and morphological approaches. Sequence comparison showed that rediae and cercariae from C. affinis resembling Neophasis sp. and metacercariae from bivalves resembling Neophasis oculata belong to brachycladiid species Orthosplanchnus arcticus. Thus, the life cycle of O. arcticus proceeds as follows: seals serve as the definitive host, C. affinis as the first intermediate host and cardiid bivalves as the second. We found one more type of redia and cercaria in C. affinis which, by molecular evidence, also belongs to Brachycladiidae and is closely related to O. arcticus. Here we refer to them as Brachycladiidae gen. sp. 1 WS. We suggest that Brachycladiidae gen. sp. 1 WS may belong to either Orthosplanchnus or Odhneriella, with beluga whales possibly being the definitive host. Morphological features of O. arcticus and Brachycladiidae gen. sp. 1 WS cercariae are summarized and matched with published data on putatively brachycladiid cercariae. We compare and discuss diversity of life cycle patterns among Brachycladiidae and Acanthocolpidae and show that they differ not only in type of definitive host, but also in both intermediate hosts.

AB - Digeneans of the family Brachycladiidae are cosmopolitan parasites restricted to marine mammals. Their life cycles are unknown. Phylogenetically, Brachycladiidae are enclosed within Acanthocolpidae, parasites of marine teleost fishes. Acanthocolpidae typically possess three-host life cycles with gastropods of the superfamily Buccinoidea acting as the first intermediate hosts for most species, and either fishes or bivalves acting as the second intermediate hosts. A few species previously identified as Neophasis differ from other Acanthocolpidae in having naticid gastropods as first intermediate hosts, and both fishes and bivalves as second ones. We assumed that this may indicate incorrect life cycle description and revised previous data on rediae and cercariae of Neophasis spp. from Cryptonatica affinis (Naticidae) and metacercariae from cardiid bivalves at the White Sea using molecular and morphological approaches. Sequence comparison showed that rediae and cercariae from C. affinis resembling Neophasis sp. and metacercariae from bivalves resembling Neophasis oculata belong to brachycladiid species Orthosplanchnus arcticus. Thus, the life cycle of O. arcticus proceeds as follows: seals serve as the definitive host, C. affinis as the first intermediate host and cardiid bivalves as the second. We found one more type of redia and cercaria in C. affinis which, by molecular evidence, also belongs to Brachycladiidae and is closely related to O. arcticus. Here we refer to them as Brachycladiidae gen. sp. 1 WS. We suggest that Brachycladiidae gen. sp. 1 WS may belong to either Orthosplanchnus or Odhneriella, with beluga whales possibly being the definitive host. Morphological features of O. arcticus and Brachycladiidae gen. sp. 1 WS cercariae are summarized and matched with published data on putatively brachycladiid cercariae. We compare and discuss diversity of life cycle patterns among Brachycladiidae and Acanthocolpidae and show that they differ not only in type of definitive host, but also in both intermediate hosts.

KW - Digenea

KW - Brachycladiidae

KW - Acanthocolpidae

KW - life cycle

KW - cercariae

KW - metacercariae

KW - Orthosplanchnus arcticus

KW - Naticidae

KW - Digenea

KW - Brachycladiidae

KW - Acanthocolpidae

KW - life cycle

KW - cercariae

KW - metacercariae

KW - Orthosplanchnus arcticus

KW - Naticidae

KW - Metacercariae

KW - Life cycle

KW - Cercariae

UR - https://www.sciencedirect.com/science/article/abs/pii/S0020751920301752

UR - http://www.scopus.com/inward/record.url?scp=85088952066&partnerID=8YFLogxK

U2 - 10.1016/j.ijpara.2020.05.011

DO - 10.1016/j.ijpara.2020.05.011

M3 - Article

VL - 50

SP - 997

EP - 1009

JO - International Journal for Parasitology

JF - International Journal for Parasitology

SN - 0020-7519

IS - 12

ER -