Description of Saccocoelioides miguelmontesi n. sp. (Digenea: Haploporidae) from characid fishes in the Iguazu River Basin based on morphological and molecular evidence.

Here we describe a new species of the genus Saccocoelioides found parasitizing Astyanax dissimilis Garavello & Sampaio, Psalidodon bifasciatus (Garavello and Sampaio) and Bryconamericus ikaa Casciotta, Almirón & Azpelicueta from the Iguazu National Park, Misiones province, Argentina. Saccocoelioides miguelmontesi n. sp. was studied based on morphological and molecular (28S rDNA and COI mtDNA sequences) data. The COI mtDNA tree indicated that the specimens collected from the three fish hosts are conspecific, with an intragroup p-distance of 0%. The new species shows an intermediate morphological configuration between the diminutive and robust forms described for Saccocoelioides by Curran (2018). Although, in the 28S rDNA tree, it is placed in a well-supported clade with the two robust species analysed (S. elongatus and S. magnus; p-distance of 1 and 2%, respectively), it differs from the robust group by the range of body size, mature egg size, oral and ventral sucker size, sucker ratio, oral sucker to pharynx ratio, and post-cecal or post-testis/body length percentage. Our results led us to redefine the robust group as having eggs shorter or equal in length to the pharynx. Saccocoelioides miguelmontesi n. sp. the 10th species reported from Argentina and the 7th species within the robust group.

Phylogenetic position of the Neotropical Family Zonocotylidae (Paramphistomoidea) using partial 28S rDNA sequences.

Six families belonging to the Paramphistomoidea superfamily have been reported in South America, with only Zonocotylidae and Balanorchiidae being endemic. The Zonocotylidae was initially classified as Aspidogastrea and then as a paramphistomoid. This family comprises a single genus, Zononocotyle, with two species. It is primarily characterized by having an attachment organ with transverse ridges and a single testis. The placement of Zonocotylidae within Paramphistomoidea is controversial, as some researchers speculate that this genus is the most primitive member of the superfamily, while others consider it an aberrant form. The main objectives of our study were to provide the first sequences of Zonocotylidae and elucidate its phylogenetic position. We amplified the 28S gene from two parasites from Cyphocharax sp. from Punta Lara, Buenos Aires. Newly generated sequences were used to infer the phylogenetic relationships with other Paramphistomoidea species using a Bayesian approach. Zonocotylidae were clustered with Dadayiinae and Kalitrematinae (Cladorchiidae) species found in freshwater fishes from South America. Genetic analyses revealed that they formed a well-supported clade with cladorchiids in freshwater hosts from South America. However, the occurrence of genera of Cladorchiidae in North America, Middle America, Asia, and Australia suggested its polyphyletic nature and may indicate the need for the erection of new families. Other Paramphistomoidea families may also require further revision. The addition of new sequences to phylogenetic analyses along with a comprehensive and more detailed description of the genera will help resolve the relationships within this group.

Integrative analysis of new Clinostomum metacercariae (Digenea, Clinostomidae) using COI mtDNA and morphology rises the number of lineages found in South American freshwater fishes.

Clinostomidae is a diverse family of digenean parasitizing fish-eating birds as adults and fishes as metacercariae. The species composition, within the genus Clinostomum has been steadily increasing in recent years. In Argentina, four named species of Clinostomum have been documented, accompanied by four metacercariae representing distinct genetic lineages whose adults have not been identified. This study focused on examining clinostomids in three fish species - Australoheros scitulus (ASI), Cichlasoma dimerus (CDIM), and Pimelodella laticeps (PLA) - at various localities in Argentina. We conducted both morphological and molecular characterizations of the Clinostomum metacercariae collected from these fish species. Molecular phylogenetic analyses using COI mtDNA were performed to determine the placement of these metacercariae within the clinostomid phylogenetic tree. Clinostomum ASC represents a distinct lineage, morphologically distinguishable from other sequenced metacercariae due to its body shape (widest anteriorly and becoming slender towards the posterior end); this lineage was found to be closely related to C. caffarae. While Clinostomum CDIM and Clinostomum PLA exhibited morphological differences, they clustered together genetically with metacercariae reported in previous studies as Clinostomum L3 and Clinostomum CVI. This outcome, coupled with a low genetic distance (0 to 3%), suggests that they are conspecific with metacercariae found in fish across Mexico, Costa Rica, and Argentina. In light of the extensive diversity of fish species in Argentine freshwater ecosystems (over 500 species), and considering the relatively constrained extent of prior investigations, the anticipation of unearthing additional Clinostomum species or lineages is plausible.

Description of Diegoglossidium maradonai n. g. and n. sp. (Digenea: Alloglossidiidae) through an integrative taxonomy approach, with an amended diagnosis of the family.

This paper describes Diegloglossidium maradonai n. g., n. sp. a parasite of the intestine of Hoplosternum littorale (Hancock) from La Plata River basin. The new genus is morphologically similar to members of Alloglossidiidae and Macroderoidiidae although they also share some traits observed in both families. Those families can be differentiated from each other by the combination of morphological features, including the density and distribution of the tegumental spines, the distribution of the vitelline follicles and the extent of the post-testicular space. The molecular analyses based on the large subunit of the ribosomal RNA gene, and the internal transcribed spacer (ITS) regions including ITS1, 5.8S and ITS2 unequivocally place the new genus in the family Alloglossidiidae which is amended based on new observed features. Diegoglossidium n. g. is characterized by a combination of characteristics, being most notably the presence of a deeply lobed ovary. Lastly, the geographical distribution and host associations of the two closely related Neotropical genera of Alloglossidiidae: Magnivitellinum and Diegoglossidium are discussed, and the host and distribution range of Magnivitellinum saltaensis is expanded into Argentina.

Metacercariae in the brain of Erythrinus cf. erythrinus (Characiformes: Erythrinidae) from Iguazú National Park (Argentina): do they belong to Dolichorchis lacombeensis (Digenea, Diplostomidae)?

In Argentina, the family Diplostomidae is composed of eight genera: Austrodiplostomum Szidat & Nani; Diplostomum von Nordmann; Dolichorchis Dubois; Hysteromorpha Lutz; Neodiplostomum Railliet; Posthodiplostomum Dubois; Sphincterodiplostomum Dubois; and Tylodelphys Diesing. During a parasitological survey of fishes from the Iguazú National Park we detected diplostomid metacercariae in the brain of Erythrinus cf. erythrinus. Fish were caught using crab traps, transported alive to the field laboratory, cold-anaesthetized and euthanized by cervical dissection. Some metacercariae were heat-killed in water and fixed in 10% formalin and others were preserved in alcohol 96% for DNA extraction. They were sequenced for the partial segment of the 28S rDNA, internal transcribed spacer (ITS) rDNA and cytochrome c oxidase subunit I (COI) mtDNA genes. Phylogenetic reconstruction was carried out using Bayesian inference and the proportion (p) of absolute nucleotide sites (p-distance) was obtained. In the 28S rDNA tree, the metacercaria sequenced grouped as Dolichorchis sp. The COI mtDNA p-distance between the metacercariae with Dolichorchis lacombeensis was 0.01. There is a small number of ITS sequences for the Diplostomidae family deposited in the GenBank. The oral sucker, ventral sucker, holdfast organ and the distance between oral and ventral suckers are larger in the adult compared with the metacercariae. Additionally, hind-body length and width are larger in the adult due to the development of the genital complex. Further studies using an integrative approach will help confirm the affiliation of other species to the genus Dolichorchis.

Saccocoelioides kirchneri n. sp. (Digenea: Haploporidae) from the killifish Cnesterodon decemmaculatus (Cyprinodontiformes: Poeciliidae) from Argentina, morphological and molecular description.

This paper presents a new haploporid digenean that expands the number of species of Saccoccoelioides to 27. The new species, Saccocoelioides kirchneri n. sp. was collected from the intestine of Cnesterodon decemmaculatus (Poeciliidae: Cyprinodontiformes) from Lago del Bosque, La Plata, Argentina. The new species possesses the diagnostic features for Saccocoelioides: a sac like ceca; the vitellarium confined in two irregular groups of follicles distributed between the ventral sucker and the anterior margin of the testis; and a uterus confined largely in the hind-body, but encroaching into the range of the ventral sucker. The new species is differentiated from the 26 congeners by the body size, pharynx size, ventral sucker size, posterior extent of ceca, posterior extent of uterus and egg size. S. kirchneri n. sp. also is supported by the molecular analysis.

Description of a new species of Auriculostoma (Digenea: Allocreadiidae) from Characidium heirmostigmata (Characiformes: Crenuchidae) from Argentina, using morphological and molecular data.

During a parasitological survey of fishes at Iguazu National Park, Argentina, specimens belonging to the allocreadiid genus Auriculostoma were collected from the intestine of Characidium heirmostigmata. The erection of the new species is based on a unique combination of morphological traits as well as on phylogenetic analysis. Auriculostoma guacurarii n. sp. resembles four congeneric species - Auriculostoma diagonale, Auriculostoma platense, Auriculostoma tica and Auriculostoma totonacapanensis - in having smooth and oblique testes, but can be distinguished by a combination of several morphological features, hosts association and geographic distribution. Morphologically, the new species can be distinguished from both A. diagonale and A. platense by the egg size (bigger in the first and smaller in the last); from A. tica by a shorter body length, the genital pore position and the extension of the caeca; and from A. totonacapanensis by the size of the oral and ventral sucker and the post-testicular space. Additionally, one specimen of Auriculostoma cf. stenopteri from the characid Charax stenopterus (Characiformes) from La Plata River, Argentina, was sampled and the partial 28S rRNA gene was sequenced. The phylogenetic analysis revealed that A. guacurarii n. sp. clustered with A. tica and these two as sister taxa to A. cf. stenopteri. The new species described herein is the tenth species in the genus and the first one parasitizing a member of the family Crenuchidae.

Pathology associated with three new Clinostomum metacercariae from Argentina with morphological and DNA barcode identification.

In the Laboratory of Parasites of Fishes, Crustaceans and Mollusks (CEPAVE), we undertook a parasitological study on three species of fish from the Espinal and Esteros del Iberá ecoregions of Argentina. Clinostomid metacercariae were found parasitizing Characidium rachovii, Crenicichla vittata and Gymnogeophagus balzanii. In this study, we analysed the damage that these parasites inflict on their hosts through the evaluation of histological sections. In addition, Clinostomum metacercariae were identified using morphological characters and DNA barcoding. In the pathological analysis, we observed that muscle tissue was the most affected. The inflammatory response showed vascular congestion areas and infiltration of numerous inflammatory cells, mainly lymphocytes. The molecular and morphological approach supports the presence of three new lineages of clinostomid metacercariae in Argentina. This could lead to the discovery of a high number of lineages or species of Clinostomum from South America.

Prosthenhystera gattii n. sp. (Digenea: Callodistomidae), a gallbladder parasite of Bryconamericus ikaa from the lower Iguazú River, described based on combined molecular and morphological evidence.

Adult forms of members of the Callodistomidae always parasitize the gallbladder of freshwater fishes and occur in Africa and America. This study provides a description of a new South American species belonging in Prosthenhystera from the gallbladder of a characid fish (Bryconamericus ikaa), and ribosomal gene sequences (28S rDNA and ITS1-5.8S-ITS2) are used to demonstrate molecular differences between the new species and congeners as well as explore interrelationships among congeners. Additionally, the first cytological analysis is conducted for a member of the family to determine chromosome number and arrangement. Prosthenhystera gattii n. sp. most closely resembles Prosthenhystera caballeroi in morphology, but the vitellarium is more extensive reaching anterior to the caecal bifurcation in the new species and the uterus is confined to the hindbody in P. gattii n. sp., whereas it extends to the level of the pharynx in P. caballeroi. Also, the testes, cirrus sac, seminal receptacle and the ratio of body length to width are larger in P. gattii n. sp. Independent Bayesian inference analyses of 28S rDNA and ITS1-5.8S-ITS2 sequence fragments produced phylograms that showed P. gattii n. sp. is more similar to Prosthenhystera obesa + Prosthenhystera oonastica than P. caballeroi + two unidentified species of Prosthenhystera, but with poor posterior probability support for the node in the ITS1-5.8S-ITS2-based phylogram. Further, the genetic distance between P. oonastica and P. gattii n. sp. are the largest among Prosthenhystera spp. Cytological analysis revealed ten metacentric chromosomes, which is fewer than the 12-18 chromosomes present in species from the closely related Gorgoderidae.

A New Species of Ascarophis (Nematoda: Cystidicolidae) Parasitizing Clinocottus analis (Pisces: Cottidae) from Baja California, Mexico.

A new species of nematode, Ascarophis morronei n. sp. (Cystidicolidae), is described from the stomach wall of the woolly sculpin Clinocottus analis (Cottidae) collected in the rocky intertidal from northwestern Baja California, Mexico. Collected nematodes were studied using both light and scanning electron microscopy. Sequence fragments for 18S rDNA molecular markers were obtained from the new nematode species, in order to test its position within the family Cystidicolidae under a phylogenetic context. Main characters distinguishing this new species include the reduced labia and the morphology of the eggs, distances of nerve ring and excretory pore from the anterior end, and left spicule of males. The new species described here is the second for the genus Ascarophis reported as adult in the Southern California Bight, and the first one recorded for the fish genus Clinocottus.

Morphological identification and DNA barcoding of a new species of Parabrachiella (Siphonostomatoida: Lernaeopodidae) with aspects of their intraspecific variation.

We present a detailed morphological description and a DNA barcoding of Parabrachiella platensis n. sp. collected from Mugil liza Valenciennes in Samborombon Bay (Buenos Aires, Argentina). This new species was compared with two Parabrachiella species parasitic on mugilids: Parabrachiella exilis (Shiino, 1956) and Parabrachiella mugilis (Kabata, Raibaut et Ben Hassine, 1971). Parabrachiella platensis n. sp. differs from those species in the shape of posterior processes, the anal slit with two pairs of bipartite papillae, the size of cephalothorax, the trunk, the maxilla, the microhabitat on the host, and the lack of caudal rami. On the host, the new species was in the nostrils (a new site for a species of the genus Parabrachiella) and in the fins base. Some minor morphological differences were observed in relation to the locations on the host. The molecular analysis conducted based on mtDNA-COI between specimens of the new species on the fins and nostrils showed a genetic similarity of 99.8%. This percentage supports that the specimens found in nostrils and fins base could represent a single species. New studies on P. platensis n. sp., including infection of the same fish with the two forms, could bring some new information. Anyway according to the genetic information provided and the minimal morphological differences spotted we conclude that the two forms are a single specie. The differences observed are possibly influenced by the place of the host where the two forms of copepods were found, nostrils and fins. The new species was also molecularly compared to other five species of Parabrachiella including P. exilis (parasitizing mugilid from Chile), Parabrachiella anisotremis, Parabrachiella auriculata, Parabrachiella merluccii, and P. hugu (the last two sequences were taken from the GenBank). The genetic distance of 9% among P. platensis n. sp. and P. exilis, which is the close morphological related species, allow to states that these two copepods on mugilids belong to different species and then validating the morphological differences found between them.

Riggia puyensis n. sp. (Isopoda: Cymothoidae) parasitizing Chaetostoma breve and Chaetostoma microps (Siluriformes: Loricariidae) from Ecuador.

A new isopod was found parasitizing Chaetostoma breve and Chaetostoma microps from the Puyo and Bobonaza rivers. The parasite found belongs to the Cymothoidae family and could be located within the genus Riggia instead of Artystone by the presence of abdominal plates fused with the telson. The specimens found represent a new species, Riggia puyensis n. sp., and could be distinguished from Riggia cryptocularis by the presence of developed eyes. The main difference of the new specie from Riggia nana and Riggia brasiliensis is the size, bigger compared with the first and smaller compared with the last species. Riggia acuticaudata have the maxilliped with simple setae, the palp without spination, and maxillule with five spines (two terminal and three subterminal) instead in R. puyensis n. sp. the maxilliped have plumose setae, the palp have spination (with one apical spine, two setae on middle article and one in the basal article) and the maxillule have five spines: two terminal, two subterminal and other spine lower to the others. Riggia paranaensis have similar size, same number of segments in the antena, and similar maxilla to R. puyensis n. sp., but the antennule in the new specie have seven segments instead 6 in R. paranaensis, the antennule and antenna present spines not mentioned in R. paranaensis. Besides, the relative position of the mandible in R. puyensis n. sp. is different compared with R. paranaensis, the maxillule have the same number of spines but with different disposition, and the maxilliped have simple setae in R. paranaensis but those are plumose in the new specie.

Riggia puyensis n. sp. (Isopoda: Cymothoidae) parasitizing Chaetostoma breve and Chaetostoma microps (Siluriformes: Loricariidae) from Ecuador.

A new isopod was found parasitizing Chaetostoma breve and Chaetostoma microps from the Puyo and Bobonaza rivers. The parasite found belongs to the Cymothoidae family and could be located within the genus Riggia instead of Artystone by the presence of abdominal plates fused with the telson. The specimens found represent a new species, Riggia puyensis n. sp., and could be distinguished from Riggia cryptocularis by the presence of developed eyes. The main difference of the new specie from Riggia nana and Riggia brasiliensis is the size, bigger compared with the first and smaller compared with the last species. Riggia acuticaudata have the maxilliped with simple setae, the palp without spination, and maxillule with five spines (two terminal and three subterminal) instead in R. puyensis n. sp. the maxilliped have plumose setae, the palp have spination (with one apical spine, two setae on middle article and one in the basal article) and the maxillule have five spines: two terminal, two subterminal and other spine lower to the others. Riggia paranaensis have similar size, same number of segments in the antena, and similar maxilla to R. puyensis n. sp., but the antennule in the new specie have seven segments instead 6 in R. paranaensis, the antennule and antenna present spines not mentioned in R. paranaensis. Besides, the relative position of the mandible in R. puyensis n. sp. is different compared with R. paranaensis, the maxillule have the same number of spines but with different disposition, and the maxilliped have simple setae in R. paranaensis but those are plumose in the new specie.

A new species of philometrid parasite (Nematoda, Philometridae) and histopathological lesions in juvenile whitemouth croakers, Micropogonias furnieri (Desmarest).

A new species of nematode parasite, Philometroides tahieli sp. nov. is described. The juvenile whitemouth croaker, Micropogonias furnieri Desmarest, was collected during the spring and summer of the years 2008-2010 from estuarial environments of Argentina. During investigations of the parasite fauna a nematode encapsulated in the musculature of the operculum was found. The nematodes were removed from the host's muscle tissue and slide-mounted in lactophenol solution to clarify the specimens. Opercular muscle with the parasite was processed for histopathological examination. Philometroides tahieli sp. nov. can be identified by the location of gravid females in the host, presence of anterior oesophageal bulb, bosses on the surface of the body, presence of transversal mounds and 14 cephalic papillae in two circular rows. The pathogenicity of the parasite is low in the natural environment, but lesions are consistent with a chronic process. The appearance of caseous necrosis suggests the presence of a locally acting substance. Philometroides tahieli sp. nov. is the second species of this genera described from brackish waters, and since the discovery of Philometroides maplestoni in 1928, is the first species of this genus recorded for South America.

Morphological aspects and histological effects of the attachment organ of Parabrachiella sp. (Copepoda: Lernaeopodidae) on the grey mullet, Mugil liza Valenciennes.

The genus Parabrachiella Wilson, 1915 (Lernaeopodidae) is represented by copepods that are highly adapted to a parasitic way of life. In Argentina, only P. insidiosa var. lageniformis Heller, 1865, P. chevreuxii Van Beneden, 1891 and P. spinicephala Ringuelet, 1945 have been cited, but none of these have been reported on mugilids. Recently, other species of this genus were found attached to the nasal cavities of juvenile grey mullets, Mugil liza Valenciennes, from Samborombón bay, Buenos Aires province. In this study, the prevalence and mean intensity of the Parabrachiella sp. on grey mullet is investigated. In addition, the damage the parasite imposes on its hosts is examined through evaluation of histological sections and immunostaining for proliferative cell nuclear antigen (PCNA). The morphology of the parasite's bulla is described from light and scanning electron micrographs.

Morphological and molecular identification of the fish-borne metacercaria of Ascocotyle (Phagicola) longa Ransom, 1920 in Mugil liza from Argentina.

This is the first report of Ascocotyle (Phagicola) longa Ransom, 1920 (Digenea: Heterophyidae) in Argentina confirmed by morphological and molecular studies. The metacercaria was found encysted in myotomal musculature, heart and mesentery of the mullet Mugil liza (Pisces: Mugilidae) from Samborombon bay. We provide a morphological description of the metacercaria which we identified using species-specific primers for A. (Phagicola) longa and nucleotid sequence. This worldwide parasite has been reported as one of the causative agents of heterophyiosis, an emerging fish-borne disease of humans, contracted by the consumption of raw mullet. The discovery of A. (Phagicola) longa in Argentina represents a warning of the potentially great impact of this parasite on public health.

[Hearing screening with evoked otoacoustic emission in the neonatal period are logistically and economically feasible]. / Cribado auditivo neonatal mediante otoemisiones acústicas por click: logística y económicamente factible.

OBJECTIVE: To design, carry out and assess a protocol for the early diagnosis of hearing loss based on the detection of evoked otoacoustic emissions (EOAE) in the neonatal period. MATERIALS AND METHODS: Five hundred twenty-five infants without risk factors for hearing loss were studied. A hearing screening protocol with EOAE was applied in the first 48 hours of life, with a second test on the fifth day of life, coinciding with phenylketonuria screening if the first test was negative. The diagnostic stage took place when the infants were aged 1 month. RESULTS: A total of 98.8 % of the program was completed. In the initial test, bilateral EOAE were obtained in 458 infants. When the EOAE were performed during the first 24 hours after birth, 72.5 % of newborns achieved a satisfactory result. This percentage rose to 93.6 %, 97.9 % and 94.7 % when the test was delayed until discharge on, respectively, the second, the fifth and subsequent days of age (p < 0.01). All the infants who did not achieve a satisfactory result in the first test underwent a second one. A total of 87.5 % of the newborns who had failed the test within the first 24 hours passed it when it was repeated at 48 hours, at the time of discharge. A third screening was necessary in seven infants (six on the fifth day of life and one, together with auditory brainstem response [ABR], on 30 days of age). One infant showed absence of EOAE in the left ear in the three tests, as well as a threshold above 70 dB to obtain the V wave in the ABR performed at 1 and 3 months of age and was diagnosed with unilateral moderate deafness, representing a prevalence of hearing loss of 1.9 % of live newborns in the general population in our environment. CONCLUSIONS: Universal hearing screening with EOAE is logistically and economically feasible. The use of a second test on the fifth day of age decreases the number of false positives, thus reducing economic cost and family anxiety, and improves recruitment, since it coincides with metabolic screening.