Cucullanus pinnai pinnai and C. pinnai pterodorasi (Nematoda Cucullanidae): what does the integrative taxonomy tell us about these species and subspecies classification?

Cucullanus pinnai has been divided in two subspecies (C. pinnai pinnai and C. pinnai pterodorasi) based on the morphology of oesophastome. While C. pinnai pinnai apparently shows low host specificity and broad geographic occurrence, with certain morphological variations, C. pinnai pterodorasi was reported once, parasitizing Pterodoras granulosus. We used an integrative taxonomic approach to evaluate whether or not populations of C. pinnai pinnai from Trychomycterus spegazzinii (Escoipe River, Argentina) and Pimelodus fur (Miranda River, Brazil), and of C. pinnai pterodorasi from Pterodoras granulosus (Miranda River, Brazil) are conspecific. Parasites were observed using light microscopy and genetically characterized based on partial sequences of the 18S and 28S rDNA, ITS1-5.8S-ITS2, and COI mtDNA. Phylogenies were reconstructed and the Generalized Mixed Yule Coalescent (GMYC), Poisson Tree Process (bPTP), and Automatic Barcode Gap Discovery (ABGD) were used for species delimitation purposes. The present samples formed well-supported monophyletic assemblages, corroborating in part the results of morphological analyses; however, they grouped according to geographic origin. Species delimitation suggested conspecificity of C. pinnai pinnai with C. pinnai pterodorasi from Brazil; consequently, the morphology of oesophastome may be an intraspecific variation. Results also indicated that C. pinnai may represent a species complex as samples from Argentina were suggestive of an independent specific entity. However, definitive affirmations are premature, since there is no autapomorphy for separating C. pinnai from Brazil and Argentina and sampling was limited to three host species from two river basins. The phylogenetic reconstructions also confirmed the artificiality of some genera within Cucullanidae.

Structure of the metazoan parasite communities of haemulid fish (Actinopterygii: Perciformes) in the South Atlantic Ocean: a comparative approach.

Haemulidae represents one of the most diverse, widespread and conspicuous families of Perciformes, in which most species are marine, some brackish and rarely from freshwater. From April 2009 to July 2012, 120 specimens of Conodon nobilis, 60 Orthopristis rubra and 50 Anisotremus virginicus were collected off the State of Rio de Janeiro, Brazil, and analyzed for metazoan parasites. A total of 16 parasite taxa were found on/in A. virginicus, 19 on/in Co. nobilis and 21 on/in O. rubra, in which ectoparasites were most common on A. virginicus and Co. nobilis and endoparasites in O. rubra. All parasites showed aggregate pattern of distribution (discrepancy index values higher than 0.70). Mean abundance, species richness and Brillouin index (diversity) differed among the host species, i.e., O. rubra showed the highest values, followed by A. virginicus and Co. nobilis with intermediate and lowest values, respectively. At infracommunity level was possible to observe high similarity of parasite composition among the three host species. The digeneans Leurodera decora and Monorchis latus, and the acanthocephalan Koronacantha sp. represent new locality records off Brazil. Moreover, five, four and two taxa are reported, for the first time, parasitizing Co. nobilis, A. virginicus and O. rubra, respectively.

Proposal of Cynoscionella n. g. (Monogenea: Diplectanidae), with description of a new species from the gills of Cynoscion phoxocephalus (Actinopterygii: Sciaenidae) in Peru and reassignment of two species of Diplectanum Monticelli, 1903.

Cynoscionella n. g. is proposed for Cynoscionella sanmarci n. sp. and two previously described species of Diplectanum Diesing, 1858 were reassigned into the new genus. The three species are gill parasites of sciaenid fishes (Perciformes: Sciaenidae). The new genus is closely related with Diplectanum (sensu stricto), but is mainly distinguished by its male copulatory organ (MCO) having a slightly sclerotized sleeve-shaped base, lacking accessory piece and accessory copulatory organ. In addition, Cynoscionella n. g. differs from Diplectanum species by having the ventral anchors with well-developed roots, and a prostatic reservoir simple. Cynoscionella sanmarci n. sp. is a parasite of the cachema weakfish Cynoscion phoxocephalus Jordan & Gilbert, a demersal teleost collected from off the coastal zone of Puerto Pizarro, Tumbes region, northern Peru. Diplectanum bilobatum Hargis, 1955 from the spotted weakfish Cynoscion nebulosus (Cuvier) and D. monticellii Domingues & Boeger, 2003 from the smooth weakfish Cynoscion leiarchus (Cuvier), are transferred to Cynoscionella n. g. as Cy. bilobatum (Hargis, 1955) n. comb. and Cy. monticelli (Domingues & Boeger, 2003) n. comb. The present finding represents the first data on the monogenean parasites of C. phoxocephalus. This is the thirteenth marine diplectanid species recorded from Peru.

Six new species of Rhamnocercus Monaco, Wood & Mizelle, 1954 (Monogenea: Diplectanidae) infecting the gills from South American sciaenid fishes.

A parasitological survey searching diplectanids (Monogenea: Diplecatnidae) infesting the gills of marine fishes from South America was carried out during the 2019-2020 period. The gills of four sciaenid species, 2 Cheilotrema fasciatum Tschudi, 1 smalleye croaker Nebris microps Cuvier, 2 royal highhat Pareques lanfeari (Barton), and 1 minor stardrum Stellifer minor (Tschudi), were sampled. Six new species of Rhamnocercus Monaco, Wood & Mizelle, 1954 were described: Rhamnocercus chacllae n. sp. and Rhamnocercus chaskae n. sp. from P. lanfeari, Rhamnocercus fasciatus n. sp. from C. fasciatum, Rhamnocercus microps n. sp. from N. microps, and Rhamnocercus rimaci n. sp. and Rhamnocercus tantaleani n. sp. from S. minor. Rhamnocercus chacllae n. sp. can be differentiated from its congeners by its L-shaped male copulatory organ (MCO) and by having an anteromedial slight notch at ventral bar. Rhamnocercus chaskae n. sp. differs from the other species of the genus by its long and straight MCO with bifid distal end and by having haptoral accessory spines at level of ventral bar with quadrifid distal portion. Rhamnocercus fasciatus n. sp. is characterized by possessing a straight and long MCO with truncated distal end, haptoral accessory spines at level of ventral bar with bifid distal portion, dorsal bars with a knob at lateral extremity, and a large vagina with bell-shaped. Rhamnocercus microps n. sp. differs from all congeners mainly by having a short and straight MCO with the distal end of internal tube spatulate and uncovered by external tube. Rhamnocercus rimaci n. sp. is can be distinguished from all other species of Rhamnocercus by having an almost J-shaped MCO with the distal end of external tube slight expanded and the distal end of internal tube narrow and uncovered by external tube. Rhamnocercus tantaleani n. sp. is mainly characterized by its MCO, which is tubular and straight, having the distal end of external tube bifurcated (right branch well-expanded and left branch narrow) and the distal end of internal tube enveloped by left branch of the external tube. This is the first data on the parasites of P. lanfeari, a little known, but popular fish in local markets from Peru. Rhamnocercus microps n. sp. is the first described species of Rhamnocercus in Brazil. The present finding brings to 12, the number of known species of Rhamnocercus. A key to Rhamnocercus species is provided.

New arrangement of three genera of fish tapeworms (Cestoda: Proteocephalidae) in catfishes (Siluriformes) from the Neotropical Region: taxonomic implications of molecular phylogenetic analyses.

Tapeworms (Cestoda: Proteocephalidae) are the dominant component of communities of intestinal parasites in pimelodid and other catfishes (Siluriformes) from South America. Even though these parasites have been studied intensively over more than one century, molecular taxonomy and phylogenetics have questioned their morphology-based classification, thus raising doubts about the systematic value of traits commonly used to circumscribe individual taxa. In the present study, members of three morphologically well-characterized genera of proteocephalids from pimelodid (Hemisorubim platyrhynchos and Sorubim lima) and auchenipterid (Ageneiosus inermis) catfishes from the Paraná or Amazon River basins were subjected to DNA sequencing of the large subunit nuclear ribosomal RNA (lsrDNA) and complete mitochondrial cytochrome c oxidase subunit I (COI). Phylogenetic analyses revealed the sister relationship between Manaosia bracodemoca and Mariauxiella piscatorum, and among Mariauxiella pimelodi and Ageneiella brevifilis. As a result, Mar. piscatorum and A. brevifilis are transferred to Manaosia and Mariauxiella, respectively, as Manaosia piscatorum n. comb. and Mariauxiella brevifilis n. comb., and the genus Ageneiella is suppressed. Diagnoses of Manaosia and Mariauxiella are amended. In addition, the present study revealed misidentification of tapeworms whose sequences are deposited in the GenBank database.

Bicentenariella n. g. (Monogenea: Dactylogyridae) including descriptions of three new species and two new combinations from serranid fishes (Actinopterygii: Serranidae: Anthiinae) in the South American Pacific Ocean.

Bicentenariella n. g. is proposed to accommodate three new species of dactylogyrid monogeneans found on the gills of the threadfin bass Pronotogrammus multifasciatus Gill (Perciformes: Serranidae) from the Southeastern Pacific Ocean off Peru: Bicentenariella claudiae n. sp. (type-species), B. sinuosa n. sp. and B. puertopizarroensis n. sp. Bicentenariella n. g. is mainly characterised by possessing a broadly X-shaped dorsal bar, which has the anterior arms longer than posterior ones and by having a ventral bar with two medial projections. Bicentenariella n. g. is also characterised by having: (i) anchors equal, each with elongate superficial root and short deep root; (ii) an haptor with bilaterally paired lobes, lacking haptoral reservoirs; (iii) hooks with protruded obtuse thumb and undilated shank; (iv) a tubular tapered-shaped male copulatory organ with basal flap bifurcated or not (MCO), lacking accessory piece; (v) a delicate membrane associated with the shaft of the MCO present or absent; (vi) a muscular trumpet-shaped vagina, vaginal aperture dextrolateral; (vii) eyespots absent, accessory chromatic granules present; and (viii) a not lobulated testis. Bicentenariella claudiae n. sp. is characterised by having a MCO with whip-shaped distal end and a rod-shaped ventral bar with hatchet-shaped lateral ends. Bicentenariella sinuosa n. sp. is typified by possessing a MCO with an irregular filamentous membrane surrounding its shaft and a dumbbell-shaped ventral bar. Bicentenariella puertopizarroensis n. sp. can be differentiated from its congeners by having a tubular-shaped MCO with twisted distal end and a narrow W-shaped ventral bar. Parancylodiscoides peruensis Cruces, Chero, Sáez & Luque, 2017 from Hemanthias peruanus (Steindachner) and P. signiferi Cruces, Chero, Sáez & Luque, 2017 from H. signifer (Garman), are transferred to Bicentenariella n. g. as B. peruensis n. comb and B. signiferi n. comb., respectively.

Testing for deterministic succession in metazoan parasite communities of marine fish.

Parasite communities are similar to free-living communities; decay of similarity over geographic distance, theory of island biogeography, species-area relationships and nestedness have been documented in both communities. Ecological succession has been studied in free-living communities but has rarely been examined in parasite communities. We use seriation with replication to test the hypothesis that succession of parasite community structure is deterministic, thus developing throughout consecutive changes along the fish ontogeny, via a seriated pattern. 12 306 marine fishes (95 species) were studied. In 40 species, a seriated pattern was detected; 25 had a tendency towards a seriated pattern, and for 31 species, succession was at random. Age-classes for each host species explained deterministic successional patterns for whole parasite communities and ectoparasites. Richness and number of age-classes explained this pattern for endoparasites. Seriated successional pattern was evident for parasite communities of long-lived marine fish, indicating that parasite communities follow sequential changes over time, like many free-living communities.

An integrative approach assesses the intraspecific variations of Procamallanus (Spirocamallanus) inopinatus, a common parasite in Neotropical freshwater fishes, and the phylogenetic patterns of Camallanidae.

Integrative taxonomy was used to evaluate two component populations of Procamallanus (Spirocamallanus) inopinatus in Brazil and the phylogeny Camallanidae. Parasite populations were collected in the characiform Anostomoides passionis from River Xingu (Amazon basin) and Megaleporinus elongatus from River Miranda (Paraguay basin). Morphology was analysed using light and scanning electron microscopy (SEM). Genetic characterization was based on partial sequences of the 18S and 28S rDNA, and COI mtDNA. Phylogenies were based on 18S and COI due to data availability. Generalized Mixed Yule Coalescent (GMYC), Poisson Tree Process (PTP) and *BEAST were used for species delimitation and validation. SEM revealed for the first time the presence of minute denticles and pore-like structures surrounding the oral opening, phasmids in females and confirmed other important morphological aspects. Statistical comparison between the two-component populations indicated morphometric variations, especially among males. The different component population of P. (S.) inopinatus showed variable morphometry, but uniform morphology and were validated as conspecific by the GMYC, PTP and *BEAST. Some camallanid sequences in GenBank have incorrect taxonomic labelling. Host, environment and geographic aspects seem to be related to some lineages within Camallanidae; however, their real phylogenetic meanings are still unclear.

A new genus and three new species of dactylogyrids (Monogenea), gill parasites of the threadfin bass, Pronotogrammus multifasciatus Gill (Perciformes: Serranidae) in the Southeastern Pacific Ocean off Peru.

Pronotogrammella n. g. is erected to accommodate Pronotogrammella boegeri n. sp. (type-species), Pr. scholzi n. sp. and Pr. multifasciatus n. sp. (Monogenea: Dactylogyridae). The new species are gill parasites of the threadfin bass Pronotogrammus multifasciatus Gill (Perciformes: Serranidae), a demersal teleost collected from off the coastal zone of Puerto Pizarro, Tumbes, Peru. Pronotogrammella n. g. is mainly characterised by having broadly fork-shaped dorsal anchors, which have an accessory anchor sclerite articulated to the tip of the superficial roots. Pronotogrammella n. g. is also characterised by having: (i) a tubular tapered-shaped male copulatory organ (MCO), filamentous distally, with a clockwise coil at distal end or not, lacking accessory piece; (ii) a dorsal bar with an anteromedial delicate umbelliform membrane supported by two processes; (iii) hooks with upright blunt thumb and uniform shank; (iv) a vaginal aperture dextrolateral; (v) a subquadrangular haptor, with inconspicuous lateral flaps and lacking haptoral reservoirs; and (vi) eye-spot or chromatic granules absent. Pronotogrammella boegeri n. sp. is characterised by its crosier-shaped MCO having a clockwise coil at distal end and by its dorsal bar with a straight anteromedial processes. Pronotogrammella scholzi n. sp. is typified by possessing of a dorsal bar with the anteromedial processes like cow horns, hoof-shaped deep roots of the dorsal anchors and a broader shaft of the MCO. Pronotogrammella multifasciatus n. sp. differs from all congeners by having a tubular MCO with twisted shaft and a base with a short and broad arm and by having an almost dumbbell-shaped ventral bar.

Four new species of dactylogyrids (Monogenea: Dactylogyridae) parasitic on gills of labrid and sparid fishes from Southeastern Pacific Ocean off Peru.

During a research on gill ectoparasites of Peruvian marine fishes, four dactylogyrid (Monogenea) species, parasitising two teleost species, Bodianus diplotaenia (Gill) (Labridae) and Calamus brachysomus (Lockington) (Sparidae), were found. Euryhaliotrema luisae n. sp. ex C. brachysomus is differentiated from other congeneric species by the morphology of the male copulatory organ, which comprises a coil of nine counterclockwise rings, and by the morphology of the anchors and bars. Euryhaliotrema magnopharyngis n. sp. ex C. brachysomus can be distinguished from all other congeners by having a well-developed pharynx occupying much of the anterior region and by the ventral bar, which is V-shaped, with well-elongated, thin arms. In addition, E. luisae n. sp. and E. magnopharyngis n. sp. can be differentiated from all other members of Euryhaliotrema Kritsky & Boeger, 2002 by the presence of a glandular oval plate lying on peduncle. Haliotrema diplotaenia n. sp. ex B. diplotaenia is characterised by the structure of the male copulatory organ, comprising a tapered-shaped cirrus tube with twisted acute tip and a filament-shaped accessory piece with medial and distal expansions, and by the morphology of the ventral bar (inverted W-shaped, with short lateral ends and two anterior conical protuberances). Haliotrema saezae n. sp. ex B. diplotaenia differs from all other members of Haliotrema Johnston & Tiegs, 1922 by having a tubular copulatory organ with curved distal tip and a filament-shaped accessory piece without lateral expansions, and by the morphology of anchors and bars. The present findings are added to the other six marine dactylogyrids previously reported from Peru.

Parasites of the Brazilian flathead Percophis brasiliensis reflect West Atlantic biogeographic regions.

With the aim of evaluating the utility of marine parasites as indicators of zoogeographical regions in the South West Atlantic, we analyzed data on assemblages of long-lived larval parasites of 488 specimens of Percophis brasiliensis distributed in 11 samples from nine localities covering the entire distribution of the species in the Argentine biogeographical Province. Near half a million long-lived parasite individuals belonging to 17 species present in the whole sample displayed clear latitudinal patterns. Data for parasite assemblages at infracommunity and component community levels were analysed in relation to the geographical distance. Significant similarity decay of parasite assemblages over distance was observed, with those based on abundances and mean abundances showing departures from predicted values of regressions. These departures were represented by higher dissimilarities between samples coming from different zoogeographical regions than between those caught within the same region, independently of the distance separating them. Consequently, zoogeographical regions were identified in a distance-decay context. Multivariate analyses corroborated a close fit of similarity between assemblages to existing zoogeographical classifications. Regressions representing distance decay of similarity, and the identification of their outliers, can therefore shed light on the existence of discontinuities or uniformities in the geographic distribution of parasite assemblages and, in turn, in the zoogeography of their fish hosts.

Redescription and first genetic characterisation of Procamallanus (Spirocamallanus) macaensis Vicente & Santos, 1972 (Nematoda: Camallanidae), including re-evaluation of the species of Procamallanus (Spirocamallanus) from marine fishes off Brazil.

Newly collected specimens of Procamallanus (Spirocamallanus) macaensis Vicente & Santos, 1972 from the intestine of Paralonchurus brasiliensis (Steindachner), off Rio de Janeiro, Brazil, are redescribed and genetically characterised. Additionally, all congeners deposited in the Coleção Helmintológica do Instituto Oswaldo Cruz (CHIOC) parasitic in marine fishes of the South Atlantic, including types of P. (S.) macaensis, were re-evaluated. The following features are described for the first time in P. (S.) macaensis: morphology and arrangement of cephalic structures, shape of deirids and location of phasmids. The position of the excretory pore, the number and arrangement of caudal papillae in males, the structure of the spicules and of tail end in both males and females are rectified. Most specimens deposited in the CHIOC identified as P. (S.) pereirai Annereaux, 1946 were transferred to P. (S.) macaensis and others were designated as Procamallanus (S.) sp. Procamallanus (S.) cruzi Guimarães, Cristófaro & Rodrigues, 1976 is considered a species inquirenda due to its poor description and the lack of match of its original description with the type-material re-examined. Moreover, several taxonomic problems were noted after observations of the specimens (mostly poorly preserved), including inadequate morphological reports as well as misidentifications. Phylogenies inferred using sequences of the SSU rDNA from camallanids (Nematoda: Camallanidae) mostly generated weakly supported clades; however, Camallanus Railliet & Henry, 1915 and Procamallanus Baylis, 1923 do not seem to be monophyletic. Based on the present results and the lack of molecular data, it would be pertinent to adopt the widely-used classification for the subgenera of Procamallanus.

Parapharyngodon hugoi n. sp., a new nematode (Oxyuroidea: Pharyngodonidae) of the tree frog Trachycephalus typhonius (Linnaeus) from the Brazilian Pantanal, including a key to the congeners from amphibians of the American continent.

A new nematode Parapharyngodon hugoi n. sp. (Oxyuroidea: Pharyngodonidae) is described parasitising the large intestine of the tree frog Trachycephalus typhonius (Linnaeus) (Anura: Hylidae) from the wetlands of Pantanal, State of Mato Grosso do Sul, Brazil. The new species exhibits a unique structure of the posterior cloacal lip in males, which is supported by a rigid V-shaped structure. Parapharyngodon hylidae parasitic in hylid frogs, including T. typhonius, from Mexico, is the most similar congener to P. hugoi n. sp. but is distinguished from the new species by the presence of a gubernaculum (vs absence), by the lateral alae in males ending far anterior to cloacal opening (vs near to it) and because in gravid females the ovaries encircle the oesophageal corpus. Additionally, the new species differs from its congeners as well as from species of Thelandros Wedl, 1862, a very closely related genus, by the combination of features such as spicule length, number of caudal papillae, morphology of the anterior cloacal lip, which is echinate, and position of ovaries. The geographical distribution of hosts seems to play an important role in the speciation process of Parapharyngodon spp.; however, due the lack of molecular data this issue along with the validity of both Thelandros and Parapharyngodon are still questions to be solved in the future, after improvement of the genetic database. A key to the species of Parapharyngodon parasitic in amphibians from the American continent is provided.

Morphology and molecular characterization hold hands: clarifying the taxonomy of Hysterothylacium (Nematoda: Anisakidae) larval forms.

During the last decade, many morphotypes of larval forms of Hysterothylacium have been proposed; however, their boundaries are taxonomically unclear. We compare newly collected material with data available for Hysterothylacium larvae, based on genetics and morphology, in order to evaluate their relationships and simplify their classification. The previously described Hysterothylacium larval type IV, type V, and type X were found in several marine fishes from Brazil. A new Hysterothylacium larval type XV, parasitic in Elops saurus from State of Sergipe, north-eastern Brazil, was proposed based on its genetic singularity and the presence of numerous spines throughout the body. Based upon phylogenetic reconstruction using the ribosomal DNA (rDNA) ITS2 sequences along with morphological traits, the following third stage larvae were considered valid (synonyms are inside parenthesis) type III (= types VII and VIII), type V (= types VI, XII, and XIII), and type X (= type XIV). Despite the lack of molecular data, Hysterothylacium larval type II is considered as synonym of type I because of their identical morphology. The morphometry of Hysterothylacium third stage larvae proved to be weak as a diagnostic tool due to its high rates of variation. Phylogenetic reconstruction using the concatenated sequences of rDNA ITS1-5.8S-ITS2 and the mitochondrion DNA (mtDNA) cox2 revealed that the sampled Hysterothylacium larval types V may represent three different species and H. deardorffovestreetorum may represent two different taxa. Furthermore, H. deardorffovestreetorum is considered species inquirenda due to its problematic description and diagnosis which are based only on larvae. A key to Hysterothylacium larvae from marine fishes is provided.

A morphological and molecular study of two species of Raphidascaroides Yamaguti, 1941 (Nematoda: Anisakidae), parasites of doradid catfish (Siluriformes) in South America, with a description of R. moraveci n. sp.

Nematodes of the genus Raphidascaroides Yamaguti, 1941 parasitising doradid catfishes (Siluriformes: Doradidae) in Brazil were studied based on morphological and molecular evaluation of newly collected material. A new species, Raphidascaroides moraveci n. sp., is described from the intestine of Platydoras armatulus (Valenciennes) from River Miranda, River Paraguay basin, Pantanal, Mato Grosso do Sul. The new species differs from all of the congeners in having short spicules (163-217 µm in length) representing less than 1% of the total body length and in the posterior region of cloacal opening covered by small rudimentary spines. In addition, it differs from the other congeneric species in the number and arrangement of the caudal papillae and the structure of lips and tail. Raphidascaroides moraveci n. sp. is the third species described from freshwater fishes and the second one in the Neotropical Region. New morphological data on R. brasiliensis Moravec & Thatcher, 1997 from Megalodoras uranoscopus (Eigenmann & Eigenmann) and Platydoras costatus (Linnaeus) (both new host records) from River Xingu, River Amazon basin, Pará, are provided including scanning electron micrographs of taxonomically important structures. The differentiation of the new species is supported by molecular data (partial sequences of the small and large subunits of the rRNA gene).

Parasites of Urophycis brasiliensis (Gadiformes: Phycidae) as indicators of marine ecoregions in coastal areas of the South American Atlantic.

The potential value of parasites as ecosystem markers was tested by analyzing the metazoan assemblages of Urophycis brasiliensis caught in four locations distributed in three ecoregions of the Warm Temperate Southwestern Atlantic. A total of 5,001 metazoan parasites belonging to 33 species were found. The identified parasites varied across locations in terms of presence, prevalence, and abundance, and their multivariate analyses resulted in clear similarity patterns. No differences were observed between two locations of the same ecoregion, whereas an evident separation of samples was observed across ecoregions in support of the existing hypotheses regarding the ecoregional division of the southwestern Atlantic. We proposed that parasite assemblages, which are composed of several metazoan phyla, are potentially useful as ecosystem indicators. This suggestion is derived from the combined evidence of the evolutionary history and biogeography of multiple lineages, which is expected to be more efficient in capturing recurrent patterns in overall biodiversity than individual lineages. Furthermore, as many parasites have complex life cycles, their distribution patterns are dependent not only on environmental conditions but also on the distribution and population density of all hosts involved in their life cycles, adding further sources of distributional variability that act synergistically to define robust geographical patterns. The selection of long-lived parasites and their comparative analysis provided evidence supporting the existence of three different stocks in the four sampled areas. The best parasite tags were those with low specificity in fish hosts, constituting promising biological tags for the stock discrimination of other fish species in the region.

Genetic and morphological evidence reveals the existence of a new family, genus and species of Echinorhynchida (Acanthocephala).

Gymnorhadinorhynchus gen. n. is proposed to accommodate its type species, G. decapteri sp. n., a parasite of the marine fish Decapterus punctatus (Cuvier), caught from the coastal waters of Brazil. Gymnorhadinorhynchus decapteri sp. n. was morphologically most similar to species of two echinorhynchid families, the Rhadinorhynchidae and the Cavisomidae, particularly in the structure of the proboscis and the absence of somatic spines, respectively. This combination of morphological features made it difficult to assign our specimen to an extant family of the Acanthocephala. Therefore, in order to clarify the systematic placement of G. decapteri, a molecular phylogenetic analysis was performed based on the SSU and LSU rDNA and the mitochondrial cox1 gene sequences obtained for the new taxon and other 26 acanthocephalan species. The results of parsimony and maximum likelihood analyses, using individual, combined and concatenated sequence data, consistently indicate that the specimens do not belong to any known family of the Echinorhynchida. Rather, G. decapteri represents a distinct lineage that is closely related to the Transvenidae, but distantly related to both the Rhadinorhynchidae and the Cavisomidae. Gymnorhadinorhynchidae fam. n. is therefore erected. This newly described family can be distinguished from other families of Echinorhynchida by the combination of the following morphological characters: a proboscis cylindrical with 10 rows of 22-26 hooks, dorsoventral differences in proboscis hooks, basal hooks forming a ring and being abruptly larger than anterior hooks, absence of trunk spines and presence of four tubular cement glands. This combination, in addition to several molecular autapomorphies, justifies the erection of a new genus, Gymnorhadinorhynchus gen. n., in order to accommodate this new species.

A new species of Cucullanus Müller, 1777 (Nematoda: Cucullanidae) parasitic in the grey triggerfish Balistes capriscus Gmelin (Osteichthyes: Balistidae) off Rio de Janeiro, Brazil.

Cucullanus brevicaudatus n. sp. (Cucullanidae) is described from the intestine of Balistes capriscus Gmelin (Balistidae) off Rio de Janeiro, Brazil. The new species can be differentiated from its congeners in the small body length, the shape of the gubernaculum, the particular size and morphology of the tail in both males and females, the arrangement of the caudal papillae, the narrow oesophageal base, and the eggs with rugged shells. In addition, the combination of some features, i.e. number of caudal papillae, spicule length, oesophagus/body length ratio, host family and geographical distribution, can help to easily distinguish the new species from other cucullanids. Considering these features, C. brevicaudatus differs from the species assigned to Dichelyne Törnquist, 1931 which exhibit morphological proximity with Cucullanus Müller, 1777. Regarding the life-cycle of cucullanid nematodes, available evidence suggests that some species are primarily heteroxenous using invertebrates (i.e. crustaceans, polychaetes) as intermediate hosts, but in other a histotrophic phase in the definitive host replaces the intermediate host.

New records and descriptions of digeneans from the Magellanic penguin Spheniscus magellanicus (Forster) (Aves: Sphenisciformes) on the coast of Brazil.

Five species of digeneans parasitic in the Magellanic penguin Spheniscus magellanicus (Forster) from off the Brazilian coast of the western Atlantic are reported for the first time from this host and described. These are Mesostephanus odhneri (Travassos, 1924) Lutz, 1935, Posthodiplostomum macrocotyle Dubois, 1937, Stephanoprora uruguayensis Holcman-Spector & Olagüe, 1989, Ascocotyle (Phagicola) longa Ransom, 1920 and Ascocotyle (Phagicola) sp. One other digenean, Cardiocephaloides physalis (Lutz, 1926) Sudarikov, 1959, was also recorded. The taxonomy of the species and available data on their life-cycles are commented upon in relation to the possible origins of digenean infections of the Magellanic penguin.

A new species of Neoascarophis (Nematoda: Cystidicolidae) parasitic in Mullus argentinae (Perciformes: Mullidae) from the Atlantic coast of South America.

A new nematode species (Neoascarophis mariae n. sp.) is described based on specimens collected from the Argentine goatfish Mullus argentinae (Hubbs et Marini) from coastal waters off the state of Rio de Janeiro, Brazil. In the genus, the new species belongs to the group of species with females that have the vulva near the posterior end of the body. Only males of Neoascarophis longispicula Moravec et Klimpel, 2009 are known and can be distinguished from those of the new species by their larger body, developed and somewhat dorsoventrally expanded flat inner part of the pseudolabia, bifurcate deirids and larger spicules (the left one with a rounded tip) with a different length ratio. Other species with females that have the vulva near the equatorial region are N. yarihige Machida, 1976 and N. bathygadi Machida, 1976. Both males and females of N. yarihige are longer than those of the new species and have a shorter vestibule; males have shorter spicules with a different length ratio. Neoascarophis bathygadi is the only member of the genus that shares the presence of a cephalic vesicle with the new species, which, however, is shorter and arises at 40 microm from the anterior end instead from the deirids, as in the new species. Both males and females of N. bathygadi are also longer than those of the new species and have a shorter vestibule; males have a larger left spicule, but shorter right spicule and a different length ratio. Ascarophis upeneichthys Johnston et Mawson, 1945, a parasite ofa mullid host, is transferred to Neoascarophis Machida, 1976 and is distinguished from the new species by having a shorter vestibule in females and shorter spicules (left spicule with a pointed tip) with a different length ratio in males.