First Molecular Diagnosis of Oestrus ovis (Linnaeus, 1758) Larvae Causing Conjunctival Ophthalmomyiasis in Mexico City, Mexico.

PURPOSE: Human ophthalmomyiasis is a rare ocular parasitosis that results from the accidental infestation of dipteran larvae of several species, including Oestrus ovis (Linnaeus, 1758). This study aims to present the fourth documented human case of ophthalmomyiasis in Mexico, identifying the etiological agent through morphological and molecular analyses. Additionally, we investigated the phylogenetic position and genetic distances among different specimens globally characterized based on mitochondrial Cox1 sequences. METHODS: A total of five larval specimens were extracted from the patient's eye, with two specimens allocated for identification based on morphological features using a stereomicroscope, and the remaining three preserved in absolute ethanol, one of them used for subsequent analysis using molecular methods. The mitochondrial Cox1 region was amplified and sequenced using automated Sanger sequencing. The resulting sequence was deposited in GenBank under accession number OR440699 and subjected to BlastN analysis against 35 other Cox1 sequences of O. ovis from GenBank. The identity and phylogenetic position of the strains were further explored using parsimony and maximum likelihood phylogenetic methods. RESULTS: Morphological examination of the larval specimens extracted from the patient's eye unequivocally identified them as O. ovis species. BlastN analysis and comprehensive phylogenetic investigations involving a total of 36 Cox1 sequences confirmed the taxonomic identity of the larvae. Notably, our sequence was positioned within the cluster formed by the Brazilian and two Iranian samples. This finding underscores a shared genetic ancestry among these distinct geographical isolates and provides valuable insights into the evolutionary relationships within O. ovis populations. CONCLUSION: The presence of O. ovis infestation in Mexico City suggests potential shifts in environmental conditions favoring fly proliferation, highlighting the need for vigilance in urban healthcare settings.

Zoonotic Thelazia californiensis in dogs from New Mexico, USA, and a review of North American cases in animals and humans.

Thelazia californiensis is a spirurid nematode found in the conjunctival sac of domestic and wild animals, including humans, across the western United States of America. Herein, we report two cases of thelaziosis by T. californiensis in dogs from New Mexico, United States, based on integrated morphological and molecular approaches. Nematode specimens collected from the conjunctiva of both dogs were identified as T. californiensis based on morphology. Our study substantially expands the knowledge on morphometry of this nematode species. Therefore, these data will be useful for accurate diagnosis of thelaziosis in domestic animals, wildlife and humans in North America, using classical, microscopy-based methods. We characterized for the first time the mitochondrial cytochrome c-oxidase subunit 1 (COI) and 12S genes of T. californiensis. While these markers support the validity of T. californiensis, they were not very informative for elucidating the phylogenetic relationships among Thelazia species. Nevertheless, the characterization of these diagnostic markers for T. californiensis will be useful for studies on the epidemiology, molecular xenomonitoring of fanniid vectors, and population genetics of this multi-host, zoonotic parasite.

Keratitis due to microfilariae in dogs: a newly recognized disease.

Parasitic agents have been associated with keratitis, but a diagnosis of parasitic keratitis has not been commonly made in domestic animals. The purpose of this study was to describe the clinical and histopathological findings in seven dogs with chronic keratitis caused by microfilariae diagnosed in Brazil. All dogs presented with superficial corneal opacities of varying degrees affecting the perilimbal and central regions of the cornea, with other opaque areas appearing as crystalline deposits and corneal vascularization. The lesions were bilateral and were associated with mild-to-moderate conjunctival hyperemia. There was no history of blepharospasm or pruritus, and no subjects presented with epithelial erosions. Corneal biopsy revealed free microfilariae in the corneal stroma, with varying degrees of inflammation and collagen fiber destruction. The microfilariae were also found in skin lesions by skin snip technique. No adult worms were found in these dogs, and no dogs were on heartworm preventative before diagnosis. Monthly doses of oral ivermectin improved ocular and dermal lesions. One dog showed complete remission with the treatment. The species of the microfilariae was not identified.

Eyeworm infections of Oxyspirura petrowi, Skrjabin, 1929 (Spirurida: Thelaziidae), in species of quail from Texas, New Mexico and Arizona, USA.

Northern bobwhite (Colinus virginianus) and Scaled quail (Callipepla squamata) have been declining steadily throughout much of their historical range over the past few decades. Even the Rolling Plains of Texas, historically rich with wild quail and one of the last remaining quail strongholds, has been suffering a population decline, most notably since 2010. Gambel's quail (Callipepla gambelii) have also been experiencing their own decline throughout their respective range, but not as significant as that of other species of quail. Eyeworms (Oxyspirura petrowi) in quail have been recognized for years but not thoroughly studied until recently. New research reveals that O. petrowi infection can cause inflammation, oedema, and cellular damage to the eye of the quail host. The objective of this research was to better understand the prevalence of the eyeworm infection in different quail species, expand on known distribution, and determine if there is a relationship between location and species infected with eyeworms. Northern bobwhite, Scaled quail and Gambel's quail were hunter-donated from one county within Texas, New Mexico and Arizona, and examined for the prevalence, mean abundance and mean intensity of eyeworm infection from November 2013 to February 2014. Quail from every location were found to have individuals with a varying degree of eyeworm infection. This is the first study to document eyeworm infection in Gambel's quail and in quail in New Mexico and Arizona, and reports the highest eyeworm infection found in Northern bobwhite and Scaled quail.

Austrodiplostomum compactum metacercariae (Digenea: Diplostomidae) in Schizodon intermedius (Characiformes: Anostomidae) from Jurumirim reservoir, Brazil.

This study reports the occurrence of Austrodiplostomum compactum metacercariae in the freshwater fish Schizodon intermedius (ximborê/piava) from a Neotropical reservoir in the Paranapanema River, state of São Paulo, Brazil. From a total of 75 fish collected, we found 38 infected with A. compactum metacercariae (prevalence = 50.67%) in the eyes. The mean intensity of infection and mean abundance were 9.05 ± 4.26 (1-155) and 4.59 ± 2.20 (0-155), respectively. Poulin's Discrepancy Index was 0.87 and four specimens presented more than 10 metacercariae in their eyes. No correlation was observed between parasite abundance and standard length, total weight and condition factor (p>0.05). These metacercariae are reported for the first time in S. intermedius.

Austrodiplostomum compactum metacercariae (Digenea: Diplostomidae) in Schizodon intermedius (Characiformes: Anostomidae) from Jurumirim reservoir, Brazil / Metacercárias de Austrodiplostomum compactum (Digenea: Diplostomidae) em Schizodon intermedius (Characiformes: Anostomidade) do reservatório de Jurumirim, Brasil

Abstract This study reports the occurrence of Austrodiplostomum compactum metacercariae in the freshwater fish Schizodon intermedius (ximborê/piava) from a Neotropical reservoir in the Paranapanema River, state of São Paulo, Brazil. From a total of 75 fish collected, we found 38 infected with A. compactum metacercariae (prevalence = 50.67%) in the eyes. The mean intensity of infection and mean abundance were 9.05 ± 4.26 (1-155) and 4.59 ± 2.20 (0-155), respectively. Poulin's Discrepancy Index was 0.87 and four specimens presented more than 10 metacercariae in their eyes. No correlation was observed between parasite abundance and standard length, total weight and condition factor (p>0.05). These metacercariae are reported for the first time in S. intermedius.

Resumo Este estudo reporta a ocorrência de metacercárias de Austrodiplostomum compactum na espécie de peixe de água doce Schizodon intermedius (ximborê/piava), oriunda de um reservatório Neotropical no rio Paranapanema, Estado de São Paulo, Brasil. Um total de 75 peixes foram coletados, sendo que 38 estavam infectados com metacercárias de A. compactum (prevalência = 50,67%) nos olhos. A intensidade média de infecção e abundância média foram 9,05 ± 4,26 (1-155) e 4,59 ± 2,20 (0-155), respectivamente. O Índice de Discrepância de Poulin foi de 0,87, e quatro exemplares apresentaram mais do que 10 metacercárias em seus olhos. Não foram observadas correlação entre abundância média e comprimento padrão, peso total e fator de condição (p>0,05). Esse é o primeiro registro dessa espécie de metacercária para S. intermedius.

Parasitism by Sphincterodiplostomum musculosum (Digenea, Diplostomidae) metacercariae in the eyes of Steindachnerina insculpta (Characiformes, Curimatidae).

New occurrences and effects of parasitism by metacercariae in fish eyes have recently been discussed in many studies. The aim of the present study was to evaluate the infection levels of the eye flukes Sphincterodiplostomum musculosum Dubois, 1936 (metacercariae) in Steindachnerina insculpta (Fernádez-Yépez, 1948) from three ecosystems under the influence of the Jurumirim reservoir (Paranapanema, Taquari and Veados Rivers). A total of 174 fish specimens were sampled between April 2011 and April 2012. There were high levels of infection by S. musculosum metacercariae in the eyes of S. insculpta from all the sampled ecosystems, thus presenting broad geographical distribution. The histological analyses revealed that the metacercariae were apparently lodged behind the retina. The smaller fish from the Taquari River were less parasitized by metacercariae than the adults. This pattern can be explained by the cumulative effect of parasitism, as demonstrated by the positive correlation between the abundance of metacercariae and fish body size.

Parasitism by Sphincterodiplostomum musculosum (Digenea, Diplostomidae) metacercariae in the eyes of Steindachnerina insculpta (Characiformes, Curimatidae) / Parasitismo por metacercárias de Sphincterodiplostomum musculosum (Digenea, Diplostomidae) nos olhos de Steindachnerina insculpta (Characiformes, Curimatidae)

New occurrences and effects of parasitism by metacercariae in fish eyes have recently been discussed in many studies. The aim of the present study was to evaluate the infection levels of the eye flukes Sphincterodiplostomum musculosum Dubois, 1936 (metacercariae) in Steindachnerina insculpta (Fernádez-Yépez, 1948) from three ecosystems under the influence of the Jurumirim reservoir (Paranapanema, Taquari and Veados Rivers). A total of 174 fish specimens were sampled between April 2011 and April 2012. There were high levels of infection by S. musculosum metacercariae in the eyes of S. insculpta from all the sampled ecosystems, thus presenting broad geographical distribution. The histological analyses revealed that the metacercariae were apparently lodged behind the retina. The smaller fish from the Taquari River were less parasitized by metacercariae than the adults. This pattern can be explained by the cumulative effect of parasitism, as demonstrated by the positive correlation between the abundance of metacercariae and fish body size.

Novas ocorrências e efeitos do parasitismo por metacercárias em olhos de peixe têm sido recentemente discutidas em muitos estudos. O objetivo deste estudo foi avaliar os níveis de infecção dos vermes de olho Sphincterodiplostomum musculosum Dubois, 1936 (metacercárias) em Steindachnerina insculpta (Fernádez-Yépez, 1948) de três ecossistemas influenciados pelo reservatório de Jurumirim (Rios Paranapanema, Taquari e Veados). Um total de 174 espécimes de peixes foi amostrado de Abril/2011 a Abril/2012. Metacercárias de S. musculosum mostraram altos níveis de infecção nos olhos de S. insculpta em todos os ecossistemas amostrados apresentando ampla distribuição geográfica. As análises histológicas revelaram que, aparentemente, estas metacercárias estavam alojadas por trás da retina. Os peixes menores do rio Taquari estavam menos parasitados por metacercárias do que os adultos. Esse padrão pode ser explicado pelo efeito cumulativo de parasitismo, evidenciado pela correlação positiva entre a abundância de metacercárias e tamanho do corpo dos peixes.

Parasitism by Sphincterodiplostomum musculosum (Digenea, Diplostomidae) metacercariae in the eyes of Steindachnerina insculpta (Characiformes, Curimatidae) / Parasitismo por metacercárias de Sphincterodiplostomum musculosum (Digenea, Diplostomidae) nos olhos de Steindachnerina insculpta (Characiformes, Curimatidae)

New occurrences and effects of parasitism by metacercariae in fish eyes have recently been discussed in many studies. The aim of the present study was to evaluate the infection levels of the eye flukes Sphincterodiplostomum musculosum Dubois, 1936 (metacercariae) in Steindachnerina insculpta (Fernádez-Yépez, 1948) from three ecosystems under the influence of the Jurumirim reservoir (Paranapanema, Taquari and Veados Rivers). A total of 174 fish specimens were sampled between April 2011 and April 2012. There were high levels of infection by S. musculosum metacercariae in the eyes of S. insculpta from all the sampled ecosystems, thus presenting broad geographical distribution. The histological analyses revealed that the metacercariae were apparently lodged behind the retina. The smaller fish from the Taquari River were less parasitized by metacercariae than the adults. This pattern can be explained by the cumulative effect of parasitism, as demonstrated by the positive correlation between the abundance of metacercariae and fish body size.

Novas ocorrências e efeitos do parasitismo por metacercárias em olhos de peixe têm sido recentemente discutidas em muitos estudos. O objetivo deste estudo foi avaliar os níveis de infecção dos vermes de olho Sphincterodiplostomum musculosum Dubois, 1936 (metacercárias) em Steindachnerina insculpta (Fernádez-Yépez, 1948) de três ecossistemas influenciados pelo reservatório de Jurumirim (Rios Paranapanema, Taquari e Veados). Um total de 174 espécimes de peixes foi amostrado de Abril/2011 a Abril/2012. Metacercárias de S. musculosum mostraram altos níveis de infecção nos olhos de S. insculpta em todos os ecossistemas amostrados apresentando ampla distribuição geográfica. As análises histológicas revelaram que, aparentemente, estas metacercárias estavam alojadas por trás da retina. Os peixes menores do rio Taquari estavam menos parasitados por metacercárias do que os adultos. Esse padrão pode ser explicado pelo efeito cumulativo de parasitismo, evidenciado pela correlação positiva entre a abundância de metacercárias e tamanho do corpo dos peixes.

Behavioral changes caused by Austrodiplostomum spp. in Hoplias malabaricus from the São Francisco River, Brazil.

Traira (Hoplias malabaricus) is a neotropical fish that is widely distributed in freshwater environments in South America. In the present study, we documented the occurrence of metacercariae of Austrodiplostomum spp. (Diplostomidae) in the eyes and cranial cavity of H. malabaricus and described parasite-induced behavioral changes in the host. The fish were collected from the upper São Francisco River, in the Serra da Canastra mountain range, Minas Gerais, transported alive to the laboratory, observed for 2 weeks, and subsequently examined for parasites. Of the 35 fish examined, 28 (80 %) had free metacercariae in the vitreous humor (mean intensity=95.4; mean abundance=76.3), and 24 (68.57 %) had free metacercariae in the cranial cavity, mainly concentrated below the floor of the brain, at the height of the ophthalmic lobe (mean intensity=12.91; mean abundance=8.85). Specimens of H. malabaricus with a high intensity of infection in the brain displayed changes in swimming behavior.

Pathology and first report of natural eye infection with the trematode Philophthalmus gralli (Digenea, Philophthalmidae) in Tinamus major (Tinamiformes, Tinamidae), Costa Rica.

The eye-fluke Philophthalmus gralli (Philophthalmidae Looss, 1899) was found in six birds known as great tinamous (Tinamus major) reared in a wild animal shelter located in Alajuela, Costa Rica. The birds presented conjunctival hyperemia, blepharitis, anorexia and weakness. Some of them suffered from unilateral blindness and ocular loss. After morphometric analysis, the specimens showed characteristics compatible with the digenean trematode P. gralli. The clinical signs of infection were resolved by manual removal of the adults, treatment with praziquantel and relocation into an environment without a natural water source. In order to determine if an ongoing cycle of this pathogen was present in the shelter, the habitat of the birds was inspected for the presence of infected intermediate hosts and contaminated water and objects. It was found that the snails Melanoides tuberculata acted as the intermediate host, and reared the infectious stages toward other animals, as shown by the reproduction of ocular philophthalmiasis in chickens artificially infected with excysted metacercaria. Moreover, three out of every ten snails found in the place were infected with rediae of P. gralli, raising the possibility of the dispersion of the parasite into new environments as well as the imminent zoonotic risk. The finding of P. gralli in Costa Rica is the first official report in Central America.

Eye trematode infection in small passerines in Peru caused by Philophthalmus lucipetus, an agent with a zoonotic potential spread by an invasive freshwater snail.

Until now, four species of eye trematodes have been found in South America. Of them, Philophthalmus lucipetus (synonymized with Philophthalmus gralli) displays a broad host spectrum, with at least 30 bird species (prevalently large water birds), five mammal species and humans serving as definitive hosts, and with snails Fagotia (Microcolpia) acicularis, Amphimelania holandri, Melanopsis praemorsa and Melanoides tuberculata serving as intermediate hosts. When examining a total of 50 birds of ten species in the wetland of Pantanos de Villa, Lima, Peru in July 2011, eye trematodes were identified visually in the edematous conjunctival sac of 11 (48%) out of 23 resident many-colored rush tyrants Tachuris rubrigastra. Based on morphometric characteristics, the trematodes were identified as P. lucipetus. ITS2 and CO1 gene of the examined specimens combined showed a 99% similarity to an Iranian isolate of Philophthalmus sp. from the intermediate host Melanoides tuberculata, an invasive freshwater snail, suggesting that these two isolates represent the same species with a wide geographical range. Moreover, the prevalence of infection with the philophthalmid cercariae was 31% in 744 Melanoides tuberculata examined in Pantanos de Villa in 2010. It is evident that P. lucipetus occurs throughout the world as well as locally, including Eurasia and South America. Here we report this trematode for the first time in Peru, and we were the first to sequence any of the South American eye trematodes. Low host specificity of P. lucipetus and the invasive character of Melanoides tuberculata as a competent intermediate host suggest that eye trematodosis caused by P. lucipetus may emerge frequently in various parts of the world, especially in the tropics. Increase of the zoonotic potential of the P. lucipetus associated with this invasive snail spreading across the world is predictable and should be of interest for further research.

Biomphalaria straminea and Biomphalaria glabrata (Mollusca: Planorbidae) as new intermediate hosts of the fish eyefluke Austrodiplostomum compactum (Trematoda: Diplostomidae) in Brazil.

Austrodiplostomum compactum has been involved in cases of ocular diplostomiasis in several species of fish in Brazil, but the molluscan intermediate hosts of the parasite remain unknown. In the present study, malacological surveys were carried out at Pampulha Reservoir, Belo Horizonte, Minas Gerais, Brazil, between January 2009 and July 2012. A total of 16,119 specimens of Biomphalaria spp. were collected and examined, of which 68/14,948 specimens (0.45%) of Biomphalaria straminea and 6/541 (1.11%) of Biomphalaria glabrata were found harboring a strigeid cercariae. Groups of 5 specimens of Cyprinius carpio were experimentally infected with these cercariae (100 larvae/fish), and metacercariae were recovered from the eyes of the fish, 65 days after infection, with a mean intensity of infection of 10.4 (8-13) metacercariae/fish. Morphological study on cercariae and metacercariae identified them as A. compactum . This is the first record of cercariae of A. compactum in Brazil, and B. straminea and B. glabrata as new intermediate hosts for the parasite.

The occurrence of Austrodiplostomum compactum (Lutz, 1928) (Digenea: Diplostomidae) metacercariae in the eyes of loricariid fish (Siluriformes: Osteichthyes: Loricariidae) from Brazil.

The aim of this study was to report the occurrence of Austrodiplostomum compactum metacercariae in the eyes of 98 specimens of loricariid fish (Hypostomus ancistroides, H. hermanni, H. iheringii, H. margaritifer, H. regani, H. strigaticeps, Hypostomus sp. and Megalancistrus parananus) from the Chavantes reservoir (23°07'36″S and 49°37'35″W) located in the rio Paranapanema, upper Paraná river basin, municipality of Ipaussu, São Paulo State, Brazil. Fish were collected from October 2007 to February 2009 using nylon monofilament gill nets and transported to the field laboratory where they were euthanized and the eyes were taken and examined under a stereomicroscope. Hypostomus ancistroides and M. parananus were not infected by this diplostomid. Hypostomus hermanni and H. margaritifer were represented by only one specimen but both had a high intensity of A. compactum metacercarie (27 and 35, respectively). Hypostomus strigaticeps (n = 45) and H. iheringii (n = 28) were the most representative specimens and the prevalence, mean intensity of infection and mean abundance were 24.4%, 10.3 and 2.7, and 64.2%, 13.1 and 8.4, respectively. No correlation was observed between the intensity of infection and the standard length (r = - 0.223; P = 0.827) and weight (r = 0.03; P = 0.779) of studied fish. Similarly, linear regression among these variables showed a poor correlation and indicated that the infection by A. compactum metacercariae occurs similarly in small and large fish specimens. A seasonal pattern of infection was not observed. Hypostomus hermanni, H. iheringii, H. margaritifer and H. strigaticeps were new hosts recorded for A. compactum metacercariae. A review of morphometric data of A. compactum metacercariae is presented.

Novas ocorrências de metacercária de Austrodiplostomum compactum (Lutz, 1928) (Platyhelminthes: Digenea) parasito de olhos de peixes da Bacia do Rio Paraná / New occurrences of metacercariae of Austrodiplostomum compactum (Lutz, 1928) (Platyhelminthes: Digenea) eye flukes of fish from the Paraná Basin

Austrodiplostomum compactum (Platyhelminthes: Digenea) parasita os olhos de várias de espécies de peixes. A presença deste parasito, em casos extremos, pode causar exoftalmia, deslocamento da retina, opacidade do cristalino e cegueira ou até a morte. O presente estudo registra novas ocorrências desta metacercária infectando os olhos de quatro novos hospedeiros de peixes, Serrasalmus maculatus coletado no reservatório de Rosana no rio Paranapanema e Hypostomus regani, Schizodon borellii e Auchenipterus osteomystax coletados na planície de inundação do alto rio Paraná.

Austrodiplostomum compactum (Platyhelminthes, Digenea) eye flukes of several species of fishes. The presence of this parasite, in extreme cases, can cause swelling of the eyelids, displacement of the retina, opacity of the crystalline lens and blindness or even death. The present study it registers new occurrences of this metacercariae infecting the eyes of four new hosts of fish, Serrasalmus maculatus collected in the Rosana reservoir in the Paranapanema river and Hypostomus regani, Schizodon borellii and Auchenipterus osteomystax collected in the the Upper Paraná River floodplain.

First report of Oxyspirura sp. from a captive fulvous owl (Strix fulvescens) in Mexico.

Nematodes similar to Oxyspirura sp. were recovered from the cornea and nictitating membrane of a fulvous owl (Strix fulvescens). The bird had been captive for several months, but died suddenly. It had no clinical history of prior diseases, including ocular lesions.

[New occurrences of metacercariae of Austrodiplostomum compactum (Lutz, 1928) (Platyhelminthes: Digenea) eye flukes of fish from the Paraná Basin]. / Novas ocorrências de metacercária de Austrodiplostomum compactum (Lutx, 1928) (Platyhelminthes: Digenea) parasito de olhos de peixes da Bacia do Rio Paraná.

Austrodiplostomum compactum (Platyhelminthes, Digenea) eye flukes of several species of fishes. The presence of this parasite, in extreme cases, can cause swelling of the eyelids, displacement of the retina, opacity of the crystalline lens and blindness or even death. The present study it registers new occurrences of this metacercariae infecting the eyes of four new hosts of fish, Serrasalmus maculatus collected in the Rosana reservoir in the Paranapanema river and Hypostomus regani, Schizodon borellii and Auchenipterus osteomystax collected in the the Upper Paraná River floodplain.

Pathology and first report of natural infections of the eye trematode Philophthalmus lachrymosus Braun, 1902 (Digenea, Philophthalmidae) in a non-human mammalian host.

The avian eye trematode Philophthalmus lachrymosus Braun, 1902 is for the first time referred naturally occurring in a non-human mammalian host. Previously, natural infections with P. lachrymosus and other species of Philophthalmus have been occasionally reported from man, with few data on experimental infections of non-human mammals. Results presented here are related to the report of two cases of philophthalmosis due to natural infections of wild Brazilian capybaras, Hydrochaeris hydrochaeris L., 1766 with P. lachrymosus and associated pathology. Clinical signs, gross and microscopic lesions as well as new morphometric data on the parasite are presented.

Diplostomum (Austrodiplostomum) compactum (Lutz, 1928) (Platyhelminthes, Digenea) metacercariae in fish from the floodplain of the Upper Paraná River, Brazil.

Diplostomum (Austrodiplostomum) compactum (Lutz, 1928) metacercariae (Platyhelminthes, Digenea) were found in six fish species, belonging to two orders (Characiformes and Perciformes) and three families (Erythrinidae, Sciaenidae and Cichlidae). A total of 477 individuals were collected, from August 1999 to May 2001, in the upper Paraná River floodplain, Brazil. The metacercariae were infecting the eyes of six host species and the brain of five of them. Plagioscion squamosissimus, Satanoperca pappaterra and Cichla monoculus presented the highest values of prevalence, mean intensity and mean abundance. Diplostomum (A.) compactum was over-dispersed in the population of Hoplias aff. malabaricus, S. pappaterra, P. squamosissimus, Crenicichla britskii and C. monoculus. No significant difference was observed in the metacercariae distribution in the right and left eyes. The abundance of D. (A.) compactum metacercariae was positively correlated with the host's relative condition factor in H. aff. malabaricus and S. pappaterra. No significant difference of the abundance of parasitism between the sex of the hosts was evidenced. In relation to the prevalence, significant difference was observed only in C. britskii. Positive correlations were verified between the prevalence of infection and the standard length of the specimens in C. britskii and the intensity of infection and the standard length of the hosts in P. squamosissimus and C. monoculus. In relation to parasite abundance and the standard length class of the host, significant differences were observed in P. squamosissimus, C. britskii and C. monoculus.

First report of parasites from pinnipeds in the Galapagos Islands, Ecuador, with a description of a new species of Philophthalmus (Digenea: Philophthalmidae).

A new species of digenetic trematode and 2 species of ectoparasites from Zalophus wollebaeki Silvertsen, 1953 (Carnivora: Otariidae) in the Galapagos Islands, Ecuador, are reported. These include an eye fluke of Philophthalmus Looss, 1899 (Echinostomata: Philophthalmidae) as well as, to our knowledge, the first report of Antarctophthirus microchir (Trouessart and Neumann, 1888) Enderlein, 1906 (Arthropoda: Anoplura) and Orthohalarachne diminuata (Doetschman, 1944) Newell, 1947 (Arthropoda: Acarina) from this host and location. Philophthalmus zalophi n. sp. differs from the 4 other marine species of Philophthalmus (P. andersoni Dronen and Penner, 1975; P. burrili Howell and Bearup, 1967; P. hegeneri Penner and Fried, 1963; and P. larsoni Penner and Trimble, 1970) by its mammalian host, large body size, lack of tegumental spines, posterior length of seminal vesicle, placement of genital pore, size ratio of oral sucker to acetabulum, shape and size of testes, and size ratio of ovary to testis.