The phylogenetic position of Choerodonicola Cribb, 2005 (Digenea: Opecoelidae) with a partial life-cycle for a new species from the blue-barred parrotfish Scarus ghobban Forsskål (Scaridae) in Moreton Bay, Australia
Choerodonicola Cribb, 2005 is a minor genus of opecoelid trematodes defined for species with exceptionally small eggs but otherwise generalised morphology. Four species are currently recognised, all from fishes collected in Japanese waters but each from different perciform families: a labrid, a scarid, a sparid and pinguipeds. We report on a new species, Choerodonicola arothokoros n. sp., from the blue-barred parrotfish Scarus ghobban Forsskål (Scaridae) collected in subtropical waters of Moreton Bay, south-east Queensland, Australia. Using genetic sequence data for the ITS2 rDNA marker, we matched adult C. arothokoros to intramollsucan stages discovered in an intertidal gastropod Herpetopoma atratum (Gmelin) (Vetigastropoda: Chilodontidae) collected in close proximity to the fish hosts. Notably, the cercariae lack a penetration stylet and are among the smallest known in the Opecoelidae. We provide the first assessment of the phylogenetic position of Choerodonicola based on sequence data generated for the phylogenetically informative 18S and 28S rRNA coding regions, for C. arothokoros and also C. renko Machida, 2014, which we recollected from the yellowback seabream Dentex hypselosomus Bleeker from the fish market in Minabe, Wakayama Prefecture, Japan. In our analyses, species of Choerodonicola resolved to neither of the major marine Plagioporinae (sensu lato) clades, clustering instead with Trilobovarium parvvatis Martin, Cutmore & Cribb, 2017, Podocotyloides parupenei (Manter, 1963) Pritchard, 1966 and Macvicaria magellanica Laskowski, Jeżewski & Zdzitowiecki, 2013. This clade is phylogenetically distinctive such that it has the potential to be recognised as a new opecoelid subfamily, but further investigation is required to establish the bounds for such a grouping and to determine the morphological and/or life-history patterns reflected by the phylogeny. Finally, we propose C. interruptus (Manter 1954) n. comb. for a species previously recognised in Plagioporus Stafford, 1904 and known only from Pseudolabrus miles (Schneider & Forster), a labrid endemic to New Zealand.
We thank the staff of Moreton Bay Research Station for their continued support enabling field collecting; A/Prof. Sho Shirakashi, Kindai University, Osaka for facilitating collection in Japan and confirming identification of Japanese sparids; an anonymous reviewer for a thorough and insightful critique which significantly improved the manuscript; and our colleague, Nicholas Wee, for assistance in the field and accidentally catching the first infected S. ghobban.
SBM and DCH are each supported by The Holsworth Wildlife Research Endowment and The Ecological Society of Australia. SBM is supported by a PhD scholarship provided through the Australian Government’s Australian Biological Resources Study (ABRS) National Taxonomy Research Grant Programme (NTRGP), Grant Number CT215-14. DCH is supported by a Moreton Bay Research Station scholarship in partnership with Sibelco Australia. Collection within Moreton Bay was part of a larger effort to characterise the metazoan parasite fauna of fishes from that region, funded by an ABRS Grant (RF215-40) awarded to SCC and THC. Collection in Japan was funded by an Australian Society for Parasitology (ASP) Network Researcher Exchange, Training and Travel Award grant to SCC.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This study was conducted in compliance with all institutional, national and international guidelines on the care and use of animals.
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