Dramatic phenotypic plasticity within species of Siphomutabilus n. g. (Digenea: Cryptogonimidae) from Indo-Pacific caesionines (Perciformes: Lutjanidae)

A survey of Indo-Pacific lutjanids of the subfamily Caesioninae revealed the presence of Siphodera gurukun Machida, 1910 and two new cryptogonimid taxa from off Heron and Lizard Islands on the Great Barrier Reef, Australia, Ningaloo Reef, Western Australia and Rasdhoo Atoll, Maldives. A combined morphological and genetic characterisation of these species shows that they form a clade distinct from the type-species of Siphodera Linton, 1910, S. vinaledwardsii (Linton, 1901), and warrants the proposal of a new genus. Here we propose Siphomutabilus n. g. and transfer Siphodera gurukun Machida, 1986 as the type-species, Siphomutabilus gurukun (Machida, 1986) n. comb. Siphodera aegyptensis Hassanine & Gibson, 2005 is transferred to Siphomutabilus as S. aegyptensis (Hassanine & Gibson, 2005) n. comb. based on morphological and ecological similarities. Siphomutabilus raritas n. sp. is described from Caesio cuning (Bloch) off Lizard Island and S. bitesticulatus n. sp. is described from Pterocaesio marri Schultz off Heron Island. The two new species are unique in that they have two testes, making their morphology broadly consistent with that of Metadena Linton, 1910, yet the molecular analyses conducted here indicates that they are unequivocally united with Siphomutabilus gurukun (which has multiple testes) to the exclusion of Metadena lutiani (Yamaguti, 1942), which was sequenced here. The dramatic phenotypic plasticity observed among such closely related species of Siphomutabilus suggests a secondary modification of what is generally considered a robust generic diagnostic character within this and other digenean families, highlighting the need for a combined morphological and molecular diagnostic approach when characterising these taxa. Siphodera Linton, 1910 is amended to include just two species, the type-species S. vinaledwardsii (Linton, 1901) Linton, 1910 and S. cirrhiti Yamaguti, 1970, which are distinguished by their lack of oral spines and multiple testes that are primarily extracaecal. Siphodera ghanensis Fischthal & Thomas, 1968 is considered a species incertae sedis here based on significant morphological and ecological differences compared with species of Siphodera and Siphomutabilus n. g.     

Brain infecting kudoids of Australia's coral reefs, including a description of Kudoa lemniscati n. sp. (Myxosporea: Kudoidae) from Lutjanus lemniscatus (Perciformes: Lutjanidae) off Ningaloo Reef, Western Australia

A survey of the myxosporean fauna of Australian marine fishes revealed the presence of a number of putative species of Kudoidae (Multivalvulida) forming pseudocysts between the outer meningeal layer and the outer surface of the brains of the lutjanids Caesio cuning, Lutjanus carponotatus, Lutjanus ehrenbergii and Lutjanus fulviflamma and the mugilid Liza vaigiensis from Lizard Island on the Great Barrier Reef, Australia and Lutjanus lemniscatus off Ningaloo Reef, Western Australia. Morphometric data combined with Bayesian inference and maximum likelihood analyses of small subunit (SSU) and large subunit (LSU) ribosomal DNA (rDNA) was used for species identification and to explore relationships among these taxa. The brain-infecting taxa examined here formed a well-supported clade to the exclusion of non-brain infecting species in the phylogenetic analyses. The combined diagnostic approach identified an undescribed taxon, Kudoa lemniscati n. sp., from the brain of L. lemniscatus (Perciformes: Lutjanidae) off Ningaloo Reef, Western Australia, which we describe and characterise here. K. lemniscati n. sp. can be distinguished from all other species of Kudoa based on the combination of the distinct tropism for forming pseudocysts in the brain tissue, spores with 7 or 8 equal shell valves and 7 or 8 polar capsules, spore size and the differences in the SSU and LSU rDNA sequence data relative to other kudoids. Kudoa chaetodoni was found in the lutjanids C. cuning and L. carponotatus, expanding the known host range for this species to include chaetodontids and lutjanids. L. ehrenbergii and L. fulviflamma were infected with Kudoa lethrini off Lizard Island, a parasite previously known only from lethrinids. Specimens putatively identified as Kudoa yasunagai from Liza vaigiensis and Lutjanus ehrenbergii were morphologically similar and genetically identical over the SSU rDNA dataset to previously reported specimens, but differed by 4 to 11 nucleotides over the LSU dataset from the remaining isolates examined here. While these data are not definitive, they suggest the presence of a K. yasunagai complex.     

The taxonomic status of <Emphasis Type="Italic">Opegaster</Emphasis> Ozaki, 1928 and the description of four new species of <Emphasis Type="Italic">Opecoelus</Emphasis> Ozaki, 1925 (Digenea: Opecoelidae) from marine teleosts in Australian waters

The similarities between Opecoelus Ozaki, 1925, Coitocaecum Nicoll, 1915, Opegaster Ozaki, 1928 and Paropecoelus Pritchard, 1966 and the difficulty of separating Opecoelus and Opegaster are discussed. It is proposed that Opegaster be reduced to synonymy with Opecoelus and the diagnosis of the latter amended to accommodate both forms. Four new species of Opecoelus are described from marine teleosts in Australian waters. These are Opecoelus woolcockae n. sp. from Acanthopagrus butcheri and A. australis from off South Australia, New South Wales and southern Queensland, O. pomatomi n. sp. from Pomatomus saltatrix off New South Wales, O. crowcrofti n. sp. from Atherinomorus ogilbyi off southern Queensland and O. queenslandicus n. sp. from Apogon fasciatus off southern Queensland. The following new combinations are formed: Opecoelus gonorhynchi (Gavrilyuk, 1979) n. comb., O. elongatus (Yamaguti, 1959) n. comb., O. pentadactylus (Manter, 1940) n. comb., O. apogonichthydis (Yamaguti, 1938) n. comb., O. cameroni (Caballero & Caballero, 1969) n. comb., O. dendrochiri (Yamaguti, 1970) n. comb., O. hawaiiensis (Yamaguti, 1970) n. comb., O. jamunicus (Srivastava, 1968) n. comb., O. longivesiculus (Yamaguti, 1952) n. comb., O. mastacembalii (Harshey, 1937) n. comb., O. mehrii (Harshey, 1937) n. comb., O. synodi (Manter, 1947) n. comb., O. tamori (Yamaguti, 1938) n. comb., O. bothi (Yamaguti, 1970) n. comb., O. caulopsettae (Manter, 1954) n. comb., O. beliyai (Pande, 1937) n. comb., O. brevifistulus (Ozaki, 1928) n. comb., O. cryptocentri (Yamaguti, 1958) n. comb., O. dactylopteri (Yamaguti, 1970) n. comb., O. dermatogenyos (Yamaguti, 1970) n. comb., O. ditrematis (Yamaguti, 1942) n. comb., O. gobii (Yamaguti, 1952) n. comb., O. hippocampi (Shen, 1982) n. comb., O. iniistii (Yamaguti, 1970) n. comb., O. lobulus (Wang, 1977) n. comb., O. macrorchis (Yamaguti, 1938) n. comb., O. parapristipomatis (Yamaguti, 1934) n. comb., O. pritchardae (Overstreet, 1969) n. comb., O. syngnathi (Yamaguti, 1934) n. comb., O. lutiani (Bravo-Hollis & Manter, 1957) n. comb., O. ovatus (Ozaki, 1928) n. comb., O. plotosi (Yamaguti, 1940) n. comb. and O. rectus (Ozaki, 1928) n. comb.; all the new combinations were previously species of Opegaster.     

Evidence for extensive cryptic speciation in trematodes of butterflyfishes (Chaetodontidae) of the tropical Indo-West Pacific

Molecular data from the cytochrome c oxidase subunit I (cox1) mitochondrial DNA gene and the second internal transcribed spacer (ITS2) nuclear rDNA region were used to test the current morphologically-based taxonomic hypothesis regarding species of Monorchiidae (Hurleytrematoides) from chaetodontid and tetraodontid fishes from six sites in the tropical Indo-West Pacific (TIWP): Heron and Lizard Islands off the Great Barrier Reef (GBR, Australia), Moorea (French Polynesia), New Caledonia, Ningaloo Reef (Australia) and Palau. The 16 morphospecies analysed differed from each other by a minimum of 55 bp (9.1%) over the mitochondrial cox1 and 8 bp (1.6%) over the ITS2 DNA regions. For two species, Hurleytrematoides loi and Hurleytrematoides sasali, specimens from the same host species in sympatry differed at levels comparable to those between pairs of distinct morphospecies for both cox1 and ITS2 sequences. We take this as evidence of the presence of combinations of cryptic species; however, we do not propose new species for these taxa because we lack identified morphological voucher specimens. For seven species, Hurleytrematoides coronatum, Hurleytrematoides deblocki, Hurleytrematoides faliexae, H. loi, Hurleytrematoides morandi, H. sasali and Hurleytrematoides sp. A, samples from some combinations of localities had base pair differences that were equal to or greater than differences between some pairs of distinct morphospecies for one or both cox1 and ITS2 sequences. For three species, H. coronatum, H. loi and H. morandi, one haplotype differed from every other haplotype by more than the morphospecies benchmark. In these cases morphological specimens could not be distinguished by morphology. These data suggest extensive cryptic richness in this genus. For the present we refrain from dividing any of the morphospecies. This is because there is a continuum of levels of intra- and interspecific genetic variation in this system, so that distinguishing the two would be largely arbitrary.     

Larval biology of butterflyfishes (Pisces,Chaetodontidae): what do we really know?

Synopsis Relatively little is known of the pelagic portion of the life history of butterflyfishes. Eggs are small (<1 mm), pelagic and hatch in less than 30 hours. Most species pass through a so-called tholichthys larval interval characterized by elaborate, distinctive head spination:Coradion larvae have different head spination. While older chaetodontid larvae can be identified by adult characters, young (preflexion) larvae generally cannot now be identified below family. In tropical plankton studies chaetodontid larvae averaged <0.1% of larvae captured, and occurred in 13% of samples. This rarity is a major hindrance to further work, but is not unexpected in view of adult abundance. Larvae of a few taxa are most abundant in shelf waters, but larvae of many chaetodontid taxa seem to be most abundant in oceanic waters. In either case, waters near reefs have the fewest chaetodontid larvae. Offshore maxima of larvae appear to exist a few kilometers seaward of Great Barrier Reef ribbon reefs. Chaetodontid larvae may prefer the upper portion of the water column. Both size and age at settlement vary widely within the family and the large genusChaetodon, and the latter varies widely within species. Average size at settlement is less than 20 mm and age is less than 40 days. No correlation was found between size and age at settlement. Behaviour and feeding of chaetodontid larvae are essentially unstudied. Chaetodontid larvae seem to be least abundant in winter. The implications of these conclusions are discussed and some suggestions for further research are made. In all areas more work is needed.     

Paralepidapedon ostorhinchi (Korotaeva, 1974) n. comb. (Digenea: Lepocreadiidae) in Oplegnathus woodwardi (Waite) (Teleostei: Perciformes: Oplegnathidae) from off Rottnest Island,Western Australia

The digenean originally designated Lepidapedon (Lepidapedon) ostorhinchi is redescribed from its type-host, Oplegnathus woodwardi [= Ostorhinchus conwaii], from the waters off Western Australia. The discovery of a uroproct indicates that the generic designation is wrong and the worm should be Paralepidapedon ostorhinchi (Korotaeva, 1974) n. comb. It is distinct from its nearest relative, P. hoplognathi (Yamaguti, 1938), in having: a prominent post-oral ring; a distinct oesophagus; short anterior diverticula on the caeca; a long external seminal vesicle, ensheathed in a membrane bound gland-cell mass; and less anteriorly extensive vitellarium.     

Four species of Stephanostomum Looss, 1899 (Digenea: Acanthocolpidae) from Seriola dumerili (Risso) (Teleostei: Carangidae) in the western Mediterranean,including S. euzeti n. sp.

Four species of Stephanostomum are described from various sites in Seriola dumerili from off Corsica, France. S. ditrematis (Yamaguti, 1939), from the stomach, pyloric caeca and duodenum, has 36 circum-oral spines. S. seriolae Yamaguti, 1970 is considered a synonym of S. ditrematis. S. filiforme Linton, 1940, from the mid-intestine, has 43-46 circum-oral spines. S. petimba Yamaguti, 1970, from the rectum, has a 42 circum-oral spines. S. euzeti n. sp. has 49-51 circum-oral spines, and differs from worms with a similar anterior extent of the vitellarium and circum-oral spine number in details of the vitelline distribution and the distances between the gonads. Attention is drawn to the presence in the rectum of S. dumerili of sympatric species differentiated mainly on circum-oral spine number.     

Two new species of Prosorhynchoides (Digenea: Bucephalidae) from Tylosurus crocodilus (Belonidae) from the great barrier reef and French Polynesia

We surveyed 14 individuals of Tylosurus crocodilus Péron & Lesueur 1821 (Belonidae) collected from the waters around Lizard Island and Heron Island, Great Barrier Reef, Queensland, Australia, and the waters around Moorea, French Polynesia. We describe two new species of bucephaline trematodes from them, Prosorhynchoides galaktionovi n. sp. and P. kohnae n. sp. They are morphologically distinct from existing Prosorhynchoides spp., with molecular data from 28S and ITS-2 ribosomal DNA, as well as cox1 mitochondrial DNA, further supporting our morphological findings. Neither species has been observed in other belonid fishes. The new species fall into the clade of species of Prosorhynchoides from belonids previously identified in Australian waters. These findings strengthen the observation that groups of bucephaline species have radiated, at least in part, in tight association with host taxa. There are now five species of Prosorhynchoides known from two belonid species in Australian waters. We, therefore, predict further richness in the nine other belonid species present.     

Revision of the monogenean subfamily Neothoracocotylinae Lebedev, 1969 (Polyopisthocotylea: Thoracocotylidae)

Members of the subfamily Neothoracocotylinae are gastrocotylinean monogeneans on the gills of scombrid fishes of the genera Scomberomorus and Acanthocybium, and reportedly of a coryphaenid fish belonging to the genus Coryphaena. We revise the diagnosis of the subfamily and its two genera and accept only two species as valid. Neothoracocotyle acanthocybii (Meserve, 1938) Hargis, 1956 is known from Acanthocybium solandri throughout the Pacific Ocean and in the western Atlantic. N. coryphaenae (Yamaguti, 1938) Hargis, 1956, known only from a single specimen and described from Coryphaena hippurus in Japan, is synonymised with N. acanthocybii. The sole member of Scomberocotyle, S. scomberomori (Koratha, 1955) Hargis, 1956, infects five species of Scomberomorus in the eastern Pacific Ocean and the western and eastern Atlantic. We record this worm from several new hosts and/or localities, including S. sierra and S. concolor in the eastern Pacific (Mexico to Colombia), S. maculatus and S. cavalla in the western Atlantic (USA to Brazil), and S. tritor in the eastern Atlantic (Sierra Leone to Nigeria).     

Revision of the monogenean subfamily Thoracocotylinae Price, 1936 (Polyopisthocotylea: Thoracocotylidae), with the description of a new species of the genus Pseudothoracocotyla Yamaguti, 1963

Members of the subfamily Thoracocotylinae are gastrocotylid monogeneans of Spanish mackerels (scombrid fishes of the genus Scomberomorus) from warm to warm-temperate seas around the world. We revise the diagnosis of the subfamily and recognise two genera and three species as valid. The genus Paradawesia Bravo Hollis & Lamothe Argumedo, 1976 is synonymised with Thoracocotyle MacCallum, 1913, and Dawesia Unnithan, 1965 and Methoracocotyle Lebedev, 1984 are synonymised with Pseudothoracocotyla Yamaguti, 1963. Thoracocotyle crocea MacCallum, 1913 (syns T. paradoxica Meserve, 1938 and Paradawesia bychowskyi Bravo Hollis & Lamothe Argumedo, 1976) is recorded from two species of Scomberomorus in the eastern Pacific (California to Peru) and four in the western Atlantic (South Carolina to Brazil). Pseudothoracocotyla ovalis (Tripathi, 1956) Yamaguti, 1963 (new syns Dawesia indica Unnithan, 1965, D. incisa Lebedev, 1970, Methoracocotyle scomberomori (Young, 1968) Lebedev, 1984, M. gigantica (Rohde, 1976) Lebedev, 1984 and Thoracotyle indica (Unnithan, 1965) Murugesh, 1995) is recorded from the gills of seven species of Scomberomorus from the Indo-west Pacific (eastern South Africa north to the Persian Gulf, and east to Fiji). Pseudothoracocotyla whittingtoni n. sp. is described from an eighth Indo-west Pacific scomberomorid, S. munroi, in Australian waters.     

Coral-associated bacterial communities on Ningaloo Reef, Western Australia

Coral-associated microbial communities from three coral species (Pocillopora damicornis, Acropora tenuis and Favites abdita) were examined every 3 months (January, March, June, October) over a period of 1 year on Ningaloo Reef, Western Australia. Tissue from corals was collected throughout the year and additional sampling of coral mucus and seawater samples was performed in January. Tissue samples were also obtained in October from P. damicornis coral colonies on Rottnest Island off Perth, 1200 km south of Ningaloo Reef, to provide comparisons between coral-microbial associates in different locations. The community structures of the coral-associated microorganisms were analysed using phylogenetic analysis of 16S rRNA gene clone libraries, which demonstrated highly diverse microbial profiles among all the coral species sampled. Principal component analysis revealed that samples grouped according to time and not species, indicating that coral-microbial associations may be a result of environmental drivers such as oceanographic characteristics, benthic community structure and temperature. Tissue samples from P. damicornis at Rottnest Island revealed similarities in bacteria to the samples at Ningaloo Reef. This study highlights that coral-associated microbial communities are highly diverse; however, the complex interactions that determine the stability of these associations are not necessarily dependent on coral host specificity.     

A new species of Podocotyloides Yamaguti, 1934 (Digenea: Opecoelidae) from a Western Australian temperate marine fish

A new species of Podocotyloides is described from Sillago bassensis caught off the coast of Western Australia. This is the second report of a species of this genus from Australian waters but the first of a new species. P. victori n. sp. is one of four species whose vitelline follicles extend into the forebody. It is distinguished from the other three species with vitelline follicles in the forebody by its relatively shorter forebody, smaller eggs and bipartite seminal vesicle. Pedunculotrema Fischthal & Thomas, 1970 is reduced to synonymy with Podocotyloides Yamaguti, 1934.     

The genus Deretrema Linton, 1910 (Digenea: Zoogonidae) from southern Great Barrier Reef fishes,with a description of Deretrema woolcockae n. sp.

Two species of Deretrema (Zoogonidae) are reported from labrid fishes from the Great Barrier Reef. D. nahaense Yamaguti, 1942 is recorded from the gall-bladders of the labrids Thalassoma hardwicke (Bennett), T. jansenii (Bleeker), T. lunare (Linnaeus) and T. lutescens (Lay & Bennett). This species is recognised, despite having been formerly synonymised with D. pacificum Yamaguti, 1942. In addition to morphological distinction, D. nahaense appears to have strict host-specificity for the genus Thalassoma. D. woolcockae n.sp. is described from the gallbladder of Hemigymnus fasciatus (Bloch). The new species is close to D. acutum Pritchard, 1963 and D. plotosi Yamaguti, 1940, but differs slightly in the distribution of the vitelline follicles, the sucker-ratio and the position of the cirrus-sac. In addition, this species also appears to have a distinct host-specificity, being restricted to one labrid species.     

Cryptic species of <Emphasis Type="Italic">Euryakaina</Emphasis> n. g. (Digenea: Cryptogonimidae) from sympatric lutjanids in the Indo-West Pacific

A survey of the endohelminth fauna of Indo-West Pacific Lutjanidae (Perciformes) revealed the presence of the species Siphoderina manilensis (Velasquez, 1961) Miller & Cribb, 2008 and S. marina (Hafeezullah & Siddiqi, 1970) Miller & Cribb, 2008 in seven Lutjanus spp. from sites off the Great Barrier Reef, the Maldives, New Caledonia and Ningaloo Reef, Western Australia. A combination of morphological and ribosomal DNA analyses of these cryptogonimids prompted the transfer of these taxa to a new genus, Euryakaina n. g., as E. manilensis n. comb. and E. marina n. comb., based on comparative analysis with other cryptogonimid taxa. Euryakaina n. g. is distinguished from all other cryptogonimid genera by the combination of a fusiform body, the few relatively small, widely spaced oral spines (sometimes absent), a highly lobed ovary, opposite to slightly oblique testes, vitelline follicles that extend from the anterior margin of the testes to slightly posterior to the intestinal bifurcation, and an excretory vesicle that bifurcates dorsal to the ovary and reunites briefly slightly posterior to the intestinal bifurcation. Morphometric analysis of these taxa alone suggests they should be reduced to synonymy, but DNA sequence analyses and ecological niche partitioning provide evidence that they form a cryptic species complex in sympatric lutjanids in the Indo-West Pacific. The secondary structure of the ITS2 rDNA for species of Euryakaina was also modelled and analysed for the presences of compensatory base changes (CBCs) or hemi-CBCs in order to explore the usefulness of these changes as a tool to help elucidate the taxonomy of this complex system. We also report what we interpret here as intraspecific variation in the ITS2 rDNA between individuals of E. manilensis from Lutjanus vitta recovered off the Great Barrier Reef and New Caledonia.     

Tormopsolus orientalis Yamaguti, 1934 (Digenea: Acanthocolpidae) from Seriola dumerili (Risso) (Perciformes: Carangidae) in the western Mediterranean Sea

Tormopsolus orientalis Yamaguti, 1934, is redescribed from Seriola dumerili from off Corsica, Majorca and Águilas, SE Spain. The vitellarium is interrupted at the level of the ovary and both testes, and a bipartite seminal vesicle is found in many specimens. Oral sucker papillae are always seen. Type-specimens and voucher specimens from off Japan, Bermuda, Panama, Curaçao and the Great Barrier Reef have been compared with the Mediterranean species. Specimens of T. medius Reimer, 1983, from Mozambique have been studied and this species is synonymised with T. orientalis.     

The Pseudoplagioporinae,a new subfamily in the Opecoelidae Ozaki, 1925 (Trematoda) for a small clade parasitizing mainly lethrinid fishes,with three new species

The Pseudoplagioporinae n. subf. (Opecoelidae) is proposed for species of Pseudoplagioporus Yamaguti, 1938, Fairfaxia Cribb, 1989, and Shimazuia Cribb, 2005, a small group of relatively distinctive, Indo-West Pacific taxa reliably known almost entirely from emperor fishes (Perciformes: Lethrinidae). These taxa were previously recognized in the Plagioporinae Manter, 1947, but that subfamily has recently been restricted to a clade of Holarctic, freshwater taxa, whereas analyses of new genetic data find the pseudoplagioporines to form a distinct clade among a larger assemblage of marine taxa. New material was sourced from fishes collected mainly in Queensland waters, Australia, but with some specimens from off Western Australia, the Northern Territory, and Japan. Orthodena tropica Durio & Manter, 1968 is transferred to Pseudoplagioporus as P. tropicus (Durio & Manter, 1968) n. comb., and Orthodena Durio & Manter, 1968 thus becomes a synonym of that genus. Three new species of Pseudoplagioporus are proposed. One, P. mediocris n. sp., like other species of Pseudoplagioporus, occurs in several species of Lethrinus. The other two new species, P. labiatus n. sp. and P. roseovulatus n. sp., apparently do not infect species of Lethrinus and were instead found only in the Bigeye emperor Monotaxis grandoculis (Forsskål) and the Redfin emperor M. heterodon (Bleeker), respectively. New host-locality combinations and the first genetic data, for the ribosomal ITS2 DNA region, and the 28S rRNA, 18S rRNA, and cox1 mtDNA genes, are reported for Pseudoplagioporus lethrini Yamaguti, 1938, P. interruptus Durio & Manter, 1968, P. tropicus, Fairfaxia lethrini Cribb, 1989, Fairfaxia cribbi Hassanine & Gibson, 2005, and Shimazuia lethrini (Yamaguti, 1938) Cribb, 2005.     

Population genetics of the corallivorous gastropod Drupella cornus at Ningaloo Reef,Western Australia

A precipitous increase in the abundance of the corallivorous snail Drupella cornus at Ningaloo Reef, Western Australia, raises fundamental questions about the population structure and genetics of this species. We examined genetic heterogeneity at ten polymorphic allozyme loci among samples of adult D. cornus from nine sites along 180 km of Ningaloo Reef, plus two sites from the Abrolhos Islands and one from the Dampier Archipelago, spanning a total distance of 1170 km. Variations in allelic frequencies were small (average F_ST=0.007), indicating that a high degree of planktonic dispersal is the norm. Nevertheless, some heterogeneity among samples was found at four of the loci. This heterogeneity occurred within Ningaloo Reef and did not increase with geographic distance. The local heterogeneity was not a function of habitat type but seemed to be associated with stage of outbreak. However, all outbreak populations came from within Ningaloo Reef and the non-outbreak populations were from outside Ningaloo Reef proper. Our results show peculiarities in the genetic structure of D. cornus on Ningaloo Reef, but the causes are not understood. Correspondence to: K. Holborn     

The subfamily Aephnidiogeninae Yamaguti, 1934 (Digenea: Lepocreadiidae), its status and that of the genera Aephnidiogenes Nicoll, 1915, Holorchis Stossich, 1901, Austroholorchis n. g., Pseudaephnidiogenes Yamaguti, 1971, Pseudoholorchis Yamaguti, 1958 and Neolepocreadium Thomas, 1960

The status of all of the putative member genera of the subfamily Aephnidiogeninae is reconsidered, based mainly on the morphology of the terminal genitalia. Aephnidiogenes Nicoll, 1915 is the only genus retained in the Aephnidiogeninae. Aephnidiogenes major Yamaguti, 1934 from Diagramma labiosum from the southern Great Barrier Reef is redescribed with particular reference to the terminal genitalia, and is shown to lack a true cirrus-sac, a condition considered to be diagnostic of the Aephnidiogeninae. Holorchis Stossich, 1901 is placed in the subfamily Lepidapedinae. Holorchis pycnoporus Stossich, 1901 from Pagellus acarne from off Spanish Sahara and from Diplodus vulgaris from off Italy and H. legendrei Dollfus, 1946 from Sparodon durbanensis and D. sargus from off eastern Cape Province, South Africa and from Pagellus erythrinus from the Adriatic Sea and Italy are studied and illustrated. The terminal genitalia of H. pycnoporus are found to be enigmatic, but those of H. legendrei are found to fit clearly into the 'Lepidapedon-like' pattern. A new genus Austroholorchis is erected in the Lepidapedinae, with A.sprenti (Gibson, 1987) n. comb. as the type-species. Its diagnostic features are its ani, infundibuliform oral sucker and the position of the ovary at about mid-level of the uterus . A. sprenti is illustrated, its hosts in Queensland waters being Sillago maculata, S. analis and S. ciliata. A. levis n. sp. is described from Sillago bassensis from south-western Western Australia. The genus PseudaephnidiogenesYamaguti, 1971 is placed in the Lepidapedinae. P. rhabdosargi (Prudhoe, 1956) from Rhabdosargus sarba from off Natal, South Africa is illustrated and the terminal genitalia of P. rhabdosargi from R. sarba and from R. holubi from off eastern Cape Province and Pseudaephnidiogenes rossi Bray, 1985 from Caffrogobius nudiceps from off eastern Cape Province, South Africa are illustrated. The genus Pseudoholorchis Yamaguti, 1958 is placed in the subfamily Lepocreadiinae. The terminal genitalia of P. pulcher (Manter, 1954) from Latridopsis ciliaris from New Zealand are illustrated. The genus Neolepocreadium Thomas, 1960 is placed in the Lepocreadiidae.