A morphological and molecular study of adults and metacercariae ofHysteromorpha triloba(Rudolpi, 1819), Lutz 1931 (Diplostomidae) from the Neotropical region

Abstract

Adults of Hysteromorpha triloba (Rudolpi, 1819), Lutz, 1931 inhabit primarily the intestine of cormorants across the globe, whereas metacercariae have been found in the body cavity of freshwater fishes of the families Cyprinidae, Ictaluridae, Ariidae, Pimelodidae and Catostomidae. In this study, adults and metacercariae identified as H. triloba were collected from the Neotropical cormorant (Nannopterum brasilianus) and from the Mexican tetra fish (Astyanax mexicanus) from the Gulf of Mexico and Pacific Ocean slopes in the Neotropical region. Partial DNA sequences of the mitochondrial gene cytochrome c oxidase subunit I (cox 1) and the internal transcribed spacers (ITS1, 5.8S and ITS2) of nuclear ribosomal DNA were generated for both developmental stages, and were compared with available sequences of H. triloba from the Nearctic region. The genetic divergence between metacercariae and adults of H. triloba from the Neotropical and Nearctic region (Canada) associated with the double-crested cormorant (Nannopterum auritus), ranged from 0 to 5.5% for cox 1 and from 0 to 0.2% for ITS. Phylogenetic analyses inferred with both molecular markers using maximum likelihood and Bayesian inference placed the adults and metacercariae in a single clade, confirming that both stages are conspecific. Our data confirmed that H. triloba is a widely distributed species across the Americas, parasitizing both the Neotropical and Nearctic cormorants in Argentina, Brazil, Venezuela, Mexico, USA and Canada.

Eye fluke effects on Danish freshwater fish: Field and experimental investigations

“…and D. pseudospathaceum); three species (T. clavata, D. baeri and Posthodiplostomum brevicaudatum) were found in the vitreous humour, and two species Posthodiplostomum cuticola and Hysteromorpha triloba were found in the fish skin. The host tissue tropism has previously been reported with T. clavata located in the vitreous humour (Buchmann et al, 1997) and Hysteromorpha triloba also located in fish body cavity (Sereno-Uribe et al, 2019). It is worth noting that Posthodiplostomum brevicaudatum (Nordmann, 1832), congeneric to Posthodiplostomum cuticola, causing black spot skin disease, was found encysted in the fish eye, as reported by previous studies (Stanevičiūtė et al, 1998;Wisniewski, 1958).…”

Validity of the Diplostomoidea and Diplostomida (Digenea, Platyhelminthes) upheld in phylogenomic analysis

“…Posthodiplostomum, though nominally part of the family, is separate from and basal to a clade composed of other diplostomids and the Strigeidae. Posthodiplostomum belongs to the Crassiphialinae Sudarikov, 1960 and is consistently recovered with other members of this subfamily (e.g., Uvulifer, Bolbophorus, Ornithodiplostomum, Mesoophorodiplostomum and Posthodiplostomum in Athokpam and Tandon, 2014;Blasco-Costa and Locke, 2017;Hernández-Mena et al, 2017;López-Jiménez et al, 2017;Sereno-Uribe et al, 2018;Locke et al, 2010, see fig. S4).…”

“…Identifications were less than straightforward in 3/7 cases, a proportion similar to the 20/44 studies in which diplostomoid diversity differed from expectations (reviewed by Blasco-Costa and Locke, 2017). One taxonomic result involved reconsideration of H. triloba, which has long been thought to be cosmopolitan (Hugghins, 1954b;Locke et al, 2011;Lutz, 1931;Sereno-Uribe et al, 2018). The genetic divergence seen in Hysteromorpha could be construed as intraspecific variation in widely separated populations (particularly the low level of rDNA variation), but we believe recently formed species to be a more plausible explanation.…”

Nuclear and mitochondrial phylogenomics of the Diplostomoidea and Diplostomida (Digenea, Platyhelminthes)1

“…Posthodiplostomum , though nominally part of the family, is separate from and basal to a clade composed of other diplostomids and the Strigeidae. Posthodiplostomum belongs to the Crassiphialinae Sudarikov, 1960 and is consistently recovered with other members of this subfamily (e.g., Uvulifer, Bolbophorus, Ornithodiplostomum, Mesoophorodiplostomum and Posthodiplostomum in Athokpam and Tandon, 2014; Blasco-Costa and Locke, 2017; Hernández-Mena et al, 2017; López-Jiménez et al, 2017; Sereno-Uribe et al, 2018; Locke et al, 2010, see fig. S4).…”

“…The first is poor taxonomic and geographic coverage (Blasco-Costa and Locke, 2017). Recent work is encouraging, with studies including members of the Proterodiplostomidae Dubois, 1936 (Hernández-Mena et al, 2017), Brauninidae Wolf, 1903 and Cyathocotylidae (Blasco-Costa and Locke, 2017; Fraija-Fernández et al, 2015), and less well-sampled regions (Blasco-Costa et al, 2016; Chaudhary et al, 2017; López-Hernández et al, 2018; Sereno-Uribe et al, 2018).…”