Molecular data show Clinostomoides Dollfus, 1950 is a junior synonym of Clinostomum Leidy, 1856, with redescription of metacercariae of Clinostomum brieni n. comb.

Abstract

The genus Clinostomoides Dollfus, 1950 was erected to accommodate a single worm from Ardea goliath sampled in the Belgian Congo. The specimen was distinguished from other clinostomids by its large size and posterior genitalia. In the following years, metacercariae of Clinostomoides brieni, have been described in Clarias spp. in southern and western Africa. A few authors have referred to Clinostomum brieni, but all such usages appear to be lapsus calami, and the validity of Clinostomoides remains widely accepted. In this study our aim was: position C. brieni among the growing clinostomids molecular database, and redescribe the species with emphasis on characters that have emerged as important in recent work. We sequenced two nuclear (partial 18S and ITS) and one mitochondrial marker (partial cytochrome c oxidase I) and studied morphology in metacercariae from hosts and localities likely to harbour the type species (Clarias spp., Democratic Republic of the Congo, South Africa). Phylogenetic analysis shows C. brieni belongs within Clinostomum Leidy, 1856. We therefore transfer C. brieni to Clinostomum, amend the diagnosis for the genus Clinostomum and provide a critical analysis of other species in Clinostomoides, all of which we consider species inquirendae, as they rest on comparisons of different developmental stages.

Size does not matter: molecular phylogeny reveals one of the largest trematodes from vertebrates, the enigmatic Ithyoclinostomum dimorphum, as a species of Clinostomum (Trematoda: Clinostomidae)

“…Data presented in this study reflects the complexity and problematic nature of the morphologically based classification involving clinostomids, complementing the recent study of Caffara et al (2019) that molecularly confirmed the placement of the large-sized Clinostomoides brieni Dollfus, 1950 within Clinostomum ; besides the large size, C . brieni further differs from the 'typical' Clinostomum species by having the genital pore post-testicular and the whole genital complex extremely close to the posterior end.…”

“…Diagnosis: As in Kanev et al (2002) , updated (broader concept) by Caffara et al (2019) , but with the following change: Body middle-sized to very large (5–100 mm long), slender to stout, may be attenuated anteriorly. Space between ventral sucker and anteriormost vitelline follicles may be void of organs.…”

“…sorbens that include: gonads located toward the posterior extremity of the body and the presence of deeply lobed or irregular-shaped testes. Given the likely plesiomorphic/homoplastic nature of morphological traits otherwise used to differentiate subfamilies and genera (e.g., genital pore position and anterior extension of vitellaria — see Caffara et al, 2019 ; present results), we also opt by not to transfer ' I .' yamagutii to the genus Clinostomatopsis .…”

“…More than 30 species have been described worldwide, resulting in a complex taxonomy revised by different authors over time ( Braun, 1901 ; Ukoli, 1966 ; Kanev et al, 2002 ). The use of molecular data has allowed important advances in the knowledge of this group, including the description of new species, the link between larval stages and adults and inferences about the phylogeny, ecology and biogeography of clinostomids (e.g., Caffara et al, 2011 , 2019 ; Locke et al, 2015 , 2019 ; Woodyard et al, 2017 ; Rosser et al, 2017 , 2020 ; Sereno-Uribe et al, 2018 ). However, a proper classification that reflects the evolutionary history of the group is still in progress and far from being achieved, mainly because molecular data for some key taxa (type genera and species) is lacking.…”

Molecular data reveal hidden diversity of the genus Clinostomum (Digenea, Clinostomidae) in Argentina, with the description of a new species from Ardea cocoi (Ardeidae)

“…The genus Clinostomum currently contains 22 putative species (Supplementary Table S1). These species were validated either morphologically, molecularly, or using both sources of information through an integrative taxonomy approach (e.g., Sereno-Uribe et al 2013Pérez-Ponce de León et al 2016;Locke et al 2019;Caffara et al 2017Caffara et al , 2019Caffara et al , 2020. Still, nine molecularly recognized species based on metacercarial stages need to be described and named (Locke et al 2015; Pérez-Ponce de León et al 2016;Montes et al 2020).…”