Pseudorhabdosynochus spp. (Monogenea: Diplectanidae) from the gills of Epinephelus spp. in Brazilian waters

Three new species of Pseudorhabdosynochus (Monogenea, Diplectanidae) from several species of Cephalopholis and Epinephelus (Perciformes, Serranidae) from Thailand

Pseudorhabdosynochus suratthaniensis n. sp. is described from the gills of Cephalopholis argus; P. cephalopholi n. sp., from the gills of C. sonnerati; and P. samaesarnensis n. sp., from the gills of Epinephelus lanceolatus. These fish were all caught in the Gulf of Thailand. Pseudorhabdosynochus suratthaniensis n. sp. is distinguished from congeneric species by the structure of its sclerotized vagina, which has a wide sclerotized trumpet and a single large primary chamber, and by the number of rows of rodlets in each of its squamodiscs. Pseudorhabdosynochus cephalopholi n. sp. is also distinguished by the structure of its sclerotized vagina that, like the P. suratthaniensis n. sp., has a sclerotized trumpet, but it also has a long coiled or curved primary canal near its midlength, and a distal part with a primary chamber and a secondary chamber communicating with the primary chamber through a short secondary canal. In addition, P. cephalopholi n. sp. is distinguished by some sclerotized organs (ventral and dorsal hamuli, ventral bar, and quadriloculate organ) with different lengths, and by the number of rows of rodlets in each of its squamodiscs. Pseudorhabdosynochus samaesarnensis n. sp. is distinguished by its sclerotized vagina that has an anterior cup-shaped trumpet and a short straight or curved primary canal. For Thailand, these are the first species of Pseudorhabdosynochus described from species of Cephalopholis and the second species of Pseudorhabdosynochus described from Epinephelus.

Parasite Fauna of the Dusky Grouper (Epinephelus marginatus, Lowe 1834) from the Central Mediterranean Sea

This study aimed to investigate parasite fauna of E. marginatus from the central Mediterranean Sea between Messina and Syracuse. In the present survey; parasite fauna of dusky grouper was investigated for two main reasons: the economic value of this species and the current lack of studies regarding the capture area. Seventy dusky groupers were caught from May 2018 to February 2020. Forty-seven out of the 70 specimens (67.2%) were infected with one or more parasite species. The most abundant species was Prosorhynchus caudovatus (42.9%), followed by Podocotyle temensis (28.6%), Didymodiclinus sp. (18.6%), Philometra jordanoi (5.7%), Anisakis Type II larvae (5.7%). Higher prevalence of infection of P. jordanoi and Contracaecum sp. was found in warm months (March to September), while P. caudovatus and P. temensis were mostly found during cold months. Weight and total length of E. marginatus were positively correlated with the parasitic load of P. jordanoi and Didymodiclinus sp. The different prevalence of parasite infection found between warm and cold months is probably related to the diet of the dusky grouper; which is characterized by mollusks that are intermediate hosts for parasite species found. None of the parasites found in the present survey is responsible for zoonosis.

Pseudorhabdosynochus kasetsartensis n. sp. (Monogenea: Diplectanidae) from the cloudy grouper Epinephelus erythrurus (Valenciennes) (Perciformes: Serranidae) in the lower Gulf of Thailand

Pseudorhabdosynochus kasetsartensis n. sp. is described from the gills of the cloudy grouper Epinephelus erythrurus (Valenciennes) caught in the lower Gulf of Thailand. The new species is distinguished from other species assigned to the genus by the structure of its sclerotised vagina which has a wide and prominent sclerotised trumpet, long, thin, coiled or curved primary canal, short secondary canal, and primary and secondary chambers that are blind extremities of the primary and secondary canals, respectively. This is the first species of Pseudorhabdosynochus Yamaguti, 1958 described from E. erythrurus and the first record of a species of Pseudorhabdosynochus in Thailand.

Redescription and molecular characterisation of Allogastrocotyle bivaginalis Nasir & Fuentes Zambrano, 1983 (Monogenea: Gastrocotylidae) from Trachurus picturatus (Bowdich) (Perciformes: Carangidae) off the Algerian coast, Mediterranean Sea

Allogastrocotyle bivaginalis Nasir & Fuentes Zambrano, 1983, the sole species of Allogastrocotyle Nasir & Fuentes Zambrano, 1983, was described from Trachurus lathami Nichols off Venezuela and never recorded since. We found monogeneans on Trachurus picturatus (Bowdich) (Carangidae) off the Algerian coast, Mediterranean Sea, which had the characteristics of the genus, including, especially, paired vaginae. We compared them to the single available specimen of A. bivaginalis, the holotype. Unfortunately, this holotype does not show clamp structure and soft internal anatomy. Our specimens were similar to A. bivaginalis in most characteristics such as body shape, vaginal openings, and number of testes, clamps and hooks in genital atrium. We detected minor differences in clamp structure but could not ascertain if these were the result of incomplete observations in the original description of real morphological differences. The host fish of our specimens were barcoded (cox1) confirming their specific identity. A phylogenetic analysis of cox1 sequences showed that our sequences of A. bivaginalis were distinct from those of Pseudaxine trachuri Parona & Perugia, 1889 (distance > 15%) and of several other gastrocotylids. Finally, we could not distinguish our Mediterranean specimens from A. bivaginalis, neither on the base of morphology (because the original description is incomplete) nor on molecules (because molecular information is lacking on A. bivaginalis from Venezuela) and ascribe them to A. bivaginalis. However, hosts are different, and localities are widely separated, so it is likely that future study will show that the species from the Mediterranean is a distinct, new, species.

Ecological and histopathological aspects of Didymodiclinus sp. (Trematoda: Didymozoidae) parasite of the dusky grouper, Epinephelus marginatus (Osteichthyes: Serranidae), from the western Mediterranean Sea

The dusky grouper Epinephelus marginatus (Lowe) is an ecologically and commercially important fish species of the Atlantic and Mediterranean coastal rocky habitats. Despite records of didymozoid infections in several grouper species, the identification and pathogenesis of these parasites in E. marginatus are lacking. The aim of this study is to characterize the didymozoids of E. marginatus, particularly their mechanisms of infection and histopathological features. Dusky groupers (n = 205) were caught off Majorca Island (western Mediterranean Sea) and examined for parasites. Of the fish sampled, 45% were infected with white and yellow didymozoid capsules and brown nodules, found on the gills and pseudobranchs. Parasite abundance had a strong positive relationship with the fish length; only fish larger than 20 cm were infected, suggesting infection via consumption of an intermediate host, for which E. marginatus size was a limiting factor. The capsules contained two convoluted viable adult trematodes, identified as Didymodiclinus sp., in close contact with host capillary vessels, with no evidence of the tissue inflammatory response. Conversely, nodules containing degraded parasites were surrounded by an intense inflammatory infiltrate. The findings suggest that Didymodiclinus sp. have the potential to evade the host's immune system by inhibiting the inflammatory response.

An ultrastructural study of the surface and attachment structures of Paradiplozoon homoion (Bychowsky & Nagibina, 1959) (Monogenea: Diplozoidae)

Background

Species of Diplozoon Palombi, 1949 (Monogenea: Diplozoidae) are blood-feeding ectoparasites mainly parasitising the gills of cyprinid fishes. Although these parasites have been the subject of numerous taxonomic, phylogenetic and ecological studies, the ultrastructure of the surface and haptor attachment structures remains almost unknown. In this study, we used transmission electron microscopy to examine the ultrastructure of attachment clamps and neodermal surface of Paradiplozoon homoion (Bychowsky & Nagibina, 1959), family Diplozoidae Palombi, 1949, thereby broadening our knowledge of platyhelminth biology.

Results

The hindbody surface of P. homoion is distinctly ridged, each ridge being supported by several muscle fibers and equipped with scales on the surface plasma membrane. Such structures have not been recorded previously in species of the family Diplozoidae. Comparisons of the surface structure of different body parts revealed slight differences in the thickness and number of organelles. Each of the clamps has a flattened bowl-like structure composed of sclerites, movable skeletal-like structures that are anchored by robust, radially oriented muscle bundles. The base of the posterior median plate sclerites is equipped with glandular cells possessing secretory vesicles.

Conclusion

This study brings detailed ultrastructural data for the surface and haptoral attachment clamps of P. homoion and provides new insights into the ultrastructure of Diplozoidae. Glandular cells at the base of the attachment clamps responsible for sclerite development in diplozoid species were observed for the first time. Our findings support the hypothesis that the structure of particular neodermal compartments is similar within the Platyhelminthes. On the other hand, the diplozoid glandular system and the mechanism of sclerite development clearly merits further attention.

Helminth parasites of finfish commercial aquaculture in Latin America

Latin America has tripled production by aquaculture up to 78 million tonnes in the past 20 years. However, one of the problems that aquaculture is facing is the presence of helminth parasites and the diseases caused by them in the region. In this review we have collected all the available information on helminths affecting commercial aquaculture in Latin America and the Caribbean (LAC), emphasizing those causing serious economic losses. Monogeneans are by far the most common and aggressive parasites affecting farmed fish in LAC. They have been recognized as serious pathogens in intensive fish culture because they reach high levels of infection rapidly, and can infect other phylogenetically related fish species. The next most important group comprises the larval stages of digeneans (metacercariae) such as Diplostomum sp. and Centrocestus formosanus, which cause serious damage to farmed fish. Since LAC aquaculture has been based mainly on exotic species (tilapia, salmon, trout and carp), most of their parasites have been brought into the region together with the fish for aquaculture. Recently, one of us (A.I.P.-T.) has suggested that monogeneans, which have generally been considered to be harmless, can produce serious effects on the growth of cultured Nile tilapia. Therefore, the introduction of fish together with their 'harmless' parasites into new sites, regions or countries in LAC should be considered a breakdown of biosecurity in those countries involved. Therefore, the application of quarantine procedures and preventive therapeutic treatments should be considered before allowing these introductions into a country.

Type material of Platyhelminthes (Monogenoidea) housed in the Helminthological Collection of the Oswaldo Cruz Institute/ FIOCRUZ (CHIOC), Rio de Janeiro, Brazil, from 1979 to 2016

A catalogue of type material of monogenoids deposited in the Helminthological Collection of the Oswaldo Cruz Institute, FIOCRUZ (CHIOC), between 1979 and 2016, is presented, given that the last list of types was produced in 1979. The monogenoid collection comprises type lots for 203 species, distributed across 14 families and 68 genera. Specific names are listed systematically, followed by type host, infection site, type locality, specimens with the collection numbers and references. The classification and the nomenclature of the species have been updated.

Species of Pseudorhabdosynochus (Monogenea, Diplectanidae) from Groupers (Mycteroperca spp., Epinephelidae) in the Mediterranean and Eastern Atlantic Ocean, with Special Reference to the 'Beverleyburtonae Group' and Description of Two New Species

Pseudorhabdosynochus Yamaguti, 1958 is a species-rich diplectanid genus, mainly restricted to the gills of groupers (Epinephelidae) and especially abundant in warm seas. Species from the Mediterranean are not fully documented. Two new and two previously known species from the gills of Mycteroperca spp. (M. costae, M. rubra, and M. marginata) in the Mediterranean and Eastern Atlantic Ocean are described here from new material and slides kept in collections. Identifications of newly collected fish were ascertained by barcoding of cytochrome c oxidase subunit I (COI) sequences. Pseudorhabdosynochus beverleyburtonae (Oliver, 1984) Kritsky & Beverley-Burton, 1986 and P. sosia Neifar & Euzet 2007 are redescribed from type-specimens and new specimens collected off Tunisia and Libya from M. marginata and M. costae, respectively. Pseudorhabdosynochus oliveri n. sp., from M. marginata (type-host) off the Mediterranean coast of France (type-locality), is described from specimens found among voucher specimens of P. beverleyburtonae deposited by Guy Oliver in the collection of the Muséum National d’Histoire Naturelle, Paris. Pseudorhabdosynochus oliveri is distinguished by the shape of its sclerotised vagina; it was not found in the other localities investigated. Pseudorhabdosynochus hayet n. sp. is described from M. rubra (type host) off Senegal (type-locality) and Tunisia. Pseudorhabdosynochus hayet is morphologically similar to P. sosia (type-host: M. costae) but was distinguished by differences in measurements of the vagina and male copulatory organ, different host, and divergent COI sequences. The four species (P. beverleyburtonae, P. sosia, P. oliveri, and P. hayet) share common characteristics such as squamodiscs with 2 innermost circular rows of rodlets and a similar general structure of the sclerotised vagina; we propose to group them into a ‘beverleyburtonae group’ within Pseudorhabdosynochus.

Pseudorhabdosynochus sulamericanus (Monogenea, Diplectanidae), a parasite of deep-sea groupers (Serranidae) occurs transatlantically on three congeneric hosts (Hyporthodus spp.), one from the Mediterranean Sea and two from the western Atlantic

Little is known of the diversity of the monogenean parasites infesting deep-sea groupers, and there is even less information available about their geographic distributions within the ranges of their hosts. To improve our understanding of these host-parasite relationships we conducted parasitological evaluations of the deep-water Haifa grouper Hyporthodus haifensis from the southern Mediterranean off Tunisia and Libya. We collected more than one species of diplectanid monogeneans from this host, but among these only one dominant species was abundant. This proved to be morphologically very similar to Pseudorhabdosynochus sulamericanus Santos, Buchmann & Gibson, 2000, a species originally described from the congeneric host H. niveatus off Brazil and also recorded from H. niveatus and H. nigritus off Florida. Here, we conducted a morphological comparison between newly collected specimens and those previously deposited in museum collections by other authors. Further, we used COI barcoding to ascertain the specific identity of the three host species to better elucidate the circumstances that might explain the unexpectedly broad distribution of P. sulamericanus. We assigned our specimens from H. haifensis to P. sulamericanus primarily on the basis of morphological characteristics of the sclerotized vagina. We also noted morphological characteristics of eastern and western Atlantic specimens that are not clearly described or not given in previous descriptions and so prepared a redescription of the species. We confirmed, by COI barcoding, that no sister-species relationships were evident among the three hosts of P. sulamericanus. Our observation that P. sulamericanus infects unrelated host species with putatively allopatric distributions was unexpected given the very limited dispersive capabilities and the high degree of host specificity common to members of Pseudorhabdosynochus. This transatlantic distribution raises questions with regard to phylogeography and assumptions about the allopatry of Atlantic grouper species from the Americas and Afro-Eurasia. Here, we propose some hypothetical explanations for our findings.

Pseudorhabdosynochus species (Monogenoidea, Diplectanidae) parasitizing groupers (Serranidae, Epinephelinae, Epinephelini) in the western Atlantic Ocean and adjacent waters, with descriptions of 13 new species

Seventeen of twenty-three species of groupers collected from the western Atlantic Ocean and adjacent waters were infected with 19 identified species (13 new) of Pseudorhabdosynochus Yamaguti, 1958 (Dactylogyridea, Diplectanidae); specimens of the Spanish flag Gonioplectrus hispanus, coney Cephalopholis fulva, marbled grouper Dermatolepis inermis, mutton hamlet Alphestes afer, and misty grouper Hyporthodus mystacinus were not infected; the yellowmouth grouper Mycteroperca interstitialis and yellowfin grouper Mycteroperca venenosa were infected with unidentified species of Pseudorhabdosynochus; the Atlantic creolefish Paranthias furcifer was infected with an unidentified species of Diplectanidae that could not be accommodated in Pseudorhabdosynochus. The following species of Pseudorhabdosynochus are described or redescribed based entirely or in part on new collections: Pseudorhabdosynochus americanus (Price, 1937) Kritsky & Beverley-Burton, 1986 from Atlantic goliath grouper Epinephelus itajara; Pseudorhabdosynochus yucatanensis Vidal-Martínez, Aguirre-Macedo & Mendoza-Franco, 1997 and Pseudorhabdosynochus justinella n. sp. from red grouper Epinephelus morio; Pseudorhabdosynochus kritskyi Dyer, Williams & Bunkley-Williams, 1995 from gag Mycteroperca microlepis; Pseudorhabdosynochus capurroi Vidal-Martínez & Mendoza-Franco, 1998 from black grouper Mycteroperca bonaci; Pseudorhabdosynochus hyphessometochus n. sp. from Mycteroperca interstitialis; Pseudorhabdosynochus sulamericanus Santos, Buchmann & Gibson, 2000 from snowy grouper Hyporthodus niveatus and Warsaw grouper Hyporthodus nigritus (new host record); Pseudorhabdosynochus firmicoleatus n. sp. from yellowedge grouper Hyporthodus flavolimbatus and snowy grouper H. niveatus; Pseudorhabdosynochus mcmichaeli n. sp., Pseudorhabdosynochus contubernalis n. sp., and Pseudorhabdosynochus vascellum n. sp. from scamp Mycteroperca phenax; Pseudorhabdosynochus meganmarieae n. sp. from graysby Cephalopholis cruentata; Pseudorhabdosynochus beverleyburtonae (Oliver, 1984) Kritsky & Beverley-Burton, 1986 from dusky grouper Mycteroperca marginata; Pseudorhabdosynochus mizellei n. sp. from red hind Epinephelus guttatus; Pseudorhabdosynochus williamsi n. sp. from rock hind Epinephelus adscensionis; Pseudorhabdosynochus bunkleywilliamsae n. sp. from Nassau grouper Epinephelus striatus; Pseudorhabdosynochus mycteropercae n. sp. from tiger grouper Mycteroperca tigris; and Pseudorhabdosynochus tumeovagina n. sp. from speckled hind Epinephelus drummondhayi. Pseudorhabdosynochus woodi n. sp. from red hind Epinephelus guttatus is described based on specimens from the US National Parasite Collection (USNPC). Drawings of the haptoral and copulatory sclerites of the type specimens in the USNPC of Pseudorhabdosynochus monaensis Dyer, Williams & Bunkley-Williams, 1994 from rock hind Epinephelus adscensionis are presented. Finally, a note confirming Pseudorhabdosynochus epinepheli Yamaguti, 1958 rather than its senior synonym Pseudorhabdosynochus epinepheli (Yamaguti, 1938) Kritsky & Beverley-Burton, 1986 as the type species of Pseudorhabdosynochus is provided.

The surface topography of Callorhynchocotyle callorhynchi (Manter, 1955) (Monogenea: Hexabothriidae), a parasite of the holocephalan fish Callorhinchus capensis

A scanning electron microscopical study, incorporating some transmission electron microscopical observations, was undertaken on the surface topography of the gill parasite Callorhynchocotyle callorhynchi (Manter, 1955) (Monogenea: Hexabothriidae) from the Cape elephant fish Callorhinchus capensis (Holocephali) off the western coast of South Africa. The study revealed the presence of several new characteristics for this species. These include the presence of regularly distributed, knob-shaped projections on the surface of the haptor, haptoral appendix and sucker peduncles measuring 0.2 μm and in concentrations of approximately 100 per 10 μm(2) and the existence of a ridge which bisects each sucker lumen, forming two different loculi. We also report, for the first time for any monogenean, the presence of 'true spines'; these occur on the luminal surface of the haptoral suckers and have all of the characteristics of the tegumental spines of digeneans, i.e. they are situated within the distal syncytial tegumental cytoplasm, rest on the basal plasma membrane, have a uniform structure and are covered apically by the tegumental surface plasma membrane. These spines are simple, straight and single-pointed. Under the scanning electron microscopy (SEM), within an area of 20 μm in diameter, 23 such spines were counted, but their concentration and arrangement varies in different regions of the sucker. At their base, they measure about 1.5 μm in width and reach approximately 2 μm in height above the general level of the tegument, but transmission electron microscopy (TEM) measurements of an entire spine indicate that they may reach 3 μm in total length. The presence of spines, possessing similar morphological characteristics in both basal polyopisthocotylean monogeneans and digeneans, represents another characteristic which may prove useful in understanding the evolutionary relationships within the Neodermata.

Pseudorhabdosynochus regius n. sp. (Monogenea, Diplectanidae) from the mottled grouper Mycteroperca rubra (Teleostei) in the Mediterranean Sea and Eastern Atlantic

Pseudorhabdosynochus regius n. sp. is described from the gills of the mottled grouper Mycteroperca rubra caught off Senegal, Tunisia and Libya (type-locality: off Dakar, Senegal). The species is distinguished from its congeners by the structure of its sclerotised vagina (length 26-35 μm), which exhibits a trumpet in continuity with the primary canal, a straight primary canal, and primary and secondary chambers included in a common sclerotised mass along the primary canal. The species is also characterised by small squamodiscs (length 20-40 μm) with 10-11 rows of rodlets. Its closest relatives (based on the structure of the sclerotised vagina) are species mostly found in the Mediterranean Sea and parasites on species of Mycteroperca. A second species of Pseudorhabdosynochus Yamaguti, 1958 is reported from the same host and localities but not described. A list of diplectanids from groupers in the Mediterranean Sea is provided. We point out that a recent article was not compliant with the new Article 8.5.3 of the International Code of Zoological Nomenclature; for this reason, three species, P. nhatrangensis Dang, Bristow, Schander & Berland, 2013, P. vietnamensis Dang et al., 2013 and P. brunei Dang et al., 2013, are invalid.

Parasite fauna of wild and cultured dusky-grouper Epinephelus marginatus (Lowe, 1834) from Ubatuba, Southeastern Brazil

This study aimed at identifying and quantifying the parasites of wild and cultured dusky grouper Epinephelus marginatus. During a year and thereby all four seasons, 20 wild and 20 cultured groupers were examined for the presence of parasites, except in the last season, in which 19 wild and 20 cultured fish were examined, totalling 159 groupers analysed from Ubatuba, southeastern Brazil. Prevalence, mean intensity of infection, mean abundance and mean relative dominance were calculated. Five species of parasites were identified in fish from both origins: Pseudorhabdosynochus beverleyburtonae (Monogenea), Neobenedenia melleni (Monogenea), Pseudempleurosoma sp. (Monogenea), Helicometrina nimia (Digenea) and larvae of Contracaecum sp. (Nematoda). The prevalence of ectoparasites, in most cases, was higher than endoparasites. The most abundant parasite was the monogenea Pseudorhabdosynochus beverleyburtonae in both wild and cultured fish, along all seasons. Neobenedenia melleni was observed in wild and cultured fish in all seasons, with a gradual increase in the number of parasites from the coldest to the hottest seasons, with the highest prevalence and mean intensity in the summer. Helicometrina nimia was found in all seasons in both wild and cultured fish, except for summer, where its presence was detected only in wild fish. Pseudempleurosoma sp. and larvae of Contracaecum sp. showed low prevalence occurring in wild and cultured fish in the autumn and spring, respectively. This study revealed high intensities of potentially pathogenic parasites that could favour disease outbreaks in culture conditions.

Five new species of Pseudorhabdosynochus (Monogenea: Diplectanidae) from the gills of Epinephelus costae (Teleostei: Serranidae)

A survey of the gill parasites of Epinephelus costae (Teleostei: Serranidae) was conducted between 2001 and 2005 in the Gulf of Gabès (Tunisia). Five new species of Diplectanidae (Monogenea) were collected, all belonging to Pseudorhabdosynochus Yamaguti, 1958: P. bouaini sp. n., P. dolicocolpos sp. n., P. enitsuji sp. n., P. sinediscus sp. n., and P. sosia sp. n. These five species differ from each other and from all described species of Pseudorhabdosynochus by the morphology and size of their sclerotized vagina. These diplectanids (except P. sinediscus) were also collected from the same host off Dakar in 1981 and 1989. The present paper includes the descriptions and taxonomic considerations of each of these species in addition to an amended diagnosis of Pseudorhabdosynochus. A key to the five new species parasitizing E. costae is provided. These five species are the first diplectanids described from E. costae.

Description of Pseudorhabdosynochus justinei n. sp. (Monogenea: Diplectanidae) and redescription of P. vagampullum (Young, 1969) Kritsky & Beverley-Burton, 1986 from the gills of the longfin grouper Epinephelus quoyanus (Valenciennes) (Perciformes: Serranidae) in Dapeng Bay, South China Sea

Pseudorhabdosynochus justinei n. sp. is reported and described from the gills of the longfin grouper Epinephelus quoyanus in Dapeng Bay, South China Sea off the town of Nan'ao, Shenzhen, Guangdong Province, China. P. justinei n. sp. is characterised by the presence of a male copulatory organ (MCO) composed of a moderately quadriloculate organ, a short cone and a long, variable internal tube, and a sclerotised vagina comprising anterior 'trumpet' with a characteristic sclerotised ring, slightly medially curved canal, heavily sclerotised principal chamber and star-shaped lateral structure with accessory chambers. It is differentiated from the most similar species, P. caledonicus Justine, 2005, by the absence of a thinly sclerotised posterior tube of the MCO and by the size and morphology of the sclerotised vagina. P. vagampullum (Young, 1969) is redescribed based on specimens collected from the same species of host and locality as P. justinei n. sp. In comparison with the original description by Young [Young, P. C. (1969). Journal of Helminthology, 43, 223-254] and the redescription by Justine [Justine, J.-L. (2005a). Systematic Parasitology, 62, 1-37; (2005b). Systematic Parasitology, 62, 39-45] based on old museum material, the new specimens of P. vagampullum clearly showed the internal anatomy of the terminal genitalia, especially the sclerotised vagina, consisting of a distal, cylindrical canal with an anterior 'trumpet' continuing as an unsclerotised, curved, bulb-shaped vaginal pore, a conical principal chamber and a star-shaped lateral structure with an accessory chambers leading to the seminal receptacle via a fine, unsclerotised duct.

Description of Pseudorhabdosynochus shenzhenensis n. sp. (Monogenea: Diplectanidae) and redescription of P. serrani Yamaguti, 1953 from Epinephelus coioides off Dapeng Bay, Shenzhen, China

One new species of diplectanid, Pseudorhabdosynochus shenzhenensis n. sp., is reported and described from the marine fish Epinephelus coioides off Nan'ao, Shenzhen, China. It can be differentiated from previously described species of the same genus by features of the haptoral and vaginal hard-parts. A second species, P. serrani Yamaguti, 1953, originally described from Serranus sp. from the western Pacific Ocean off the Celebes (now called Sulawesi), is redescribed based on new material from E. coioides.

Parasite biodiversity in a coral reef fish: twelve species of monogeneans on the gills of the grouper Epinephelus maculatus (Perciformes: Serranidae) off New Caledonia, with a description of eight new species of Pseudorhabdosynochus (Monogenea: Diplectanidae)

Coral reefs are known for their high level of biodiversity, but parasite biodiversity has not been evaluated. Cases such as Epinephelus maculatus, described here, show that the numerical estimation of parasite biodiversity in coral reefs could reach more than ten times the number of fish species; consequently, the extinction of certain fish species from endangered coral reefs would result in the co-extinction of at least ten times the number of parasite species. E. maculatus is a grouper of intermediate size (1-2 kg) and common in the coral reefs of New Caledonia, South Pacific. Based on the examination of more than 800 monogenean specimens, 12 species of monogeneans (ten diplectanids and two ancyrocephalids) were differentiated on the gills. These species of diplectanids have not been found in other epinephelines in the same area and thus are considered as specific to this host. In addition, three species of copepods, and isopod larvae, are present on the gills; E. maculatus thus has a total of 16 species of gill ectoparasites, which can be found together on a single individual fish. Diplectanids include Laticola dae Journo & Justine, 2006, which is the most abundant species representing about 50% of the specimens, and nine species which are rare, each representing 2-7% of the specimens: Diplectanum uitoe n. sp. and eight species of Pseudorhabdosynochus Yamaguti, 1958. D. uitoe, provisionally attributed to Diplectanum Diesing, 1858, is characterised by a small conical penis with internal walls. Pseudorhabdosynochus auitoe n. sp., P. buitoe n. sp., P. cuitoe n. sp., P. duitoe n. sp., P. euitoe n. sp. and P. fuitoe n. sp. are differentiated on the basis of the morphology of the sclerotised vagina, but are very similar in other characteristics; P. guitoe n. sp. is characterised by a quadriloculate organ with very thick walls and a very small sclerotised vagina; and P. huitoe n. sp. is characterised by its sclerotised vagina and by very long ventral and dorsal haptoral bars. Two rare (2-3% of specimens) ancyrocephalids, Haliotrema epinepheli Young, 1969 and Haliotrema sp., are briefly described in relation to the male copulatory organs and haptoral bars; H. epinepheli is apparently a generalist species found in various epinephelines and other fish species. A table of the 50 species of diplectanids (Pseudorhabdosynochus, Laticola Yang et al., 2006, Echinoplectanum Justine & Euzet, 2006 and Diplectanum) from serranids is provided.

Laticola dae n. sp. (Monogenea: Diplectanidae) from Epinephelus maculatus (Perciformes: Serranidae) off New Caledonia

Laticola dae n. sp. is described from specimens collected from the gill-filaments of the highfin grouper Epinephelus maculatus, a coral reef fish caught off Nouméa, New Caledonia, South Pacific. The species is characterised by a spoon-shaped sclerotised male copulatory organ, with four thin walls and 73-[Formula: see text]m in outer length, and a sclerotised vagina in form of a disc, 16-[Formula: see text]m in diameter, with a smaller hemisphere on one side. Laticola Yang et al., 2006 was described to accommodate diplectanids from Lates calcarifer (Centropomidae); this is the first Laticola described from a serranid. Other diplectanids, including several species of Pseudorhabdosynochus Yamaguti, 1958, were also found on the same species of fish; specimens of L. dae represented about half of the diplectanids collected; all other species were rare.

Diplectanids (Monogenea) parasitic on the gills of the coralgroupers Plectropomus laevis and P. leopardus (Perciformes, Serranidae) off New Caledonia, with the description of five new species and the erection of Echinoplectanum n. g

Echinoplectanum n. g. is erected for diplectanids which have a male copulatory organ comprising a tubular sclerotised penis with a muscular reservoir at its proximal extremity and an protrusible cirrus, often with spiny ridges, at its distal extremity, and a female copulatory organ comprising a sclerotised vaginal sac, often with two thin tubes. All species have similar squamodiscs made of rows of rodlets, with the central rows forming closed circles, and haptoral parts with a similar shape but different measurements; they are distinguished on the basis of the size and morphology of the male copulatory organ and sclerotised vagina. Five new species are included in Echinoplectanum and are all parasites of coralgroupers, Plectropomus spp., off New Caledonia, South Pacific. Two are from P. laevis (Lacépède): E. laeve n. sp. (type-species) has a large elongate penis, 53[Formula: see text]m in length, a cirrus with spiny ridges and a spherical vagina with two long thin tubes; and E. chauvetorum n. sp. has a large elongate penis, 51[Formula: see text]m in length, a cirrus with thin spiny ridges, and a pear-shaped vagina with two short thin tubes. Three species are from P. leopardus (Lacépède): E. leopardi n. sp. has an elongate penis, 36[Formula: see text]m in length, an unspiny cirrus and a triangular vagina; E. pudicum n. sp. has a very small elongate penis 14[Formula: see text]m in length and no visible vagina; and E. rarum n. sp. has a short thick penis 18[Formula: see text]m in length and a ring-shaped vagina with two thin tubes. In addition, Diplectanum plectropomi Young, 1969, from P. maculatus off Western Australia, and D. echinophallus Euzet & Oliver, 1965 from Epinephelus marginatus in the Mediterranean Sea and Senegal, West Africa, both herein redescribed from the type-specimens, are transferred to Echinoplectanum, as E. plectropomi n. comb. and E. echinophallus n. comb., respectively. Six of the seven species of Echinoplectanum are parasitic in members of Plectropomus from the South West Pacific, but one (E. echinophallus) is a parasite of Epinephelus marginatus and has been recorded only from the Mediterranean and East Atlantic; it is suggested that Echinoplectanum is associated with Plectropomus, a basal genus among the epinephelines, and that host-switching to Epinephelus marginatus occurred, whose distribution extends from Europe to the Indian Ocean. Morphological characteristics of the copulatory organs suggest that a "chastity belt versus spiny penis" sperm competition pattern prevails in Echinoplectanum spp.

Description of Pseudorhabdosynochus seabassi sp. n. (Monogenea: Diplectanidae) from Lates calcarifer and revision of the phylogenetic position of Diplectanum grouperi (Monogenea: Diplectanidae) based on rDNA sequence data

Pseudorhabdosynochus seabassi sp. n. (Monogenea: Diplectanidae) from the gill filaments of Lates calcarifer Bloch, a marine teleost fish held in floating sea cages in Guangdong Province, China, is described based on morphological observations and molecular data. The shapes of the male copulatory organs (MCO) of Pseudorhabdosynochus spp. were the focus of this study. The typical proximal part of the MCO in most species of Pseudorhabdosynochus is reniform, heavily sclerotized, and divided into four chambers. However, the new species from L. calcarifer has a bulbous proximal region with four concentric layers of apparent muscular origin, instead of a reniform structure with four compartments. This organ is also different in Diplectanum grouperi Bu, Leong, Wong, Woo et Foo, 1999, being sclerotized, cup-shaped, wide proximally with four concentric muscular layers and tubular distally. The 3' terminal portion of the small subunit ribosomal RNA gene (ssrDNA) and the 5' terminal region (domains C1-D2) of the large subunit ribosomal RNA gene (lsrDNA) were used to reconstruct the phylogenetic relationships of P. seabassi and D. grouperi with related taxa utilizing maximum-parsimony and neighbour-joining methods. Phylogenetic analyses unequivocally placed D. grouperi amongst Pseudorhabdosynochus using either ssrDNA or lsrDNA data. All species of Pseudorhabdosynochus (including D. grouperi) used in this study clustered together, inferring monophyly. Based on molecular phylogenetic evidence, we propose that D. grouperi from Epinephelus coioides Hamilton be transferred to Pseudorhabdosynochus as P. grouperi comb. n.

Pseudorhabdosynochus venus n. sp. (Monogenea: Diplectanidae) from Epinephelus howlandi (Perciformes: Serranidae) off New Caledonia

Pseudorhabdosynochus venus n. sp. is described from specimens collected from the gills of Epinephelus howlandi off Nouméa, New Caledonia, South Pacific. The male sclerotised quadriloculate organ of P. venus, 61-101 microm in internal length, has an anterior chamber with a thin anterior wall, a very short cone and a short posterior tube. The sclerotised vagina, 50-67 microm in total length, is composed of an anterior open trumpet, an S-shaped canal, a tear-shaped principal chamber and a spherical accessory chamber; all parts are heavily sclerotised. The two squamodiscs have 10-11 rows of separate rodlets and no central closed row of rodlets. P. venus is differentiated from all other species of Pseudorhabdosynochus by the spectacular morphology of its sclerotised vagina. It is the first diplectanid described from E. howlandi.

Pseudorhabdosynochus summanoides n. sp. (Monogenea: Diplectanidae) from Epinephelus coioides in Dapeng Bay, South China Sea, with observations on several similar species of Pseudorhabdosynochus Yamaguti, 1958

One new species of diplectanid monogenean, Pseudorhabdosynochus summanoides n. sp., is reported and described from the marine fish Epinephelus coioides off Nan'ao Shenzhen, China. P. summanoides differs from its closest relative, P. summanae (Young, 1968), by the shape of its vaginal hard-parts, which have a tightly twisted distal region and an accessory patch on the proximal curve. During the course of this work, type-material of several species of Pseudorhabdosynochus was examined and aspects of the vagina and haptor are redescribed and/or figured. These species include P. americanus (Price, 1937), P. hargisi (Oliver & Paperna, 1984), P. amplidiscatus (Bravo-Hollis, 1954), P. epinepheli (Yamaguti, 1938), P. riouxi (Oliver 1986), P. melanesiensis (Laird, 1958), P. cupatus (Young, 1969), P. bocquetae (Oliver & Paperna, 1984), P. kritskyi Dyer et al., 1995, P. capurroi Vidal-Martinez, 1998, P. querni (Yamaguti, 1968) and P. summanae (Young, 1969). Several closely related species are considered in terms of their conspecificity: P. hargisi is proposed as a junior synonym of P. americanus; P. capurroi is suggested as a likely synonym of P. kritskyi; and it is suggested that P. cupatus and P. bocquetae may eventually be demonstrated to be consepcific with P. melanesiensis.

Species of Pseudorhabdosynochus Yamaguti, 1958 (Monogenea: Diplectanidae) from Epinephelus fasciatus and E. merra (Perciformes: Serranidae) off New Caledonia and other parts of the Indo-Pacific Ocean, with a comparison of measurements of specimens prepared using different methods, and a description of P. caledonicus n. sp

Species of Pseudorhabdosynochus were studied from fresh specimens collected from Epinephelus fasciatus and E. merra off New Caledonia, South Pacific, and specimens deposited in Museums. Experiments on two species demonstrated that the sclerotised hollow organs, such as the quadriloculate male copulatory organ and the vagina, may show differences in measurements of up to 50% when flattened. P. caledonicus n. sp. is described from E. fasciatus in New Caledonia, on which it is relatively rare; it is distinguished on the basis of the quadriloculate organ, which has a very thin anterior wall, the sclerotised parts of the vagina in form of a straight tube with a star-shaped lateral structure, and the squamodiscs composed of 11 open rows of rodlets. P. cupatus (Young, 1969) is redescribed from abundant material from E. fasciatus off New Caledonia (new geographical record) and compared with paratype specimens from Australia (from E. fasciatus and E. merra) and specimens from E. fasciatus in the Red Sea (both herein redescribed and figured); a specimen was also found on a slide from E. merra off Vanuatu. P. melanesiensis (Laird, 1958) is redescribed from material from E. merra off New Caledonia (new geographical record) and compared with type-specimens (herein redescribed and figured) from the same host off Vanuatu. The structure of the sclerotised vagina in P. cupatus and P. melanesiensis is very similar, with a thin-walled tube and a heavily sclerotised structure with three loculi. P. vagampullum (Young, 1969) is redescribed from the paratypes from E. merra from Australia, but was not found in New Caledonia; specimens included among its paratypes (from E. merra in Australia), but different, are herein attributed to Pseudorhabdosynochus sp. 3. P. lantauensis (Beverley-Burton & Suriano, 1981) is redescribed from the paratype specimens from E. longispinis off Hong-Kong. A specimen found among the paratypes of P. cupatus belongs to a different species, herein designated as Pseudorhabdosynochus sp. 1. Specimens from E. longispinis off Hong-Kong, previously attributed to P. cupatus, are attributed to another species, Pseudorhabdosynochus sp. 2. The three species P. cupatus, Pseudorhabdosynochus sp. 1 and Pseudorhabdosynochus sp. 2 have in common a 'lamellosquamodisc' composed of central telescopic lamellae and peripheral rows of rodlets; they can be distinguished by the shape of the sclerotised vagina and measurements of the haptoral hard-parts. Specimens from E. longispinis off Hong-Kong, previously attributed to P. vagampullum, probably belong to a different species. Consequently, after these modified determinations, P. cupatus parasitises only E. fasciatus and E. merra, and P. melanesiensis and P. vagampullum parasitise only E. merra. With their wide geographical distribution and different species of Pseudorhabdosynochus in different localities, E. fasciatus and E. merra appear to represent excellent models for investigating monogenean biogeography in the Indo-Pacific Ocean.

PCR-based identification and delineation of members within the Pseudorhabdosynochus lantauensis complex (Monogenea: Diplectanidae)

Molecular methods using genetic markers in the nuclear ribosomal DNA (rDNA) were established to identify and distinguish between two members within the Pseudorhabdosynochus lantauensis complex and two morphologically distinct congeners, Pseudorhabdosynochus epinepheli and Pseudorhabdosynochus coioidesis, from different marine fish species and various geographical origins. Supported by selective DNA sequencing, it was demonstrated that the polymerase chain reaction (PCR)-coupled single-strand conformation polymorphism analysis of the first internal transcribed spacer and restriction fragment length polymorphism analysis of a variable region (representing the D1-D3 domains) in the large subunit of rDNA achieved the identification and delineation of all four taxa examined. These PCR-based approaches provide useful complementary tools to traditional methods for the accurate identification of species within the genus Pseudorhabdosynochus (irrespective of developmental stage) and have major implications for studying the ecology, transmission, and population genetic structures of these and other related parasites and for the prevention and control of the diseases they cause.

Pseudorhabdosynochus hirundineus n. sp. (Monogenea: Diplectanidae) from Variola louti (Perciformes: Serranidae) off New Caledonia

Pseudorhabdosynochus hirundineus n. sp. is described from specimens collected from the gills of Variola louti off Nouméa, New Caledonia, South Pacific. No diplectanid was found on V. albimarginata from the same location. The male sclerotised quadriloculate organ of P. hirundineus is 42 microm in internal length, with a long posterior tube; and the sclerotised vagina, 36 microm in length, is composed of a long tube with anterior open trumpet and two posterior, heavily sclerotised chambers. The two squamodiscs, each with 11-15 rows of rodlets and no central closed row of rodlets, are dissimilar in shape, the ventral being round and the dorsal being oval. By the morphology of its sclerotised vagina, P. hirundineus appears close to P. epinepheli (Yamaguti, 1938) but it is differentiated from it by the shape of its squamodiscs. Pseudorhabdosynochus spp. previously recorded from epinephelines are parasites of species of Epinephelus and Mycteroperca; this is the first species from a species of Variola.

NEOTROPICAL MONOGENOIDEA. 43. DIPLECTANUM MONTICELLII N. SP. (DIPLECTANIDAE) FROM THE GILLS OF CYNOSCION LEIARCHUS (PERCIFORMES: SCIAENIDAE) IN BRAZIL

Diplectanum monticellii n. sp. is described from the gills of Cynoscion leiarchus, a marine Sciaenidae, from Itacuruçá, Rio de Janeiro (type locality); Baía de Guaratuba, Paraná; and Pontal do Sul, Paraná in Brazil. The new species is characterized by the following features: bell-shaped male copulatory organ with a sleevelike base, accessory piece absent, vas deferens looping left intestinal cecum, vaginal aperture sinistroventral, and ventral anchor with elongate superficial and deep roots.

Diplectanum squamatum n.sp. (Monogenea:Diplectanidae) fro the gills of Cynoscion guatucupa (Sciecidae) in southwest Atlantic waters

Diplectanum squamatum n. sp. is described from the gills of the sciaenid Cynoscion guatucupa collected off Mar del Plata, Argentina. The new species is distinguished from other species of the genus by the morphology of the hamuli and the male copulatory organ, and presence of scales on the haptor and body. This is the first species of Diplectanum to be reported from southwest Atlantic waters and, with the possible exception of D. cayennense Euzet & Durette-Desset, 1974, the only species from the Atlantic coast of South America.