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The present study describesOligogonotylus andinussp. nov.and its life cycle from a rural fish farm in Sopetrán, Antioquia, Colombia. The endemic species of snailAroapyrgus colombiensisand the fishesPoecilia caucanaandAndinoacara latifronsare identified as the first intermediate host, the second intermediate host and the definitive host, respectively. The new species was defined through an integrative approach, combining the traditional morphology of its developmental stages with molecular analyses of the markers ITS2 from ribosomal DNA and COI from mitochondrial DNA. This new species can be distinguished from its congeners by genetic divergence, the position of the vitelline fields, and the number of gonotyls. This work represents the first report of a species of this genus in South America.

Using the immunocytochemical method and confocal scanning laser microscopy, we obtained pioneering data on the muscle system organization and presence and localization of biogenic amine serotonin and FMRFamide-related peptides in the nervous system of the trematode Prodistomum alaskense (Ward and Fillingham, 1934) Bray and Merrett 1998 (family Lepocreadiidae). This flatworm is an intestinal parasite of endemic representatives of the marine fauna of the northwestern Pacific Ocean — the prowfish (Zaprora silenus Jordan, 1896) and the lumpfish (Aptocyclus ventricosus (Pallas, 1769)). We provide data of scanning electron microscopy on the tegumental topography of P. alaskense. The body wall musculature of P. alaskense has three layers of muscle fibres — the outer circular, intermediate longitudinal, and inner diagonal. The muscle system elements are well developed in the attachment organs, digestive and reproductive systems, and in the excretory sphincter. Serotonin– and FMRFamide–immunopositive neurons and neurites are found in the head ganglia, circular commissure, longitudinal nerve cords, and in the transversal connective commissures. The innervation of the oral and ventral suckers, pharynx, and the reproductive system compartments by the serotonergic and FMRFamide–immunopositive neurites is revealed. The results discus connection with the published data on the presence and functional roles of the serotonin and FMRFamide-related peptides in Platyhelminthes.

This review investigated information about metacercariae of Clinostomum Leidy, 1856 published over 91 years (1928 to 2019) to search for infection and geographic distribution patterns of this digen...

Abstract Data on trematode life cycles, fish host distribution, transmission, and fish and snail infection are reported in this review. European freshwater trematodes of the genus Sanguinicola (Aporocotylidae) remain an insufficiently studied group of trematodes. Five species of Aporocotylidae (Sanguinicola armata, S. inermis, S. intermedia, S. volgensis, and S. rutili) in freshwater fish of Europe are described. In addition, they have been found in the water bodies of Central Asia and West Siberia (Ob-Irtysh River basin). The life cycle allowing us to assign the cercariae and adults to a certain species is known only for S. armata, S. inermis, and S. rutili. Trematodes of the genus Sanguinicola are found in 26 fish species assigned to 7 families and 4 orders and 24 gastropod species assigned to 7 families. With few exceptions, the sanguinicolid infection of fish and snails is rather low in the natural water bodies.

In this study, we elucidated the phylogenetic position of a Pacific species Pronoprymna petrowi, a Caspian species Pronoprymna ventricosa, an Antarctic species of the genus Steringophorus, S. lipar...

We report the first molecular identification of Phyllodistomum macrocotyle (Digenea: Gorgoderidae) from the Northern Dvina River Basin, Northwest Russia. Comparative analysis of our sequence was 100% identical to the 28S and ITS2 rDNA sequences of the species P. macrocotyle in zebra mussels discovered in Poland (Wigry Lake), Lithuania (Elektrenai Reservoir and Sirvinta River), Russia, Belarus (Lepelskoe Lake and Lukomskoe Lake), and in fish Leuciscus idus, Scardinius erythrophthalmus in Russia (Rybinsk Reservoir on the Volga River). At the same time, some sequences of the 28S rDNA of P. macrocotyle in zebra mussel detected in Lithuania, and Belarus were different from our sequence on 0.2-0.6%. The ITS2 sequences which have 100% similarity with our specimens of P. macrocotyle were discovered in sporocyst of phyllodistomes from its intermediate host D. polymorpha in Poland, Lithuania, Russia, and Belarus. Our observation in the Yuras and Isakogorka rivers represents the northernmost record of this host-specific parasite, to the best of our knowledge.

Azygia hwangtsiyui (Trematoda, Azygiidae), a neglected parasite of predatory fishes, is little-known in terms of its molecular epidemiology, population ecology and phylogenetic study. In the present study, the complete mitochondrial genome of A. hwangtsiyui was sequenced and characterized: it is a 13,973 bp circular DNA molecule and encodes 36 genes (12 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes) as well as two non-coding regions. The A+T content of the A. hwangtsiyui mitogenome is 59.6% and displays a remarkable bias in nucleotide composition with a negative AT skew (–0.437) and a positive GC skew (0.408). Phylogenetic analysis based on concatenated amino acid sequences of twelve protein-coding genes reveals that A. hwangtsiyui is placed in a separate clade, suggesting that it has no close relationship with any other trematode family. This is the first characterization of the A. hwangtsiyui mitogenome, and the first reported mitogenome of the family Azygiidae. These novel datasets of the A. hwangtsiyui mt genome represent a meaningful resource for the development of mitochondrial markers for the identification, diagnostics, taxonomy, homology and phylogenetic relationships of trematodes.

Background Parasites may mediate the success of biological invasions through their effect on host fitness and thus, on host population growth and stability. However, a release from the pressure of parasites is strongly related to the genetic differentiation of the host. In invasive host populations, the number of available genetic variants, allowing them to ‘fight’ the infection, are likely to be influenced by founder events and genetic drift. The level standing genetic variation of invasive populations may be crucial in successfully adapting to new environments and resisting diseases. We studied invasive populations of raccoon that experienced a random reduction in genetic diversity during the establishment and evaluated the relationship between host immune genetic diversity and intestinal parasites infection. Results We distinguished two different genetic clusters that are characterized by different sets of functionally relevant MHC-DRB alleles. Both clusters were characterized by considerably different allele-parasite associations and different levels of parasite infection. The specific resistance MHC-DRB alleles explained the lower prevalence of Digenea parasites. An increased infection intensity was related to the presence of two MHC-DRB alleles. One of these alleles significantly decreased in frequency over time, causing a decrease of Digenea abundance in raccoons in consecutive years. Conclusions Our findings suggest that intestinal parasites can exert selective pressure on an invasive host with lowered levels of immune genetic diversity and contribute to promoting local adaptation over time. The random genetic drift that created the two different genetic clusters in the invasive raccoon range imposed completely different MHC-parasite associations, strongly associated with the infection status of populations. Our findings underline the role of standing genetic variation in shaping host-parasite relationships and provide empirical support that functional genetic variation may be, at least partly, responsible for differences in the success of invasive populations.

Made available in DSpace on 2020-12-10T19:50:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-02-24 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Fundo deApoio a Pesquisa FAP/UNIVILLE Digeneans of the genus Ogmogaster Jagerskiold, 1891 are intestinal parasites of whales and pinnipeds. Due to the difficulty in recovering these parasites from opportunistic stranding events of their hosts, very little morphological and molecular data are available on the species of this genus. During a beach monitoring survey on the Southern Brazilian coast, a dwarf minke whale Balaenoptera acutorostrata (Lacepede, 1804) was necropsied and some digeneans were found in its intestine. Morphological and molecular analyses based on the ribosomal DNA SSU and the mitochondrial DNA COI genes were conducted. The morphological data along with the phylogenetic reconstructions allowed the identification of Ogmogaster antarctica Johnston, 1931. This is the first report of O. antarctica infecting a B. acutorostrata in the South Atlantic Ocean. The morphological data, the molecular characterization and the phylogenetic positioning of O. antarctica presented in this study contribute to the knowledge of the helminth diversity of large whales. Sao Paulo State Univ UNESP, Dept Parasitol, Inst Biosci, Campus Botucatu 250, BR-18618689 Sao Paulo, Brazil Univ Sao Paulo, Dept Pathol, Sch Vet Med & Anim Sci, BR-05508270 Sao Paulo, Brazil Univ Reg Joinville UNIVILLE, Lab Ecol & Conservat Coastal & Marine Tetrapods, Duque Caxias Rd 6-365, BR-89240000 Sao Francisco Do Sul, SC, Brazil Sao Paulo State Univ UNESP, Dept Parasitol, Inst Biosci, Campus Botucatu 250, BR-18618689 Sao Paulo, Brazil CNPq: 140873/2017-1 CNPq: 10477/2017-4 CNPq: 307808/2014-9 CNPq: 440496/2015-2 FAPESP: 2016/50377-1

— Ontogenetic data can be used in phylogenetic analyses (1) as tests of character homology, (2) for polarizing transformation series, and (3) as characters themselves. The ontogenetic sequence of semaphoronts can change by addition, substitution, or deletion of stages which are either terminal or nonterminal. Outgroup comparisons can use life cycle data as well as morphological data to establish a general reference system of inferred genealogy, which can then be used to distinguish which of the six ontogenetic sequence changes has occurred in a particular phylogeny. A cladistic study of the parasitic platyhelminths suggests that the evolution of the Digenea involved a nonterminal addition of ontogenetic stages and a terminal addition of a second host to the ancestral life cycle. The evolution of the Cestoidea appears to have involved a terminal addition of ontogenetic stages and a nonterminal addition of a second host. The “complex life cycles” of the two groups are thus different in nature and etiology. Further cladistic analysis, within the Digenea, suggests that the plesiomorphic state of the intercalated ontogenetic stages was a miracidium-sporocyst-cercariae sequence. Rediae are concluded to have been intercalated between sporocysts and cercariae at a later point. The mutual exclusivity of rediae and daughter sporocysts in a life cycle is noted.

Made available in DSpace on 2022-04-29T08:36:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 Petrobras Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) This is the first confirmed report of Pholeter gastrophilus infecting three delphinid species from Brazilian waters, Steno bredanensis, Tursiops truncatus, and Feresa attenuata. The worms were identified based on morphological and molecular data using the 28S rDNA and COI mtDNA genes. The present study increases the distribution area of this trematode species and provides new molecular data to be used in future phylogenetic studies of the group, thus contributing to scientific knowledge on marine parasites. Institute of Biosciences Department of Parasitology São Paulo State University (UNESP) Campus Botucatu Institute of Biology Department of Morphology Federal University of Pelotas (UFPel) Laboratory of Ecology and Conservation of Coastal and Marine Tetrapods University of the Region of Joinville (UNIVILLE) Institute of Biosciences Department of Parasitology São Paulo State University (UNESP) Campus Botucatu CNPq: 10477/2017-4 CNPq: 140873/2017-1 FAPESP: 2016/50377-1 CNPq: 309125/2017-0 CNPq: 440496/2015-2

The assignment of species to Faustula Poche, 1926 (Faustulidae Poche, 1926) is reconsidered with the proposal of Gangafaustula n. gen. to accommodate Gangafaustula makundai (Agarwal & Verma, 1981) n. comb.; Gobifaustula n. gen. to accommodate Gobifaustula qikouensis (Qui & Li, 1995) n. comb.; Lingulitrema n. gen. to accommodate Lingulitrema hilsai (Kumar & Agarwal, 1984) n. comb.; Schellitrema n. gen. to accommodate Schellitrema gasterostei (Schell, 1973) n. comb. and Varanasifaustula n. gen. to accommodate Varanasifaustula indica (Agarwal & Verma, 1981) n. comb. Faustula hilsai Kumar & Agarwal, 1984 is determined to be a species distinct from Faustula hilsai Rizvi, 1971 and F. hilsai Rizvi, 1971 is synonymized with Faustula basiri Hafeezullah & Siddiqi, 1970. Faustula rahemii Al-Daraji, 2004 also is synonymized with F. basiri. Faustula pyriformis Kumar & Agarwal, 1984 is transferred to Pronoprymna Poche, 1926 as Pronoprymna pyriformis (Kumar & Agarwal, 1984) n. comb. Faustula sayori (Yamaguti, 1942) Yamaguti, 1958, now synonymized with Pronoprymna petrowi (Layman, 1930) Bray & Gibson, 1980, is renamed Pronoprymna sayori (Yamaguti, 1942) n. comb. based on the presence of an entire (smooth) ovary in P. petrowi (Syn. Monorcheides petrowi Layman, 1930) as originally described, and Faustula varanasiensis (Agarwal & Kumar, 1977) is transferred to Bacciger Nicoll, 1914 as Bacciger varanasiensis (Agarwal & Kumar, 1977) n. comb. We currently propose the following 5 species be retained in Faustula: F. basiri; Faustula brevichrus (Srivastava, 1935) Yamaguti, 1958; Faustula clupeae (Srivastava, 1935) Yamaguti, 1958; Faustula gangetica (Srivastava, 1935) Yamaguti, 1958 and Faustula keksooni (MacCallum, 1918) Poche, 1926. A revised key to the species of Faustula and a key to the genera within the Faustulidae are provided.

Neopsilotrema is a small genus of psilostomid digeneans parasitic in the intestine of birds in the Palearctic and Nearctic. At present, the genus includes 4 species: Neopsilotrema lisitsynae from the Palearctic and Neopsilotrema affine, Neopsilotrema lakotae, and Neopsilotrema marilae from the Nearctic. Herein, we describe a new species, Neopsilotrema itascae n. sp., from lesser scaup Aythya affinis collected in Minnesota. The species can be distinguished from congeners on the basis of the ventral sucker:oral sucker width ratio, body width:length ratio, and cirrus sac size, along with other characters. We generated new 28S ribosomal deoxyribonucleic acid (DNA) and NADH dehydrogenase (ND1) mitochondrial DNA sequence data of a variety of psilostomids from the Palearctic and Nearctic along with sequences of the ribosomal internal transcribed spacer (ITS) region (ITS1 + 5.8S + ITS2) from 3 Neopsilotrema species. The molecular phylogenetic affinities of a variety of psilostomid taxa were studied using 28S sequence data. The 28S sequences of psilostomids demonstrated 1-7.9% intergeneric divergence, whereas the sequences of ND1 had 17.7-34.1% intergeneric divergence. The interspecific divergence among members of Neopsilotrema was somewhat lower (0.2-0.5% in 28S; 0.3-0.4% in ITS; 12-15.7% in ND1). Our comparison of DNA sequences along with morphologic study suggests Holarctic distribution of N. lisitsynae.

Species of Astiotrema Looss, 1900 (sensu lato) infect a wide range of fishes, amphibians and reptilians. They also possess a considerably wide spectrum of morphological features. Several species were recognized for variable, confusing, overlapping and unspecialized morphological characters rather than for unique distinguishing features, causing continuing dispute around the validity of several species. Following comprehensive review, a revised restricted concept of Astiotrema is proposed including a morphologically strict definition. Both Tremiorchis Mehra & Negi, 1926 and Astioglossimetra Bilqees, Khatoon & Khan, 2002 are synonymized with Astiotrema (sensu stricto). Several nominal species are synonymized, others are excluded and characters for each recognized species are presented and explained. Only eight species are recognized: Astiotrema cyclemysi Siddiqi, 1965, Astiotrema emydis Ejsmont, 1930, Astiotrema fotedari Dhar, 1977, Astiotrema impletum (Looss, 1899) Looss, 1900, Astiotrema karachiensis (Bilqees, Khatoon & Khan, 2002) n. comb., Astiotrema odhneri Bhalerao, 1936, Astiotrema ranarum (Mehra & Negi, 1926) Fotedar, 1971 and Astiotrema reniferum (Looss, 1898) Looss, 1900. A key to the species of Astiotrema (sensu stricto) is presented, a comprehensive list of all host-locality records is included and host-parasite specificity is elucidated.

Macroscopic examination of 622 Salado salamanders, Eurycea chisholmensis Chippindale, Price, Wiens and Hillis, 2000, collected between June 2018 and July 2020 from 3 springs in Williamson County, Texas, U.S.A., revealed the presence of encapsulated metacercariae of Clinostomum cf. marginatum (“yellow grub”) in 3 (0.5%) hosts. Two of these 3 salamanders were examined and released unharmed per permit requirements, but 1 was found dead, and it harbored 6 total metacercariae, 4 on the head region (including 1 behind the left eye), 1 near the left front leg, and 1 in the tail. Morphological identification of C. cf. marginatum was achieved by comparison to previous accounts. Molecular identification was accomplished by comparing sequence homology and phylogenetic analysis using an 828 base pair partial sequence of the internal transcribed spacer region. This is the first report of any parasite from E. chisholmensis, a federally threatened species.

Herein we describe a new species and propose a new genus, Posthovitellinum psiloterminae n. gen., n. sp. (Lissorchiidae: Asymphylodorinae), based on specimens that infect the intestine of Cyclocheilos enoplos (Bleeker, 1849) (Cypriniformes: Cyprinidae), a migratory riverine carp from the Mekong River (Dong Thap province, Vietnam). The new species is assigned to Lissorchiidae by having a combination of features: spinous tegument, subterminal oral sucker, pre-equatorial ventral sucker, median and pretesticular ovary, submarginal genital pore at level of the ventral sucker, follicular vitellarium distributing in 2 lateral fields, and lacking eyespot pigment in the adult. It cannot be assigned to any existing asymphylodorine genus because it has the combination of a well-developed cirrus-sac, an unarmed ejaculatory duct and metraterm, a follicular vitellarium distributing in 2 lateral fields located between the posterior margin of the ventral sucker and the mid-level of the testis, and a sinistral, submarginal genital pore. The new species has an elongate, claviform cirrus-sac, a single, large, elongate-oval testis at the posterior extremity of the body, operculate eggs, and an I-shaped excretory bladder with secondary branches at the level of the testis and extending anteriad to the level of the pharynx. Bayesian inference analysis of the partial large subunit ribosomal DNA gene (28S rDNA) recovered the new species sister to Asaccotrema vietnamienseSokolov and Gordeev, 2019; these species differed by 118 nucleotides (12%; 983 bp fragment). This is the first lissorchiid reported from the Mekong River; only the second from southern Vietnam; and the fourth reported from a cyprinid fish in Vietnam. The aforementioned phylogenetic analysis included previously unpublished sequences representing lissorchiids infecting the intestine of North American suckers (Cypriniformes: Catostomidae): Lissorchis cf. nelsoni from spotted sucker; Minytrema melanops (Rafinesque, 1820) and Lissorchis cf. gullaris (immature) from smallmouth buffalo, Ictiobus bubalus (Rafinesque, 1818). Asymphylodora atherinopsidisAnnereaux, 1947, herein is treated as a species incertae sedis. The 28S tree topology suggests that Lissorchiinae may comprise more than 1 lineage, but additional species are needed to confidently assert this.

Introduction Radix auricularia (Linnaeus, 1758) is a freshwater gastropod belongs to the Lymnaeidae (pond snails) family which act as intermediate hosts or vectors of various parasitic flukes. No study has yet been undertaken on the prevalence of Petasiger spp. infection in R. auricularia . Species of Petasiger (Dietz, 1909) are a cosmopolitan parasite that utilize snails as the first intermediate host, with vertebrates like amphibians larvae and fish as the second intermediate host, followed by fish-eating birds. The current paper is considered to be the first report of Petasiger exaeretus parasitized R. auricularia in Iraq, which is supported with molecular and phylogenetic analysis. Material and methods Freshwater snails R. auricularia were collected during October 2016 – September 2017 from different locations of Sufaia village on the Greater Zab river, Erbil province, Iraq. Results A total of 307 freshwater snails R. auricularia were collected, only five of them were infected with a prevalence of Petasiger exaeretus (1.62%). Conclusions The current study agrees with the opinion of Selbach, Soldánová (26), which suggested the possibility of a much higher morphological diversity within Petasiger species, based on the number of described cercariae, compared with adult forms.It is clear that P. phalacrocoracis specimens have often been erroneously designated as P. exaeretus by many authors (Našincová et al., 1994). Certain morphological similarities and dissimilarities between P. exaeretus and P. phalacrocoracis can be detected: the pear-shaped body resembles P. exaeretus , whereas, P. phalacrocoracis have an elongated body.

Interactions between parasite species may influence their distribution and abundance within communities. Experimental single-species infections of Diplostomum spp. in the gut of the definitive host, the Ringed-billed Gull (Larus delawarensis Ord, 1815), were compared with mixed-species infections to explore interactions among parasites. Three species of Diplostomum von Nordmann, 1832 (Digenea), designated as Diplostomum sp. 1, Diplostomum sp. 4, and Diplostomum baeri Dubois, 1937, were examined for intestinal distribution and fecundity in single and mixed infections. In single-species infections, most specimens of Diplostomum sp. 1 and D. baeri were recovered from the mid-region of the intestine, whereas Diplostomum sp. 4 were mainly present in the anterior region. Significant spatial displacement was observed only for D. baeri when Diplostomum sp. 1 was also present. Intensity was directly correlated to the number of occupied intestinal segments, and there was no significant difference in mean linear span for each species between single-species and mixed-species infections. Diplostomum sp. 4 had the highest mean number of eggs per worm in utero in single-species infections. In mixed-species infections, the fecundity of Diplostomum sp. 4 declined dramatically in the presence of Diplostomum sp. 1, whereas fecundity of Diplostomum sp. 1 increased in the presence of D. baeri. These results highlight interspecific interactions that may play a role in population dynamics of Diplostomum spp. and community structure.

Dendrorchis retrobiloba Volonterio & Ponce de León, 2005 was first described from the swim bladder of Astyanax fasciatus (Cuvier, 1819) from Montevideo, Uruguay. In this study, we necropsied specimens of A. aff. fasciatus collected from Lake Guaíba, in Rio Grande do Sul, Brazil, for the analysis of their helminths. The digeneans were identified as D. retrobiloba by their elongated body, oral sucker longer than ventral sucker, and 2 posterior lobes. This is the first report of D. retrobiloba in A. aff. fasciatus from Lake Guaíba and extends the known geographic distribution of this parasite.

Despite over 100 years of digenean trematode parasite species descriptions, from a wide diversity of vertebrate and invertebrate host species, our ability to recognize the diversity of trematode species within a single lake remains an incredible challenge. The most challenging aspect is the identification of species from larval stages derived from intermediate hosts, due to the disjointed data of adult worm morphological descriptions, from which species are named, and links to corresponding molecular identifiers in depauperate databases. Cryptic species also play a significant role in the challenge of linking trematode larvae to adults, species identifications, and estimating diversity. Herein, we utilize a large, longitudinal dataset of snail first‐intermediate host infection data from lakes in Alberta, Canada, to infer trematode larval diversity using molecular phylogenetics and snail host associations. From our assessments, we uncover a diversity of 79 larval trematode species among just five snail host species. Only 14 species were identified to a previously described species, while the other 65 species are either cryptic or otherwise unrepresented by mitochondrial genes in GenBank. This study currently represents the largest and most diverse singular molecular survey of trematode larval fauna composed of over one thousand mitochondrial sequences. Surprisingly, rarefaction analyses indicate we have yet to capture the complete diversity of trematodes from our sampling area.

On 28 August 2015, a dead fin whale Balaenoptera physalus (Linnaeus, 1758) was collected from the waters of the Gulf of Gdan΄%%KERN_ERR%%sk (Baltic Sea). The individual was a male in a poor nutritional condition with an empty stomach. Over 34000 Ogmogaster antarcticus flukes were found in the colon and rectum. This is the first observation of O. antarcticus in the Baltic Sea.

Monitoring studies of the species diversity in marine ecosystems provide important data on ecological changes caused by global warming and anthropogenic influence. The present work was aimed to analyze the species diversity of the helminths parasitic in teleost fishes inhabiting the area near the Ukrainian Antarctic Station “Akademik Vernadsky” (Galindez Island, Argentine Islands, West Antarctica). During April–January of 2014–2015 and 2019–2020, 156 specimens of six fish species (Notothenia coriiceps, N. rossii, Chaenocephalus aceratus, Parachaenichthys charcoti,Trematomus bernacchii, and Harpagifer antarcticus) were examined. Totally, 21,166 specimens of 31 helminth species were collected and assigned to five taxonomic groups: Monogenea (1 species), Digenea (10), Nematoda (5), Cestoda (4), and Acanthocephala (11). Twenty-six helminth species were found in N. coriiceps, 14 in N. rossii, 27 in P. charcoti, 23 in Ch. aceratus, 16 in T. bernacchii, and six in H. antarcticus. Larval stages of anisakid nematodes prevailed in the helminth community of Ch. aceratus (66 %) and P. charcoti (40 %), while other fish species were mostly infected with acanthocephalans,trematodes and cestodes. The present data on the species diversity of helminth communities can be used as a baseline for long-term monitoring studies of fish parasites in the region of the Argentine Islands.

Philophthalmus is a genus of globally distributed parasitic eye flukes with some members of the genus found in disparate locales. In particular, Philophthalmus gralli, a zoonotic trematode, appears to be a relatively new introduction to the Americas, facilitated by spillover from the invasive snails Melanoides tuberculata (red-rimmed melania) and Tarebia granifera (quilted melania), which were introduced via the aquarium trade, and perhaps furthered by avian dispersal. Given that two known intermediate hosts of Philophthalmus flukes are actively expanding their range as a result of human activities, we hypothesize that this spread is also associated with the spread of Philophthalmus flukes. To address this, we systematically reviewed the literature and examined whether the global expansion of P. gralli flukes is associated with the spread of invasive snails M. tuberculata and T. granifera. Here, we show that (1) specimens of P. gralli are only found in intermediate snail hosts M. tuberculata or T. granifera, suggesting intermediate host specificity for these 2 species, and (2) specimens of P. gralli have rarely been found outside the ranges (native and introduced) of M. tuberculata or T. granifera. Given the importance of distribution information of parasites in the role of identifying parasite invasions, we also review the known distribution of all Philophthalmus species. Considering recent outbreaks in humans and wild and domestic animal species, the continued spread of Philophthalmus presents a potential threat to veterinary and public health and conservation.

The hawksbill turtle Eretmochelys imbricata is a critically endangered species with a worldwide distribution. Limited information is available about the naturally occurring intestinal parasites of this species and what impact these parasites may have on the health of the hawksbill turtle. Diaschistorchis pandus was identified postmortem in 5 hawksbill turtles from Grenada, West Indies, using morphologic characterization. Sanger sequencing was performed for conserved ribosomal regions (5.8S, ITS2, 28S) and the mitochondrial cytochrome c oxidase subunit 1 gene (COI). Phylogenetic analysis of the 28S rRNA gene sequence data shows D. pandus clustering with other trematodes in the family Pronocephalidae, corroborating morphological classification. No genetic sequences have been previously reported for this trematode species, which has limited the collection of objective epidemiological data about this parasite of marine turtles.

To date, 9 species of Schistosomatidae have been found parasitizing the nasal tissues of mammal and bird hosts in the Eastern Hemisphere, 5 species in Rwanda (Africa), 2 in Australia (Oceania) and 2 in Eurasia. During a parasitological survey of black necked swans, Cygnus melancoryphus, an anatid endemic to South America, schistosome worms in the nasal tissue were found; the first in the Americas. Morphological results based on male worms and in isolated eggs. The worms have a spiny tegument, filiform body with rounded posterior end, two muscular suckers, a robust gynaecophoric channel with thickened cross bands, and around 130 testes. The eggs are elongate with an asymmetrical bulge, with a slender process at one end and a longer curved process at the other. Diagnostic morphological characteristics do not match with any schistosome genus. Part of the mitochondrial cox1 and nuclear DNA 28S partial genes were sequenced and compared to Schistosomatidae in GenBank. The genetic results confirm the distinctiveness of the specimens since they do not group with any described genus or undescribed lineage other than cercariae of “Chilina lineage 1” that emerge from the Patagonian Chilina gibbosa, a freshwater snail endemic to South America. Based on morphological and genetic characterization of these schistosomes, these specimens represent a new genus and species that parasitizes black necked swans as adults in the nasal tissue, and C. gibbosa is the first intermediate host, both hosts being endemic to South America.

The digenetic trematode family Gorgocephalidae comprises just a few species, and the literature devoted to the lineage consists of only a handful of reports. With one exception, all reports have been based on material collected in the Indo-West Pacific, an expansive marine ecoregion stretching from the east coast of Africa to Easter Island, Hawaii and French Polynesia. We collected adult and intramolluscan gorgocephalids from kyphosid fishes and littorinid gastropods from several Australian localities, and from South Africa and French Polynesia. Specimens of Gorgocephalus kyphosi and G. yaaji were collected from, or near, their type-localities, providing new morphological and molecular (COI, ITS2 and 28S) data needed for a revised understanding of species boundaries in the family. Two new species are recognized: Gorgocephalus euryaleae sp. nov. and Gorgocephalus graboides sp. nov. New definitive host records are provided for described species and three new intermediate hosts are identified. These new records are all associated with Kyphosus fishes and littorinid gastropods, reaffirming the restriction of gorgocephalids to these hosts. Most significantly, we provide evidence that G. yaaji is distributed from South Africa to French Polynesia, spanning the breadth of the Indo-West Pacific. Our findings have significant relevance regarding digenean species delineation over geographic range.

Cardicola Short, 1953 is the most speciose aporocotylid genus (35 species) and includes marine and estuarine species of fish blood flukes that infect "higher ray-finned fishes" (Euteleostei). Several clades within Cardicola are recovered in phylogenetic analyses of the large subunit ribosomal DNA (28S), but morphological synapomorphies for those nucleotide-based clades remain elusive. The type species, Cardicola cardiocola (Manter, 1947) Short, 1953, has not been recollected in 73 yr and the original description was incomplete; making a genus revision challenging because of the ambiguous systematic position of its type species. Herein, we redescribe C. cardiocola by using the holotype (USNM 1337732) and new specimens collected from the type host, jolthead porgy, Calamus bajonado (Sparidae), from nearby the type locality. It differs from its congeners by the combination of having a body that is 5 times longer than wide, an anterior sucker with concentric rows of spines, 2-6 tegumental body spines per row, an esophageal gland that is 22-43% of the esophageal length, a testis that is 3-5 times longer than wide and that fills the intercecal space, a vitelline duct connecting to the anterior aspect of the ootype, an ascending uterus that lacks any coil, a descending uterus yielding a single coil, an obvious cirrus sac separated by constriction from the seminal vesicle, a tegumental protrusion surrounding the terminal end of cirrus sac, and a male genital pore that is posterior to the remainder of the genitalia. We also describe a new congener infecting the heart of yellowedge grouper, Hyporthodus flavolimbatus (Serranidae), from the Gulf of Mexico. It differs from its congeners by the combination of having an anterior sucker that does not extend beyond the anterior body margin, 2-5 tegumental body spines per row, posterior ceca that are 9 times length of the anterior ceca and that lack any coil, a testis that is 3 times longer than wide and that does not fill the intercecal space, an ovary that is >60% of the body width, a vitelline duct that connects to the anterior aspect of the ootype, a uterus that is >10% of the body width and that extends posterior to all genitalia, and a rounded posterior body margin. It is the first species of Cardicola to be described from a grouper (Serranidae). The 28S and internal transcribed spacer 2 phylogenetic analyses recovered the new species as a distinct lineage within the clade of Cardicola spp.

Sea turtles are difficult to sample because of their protected status; however, museum collections and sea turtle stranding networks provide unique opportunities for parasitological research. Four gastrointestinal tracts from stranded, endangered green turtles, Chelonia mydas, were collected between 1993 and 1995 from the upper Texas coast and opportunistically sampled for parasite fauna. Two new species of Telorchis, a common freshwater amphibian and reptilian intestinal parasite genus, were found and described. Telorchis marinus n. sp. differs from Telorchis mydas n. sp. by its short body length, lack of pharyngeal glands, long esophagus relative to total body length, short and straight cirrus sac, short ventral sucker to ovary length relative to total body length, and an ovary located in the anterior one-third of body; it differs from its congeners in the number of ovary lengths between the ventral sucker and ovary, the number of ventral sucker lengths the cirrus sac extends beyond the posterior margin of the ventral sucker, and the vitelline field extent. Telorchis mydas differs from its congeners in the number of ovary lengths between the ventral sucker and ovary, the number of ventral sucker lengths the cirrus sac extends beyond the posterior margin of the ventral sucker, and the combination of having its ovary position near the midbody and a long, sinuous cirrus sac that is 35-44% of the total body length. Given the taxonomic complexities within Telorchis, a revised key to North American species is provided using morphological characteristics to assist future researchers in delineating true species and appropriate synonymies with molecular explorations. We reject the majority of synonymies in the genus until molecular data are available; we accept the synonymies of Telorchis necturi as Telorchis stunkardi and Telorchis gutturosi as Telorchis chelopi. Both Telorchis linstowi and Telorchis stossichi should be considered as species inquirenda. This is the first confirmed report of Telorchis from a marine host and the first report on parasites of cheloniid sea turtles in Texas, and this study adds to the ever-growing evidence that collections are essential to understanding biodiversity.

Paratanaisia bragai is a trematode that reaches sexual maturity in the kidney collecting ducts of domestic and wild birds, while the gastropods Subulina octona and Leptinaria unilamellata serve as its intermediate hosts. The morphology of P. bragai eggs is described here for the first time, using light, scanning and transmission electron microscopy. Embryonic eggs, obtained from adult worms collected from naturally infected definitive hosts, appeared elliptical, with an evident operculum, by all three microscopic techniques employed. Scanning electron microscopy revealed that the abopercular region presents a prominent U-shaped knob, which stands out from the egg surface. The thickness of the eggs, measured from ultrathin sections, were 0.34 ± 0.06 µm (0.29–0.50) at the ends and 0.31 ± 0.05 µm (0.24–0.36) in the middle region. The internal shell layer was more electron-dense and thinner than the middle layer, which comprised nearly the entire shell, while the external layer was less electron-dense and thinner than the internal layer. Rupture of the eggs, by the coverslip pressure, revealed the miracidia of P. bragai that was characterized by light and transmission electron microscopy.

Here we describe a new heterophyid species, Heterophyes yacyretana n. sp., and resolve its life cycle experimentally. We found the prosobranch snail Aylacostoma chloroticum in Candelaria, Province of Misiones, Argentina (a sector of the High Parana River affected by the Yacyreta Dam), naturally infected with opisthorchioid cercariae. These cercariae lacked pigmented eyespots as well as body pigment and possessed 7 pairs of penetration glands arranged in 2 lateral bands, together with 18 pairs of flame cells and a V-shaped excretory vesicle. We exposed specimens of 21 fish species to emerging cercariae and obtained metacercariae from the muscles of the caudal peduncle of 3 species of siluriform fish, and adults from chicks infected with experimentally obtained metacercariae from the albino variety of the bronce corydoras, Corydoras aeneus. The new species differs from other species in the genus by the number of sclerites on the genital sac, the distribution of the vitelline follicles, and the combination of the size relationship of the suckers and the genital sac with respect to the posterior extent of intestinal ceca. Heterophyes yacyretana is the first species of the genus reported from the Americas.

Distribution of trematodes of the species Dicrocoelium dendriticum (Rudolphi, 1819) Looss, 1899 (Digenea: Dicrocoeliidae) parasitizing cattle (Bos taurus Linnaeus, 1758), sheep (Ovis aries Linnaeus, 1758) and goat (Capra aegagrus hircus Linnaeus, 1758) was studied in the Poltava and Kirovohrad regions of Ukraine. The recorded prevalence of infection is 26.9 % in cattle, 28.42 % in sheep and 24.5 % in goat. D. dendriticum is the only species of the genus Dicrocoelium which infects domestic animals in the central regions of Ukraine. The trematodes obtained from cattle are significantly different from those isolated from sheep and goat by length, width and area of body, and length of vitelline ducts.

Three digeneans belonging to the Opecoelidae are reported and described from triggerfishes (Tetraodontiformes: Balistidae) collected in the northern Red Sea off Egypt. Both Macvicaria longicirrata (Manter, 1963) Aken-Ova, Cribb & Bray, 2008 and Neopycnadena tendu (Bray & Justine, 2007) n. comb. were recovered from the intestine of the titan triggerfish, Balistoides viridescens (Bloch & Schneider)—each represents a new host record—and Gaevskajatrema balistes n. sp. was found parasitizing the lower intestine of the Picasso triggerfish, Rhinecanthus assasi (Forsskål). We continue to support synonymy of Gaevskajatrema ponticum (Koval, 1966) Machkevsky, 1990 with Gaevskajatrema perezi (Mathias, 1926) Gibson & Bray, 1982, not as a differentiated species. We adopt the restricted posterior extension of the ceca and vitellarium to the testicular zone, without extension of either into the post-testicular space, as diagnostic in distinguishing Gaevskajatrema. Gaevskajatrema balistes n. sp. differs from G. perezi based on its substantially smaller body size with fewer eggs, a longer cirrus-pouch reaching ovarian level and it parasitizes a distinct host group from a structurally and ecologically different ecosystem. Neopycnadena n. gen. is erected for Pseudopycnadena tendu Bray & Justine 2007 based on its possessing a large broadly oval cirrus-pouch with a massive field of prostatic cells occupying the entire volume of the cirrus-pouch, a wide, cup-shaped and thick-walled ejaculatory duct, distinct dorsal position of the excretory pore, the bifurcal dextral position of the genital pore, its report from a distinct host group and distant locality and its phylogenetic uniqueness compared with Pseudopycnadena fischthali Saad-Fares & Maillard 1986. Neopycnadena n. gen. is ecologically similar to opistholebetines in their life-cycles and morphology; however, phylogenetically separate from opistholebetines as well as from the Polypipapiliotrematinae Martin, Cutmore & Cribb in Martin, Sasal, Cutmore, Ward, Aeby & Cribb, 2018 and members of Clade [C] of Martin and colleagues, thus we conclude that Neopycnadena n. gen. is unique. Neopycnadeninae n. subfam. is proposed to accommodate Neopycnadena n. gen. We consider that the probable characterization of tetraodontiform specialist taxa (as indicated by the presence of a muscular post-oral ring) and the specificity of the Opistholebetinae Fukui, 1929 sensu stricto with a tetraodontiform host are no longer reliable characters differentiating Gaevskajatrema and Macvicaria Gibson & Bray, 1982. The nature of the post-oral structure is discussed and it is adopted to be a diagnostic feature at the generic level among taxa of the Opistholebetinae sensu latu. It is concluded that the expanded concept of the Opistholebetinae is more supported than the restricted one, Birendralebes Srivastava & Ghosh, 1972 remains incertae sedis within the Opecoelidae Ozaki, 1925 rather than in the Opistholebetinae, and we provide a generic key to the Opistholebetinae.

Museum specimens of a previously unknown species of the Anchitrematidae from a freshwater fish collected from the River Nile at Qena, Egypt were examined. This species is somewhat similar to species of Anchitrema, but was found to have a thick, continuous, shelf-like rim around the periphery of the ventral aspect of the distome, the lateral aspect of the forebody was composed of large internal patches of lightly vacuolated, somewhat glandular cells that formed pad-like structures (pelops-like structures), and it possessed a uterine seminal receptacle; characteristics that previously have not been found in any species in the family. Species currently assigned to Anchitrema or Mujibia (the only two genera in the family) are known only from reptiles and mammals and no species has previously been reported from a freshwater fish. We feel that these differences are sufficient enough to warrant the erection of Piscianchitrema n. gen. and amendation of the family. We support the synonymies of Anchitrema congolense with Anchitrema latum, and Anchitrema lucknowensis with Anchitrema indicum. The current status of species previously described in the family is discussed, and keys to the genera and species of Anchitrema are provided.

International audience; Three new monorchiid trematodes are reported from fishes of the families Nemipteridae and Pomacanthidae; two species are described from the southern Great Barrier Reef and the third from off Moorea, French Polynesia. Allobacciger polynesiensis sp. nov. is described from Centropyge flavissima (Cuvier), Allobacciger brevicirrus sp. nov. from Scolopsis bilineata (Bloch) and Scolopsis margaritifera (Cuvier), and Allobacciger annulatus sp. nov. from Centropyge tibicen (Cuvier), Centropyge vroliki (Bleeker) and Centropyge bicolor (Bloch). The three species most closely resemble the type-species, Allobacciger macrorchis Hafeezullah & Siddiqi, 1970, as well as Allobacciger centropygis Machida & Uchida, 2001, differing primarily in the morphology of the terminal genitalia and excretory vesicle. With the introduction of these new species, the most recent generic concept does not accurately reflect all species in the genus, and we provide a revised generic diagnosis to accommodate the new taxa. Complete ITS2 rDNA, partial 28S rDNA, partial 18S rDNA and partial cox1 mtDNA sequence data were generated for the three new species; all markers distinguish the three species reported here unambiguously. Phylogenetic analyses of the new sequence data show that the three new species of Allobacciger Hafeezullah & Siddiqi, 1970 form a well-supported clade.

Gaharitrema droneni n. gen., n. sp. (Digenea: Zoogonidae: Lepidophyllinae) is described from the intestine of the pudgy cuskeel, Spectrunculus grandis (Gunther, 1877) (Ophidiiformes: Ophidiidae), collected at 2,800 m depth from the northeastern Pacific Ocean off Oregon. The new genus is distinguished from BrachyenteronManter, 1934 and SteganodermaStafford, 1904, the 2 closest lepidophylline genera, and from 4 other zoogonid genera erected since 2007, the last major revision of the family, by a combination of diagnostic features including a pyriform or spindle-shaped body, smooth testes and ovary, narrow ceca that reach with the vitellarium into the hindbody, an unspecialized ventral sucker, non-filamented eggs, a claviform cirrus pouch, and an unpocketed ejaculatory duct and metraterm, and the new genus lacks circumoral spines. We present updated keys to the 3 subfamilies of the Zoogonidae Odhner, 1902, as well as to the genera of the Cephaloporinae Yamaguti, 1934 and the Lepidophyllinae Stossich, 1903. A listing of the parasites known from S. grandis also is presented. This study documents the third family of digeneans (Zoogonidae) known to parasitize S. grandis, and it is a new host record (i.e., the first zoogonid reported from this host species). We discuss the relatively impressive presence of the Zoogonidae and their hosts within the deep sea. Specifically, of the 35 genera we recognize within this digenean family, 14 (40%) have deep-sea representatives. At least 37 species within 27 genera and 19 families within 11 orders of deep-sea fish are known to harbor zoogonids. Furthermore, of the 37 known deep-sea fish species parasitized by zoogonids, only 5 (13.5%) harbor 2 or more zoogonid species; the remaining 32 (86.5%) harbor only 1 parasite species each, indicating strong host specificity. Finally, the dietary ecology of S. grandis is presented, allowing us to speculate that Gaharitrema droneni may be utilizing gastropods and polychaetes as well as S. grandis to complete its life cycle in the deep sea.

The objective of this study was to report helminth parasite species of Passer domesticus (Linnaeus, 1758) (sparrow) and to analyze infection rates in relation to total length, body mass and sexual gender of hosts. Each of the 100 sparrows caught in the urban area of Pelotas, Rio Grande do Sul, Brazil, was weighed, measured, submitted to euthanasia and necropsied for collection of helminths. The helminths and their respective prevalence were: Synhimantus ( Dispharynx ) nasuta (2%), Aproctella sp. (1%) (Nematoda), Prosthogonimus ovatus (8%), Eumegacetes sp. (2%), Tanaisia zarudnyi (4%) (Digenea), Choanotaenia passerina (26%) (Cestoda), and Mediorhynchus sp. (2%) (Acanthocephala). The prevalence and mean intensity of infection of the C. passerina between male and female hosts did not present significant differences, and there was no correlation between the abundance of parasite species, body mass and total length of the sparrows. The helminth fauna of P. domesticus has remained the same throughout the propagation of this bird for new geographical areas and ecosystems, with the exception of the nematode Aproctella sp., found for the first time parasitizing this host.

Adults of a species of Cryptocotyle were found infecting the intestine of the kelp gull, Larus dominicanus Lichtenstein, 1823, and metacercariae were found in the fins and muscle of the galaxiid fish, Galaxias platei Steindachner, 1898 (local name ‘‘puyen grande’’), in Nahuel Huapi National Park (Patagonia). Morphometrics and genetic markers of mitochondrial cytochrome oxidase (COI) and ribosomal internal transcribed spacer 1 (ITS1) confirmed that adults and metacercariae were conspecific and represent a new species, Cryptocotyle dominicana n. sp. The only congener known from South America (Cryptocotyle thapari McIntosh, 1953) matures in river otters (Lutra spp. and Pteronura spp.) in Brazil and Bolivia and differs from the new species in the arrangement of the testes, which are located in tandem in the species from otters. Adults of the new species resemble Cryptocotyle lingua (Creplin, 1825) Fischoeder, 1903 from marine environments of the Northern Hemisphere, both species being characterized by having a linguiform body, oblique testes, and vitelline follicles that extend posteriorly to the level of the ventral sucker. Considering the morphological findings that differentiate the new species from other Cryptocotyle, as well as the molecular analysis that shows significant differences from C. lingua, we conclude that these specimens represent a new species, the first of the genus Cryptocotyle to be described from birds in South America. Fil: Casalins, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Arbetman, Marina Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Viozzi, Gustavo Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Flores, Verónica Roxana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina

Biotic or abiotic factors responsible for temporal or spatial variation in metazoan parasite communities of the green jack Caranx caballus were studied over a nine-year period using samples collected at locations along the south-central Pacific coast of Mexico. A total of 708 fish were collected from six locations between December 2009 and October 2017. Thirty-two parasite species were identified: three Monogenea, nine Digenea, two Cestoda, five Nematoda, eight Copepoda, and three Isopoda. At the component community level, parasite species richness varied significantly from seven (Zihuatanejo 2016) to 18 (Acapulco Bay 2011). The component communities and infracommunities of C. caballus exhibited a similar pattern: low species numbers, low diversity, and dominance by a single species (mainly the monogenean Pseudomazocraes selene or the digenean Bucephalus varicus). Parasite community structure and species composition varied between locations and/or sampling years. The main factors responsible for t...

The California horn snail, Cerithideopsis californica, lives in estuarine habitats from California (USA) in North America to Piura (Peru) in South America. Throughout this range, the snail serves as first intermediate host for a diverse guild of digenean trematodes. These parasites are used in teaching laboratories, and have been subject to a large amount of taxonomic, biological, evolutionary, and ecological research. Despite the abundance of research on these trematodes, we lack a satisfactory guide to these parasites. This manuscript treats the 19 trematode species that we are currently able to distinguish morphologically. I provide taxonomic affinities, information on second intermediate host use, an identification key focused on cercaria traits, information and a key for regressed infections lacking cercariae, information on early infections, and species accounts. The species accounts present photographs, additional diagnostic information, taxonomic notes, information concerning cryptic species, and connections to relevant literature. The primary aim of this manuscript is to facilitate research on this trematode guild by serving as an identification tool, and by providing background information, including highlighting gaps in our knowledge.

The red octopus Octopus maya Voss et Solís-Ramírez, 1966 is an endemic species found exclusively off the coast of the Yucatán Peninsula, Mexico; its fishery is one of the most important along the Atlantic coast of Mexico and the Caribbean Sea. To date, the parasite fauna of Octopus spp. in southern Mexico remains unknown. In this study, we present the parasite fauna of O. maya from 8 localities along the Yucatán Peninsula. From August 2009 to June 2010, a total of 1202 specimens of O. maya were caught by artisanal fisheries and examined. Twenty parasite taxa were recorded from all octopus examined: 7 cestodes, 8 digeneans, 3 nematodes, 1 copepod and 1 coccidian. All taxa are new records for this host species, and the sampled locations represent new records of the geographic distribution of these parasite taxa. The gills and the intestine were the micro-habitats in which the highest number of taxa were found. More than half of the parasites (13 taxa) that we found infected O. maya via its feeding habits, although a high number of taxa (n = 9) colonized via active transmission. Cestoda and Digenea were the taxonomic groups with the highest number of taxa. Prochristianella sp. showed the highest prevalence and mean abundance values in the localities where it was present. This work represents the first study on the parasite fauna of any cephalopod species in Mexico.

The human liver fluke Opisthorchis viverrini (Platyhelminthes, Trematoda, Digenea) uses snails of the genus Bithynia as first intermediate host. Peculiarly among trematodes, the eggs of O. viverrini hatch within the digestive tract of its snail host. It remains uncertain whether hatching in this species is mediated through mechanical fracture of the eggshell or by digestion with specific digestive enzymes. This study aimed to characterize enzymes with specific inhibitors and factors involved in the hatching activity of O. viverrini eggs. For measuring egg hatching in vivo, 50 O. viverrini mature eggs were fed to individual Bithynia siamensis goniomphalos snails at various temperature conditions for 24 hr. Ex vivo, mature eggs were incubated with crude snail extract and commercial leucine aminopeptidase (LAP). Egg-hatching of O. viverrini was temperature dependent, with optimal hatching occurring at 24-28 C, with a peak of hatching of 93.54% in vivo and 30.55% ex vivo occurring at these temperatures. Ex vivo hatching rates increased to 45.87% under anaerobic conditions at 28 C. Some 22.70% and 16.21% of heat-killed eggs also hatched within the snail digestive tract and snail extract, respectively, indicating that host molecules are involved in the hatching response. Most eggs hatch in the anterior regions of the digestive tract. Hatching was completely inhibited in the presence of bestatin, an inhibitor of LAP, but not in the presence of phosphatase inhibitors. Bestatin inhibition of hatching was reversible. Finally, egg hatching could be induced by addition of a porcine LAP. The results indicate that this digenean utilizes both LAP of the snail host and movement of miracidia for hatching.

The effect of temperature on cercarial release has been well documented for several digenean species; however, there have been no prior studies assessing shedding of cercariae from snails infected with the azygiid, Proterometra macrostoma. Snails, Pleurocera semicarinata, were collected at the Lemon's Mill site on North Elkhorn Creek in Scott County, Kentucky during June and July 2016. Snails shedding cercariae (n = 453) were assigned to temperature treatments (10, 13, 15, 18, 20, 25, and 30°C) that were within the range of previously reported seasonal water temperatures at North Elkhorn Creek. Snails were acclimated to experimental temperatures for 3 d. Cercarial counts were then made at 0900 h daily over the next 7 d, and the average 7-d cercarial release was calculated for each snail. The minimum emergence threshold temperature for Pr. macrostoma cercarial release was determined to be approximately 13°C, whereas the minimum development threshold temperature was between 10 and 12°C. Notably, cercarial release increased with temperature up to 25°C, but declined at 30°C. Q10 values calculated from 10°C intervals were greatest at the lowest (13–23°C) temperature interval (Q10 = 16.1), and declined at the higher (15–25 and 20–30°C) intervals (Q10 = 4.3 and Q10 = 1.8, respectively). Snail survivorship within combined replicates ranged from 87.1 to 100% over the 10-d experiment, with the lowest survivorship observed at 30°C. These results are discussed with regard to climate change and global warming.

River cooters (Pseudemys concinna [Le Conte, 1830]) from the Pascagoula River (30°37′07.67″N; 88°36′44.53″W; Mississippi, U.S.A.) were infected by Spirorchis scripta Stunkard, 1923, and Spirorchis testiplexus n. sp. The new species resembles Spirorchis artericola (Ward, 1921) Stunkard, 1921, and Spirorchis innominatus Ward, 1921 (type species), by having a median esophageal diverticulum, ceca that extend slightly posterior to the genitalia, 10 testes, and a testicular column that extends anteriad to near the cecal bifurcation. Based on a comparative morphological study of existing type materials, vouchers, and published descriptions of similar congeners, S. testiplexus is unique by the combination of having a proportionally wider body, laterally directed cecal diverticula, deeply lobed testes, a testicular column that fills the intercecal space, and an external seminal vesicle that occupies the space between the posterior-most testis and the ovary and that passes dorsal or dorsolateral to the ovary. The large-subunit rDNA (28S) Bayesian inference phylogenetic analysis (including 16 turtle blood fluke species of 7 genera) showed a strongly supported monophyletic Spirorchis MacCallum, 1918, grouping sister to Spirhapalum siamensis Tkach, Snyder, and Vaughn, 2009.

A new species of Asymphylodora (Trematoda: Lissorchiidae) is described from the intestine of a bata (Labeo bata) collected from the Sharda Canal in Biswan (Sitapur), state of Uttar Pradesh, India. This is the fifth species of Asymphylodora named in India and the largest specimens reported from India (other than Asymphylodora indica, Asymphylodora kedarai, Asymphylodora ritai, and Asymphylodora punctatusi). It is also the second largest known in the genus next to Asymphylodora atherinopsidis. Members of the new species are similar to A. kedarai and A. punctatusi in that they possess the genital pore and cirrus on the right side of body rather than left as in the other species in world. In the new species the prepharynx is well developed, the esophagus is longer, the ceca extend posterior to the end of the testis, the size of testis is much larger, the vitellaria extend to near the anterior end of the ovary, there are both a spiny cirrus and a metraterm, and the body is longer than in both A. kedarai and A. punctatusi. Moreover, specimens of new species possess an ovary overlapping the anterodorsal margin of the testis rather than a pretesticular ovary as in A. punctatusi, and the sucker width ratio differs (1:0.90 in the newly described species versus 1:0.84 in A. punctatusi). The newly described species can be distinguished from A. kedarai by the presence of an undivided unipartite seminal vesicle and in relation to sucker width ratio (1:1.55 in A. kedarai). This is the first report of a species in the genus Asymphylodora from L. bata. Diagnosis for the genus is amended.