Phylogenetic position of Sphincterodiplostomum Dubois, 1936 (Digenea: Diplostomoidea) with description of a second species from Pantanal, Brazil

Abstract

Sphincterodiplostomum is a monotypic genus of diplostomid digeneans that parasitize fish-eating birds in the neotropics. The type species Sphincterodiplostomum musculosum has a unique, dorsal, tubular invagination in the opisthosoma with a muscular sphincter. Whereas larvae of S. musculosum are relatively commonly reported in Neotropical fish helminth surveys, adult specimens from birds are rarely collected. Prior to our study, no DNA sequence data for S. musculosum were available. Our molecular and morphological study of mature and immature adult Sphincterodiplostomum specimens from three species of birds and one species of crocodilian revealed the presence of at least two species of Sphincterodiplostomum in the neotropics. We provide the first molecular phylogeny of the Diplostomoidea that includes Sphincterodiplostomum. In addition, this is the first record of S. musculosum from caimans, along with the first record of fully mature adult S. musculosum from green kingfisher Chloroceryle americana. The new species of Sphincterodiplostomum (Sphincterodiplostomum joaopinhoi n. sp.) can be morphologically distinguished from S. musculosum based on the anterior extent of vitelline follicles, narrower prosoma, substantially smaller holdfast organ and structure of tegumental spines. Our data revealed 0.7% interspecific divergence in 28S and 10.6–11.7% divergence in cox1 sequences between the two Sphincterodiplostomum species.

Unravelling the diversity of the Crassiphialinae (Digenea: Diplostomidae) with molecular phylogeny and descriptions of five new species

“…1 ), which is consistent with other recent molecular phylogenetic studies of the Diplostomidae (e.g. Hernández-Mena et al., 2017 ; Achatz et al., 2019b , c , d , 2020b , 2021a ; Queiroz et al., 2020 ; Tkach et al., 2020 ), it is our opinion that the subfamilies of the Diplostomidae should also be abandoned. Therefore, we do not consider the four diplostomid subfamilies to be valid.…”

“…1 ), similar to previous molecular phylogenetic analyses of the Diplostomoidea (e.g. Blasco-Costa and Locke, 2017 ; Hernández-Mena et al., 2017 ; Achatz et al., 2019b , c , d , 2020b , 2021a ; Queiroz et al., 2020 ; Tkach et al., 2020 ; Locke et al., 2021 ). Overall, the phylogeny consisted of a large basal polytomy with multiple independent clades.…”

“…Likewise, several recent molecular phylogenetic studies have demonstrated non-monophyly of these currently accepted taxa (e.g. Blasco-Costa and Locke, 2017 ; Hernández-Mena et al., 2017 ; Achatz et al., 2019b , c , d , 2020b , 2021a ; Queiroz et al., 2020 ; Tkach et al., 2020 ). Prior to our study, only five genera of crassiphialines had available 28S sequence data ( Bolbophorus , Crassiphiala , Ornithodiplostomum , Posthodiplostomum and Uvulifer ).…”

Molecular phylogenetic analysis of Neodiplostomum and Fibricola (Digenea, Diplostomidae) does not support host-based systematics

“…2), similar to previous molecular phylogenetic analyses of the Diplostomoidea (e.g. Blasco-Costa and Locke, 2017; Hernández-Mena et al ., 2017; Achatz et al ., 2019 b , 2019 c , 2022, 2020, 2021 a ; Queiroz et al ., 2020; Tkach et al ., 2020; Locke et al ., 2021). All sequences of taxa/lineages representing Fibricola formed a 99% supported clade (clade I) with four Neodiplostomum species: N. microcotyle , N. reflexum and N. vaucheri as well as unidentified species-level lineage Neodiplostomum sp.…”

“…Similar to other previous molecular phylogenetic studies, in our analyses Neodiplostomum did not form a clade with other members of the formerly accepted Diplostominae (Figs 1–3) (e.g. Achatz et al ., 2019 b , 2021 a , 2021 c ; Queiroz et al ., 2020). Our results, along with other recent molecular phylogenetic studies (e.g.…”