Paradiscogaster flindersi and P. oxleyi n. sp. (Digenea: Faustulidae): overlapping host and geographical distributions in corallivore chaetodontid fishes in the tropical Indo-west Pacific

A paradigm for the recognition of cryptic trematode species in tropical Indo-west Pacific fishes: the problematic genus Preptetos (Trematoda: Lepocreadiidae)

Molecular data have transformed approaches to trematode taxonomy by providing objective evidence for the delineation of species. However, although the data are objective, the interpretation of these data regarding species boundaries is subjective, especially when different markers conflict. Conserved markers can lead to an underestimation of richness and those used for finer species delineation have the capacity to inflate species recognition, perhaps unrealistically. Here we examine molecular and morphological evidence for species recognition in an especially confusing system, the lepocreadiid genus Preptetos Pritchard, 1960 in acanthuriform fishes of the tropical Indo-west Pacific. We consider species boundaries within this genus based on combined data (ITS2 and 28S rDNA; cox1 mtDNA and morphometrics) for substantial new collections. Delineation of species using only morphological data suggest fewer species than analysis of the sequence data; the latter suggests the presence of potential cryptic species and analysis of different markers suggests the presence of differing numbers of species. We conclude that an integrative interpretation creates the most satisfying taxonomic hypothesis. In the light of the new data, we have chosen and propose a model of trematode species recognition that demands reciprocal monophyly in the most discriminating available molecular marker plus distinction in morphology or host distribution. By invoking these criteria, we distinguish eight species in our new tropical Indo-west Pacific collections. Six of these are new (Preptetos allocaballeroi n. sp., Preptetos paracaballeroi n. sp., Preptetos pearsoni n. sp., Preptetos prudhoei n. sp., Preptetos quandamooka n. sp. and Preptetos zebravaranus n. sp.) and we continue to recognise Preptetos cannoni Barker, Bray & Cribb, 1993 and Preptetos laguncula Bray and Cribb, 1996. Notably; two of the new species, P. allocaballeroi n. sp. and P. paracaballeroi n. sp., are morphologically cryptic relative to each other. Our criteria lead us to recognise, as species, populations with unvarying morphology and similar host relationships but which may have a complex population structure over their range. In our view, this paradigm has the capacity to render tractable the interpretation of the species status of the huge trematode fauna of the tropical Indo-west Pacific.

Intermediate host switches drive diversification among the largest trematode family: evidence from the Polypipapiliotrematinae n. subf. (Opecoelidae), parasites transmitted to butterflyfishes via predation of coral polyps

Podocotyloides stenometra Pritchard, 1966 (Digenea: Opecoelidae) is the only trematode known to infect anthozoan corals. It causes disease in coral polyps of the genus Porites Link (Scleractinia: Poritidae) and its life-cycle depends on ingestion of these polyps by butterflyfishes (Perciformes: Chaetodontidae). This species has been reported throughout the Indo-Pacific, from the Seychelles to the Galápagos, but no study has investigated whether multiple species are involved. Here, we recollect P. stenometra from its type-host and type-locality, in Hawaiian waters, and describe four new species from examination of 768 butterflyfishes from French Polynesia. On the basis of morphology, phylogeny and life-history, we propose Polypipapiliotrema Martin, Cutmore & Cribb n. gen. and the Polypipapiliotrematinae Martin, Cutmore & Cribb n. subf., for P. stenometra (Pritchard) n. comb., P. citerovarium Martin, Cutmore & Cribb n. sp., P. hadrometra Martin, Cutmore & Cribb n. sp., P. heniochi Martin, Cutmore & Cribb n. sp., and P. ovatheculum Martin, Cutmore & Cribb n. sp. Given the diversity uncovered here and the ubiquity, abundance and diversity of butterflyfishes on coral reefs, we predict that Polypipapiliotrema will prove to comprise a rich complex of species causing disease in corals across the Indo-Pacific. The unique life-cycle of these taxa is consistent with phylogenetic distinction of the group and provides evidence for a broader basis of diversification among the family. We argue that life-cycle specialisation, in terms of adoption of disparate second intermediate host groups, has been a key driver of the diversification and richness of the Opecoelidae, the largest of all trematode families and the group most frequently encountered in coral reef fishes.

Lepotrema Ozaki, 1932 (Lepocreadiidae: Digenea) from Indo-Pacific fishes, with the description of eight new species, characterised by morphometric and molecular features

We review species of the genus Lepotrema Ozaki, 1932 from marine fishes in the Indo-West Pacific. Prior to the present study six species were recognised. Here we propose eight new species on the basis of combined morphological and molecular analysis: Lepotrema acanthochromidis n. sp. ex Acanthochromis polyacanthus from the Great Barrier Reef (GBR); Lepotrema hemitaurichthydis n. sp. ex Hemitaurichthys polylepis and H. thompsoni from Palau and French Polynesia; Lepotrema melichthydis n. sp. ex Melichthys vidua from Palau and the GBR; Lepotrema amansis n. sp. ex Amanses scopas from the GBR; Lepotrema cirripectis n. sp. ex Cirripectes filamentosus, C. chelomatus and C. stigmaticus from the GBR; Lepotrema justinei n. sp. ex Sufflamen fraenatum from New Caledonia; Lepotrema moretonense n. sp. ex Prionurus microlepidotus, P. maculatus and Selenotoca multifasciata from Moreton Bay; and Lepotrema amblyglyphidodonis n. sp. ex Amblyglyphidodon curacao and Amphipron akyndynos from the GBR. We also report new host records and provide novel molecular data for two known species: Lepotremaadlardi Bray, Cribb & Barker, 1993 and Lepotremamonile Bray & Cribb, 1998. Two new combinations are formed, Lepotrema cylindricum (Wang, 1989) n. comb. (for Preptetos cylindricus) and Lepotrema navodonis (Shen, 1986) n. comb. (for Lepocreadium navodoni). With the exception of a handful of ambiguous records, the evidence is compelling that the host-specificity of species in this genus is overwhelmingly oioxenous or stenoxenous. This renders the host distribution in three orders and ten families especially difficult to explain as many seemingly suitable hosts are not infected. Multi-loci molecular data (ITS2 rDNA, 28S rDNA and cox1 mtDNA) demonstrate that Lepotrema is a good generic concept, but limited variability in sequence data and differences in phylogenies produced for different gene regions make relationships within the genus difficult to define.

Four new species of Paradiscogaster Yamaguti, 1934 (Digenea: Faustulidae) from batfishes (Perciformes: Ephippidae) on the Great Barrier Reef, Australia

Examination of three species of batfishes (Teleostei: Epphippidae) from off Lizard and Heron Islands on the Great Barrier Reef led to the discovery of specimens of the trematode genus Paradiscogaster Yamaguti, 1934 (Digenea: Faustulidae). Morphological analysis demonstrated that the new specimens represented four morphotypes which we interpret to be new species: Paradiscogaster martini n. sp., P. vichovae n. sp. and P. brayi n. sp. from Platax orbicularis (Forsskål) and P. pinnatus (Linnaeus) off Lizard Island, and P. nitschkei n. sp. from P. teira (Forsskål) off Heron Island. Published material was re-examined and the specimens identified as P. chaetodontis okinawensis Yamaguti, 1971 from P. pinnatus from Okinawa, Japan, actually represent the new species P. brayi n. sp., demonstrating that some species of Paradiscogaster have wide geographical distributions. ITS2 rDNA data for the four morphotypes differ by 4-39 base pairs confirming the delineation of the four species proposed. A feature of this study is the recognition of Platax spp. as an important host group for Paradiscogaster, with the new species placing them as the second richest host group for these parasites after the Chaetodontidae.

Gill monogenean communities (Platyhelminthes, Monogenea, Dactylogyridae) of butterflyfishes from tropical Indo-West Pacific Islands

We studied the monogenean communities of 34 species of butterflyfish from the tropical Indo-West Pacific, identifying 13 dactylogyrid species (including two species that are presently undescribed). Monogenean assemblages differed significantly between host species in terms of taxonomic structure, intensity and prevalence. Parasite richness ranged from 0 (Chaetodon lunulatus) to 11 (C. auriga, C. citrinellus and C. lunula). Host specificity varied between the dactylogyrids species, being found on 2–29 of the 34 chaetodontid species examined. Sympatric butterflyfish species were typically parasitized by different combinations of dactylogyrid species, suggesting the existence of complex host–parasite interactions. We identified six clusters of butterflyfish species based on the similarities of their dactylogyrid communities. Dactylogyrid richness and diversity were not related to host size, diet specialization, depth range or phylogeny of butterflyfish species. However, there was a weak positive correlation between monogenean richness and diversity and host geographical range. Most communities of dactylogyrids were dominated by Haliotrema aurigae and H. angelopterum, indicating the importance of the genus Haliotrema in shaping monogenean communities of butterflyfishes. This study casts light on the structure of the monogenean communities of butterflyfishes, suggesting that the diversity and complexity of community structures arises from a combination of host species-specific parameters.

A review of the genus Antorchis Linton, 1911 (Trematoda: Faustulidae) from Indo-Pacific fishes with the description of a new species

Species of the faustulid genus Antorchis Linton, 1911 of the tropical Indo-West Pacific are reviewed. We recognise five species in the region, including a novel form. Antorchis nasonis n. sp. is described from Naso annulatus (Quoy & Gaimard) and N. tonganus (Valenciennes) on the southern Great Barrier Reef (GBR). We interpret specimens reported from Naso hexacanthus (Bleeker) from Japan as the same species. This species appears to be the only faustulid known from acanthurid fishes and differs from all other species in the genus in having the prominent dorsal genital invagination close to the posterior end of the body. In addition, new host and locality records are reported for two described species of Antorchis, A. pomacanthi (Hafeezullah & Siddiqi, 1970) and A. tsushimaensis (Machida, 1971). The wide distribution of A. pomacanthi was further demonstrated by the generation of identical ITS2 rDNA sequences for specimens from Ningaloo Reef off Western Australia, off Lizard and Heron Islands (GBR) and off New Caledonia, localities separated by up to 5,300 km. The host-specificity of the genus is considered.

Pseudobacciger cheneyae n. sp. (Digenea: Gymnophalloidea) from Weber's chromis (Chromis weberi Fowler & Bean) (Perciformes: Pomacentridae) at Lizard Island, Great Barrier Reef, Australia

A new species of digenean, Pseudobacciger cheneyae n. sp., is described from the intestines of Weber's chromis (Chromis weberi Fowler & Bean) from off Lizard Island, Great Barrier Reef, Australia. This species differs from the three described species of Pseudobacciger Nahhas & Cable, 1964 [P. cablei Madhavi, 1975, P. harengulae Yamaguti, 1938 and P. manteri Nahhas & Cable, 1964] in combinations of the size of the suckers and the length of the caeca. The host of the present species is a perciform (Family Pomacentridae) which contrasts with previous records of the genus which are almost exclusively from clupeiform fishes. The genus Pseudobacciger is presently recognised within the family Faustulidae (Poche, 1926) but phylogenetic analyses of 28S and ITS2 rDNA show that the new species bears no relationship to species of four other faustulid genera (Antorchis Linton, 1911, Bacciger Nicoll, 1924, Paradiscogaster Yamaguti, 1934 and Trigonocryptus Martin, 1958) but that instead it is nested within the Gymnophalloidea (Odhner, 1905) as sister to the Tandanicolidae (Johnston, 1927). This result suggests that the Faustulidae is polyphyletic.