The life cycle of Paracardicoloides yamagutii Martin, 1974 (Digenea: Sanguinicolidae)

The sanguinicolids Paracardicoloides yamagutii Martin, 1974 and Plethorchis acanthus Martin, 1975 were obtained from their definitive hosts, Anguilla reinhardtii Steindachner and Mugil cephalus Linnaeus (respectively) in the tributaries of the Brisbane River, Queensland, Australia. Two putative sanguinicolid cercariae were collected from a hydrobiid gastropod, Posticobia brazieri Smith, in the same waters. The two cercariae differ markedly in size and the form of their sporocysts. Both putative cercariae develop in the digestive gland of Po. brazieri. The ITS2 rDNA region from these sanguinicolids and a Clinostomum species (utilised as an outgroup due to the close morphological similarities between the cercarial stages of the Clinostomidae and the Sanguinicolidae) were sequenced and aligned. Comparison of the ITS2 sequences showed one cercaria to be that of P. yamagutii. This is the first sanguinicolid life history determined by a molecular method. P. yamagutii is the fourth sanguinicolid known to utilise a freshwater hydrobiid gastropod as its intermediate host. ITS2 rDNA is effective in distinguishing sanguinicolids at the species level.

Chaulioleptos haywardi n. gen., n. sp (Digenea : Sanguinicolidae) from Filimanus heptadactyla (Perciformes : Polynemidae) of Moreton Bay, Australia

Here we describe the first Species of sanguinicolid blood fluke (Trematoda: Digenea) from a polynemid fish. Chaulioleptos haywardi n. gen., n. sp. is described from Filimanus heptadacryla Cuvier, 1829 (Perciformes: Polynemidae), the sevenfinger threadfin from Sandgate, Moreton Bay (southeast Queensland, Australia). Chaidioleptos haywardi differs from existing sanguinicolid genera in the combined possession of the following 7 characters: 2 testes, an entirely postovarian uterus, a uterine chamber, separate genital pores, an H-shaped intestine with abbreviated anterior caeca, tegumental spines in incomplete ventromarginal transverse rows that are continuous along the length of the body, and vitelline follicles that are tightly compacted and subsequently appear to form a solid branching mass occupying the area anterior to intestinal bifurcation and extending posteriorly to the level of the posterior margin of the anterior testis. Chaulioleptos haywardi is most closely related to Paracardicola Martin, 1960 and Adelomyllos Nolan and Cribb, 2004.

An exceptionally rich complex of Sanguinicolidae von Graff, 1907 (Platyhelminthes : Trematoda) from Siganidae, Labridae and Mullidae (Teleostei : Perciformes) from the Indo-West Pacific Region

We describe an unprecedented radiation of sanguinicolid blood flukes ( Digenea: Sanguinicolidae) from two species of Labridae (Choerodon venustus and C. cauteroma), seven species of Mullidae (Mulloidichthys vanicolensis, Parupeneus barberinoides, P. barberinus, P. bifasciatus, P. cyclostomus, P. indicus and P. multifasciatus) and ten species of Siganidae (Siganus argenteus, S. corallinus, S. doliatus, S. fuscescens, S. lineatus, S. margaritiferus, S. puellus, S. punctatus, S. virgatus and S. vulpinus) from sites off Australia and Palau. The flukes were morphologically similar in having the combination of a long thread-like body, tegumental spines in lateral transverse rows, a vestigial oral sucker bearing concentric rows of fine spines, an H-shaped intestine, a cirrussac, a notch level with the male genital pore, a lateral or post-ovarian uterus, a uterine chamber and separate genital pores. These species are divided into two genera on the basis of testis number. Sanguinicolids from Siganus fuscescens have a single large testis between the intestinal bifurcation and the ovary and are placed in Ankistromeces Nolan & Cribb, 2004. Species from the remaining nine species of Siganidae, Labridae and Mullidae are placed in Phthinomita n. g.; these species have two testes, the anterior testis being large and between the intestinal bifurcation and the ovary whereas the small posterior testis is at the posterior end of the body and appears rudimentary or degenerate and probably non-functional. The second internal transcribed spacer (ITS2) of ribosomal DNA ( rDNA) from 29 host/parasite/location combinations (h/p/l) was sequenced together with that of Ankistromeces mariae Nolan & Cribb, 2004 for comparison. From 135 samples we found 19 distinct genotypes which were interpreted as representing at least that many species. Replicate sequences were obtained for 25 of 30 h/p/l combinations ( including A. mariae); there was no intraspecific variation between replicates sequences for any of these. Interspecific variation ranged from 1 - 41 base differences (0.3 - 12.7% sequence divergence). The 19 putative species were difficult to recognise by morphological examination. We describe 13 new species; we do not describe (= name) six species characterised solely by molecular sequences and three putative species for which morphological data is available but for which molecular data is not. We have neither morphological nor molecular data for sanguinicolids harboured in five hosts species ( Siganus margaritiferus, S. puellus, Choerodon cauteroma, Parupeneus indicus and P. multifasciatus) in which we have seen infections. Where host species were infected in different localities they almost always harboured distinct species. Some host species ( for example, S. argenteus and S. lineatus from Lizard Island) harboured two or three species in a single geographical location. This suggests that, for parts of this system, parasite speciation has outstripped host speciation. Distance analysis of ITS2 showed species from each host family ( Siganidae, Mullidae and Labridae) did not form monophyletic clades to the exclusion of species from other host families. However, a host defined clade was formed by the sequences from sanguinicolids from S. fuscescens.

Two new blood flukes (Digenea: Sanguinicolidae) from epinephelinae (Perciformes: Serranidae) of the Pacific Ocean

Pearsonellum pygmaeus n. sp. is described from Cromileptes altivelis (Serranidae), the Barramundi Cod, from Heron Island (southern Great Barrier Reef) and Lizard Island (northern Great Bat-Her Reef). This new species differs from Pearsonellum eorventum (type and only species) in the combination of smaller overall body size, the relative distance of the brain from the anterior end, the relative lengths of both the oesophagus and the testis, the degree to which the testis extends outside the intercaecal field, the shape of the testis, the shape and size of the ovary and the extent to which the uterzus loops around the ovary. There are in addition, 20 base pair differences between the ITS2 rDNA sequence of P. pygmaeus n. sp. and that of P corventum. Three new host records for P. corventum are reported. Adelomyllos teenae n. g., n. sp. is described from Epinephelus coioides (Serranidae), the Estuary Cod, from Moreton Bay, southeast Queensland. The new genus differs from the 22 other sanguinicolid genera in the combined possession of two testes, a cirrus-sac, separate genital pores, a post-ovarian uterus and an H-shaped intestine. A. teenae n. sp. is the third sanguinicolid described from the Epinephelinae. Sanguinicolids have now been reported from 11 species of Serranidae. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

Sanguinicola maritimus n. sp (Digenea : Sanguinicolidae) from Labridae (Teleostei : Perciformes) of southern Australian waters

A new species of Sanguinicola Plehn, 1905 is described from the marine teleosts Notolabrus parilus (Richardson) and N. tetricus (Richardson) (Perciformes: Labridae) from Western Australian and Tasmanian waters. This host distribution is strikingly anomalous; however, the present material fulfils the morphological criteria of Sanguinicola. S. maritimus n. sp. differs from previously described species in having the combination of a body 1,432-1,701 mu m long, the oesophagus 18.3-21.7% of the body length, the testis occupying 42.8-52.3% of the body length, an oviducal seminal receptacle and Mehlis' gland present, ovoid eggs, and vitelline follicles that extend anteriorly past the nerve commissure, laterally past the lateral nerve chords and posteriorly to the anterior margin of the cirrus-sac. S. maritimus also lacks a protrusible anterior proboscis. It also differs in the combination of host and geographical location, being the first Sanguinicola species from a marine teleost and the first from Australian waters.

Cardicola Short, 1953 and Braya n. gen. (Digenea : Sanguinicolidae) from five families of tropical Indo-Pacific fishes

A survey of Pacific coral reef fishes for sanguinicolids revealed that two species of Lutjanidae (Lutjanus argentimaculatus, L. bohar), six species of Siganidae (Siganus corallinus, S. fuscescens, S. lineatus, S. margaritiferus, S. punctatus, S. vulpinus), seven species of Chaetodontidae (Chaetodon aureofasciatus, C. citrinellus, C. flavirostris, C. lineolatus, C. reticulatus, C. ulietensis, C. unimaculatus), three species of Scombridae (Euthynnus affinis, Scomberomorus commerson, S. munroi) and three species of Scaridae (Chlorurus microrhinos, Scarus frenatus, S. ghobban) were infected with morphologically similar sanguinicolids. These flukes have a flat elliptical body, a vestigial oral sucker, a single testis, separate genital pores and a post-ovarian uterus. However, these species clearly belong in two genera based on the position of the testis and genital pores. Sanguinicolids from Lutjanidae, Siganidae, Chaetodontidae and Scombridae belong in Cardicola Short, 1953; the testis originates anteriorly to, or at the anterior end of, the intercaecal field and does not extend posteriorly to it, the male genital pore opens laterally to the sinistral lateral nerve chord and the female pore opens near the level of the ootype ( may be anterior, lateral or posterior to it) antero-dextral to the male pore. Those from Scaridae are placed in a new genus, Braya; the testis originates near the posterior end of the intercaecal field and extends posteriorly to it, the male pore opens medially at the posterior end of the body and the female pore opens posterior to the ootype, antero-sinistral to the male pore. The second internal transcribed spacer (ITS2) of ribosomal DNA from these sanguinicolids and a known species, Cardicola forsteri Cribb, Daintith & Munday, 2000, were sequenced, aligned and analysed to test the distinctness of the putative new species. Results from morphological comparisons and molecular analyses suggest the presence of 18 putative species; 11 are described on the basis of combined morphological and molecular data and seven are not because they are characterised solely by molecular sequences or to few morphological specimens (n= one). There was usually a correlation between levels of morphological and genetic distinction in that pairs of species with the greatest genetic separation were also the least morphologically similar. The exception in this regard was the combination of Cardicola tantabiddii n. sp. from S. fuscescens from Ningaloo Reef ( Western Australia) and Cardicola sp. 2 from the same host from Heron Island ( Great Barrier Reef). These two parasite/ host/location combinations had identical ITS2 sequences but appeared to differ morphologically ( however, this could simply be due to a lack of morphological material for Cardicola sp. 2). Only one putative species ( Cardicola sp. 1) was found in more than one location; most host species harboured distinct species in each geographical location surveyed ( for example, S. corallinus from Heron and Lizard Islands) and some ( for example, S. punctatus, S. fuscescens and Chlorurus microrhinos) harboured two species at a single location. Distance analysis of ITS2 showed that nine species from siganids, three from scombrids and five from scarids formed monophyletic clades to the exclusion of sanguinicolids from the other host families. Cardicola milleri n. sp. and C. chaetodontis Yamaguti, 1970 from lutjanids and chaetodontids, respectively, were the only representatives from those families that were sequenced. Within the clade formed by sanguinicolids from Siganidae there wasa further division of species; species from the morphologically similar S. fuscescens and S. margaritiferus formed a monophyletic group to the exclusion of sanguinicolids from all other siganid species.

Ankistromeces mariae n. g., n. sp (Digenea : Sanguinicolidae) from Meuschenia freycineti (Monacanthidae) off Tasmania

Ankistromeces mariae n. g., n. sp. is described from Meuschenia freycineti (Monacanthidae), the six-spined leatherjacket, from off northern Tasmania. The new genus differs from the 21 other sanguinicolid genera in the combination of the anteriorly intercaecal and posteriorly post-caecal single testis, the presence of a cirrus-sac, the absence of an auxiliary external seminal vesicle, separate genital pores, the typically post-ovarian uterus and the H-shaped intestine. A. mariae is the first sanguinicolid to be reported from a monacanthid fish.

First report of intramolluscan stages of a gorgoderid digenean from a marine bivalve

A survey of bivalves from Heron Island on the Great Barrier Reef, Australia, revealed a novel digenean infection in Lioconcha castrensis (Bivalvia: Veneridae). The cercaria has oral and ventral suckers, a dorsoventrally orientated stylet embedded in the oral sucker, penetration glands, and a large tail that is inflated at its base. This morphology is broadly consistent with that of previously described gorgoderid cercariae. Partial large subunit ribosomal RNA gene (D1-D3 domains) was sequenced and aligned with sequences from other gorgoderids and related families. Phylogenetic analysis also suggests that the species belongs to the Gorgoderinae. To our knowledge, this is the first report of a gorgoderid from a marine bivalve.

Patterns of digenean parasitism of bivalves from the Great Barrier Reef and associated waters

Digenean parasites of marine bivalves are relatively poorly known, particularly in Australia. We surveyed 2256 bivalve individuals ( 47 species, 17 families) from Queensland marine waters incorporating south-east Queensland, Heron Island ( southern Great Barrier Reef) and Lizard Island ( northern Great Barrier Reef). Infections of trematode species from three families, Bucephalidae, Gorgoderidae and Monorchiidae, were found. Overall prevalence of infection was 2.3%. The Bucephalidae was the most commonly found family; 11 species were found in Tellinidae, Ostreidae, Isognomonidae and Spondylidae - the latter two previously unknown as hosts for bucephalids. A single gorgoderid infection was found in a venerid, Lioconcha castrensis. Five species of monorchiids were found from Tellinidae and Lucinidae. All infections are new host/parasite records. No infections were found in 35 of the 47 bivalve species sampled. The generally low prevalence of infection by digeneans of bivalves suggests that it is unlikely that any of the species reported here are seriously damaging to bivalve populations in these waters. We deduce that, at best, we have some life-cycle information but no actual identifications for 10% of the species of trematodes that infect bivalves of Queensland marine waters.

The use and implications of ribosomal DNA sequencing for the discrimination of digenean species

In just over a decade, the use of molecular approaches for the recognition of parasites has become commonplace. For trematodes, the internal transcribed spacer region of ribosomal DNA (ITS rDNA) has become the default region of choice. Here, we review the findings of 63 studies that report ITS rDNA sequence data for about 155 digenean species from 19 families, and then review the levels of variation that have been reported and how the variation has been interpreted. Overall, complete ITS sequences (or ITS1 or ITS2 regions alone) usually distinguish trematode species clearly, including combinations for which morphology gives ambiguous results. Closely related species may have few base differences and in at least one convincing case the ITS2 sequences of two good species are identical. In some cases, the ITS1 region gives greater resolution than the ITS2 because of the presence of variable repeat units that are generally lacking in the ITS2. Intraspecific variation is usually low and frequently apparently absent. Information on geographical variation of digeneans is limited but at least some of the reported variation probably reflects the presence of multiple species. Despite the accepted dogma that concerted evolution makes the individual representative of the entire species, a significant number of studies have reported at least some intraspecific variation. The significance of such variation is difficult to assess a posteriori, but it seems likely that identification and sequencing errors account for some of it and failure to recognise separate species may also be significant. Some reported variation clearly requires further analysis. The use of a yardstick to determine when separate species should be recognised is flawed. Instead, we argue that consistent genetic differences that are associated with consistent morphological or biological traits should be considered the marker for separate species. We propose a generalised approach to the use of rDNA to distinguish trematode species.