Two new species of Diaphorocleidus and new data on D. affinis (Monogenoidea: Dactylogyridae) parasitizing Bryconops cf. affinis (Characiformes: Iguanodectidae) from the Munim River basin, State of Maranho, northeastern Brazil.

During a study conducted on the helminth fauna of fishes in the middle Munim River basin, State of Maranho, northeastern Brazil, three species (two new) of Diaphorocleidus Jogunoori, Kritsky & Venkatanarasaiah, 2004 are reported from the gills of the piaba Bryconops cf. affinis (Iguanodectidae): Diaphorocleidus affinis (Mizelle, Kritsky & Crane, 1968), D. forcipiformis n. sp. and D. munimensis n. sp. New morphological data, drawings, and geographic distribution were provided for D. affinis. Diaphorocleidus forcipiformis n. sp. is characterized by a male copulatory organ with 2 rings counterclockwise and base forming a small tube with two circular flanges and accessory piece bifurcated, claw-shaped, with parts similar in shape and size, one of them distally bifid. Diaphorocleidus munimensis n. sp. is differentiated by the accessory piece, which is composed of two large pieces, united in their proximal part, claw-shaped, and distally hooked. The findings of this initial survey on the helminth parasites of fishes in this area emphasize the importance of carrying out comparable surveys on other fish species. Such surveys may lead to the identification of unknown species or new occurrences.

Two new species of Anacanthorus (Monogenoidea, Dactylogyridae) parasitizing serrasalmid fish in Brazil.

During studies on fish parasites, two new species of Anacanthorus were found parasitizing serrasalmid fishes, Anacanthorus simpliciphallus sp. n. from the hybrid Piaractus mesopotamicus x Piaractus brachypomus and Anacanthorus brandtii sp. n. from Serrasalmus brandtii. Anacanthorus simpliciphallus sp. n. resembles Anacanthorus reginae in the morphology of the male copulatory organ (MCO) and accessory piece but differs from A. reginae in terms of the smaller size of the accessory piece, which corresponds approximately half the size of the MCO and by the presence of a conspicuous metraterm, with a membranous terminal region. Anacanthorus brandtii sp. n. differs from Anacanthorus scapanus by the expansion of the accessory piece, from Anacanthorus jegui by the ratio MCO (male copulatory organ) /AP (accessory piece) and by the expansion of hook shank, from Anacanthorus sciponophallus and A. reginae by the ratio MCO/AP. Anacanthorus brandtii sp. n. can be distinguished from A. reginae and A. simpliciphallus sp.n. by the size of hooks which is similar in A. reginae and A. simpliciphallus sp. n. and dissimilar in A. brandtii sp. n. The two new species also differ from each other by the expansion of shank.

Dactylogyrids (Platyhelminthes, Monogenea) from the gill lamellae of doradids (Siluriformes) with description of five new species of Cosmetocleithrum and new geographical distribution for known species from the Neotropical Region, Brazil.

Five new species of Cosmetocleithrum were described parasitizing the gill filaments of neotropical doradid fishes. Cosmetocleithrum undulatum n. sp., Cosmetocleithrum brachylecis n. sp. and Cosmetocleithrum ludovicense n. sp. are described from Platydoras brachylecis from a market-place of São Luís, State of Maranhão, Brazil. Cosmetocleithrum sacciforme n. sp. and Cosmetocleithrum basicomplexum n. sp. are described from Oxydoras niger from Juruá River, State of Acre, Brazil. Cosmetocleithrum undulatum and Cosmetocleithrum brachylecis resemble Cosmetocleithrum falsunilatum Feronato, Razzolini, Morey & Boeger, 2022 mainly by the unique male copulatory organ (MCO) morphology but differ from these and all congeneric species mainly by the morphology of the MCO, accessory piece and hooks pairs. Cosmetocleithrum ludovicense is closer to Cosmetocleithrum confusus Kritsky, Thatcher & Boeger, 1986 and to Cosmetocleithrum akuanduba Soares, Santos Neto & Domingues, 2018 but differs from those mainly by the morphology of the accessory piece. Cosmetocleithrum sacciforme differs from all congeneric species mainly by the morphology of the accessory piece formed by a single plate of saccular appearance. Cosmetocleithrum basicomplexum also shares morphological characters with Cosmetocleithrum gigas Morey, Cachique & Babilonia, 2019 considering the size of the body and shape of the anchors, but differs mainly in the morphology of the bars and hooks. Besides the new species, new data are presented for Cosmetocleithrum leandroi Soares, Neto & Domingues, 2018, C. akuanduba and C. confusus regarding morphological characteristics and biogeography.

Title: Dactylogyridae (Platyhelminthes, Monogenea) des lamelles branchiales de Doradidae (Siluriformes) avec description de cinq nouvelles espèces de Cosmetocleithrum et nouvelle répartition géographique d'espèces connues de la région néotropicale au Brésil. Abstract: Cinq nouvelles espèces de Cosmetocleithrum sont décrites, parasitant les filaments branchiaux de poissons Doradidae néotropicaux. Cosmetocleithrum undulatum n. sp., Cosmetocleithrum brachylecis n. sp. et Cosmetocleithrum ludovicense n. sp. sont décrits de Platydoras brachylecis provenant d'un marché de São Luís, État du Maranhão, Brésil. Cosmetocleithrum sacciforme n. sp. et Cosmetocleithrum basicomplexum n. sp. sont décrits d'Oxydoras niger de la rivière Juruá, État d'Acre, Brésil. Cosmetocleithrum undulatum et Cosmetocleithrum brachylecis ressemblent à Cosmetocleithrum falsunilatum Feronato, Razzolini, Morey & Boeger, 2022 principalement par la morphologie unique de l'organe copulateur mâle (OCM), mais diffèrent de ces espèces et de toutes les espèces congénères principalement par la morphologie de l'OCM, de la pièce accessoire et des paires de crochets. Cosmetocleithrum ludovicense est proche de Cosmetocleithrum confusus Kritsky, Thatcher & Boeger, 1986 et de Cosmetocleithrum akuanduba Soares, Santos Neto & Domingues, 2018 mais en diffère principalement par la morphologie de la pièce accessoire. Cosmetocleithrum sacciforme se distingue de toutes les espèces congénères principalement par la morphologie de la pièce accessoire formée d'une seule plaque d'aspect sacculaire. Cosmetocleithrum basicomplexum partage également des caractères morphologiques avec Cosmetocleithrum gigas Morey, Cachique & Babilonia, 2019 compte tenu de la taille du corps et de la forme des anchors, mais en diffère principalement par la morphologie des barres et des crochets. Outre les nouvelles espèces, de nouvelles données sont présentées pour Cosmetocleithrum leandroi Soares, Neto & Domingues, 2018, C. akuanduba et C. confusus concernant les caractéristiques morphologiques et la biogéographie.

New and previously described species of Ameloblastella (Monogenoidea: Dactylogyridae) parasitizing Hypophthalmus marginatus and Pimelodina flavipinnis (Siluriformes: Pimelodidae) from the Tocantins River, Maranhão State, Brazil.

A new and two previously described species of Ameloblastella Kritsky, Mendoza-Franco & Scholz, 2000 were found in the gills of two pimelodid catfishes from the Tocantins River, Maranhão State, Brazil: Ameloblastella prima n. sp. from Pimelodina flavipinnis Steindachner, and A. edentensis Mendoza-Franco, Mendoza-Palmero & Scholz, 2016 and A. peruensis Mendoza-Franco, Mendoza-Palmero & Scholz, 2016 from Hypophthalmus marginatus Valenciennes. The new species differs from its congeners by having an accessory piece tubular, covered by a delicate membranous cap at 2/3 of the length, by the shape of the ventral and dorsal anchors, in which the ventral anchor is represented by a curved shaft in a position of 80° degrees, with delicate ornamentations located at the superficial and deep root areas, and the dorsal anchor with a long, well-developed and convex superficial root and short deep root, also presenting delicate ornamentations at the superficial and deep root areas. The present study provides new biogeographical data on the two previously described species of Ameloblastella and improves the knowledge on the species of Monogenoidea from the Neotropical Region, increasing to 14 the number of known species of Ameloblastella for this region.

Two new species of Curvianchoratus (Monogenoidea, Dactylogyridae) parasitizing Psectrogasteramazonica (Characiformes, Curimatidae) and a new record for Curvianchoratussingularis in the Tocantins River, Maranhão, Brazil.

Several studies have demonstrated parasitism by monogenoids in characiform fish in the Neotropics. During studies on the helminth fauna of curimatids from the Tocantins River, specimens of Psectrogasteramazonica Eigenmann & Eigenmann, 1889 were examined and species of Curvianchoratus Hanek, Molnar & Fernando, 1974 were found. Species of the genus are characterized mainly by the complex shape of haptoral anchors with a modified dorsal anchor, composed by two subunits, dorsal-median and dorsal. To date, two species of Curvianchoratus are known to parasitize curimatid fishes: the type species Curvianchoratushexacleidus Hanek, Molnar & Fernando, 1974 and Curvianchoratussingularis (Suriano, 1980). During examination of specimens of P.amazonica collected in the Tocantins River, Embiral, Imperatriz, Maranhão State, Brazil, two new species of Curvianchoratus were found and are described herein. Curvianchoratuspsectrogasterisp. nov. and Curvianchoratusdominguesisp. nov. are characterized by possessing the male copulatory organ formed by a long cirrus and a claw-shaped accessory piece, connected to the base of the male copulatory organ by a ligament. The new species differs from the two known congeneric species mainly by the morphology of the dorsal-median and dorsal subunits of the dorsal anchor. Curvianchoratuspsectrogasterisp. nov. also differs from other species of the genus by the absence of the ventral bar and Curvianchoratusdominguesisp. nov. by the size and shape of the ventral bar. An amendment to the diagnosis of Curvianchoratus is provided to accommodate the new species. The present study increases the number of Curvianchoratus species to four and extends the occurrence of the genus to the Tocantins-Araguaia Basin.

New species of Polystomoides (Monogenoidea: Polystomatidae) parasitizing the urinary bladder of a freshwater turtle in Brazil.

Trachemys dorbigni is the most abundant freshwater turtle species in Rio Grande do Sul, southern Brazil. Chelonians are known to host a wide variety of pathogens, including viruses, bacteria, hemoparasites and helminths. Among these, nine genera of polystomatid flatworms (Monogenoidea; Polystomatidae) infect freshwater turtles: Apaloneotrema, Aussietrema, Fornixtrema, Manotrema, Pleurodirotrema, Polystomoidella, Polystomoides, Uropolystomoides and Uteropolystomoides. However, little is known about the biology of these parasites in the Neotropical Realm. Through investigative cystoscopy, specimens of Polystomatidae were located inside the urinary bladder of the host T. dorbigni. Retrieved specimens were fixed and stained whole mounts prepared for taxonomic identification. In the present paper, a new species of Polystomoides (Monogenoidea: Polystomatidae) parasitizing the urinary bladder of a freshwater turtle of the species T. dorbigni in Brazil is described. Polystomoides santamariensis n. sp. differs from the congeneric species on the length of the genital spines, which are longer. Given the enormous diversity of freshwater turtles around the world, it is likely that a large number of chelonian polystomatids are still unknown.

A New Species of Unibarra (Monogenoidea, Dactylogyridae) Parasite of Oxydoras niger From Juruá River, State of Acre, Brazil and New Data for U. paranoplatensis.

Monogenoids are ectoparasites that have a simple one-host lifecycle, high species diversity, and a relatively high host specificity. During studies on the helminth fauna of fishes from the Jurua River, in Acre State, Brazil, a new species of the monotypic genus Unibarra Suriano & Incorvaia, 1995 was found parasitizing Oxydoras niger Valenciennes, 1821. Unibarra juruaensis n. sp. is allocated in the genus based on the presence of a single haptoral bar, marginal hooks similar in shape and size, gonads partially overlapping, and a conspicuous filament which connects the base of the male copulatory organ with the accessory piece. The new species differs from the only species of the genus by the smaller size of the body and of the structures, by the morphology of copulatory complex, with an accessory piece thinner than that of U. paranoplatensis Suriano & Incorvaia, 1995 and by the presence of two eyespots. The type species, U. paranoplatensis, is referred in a new host, Pimelodus blochii Valenciennes, 1840, with new morphological data. A table of measurements of the new species and previous and the present reports of U. paranoplatensis is presented.

Diversity of Nematoda and Digenea from different species of characiform fishes from Tocantins River, Maranhão, Brazil.

During a survey of the helminth fauna of characiform fishes from the Tocantins River, Brazil, 185 fish specimens from 22 species were studied. Twelve species of Nematoda and nine species of Digenea were collected. Some of these helminth species were reported for the first time in their hosts, thus representing new host records: Procamallanus (Spirocamallanus) sp. in Bivibranchia notata, Brycon pesu, Chalceus macrolepidotus, Hemiodus microlepis and Hemiodus unimaculatus; Procamallanus (Spirocamallanus) inopinatus in Triportheus elongatus; Goezia sp. (larva) in Boulengerella cuvieri; Rhabdochona acuminata in Brycon pesu and Triportheus trifurcatus; Raphidascaris sp. (larva) in Caenotropus labyrinthicus; Cosmoxynema vianai in Cyphocharax gouldingi; Rondonia rondoni in Leporinus fasciatus and Mylesinus paucisquamatus; Klossinemella iheringi in Mylesinus paucisquamatus; Cucullanidae gen. sp. in Myloplus rubripinnis; Rhabdochona sp. in Triportheus elongatus; Alphamphistoma sp. in Myleus setiger; Chalcinotrema sp. in Cyphocharax gouldingi; Pacudistoma guianense in Hemiodus unimaculatus and Myleus torquatus; Pseudocladorchis cylindricus in Hemiodus unimaculatus; Dadaytrema oxycephala in Mylesinus paucisquamatus; Travassosinia dilatata in Myloplus asterias; and Genarchella genarchella in Raphiodon vulpinus. Studies identifying new hosts and new localities for parasites have contributed to the knowledge of local biodiversity. A list of previous records of helminths included in the present study, providing hosts, localities, and references, is presented here.

Neonematobothrium annakohnae n. sp. (Digenea: Didymozoidae) parasitizing Euthynnus alletteratus (Perciformes: Scombridae) in the Southwest Atlantic Ocean.

PURPOSE: Describe a new species of didymozoid digenean Neonematobothrium Yamaguti, 1965 from the operculum of the scombrid fish, Euthynnus alletteratus (Rafinesque, 1810), in the Southwest Atlantic Ocean off Brazil. METHODS: Thirty-four specimens of E. alletteratus were collected in the coastal zone of the state of Rio de Janeiro and obtained from local fishermen between 2006 and 2018 in the municipal market of São Pedro in Niterói, Brazil. The parasites were fixed in AFA (93% ethanol 70%, 5% formaldehyde, 2% glacial acetic acid) without pressure, stained with Langeron alcoholic acid carmine, dehydrated in an alcohol series, cleared in beachwood creosote or clove oil and mounted in Canada balsam as permanent slides. RESULTS: Neonematobothrium annakohnae n. sp. is a member of the genus based on a combination of the following characteristics: body free, uncapsulated; body long and dorsoventrally flattened; esophagus surrounded by gland cells; ovary and vitellarium single, long, narrow and unbranched in the anterior and posterior halves of the body, respectively; uterus with three loops; and site of infection in subcutaneous tissue of scombrid fish. The new species differs from the two recognized species of the genus mainly by the size of the body, which is much larger, the shape of the genital pore, which is differentiated in a structure similar to a small sucker and by esophagus without diverticula. CONCLUSIONS: Neonematobothrium annakohnae n. sp. parasite of E. alletteratus from the Southwest Atlantic Ocean, described herein, represents the third species of Didymozoidae belonging to the genus Neonematobothrium. The two known species Neonematobothrium kawakawa Yamaguti, 1965 and Neonematobothrium dorsale Yamaguti, 1970 were described from fish belonging to the same genus of the host from Pacific Ocean. The diagnosis of the genus is enlarged to "esophagus with or without diverticula", to fill the characteristics presented by the new species. The description of N. annakohnae n. sp. demonstrates the need to expand the studies of these interesting and intriguing group of parasites, due to the fact that number of known didymozoids taxa in the Atlantic Ocean is far from representing the real situation.

New host record and geographical distribution of Nematoda parasitizing Hypophthalmus marginatus Valenciennes (Siluriformes) from the Tocantins River, Brazil

Hypophthalmus marginatus is among the most commercialized fish from the Amazon region, with fish fillets exported to Southeastern Brazil and other countries. In the present study, the H. marginatusanalyzed were parasitized by third-stage larvae of Hysterothylaciumsp. and Anisakissp. These nematodes are being reported for the first time in H. marginatus collected from the Tocantins River, representing a new host and geographical records, and expanding knowledge of the hosts of these nematodes in the Neotropical Region. A brief description with original measurements is presented.

First record of a mermithid worm (Nematoda, Mermithidae) parasitizing a third instar nymph of Triatoma sordida (Stål, 1859) (Hemiptera, Reduviidae, Triatominae) from Mato Grosso, Brazil.

A juvenile specimen of a mermithid (Nematoda) was found parasitizing a third instar nymph of Triatoma sordida from Mato Grosso, Brazil. This is the first record of mermithid parasitism in a triatomine species. The Mermithidae represents a family of nematodes that are specialized insect parasites. Entomonematodes are one of the highly influential agents regulating the population dynamics of insects. This report introduces the opportunity to think about mermithids as a possible candidate for use as triatomine biological control.

Seasonality of parasitic helminths of Leporinus macrocephalus and their parasitism rates in farming systems in the Amazon / Sazonalidade de helmintos parasitos de Leporinus macrocephalus e seus índices parasitários em sistemas de cultivo na Amazônia

Abstract The objective of the present study was to analyze the seasonality of parasitic helminths of Leporinus macrocephalus from fish farms in the municipality of Cruzeiro do Sul, Acre, Brazil, and their parasitism rates. Between June 2014 and March 2015, 200 specimens were sampled from two fish farms: one with a semi-intensive system and the other with an extensive system (100 fish from each farm: 50 during the dry season and 50 during the rainy season). Fifteen species of parasites were found, with seasonal variations of some according to the farming system. In the semi-intensive fish farm, there was greater prevalence of infection during the dry season. Also, Urocleidoides paradoxus, Procamallanus (Spirocamallanus) inopinatus, Goezia leporini and Rhabdochona (Rhabdochona) acuminata presented differences in their parasitism rates between the seasons. In the extensive fish farm, no variation in the prevalence of infection was observed between the seasons and two species Tereancistrum parvus and G. leporini demonstrated differences only regarding the mean intensity of infection. The data presented here may help fish farmers to understand the parasite dynamics of L. macrocephalus in farming systems during the dry and rainy seasons in the state of Acre.

Resumo O presente estudo teve como objetivo analisar a sazonalidade dos helmintos parasitos de Leporinus macrocephalus provenientes de pisciculturas no município de Cruzeiro do Sul, Acre, Brasil e seus índices parasitários. Durante o período de junho de 2014 a março de 2015 foram coletados 200 espécimes obtidos de duas pisciculturas, uma de sistema semi-intensivo e outra de sistema extensivo, sendo 100 peixes em cada, durante as estações seca e chuvosa, 50 espécimes por estação. Foram registradas quinze espécies de parasitos, com variação sazonal de ocorrência de alguns nos sistemas de cultivo. Na piscicultura semi-intensiva houve maior prevalência de infecção na seca, e Urocleidoides paradoxus, Procamallanus (Spirocamallanus) inopinatus, Goezia leporini e Rhabdochona (Rhabdochona) acuminata apresentaram diferenças dos índices parasitários entre as estações. Na piscicultura extensiva não foi detectada variação da prevalência de infecção entre as estações e duas espécies, Tereancistrum parvus e G. leporini assinalaram diferença apenas na intensidade média de infecção. Os dados apresentados neste estudo podem auxiliar os piscicultores na compreensão da dinâmica parasitária de L. macrocephalus em sistemas de cultivos durante as estações seca e chuvosa no estado do Acre.

Seasonality of parasitic helminths of Leporinus macrocephalus and their parasitism rates in farming systems in the Amazon.

The objective of the present study was to analyze the seasonality of parasitic helminths of Leporinus macrocephalus from fish farms in the municipality of Cruzeiro do Sul, Acre, Brazil, and their parasitism rates. Between June 2014 and March 2015, 200 specimens were sampled from two fish farms: one with a semi-intensive system and the other with an extensive system (100 fish from each farm: 50 during the dry season and 50 during the rainy season). Fifteen species of parasites were found, with seasonal variations of some according to the farming system. In the semi-intensive fish farm, there was greater prevalence of infection during the dry season. Also, Urocleidoides paradoxus, Procamallanus (Spirocamallanus) inopinatus, Goezia leporini and Rhabdochona (Rhabdochona) acuminata presented differences in their parasitism rates between the seasons. In the extensive fish farm, no variation in the prevalence of infection was observed between the seasons and two species Tereancistrum parvus and G. leporini demonstrated differences only regarding the mean intensity of infection. The data presented here may help fish farmers to understand the parasite dynamics of L. macrocephalus in farming systems during the dry and rainy seasons in the state of Acre.

New species and reports of dactylogyrids (Monogenoidea) from Salminus franciscanus (Actinopterygii: Bryconidae) from the upper São Francisco River, Brazil.

Six species of dactylogyrid monogenoideans were collected at the upper São Francisco River, State of Minas Gerais, Brazil, from the gills of Salminus franciscanus. Anacanthorus adkruidenieri sp. n. and Anacanthorus paradouradensis sp. n. are described and compared with the other species of Anacanthorus. Anacanthorus adkruidenieri sp. n. is more similar to A. kruidenieri and A. parakruidenieri, but it can be distinguished from both by the rod-shaped accessory piece, which is articulated with the base of the male copulatory organ and is coiled around it, and by the shank of the hook, with expanded proximal bulbous portion bearing a central, elliptical foramen. Anacanthorus paradouradensis sp. n. resembles A. douradensis, but differs in the accessory piece, which is approximately half the length of the copulatory organ. Salminus franciscanus is a new host record and the São Francisco Basin is a new locality record for Anacanthorus daulometrus, Annulotrematoides glossophallus, Jainus iocensis and Tereancistrum arcuatus.

A new species of diplectanid (Monogenoidea) from Paranthias colonus (Perciformes, Serranidae) off Peru.

Pseudorhabdosynochus jeanloui n. sp. (Monogenoidea, Diplectanidae) is described from specimens collected from the gills of the Pacific creolefish, Paranthias colonus (Perciformes, Serranidae) from a fish market in Chorrillos, Lima, Peru. The new species is differentiated from other members of the genus by the structure of its sclerotized vagina, which has two spherical chambers of similar diameter. This is the first Pseudorhabdosynochus species described from the Pacific coast of America, the third species of the genus reported from South America and the first described from a member of Paranthias.

Scanning electron microscopy on Gotocotyla acanthura (Monogenea, Gotocotylidae) from Pomatomus saltatrix (Ostheichthyes, Pomatomidae) in Brazil.

Gotocotyla acanthura (Parona & Perugia, 1896) Meserve, 1938 collected from the gills of Pomatomus saltatrix from the coast of the state of Rio de Janeiro state was analyzed using scanning electron microscopy (SEM). The study demonstrated the presence of a buccal cavity, a genital atrium on the ventral surface and a muscular structure on the dorsal surface at the level of the body constriction. An elongated haptor with 80 to 120 pedunculated clamps symmetrically distributed in two rows, with rib-like thickenings and a curved lappet bearing a pair of hooks at the posterior extremity of the body were also observed. The cirrus could be seen protruding from the genital atrium, armed with pectinate spines along its length and presenting up to eight pointed spines around the genital atrium.

Scanning electron microscopy on Gotocotyla acanthura (Monogenea, Gotocotylidae) from Pomatomus saltatrix (Ostheichthyes, Pomatomidae) in Brazil / Microscopia eletrônica de varredura de Gotocotyla acanthura (Monogenea, Gotocotylidae) parasita de Pomatomus saltatrix (Ostheichthyes, Pomatomidae) no Brasil

Gotocotyla acanthura (Parona & Perugia, 1896) Meserve, 1938 collected from the gills of Pomatomus saltatrix from the coast of the state of Rio de Janeiro state was analyzed using scanning electron microscopy (SEM). The study demonstrated the presence of a buccal cavity, a genital atrium on the ventral surface and a muscular structure on the dorsal surface at the level of the body constriction. An elongated haptor with 80 to 120 pedunculated clamps symmetrically distributed in two rows, with rib-like thickenings and a curved lappet bearing a pair of hooks at the posterior extremity of the body were also observed. The cirrus could be seen protruding from the genital atrium, armed with pectinate spines along its length and presenting up to eight pointed spines around the genital atrium.

Gotocotyla acanthura (Parona & Perugia, 1896) Meserve, 1938, coletado das brânquias de Pomatomus saltatrix do litoral do Estado do Rio de Janeiro, foi estudado por microscopia eletrônica de varredura (MEV). O estudo demonstrou a presença de uma cavidade bucal, átrio genital na superfície ventral e uma estrutura muscular na superficie dorsal ao nível da constricção do corpo. Na extremidade posterior do corpo, foi observado o haptor alongado, apresentando 80 a 120 pinças pedunculadas, distribuídas em duas fileiras simétricas e uma porção terminal curvada provida de um par de ganchos. O cirro foi visualizado projetando-se do átrio genital, armado com espinhos pectinados ao longo do seu comprimento, apresentando até 8 espinhos pontiagudos ao redor do átrio.

A new species of Mymarothecium and new host and geographical records for M. viatorum (Monogenea: Dactylogyridae), parasites of freshwater fishes in Brazil.

Mymarothecium boegeri sp. n. (Monogenea: Dactylogyridae) is described from the gills of Colossoma macropomum Cuvier (Characidae), collected from the aquaria of the "Centro de Pesquisas em Aquicultura, Departamento Nacional de Obras Contra as Secas (DNOCS)", Pentecoste City, State of Ceará, Brazil. Mymarothecium viatorum Boeger, Piasecki et Sobecka, 2002 is reported from the type host, Piaractus brachypomus (Cuvier) (Characidae) and from a new host, P. mesopotamicus (Holmberg) (Characidae), confirming the occurrence of M. viatorum in the Neotropical Region. The new species differs from the congeneric species in the structure of male copulatory complex; it is more closely related to M. viatorum by the presence of a posteromedial projection on ventral bar.

Ultrastructural studies of the Mehlis' gland in Metamicrocotyla macracantha (Monogenea, Microcotylidae) parasite of Mugil liza (Teleostei)

A ultraestrutura da glândula de Mehlis de Metamicrocotyla macracantha, parasita de brânquia coletado de Mugil liza do Rio de Janeiro, Brasil,foi estudado através da microscopia eletrônica de transmissão. A glândula de Mehlis consiste de dois tipos de células secretoras, S1 e S2, cada uma produzindo um corpo secretor diferente. Os corpos S1 são esféricos, em forma de lamelas e observados em diferentes estágios de desenvolvimentos no citoplasma dessas células. Os corpos S2 são esféricos a ovais com conteúdos densos, apresentando uma estrutura cristalina. O citoplasma das células da glândula de Mehlis apresenta também ribossomas livres, retículo endoplasmático granular e complexo de Golgi, organelas características de células secretoras.

Monogenea parasites of Micropogonias furnieri (Desmarest, 1823) (Pisces, Sciaenidae) from the littoral of Rio de Janeiro state, Brazil

From the gills of 100 Micropogonia furnieri (Desmarest, 1823) from Atlantic coast of Rio de Janeiro State, were recovered Macrovalvitrema sinaloense Caballero & Bravo-Hollis, 1955, Pterinotrematoides mexicanum Caballero & Bravo-Hollis, 1955, Rhamnocercus rhmnocercus Monaco, Wood & Mizelle, 1954 and Encotyllabe spari Yamaguti, 1934. M. furnieri represents a new host record for them and a new geographical dsitribution is referred for M. sinaloense, P. mexicanum and R. rhmnocercus.