Two new species of threadlike blood flukes (Aporocotylidae), with a molecular revision of the genera Ankistromeces Nolan & Cribb, 2004 and Phthinomita Nolan & Cribb, 2006.

Ankistromeces Nolan & Cribb, 2004 and Phthinomita Nolan & Cribb, 2006 are sister genera of threadlike blood flukes (Trematoda: Aporocotylidae) infecting teleost fishes of the tropical Indo-west Pacific. Here, we report new collections of these genera from Australia, Indonesia, and Japan. A new species of Ankistromeces, Ankistromeces kawamurai n. sp., is described from Siganus spinus (Linnaeus) off Okinawa, Japan, and a new species of Phthinomita, Phthinomita abdita n. sp., from Choerodon cephalotes (Castelnau), in Moreton Bay, Australia; the new species are morphologically cryptic within their respective genera and are delineated by molecular and ecological data. Ankistromeces olsoni Nolan & Cribb, 2006 is reported from Siganus fuscescens (Houttuyn) off Heron Island (southern Great Barrier Reef), Lizard Island (northern Great Barrier Reef), and Okinawa and Wakayama Prefectures, Japan and from Siganus spinus (Linnaeus) from off Bali, Indonesia. Ankistromeces mariae Nolan & Cribb, 2004 is re-reported from the type-host, Meuschenia freycineti (Quoy & Gaimard), from a new location, Gypsy Bay, Tasmania. Phthinomita poulini Nolan & Cribb, 2006 is re-reported from its type-locality, Lizard Island, from a range of mullids, including five new host species, and its range is extended to include Moreton Bay. Phthinomita symplocos Nolan & Cribb, 2006 is reported from Bali and P. hallae Nolan & Cribb, 2006, P. jonesi Nolan & Cribb, 2006, P. littlewoodi Nolan & Cribb, 2006, and P. munozae Nolan & Cribb, 2006 are each re-reported from their type-host and type-localities. New cox1 mtDNA data were generated for all known species of these two genera from new and archival material. Analyses of these data enabled an evaluation of all known Phthinomita species; P. robertsthomsoni Nolan & Cribb, 2006 is synonymised with P. adlardi Nolan & Cribb, 2006, and P. brooksi Nolan & Cribb, 2006 is synonymised with P. sasali Nolan & Cribb, 2006. We highlight the failure of ITS2 data to delineate closely related aporocotylid species. In contrast, cox1 sequence data are proving reliable and effective in this context and we recommend their incorporation in future studies of blood fluke taxonomy.

A complex of the blood fluke genus Psettarium (Digenea: Aporocotylidae) infecting tetraodontiform fishes of east Queensland waters.

Seven species of Psettarium (Digenea: Aporocotylidae), including four new species, are reported from tetraodontiform fishes from off coastal east Queensland. Psettarium pandora n. sp. infects the yellow boxfish, Ostracion cubicus (Ostraciidae), the first known aporocotylid to infect this family of fishes. Three new species are reported from pufferfishes of the genus Arothron (Tetraodontidae): Psettarium yoshidai n. sp. infects the map puffer (Arothron mappa), Psettarium hustoni n. sp. infects the black-spotted puffer (A. nigropunctatus) and Psettarium martini n. sp. infects the starry puffer (A. stellatus). We also report three species of Psettarium from Australian waters for the first time. Paracardicola hawaiensis Martin, 1960, the sole species of Paracardicola, is redescribed based on specimens collected from the type-host, the stars-and-stripes puffer, Arothron hispidus. Paracardicola is synonymised with Psettarium and P. hawaiensis is recombined as Psettarium hawaiiense (Martin, 1960) n. comb. Psettarium pulchellum Yong, Cutmore, Bray, Miller, Semarariana, Palm & Cribb, 2016, described from the narrow-lined puffer (Arothron manilensis) from off Bali, Indonesia, is reported from the same fish species at two locations on the Queensland coast, significantly extending the range of this species. Psettarium nolani (Bray, Cribb & Littlewood, 2013), originally described from French Polynesia, is reported from A. hispidus, A. manilensis and A. stellatus, representing both new host and locality records for this species. Molecular phylogenetic analysis shows these species to all be closely related, such that they cannot be considered to represent separate genera despite their differing morphology. Analysis of 28S sequence data for Psettarium anthicum Bullard & Overstreet, 2006, a non-tetraodontiform-infecting species, shows it to be distantly related to all other species of Psettarium for which sequence data are available. The species is re-assigned to a new genus, Cardallagium n. gen., as Cardallagium anthicum (Bullard & Overstreet, 2006) n. comb. We think it likely that the host range of species of Psettarium is limited to tetraodontiform fishes. We assessed the infection biology of two species, P. nolani and P. hawaiiense n. comb. infecting A. hispidus, using histology to assess the pathways of egg release for these species. Eggs of both species were observed in both circulatory and visceral organs of infected hosts, often in high numbers. Eggs were seen trapped in the mucosal layer of the intestine and, in rare instances, causing lesions in the laminar epithelium, providing the strongest evidence yet that they pass through the gut wall and escape the host via the faeces. Lastly, we discuss the biogeographical implications of our findings, noting that some Psettarium species now show very wide geographical distributions.

Three new species of blood flukes (Digenea: Aporocotylidae) infecting pufferfishes (Teleostei: Tetraodontidae) from off Bali, Indonesia.

We describe three new species of blood flukes (Aporocotylidae) and propose their classification within the genus Psettarium Goto & Ozaki, 1929. All three species were collected from the circulatory systems of pufferfishes caught off Bali, central Indonesia. Psettarium pulchellum n. sp. was found in the gills of both the narrow-lined puffer (Arothron manilensis de Procé) and the spiny blaasop (Tylerius spinosissimus Regan), while P. ogawai n. sp. and P. jimbaranense n. sp. were found in the gills of the reticulated puffer (Arothron reticularis Bloch & Schneider). The morphological characteristics of these taxa necessitated emendation of the diagnosis for the genus Psettarium, to accommodate the presence of an oral sucker, multiple or entirely post-caecal testes and a degenerate posterior testis. Features such as proportion of body length occupied by the oesophagus, and posterior caeca being ≥7× the length of anterior caeca, are no longer regarded as useful genus-level characters. Additionally, Sasala nolani is reassigned to this genus as Psettarium nolani n. comb. In phylogenetic analyses of the 28S and ITS2 rDNA regions, all three new taxa form a well-supported clade, together with Psettarium sinense and Psettarium nolani n. comb., the two other species of tetraodontid-infecting aporocotylids for which comparative rDNA data were available. The short branch lengths within this clade, despite dramatic morphological differences between the five species, suggest that rapid morphological diversification has occurred among the tetraodontid-infecting aporocotylids. The genus Psettarium has long been considered problematic. Further commentary is given on the history of this genus and how the issues presented might be resolved.

The ghost of parasites past: eggs of the blood fluke Cardicola chaetodontis (Aporocotylidae) trapped in the heart and gills of butterflyfishes (Perciformes: Chaetodontidae) of the Great Barrier Reef.

We explored the distribution of Cardicola chaetodontis in chaetodontid fishes from the Great Barrier Reef. We found just four infections of adult worms in 238 individuals of 26 chaetodontid species. By contrast, eggs were present in hearts of 75 fishes (31·5%) and 19 of 26 chaetodontid species (all Chaetodon species). In 10 cases eggs contained moving miracidia; all the others were dead and degenerating. Eggs were sought in the gills of 51 individual fish. There were 17 cases of eggs being present in gills while present in the heart, but also 13 cases where eggs were absent from gills but present in the heart, suggesting that eggs remain longer in heart tissue than in gills. ITS2 rDNA sequences from two adult worms and eggs extracted from gills of five fishes (all different species) were identical to previously reported sequences of C. chaetodontis except for a single base-pair difference in two samples. We conclude that aporocotylid eggs trapped in fish heart tissues may inform understanding of the distributions and host ranges of aporocotylids, especially where adult prevalence is low. The low host-specificity of C. chaetodontis contrasts with higher specificity of trematodes of chaetodontids that have trophic transmission.