High-intensity cardiac infections of Phthinomita heinigerae n. sp. (Digenea: Aporocotylidae) in the orangelined cardinalfish, Taeniamia fucata (Cantor), off Heron Island on the Great Barrier Reef
Graphical abstract
Introduction
The Aporocotylidae Odhner, 1912 (Platyhelminthes: Trematoda) is a family of parasitic flatworms that has, in recent years, emerged as an increasingly rich, and morphologically diverse, group of digeneans. There are currently 142 accepted species from 37 genera [1], [2], [3], [4], [5], which infect a broad range of fishes. Species from seven genera have been recorded from fishes of the Great Barrier Reef (GBR): Ankistromeces Nolan & Cribb, 2004 (see [6]); Braya Nolan & Cribb, 2006 (see [7]); Cardicola Short, 1953 (see [7], [8], [9]); Pearsonellum Overstreet & Køie, 1989 (see [10], [11]); Plethorchis Martin, 1975 (see [12]); Phthinomita Nolan & Cribb, 2006 (see [6]); and, Rhaphidotrema Yong & Cribb, 2011 (see [13]). Phthinomita is the most complex of these, consisting of 11 recognised species and numerous undefined ‘types’ represented by a unique DNA sequence or single morphological specimen. Unlike most aporocotylids, which are typically characterised by a flat body that may be linear, elliptical, or lanceolate, species of Phthinomita are long and thread-like. As adults, they wind through the intertrabecular spaces of the ventricle of their hosts, which to date include species of labrid (wrasses), mullid (goatfishes), and siganid (rabbitfishes or spinefoots). Due to the extreme morphological similarity that exists among species of Phthinomita, an effect most likely due to their site of infection, this group is best described as a complex of cryptic species. As such, genetic data are required to enhance traditional methods of species characterisation (i.e. microscopic and morphological examination, host and geographic distribution) and the delineation of species is only possible though this integrated approach (see [14]). Here, we report Phthinomita heinigerae n. sp. from the ventricle of the orangelined cardinalfish, Taeniamia fucata (Cantor) (Perciformes: Apogonidae), collected during the CReefs project from 2009 to 2012 (http://www.aims.gov.au/creefs/field-program.html), from off Heron Island on the southern GBR.
Section snippets
Sample collection
Between 2009 and 2012, 22 species of apogonid from nine genera (Table 1) were collected from five sites off Heron Island on the southern GBR (23.4420° S, 151.9140° E), eight sites off Lizard Island on the northern GBR (14.6680° S, 145.4617° E), and from seven sites on Ningaloo Reef, off Western Australia (22.5625, 113.810278). Apogonid fishes were stored in an 80 l container before being euthanised by an overdose of clove oil, in strict accordance with the Queensland Museum's Animal Ethics
Aporocotylid prevalence and specificity
The hearts of 19 of the 724 apogonid specimens examined (2.6%) were infected with thread-like aporocotylids (see Table 1). All 19 infected individuals were identified as the orangelined cardinalfish, T. fucata, which were all collected from a single site in the Heron Island lagoon (19/20; 95% prevalence); none of the 27 T. fucata specimens collected from two sites off Lizard Island (Casuarina beach and Turtle beach) were infected.
Morphology
Class Trematoda Rudolphi, 1808
Subclass Digenea Carus, 1863
Order
Taxonomy
Phthinomita heinigerae n. sp. can be differentiated from all current species of Phthinomita by the combined possession of a body 2977–3539 long and 16.5–22.4 times longer than wide, an anterior testis that is 6.2–8.2 times longer than wide and 8.3–13.0 times longer than the posterior testis, a posterior testis whose width is 35–56% of the body width, and having the ovary positioned 11–13% of the body length from the posterior end (see Table 2). In addition, P. heinigerae n. sp. differs further
Conflict of interest
The authors declare they have no competing interests.
Acknowledgements
This study was funded by, and is a contribution from, the Australian node of the CReefs global research initiative (grant number: 209/29), a project generously sponsored by BHP Billiton in partnership with The Great Barrier Reef Foundation, the Australian Institute of Marine Science, the Australian Biological Resources Study, and the Alfred P. Sloan Foundation. CReefs is a field program of the Census of Marine Life. We gratefully thank the staff of the Heron and Lizard Island Research Stations
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