Parasitic Nematode Species Research Articles

Genetic dissection of Meloidogyne incognita resistance genes based on VIGS functional analysis in Cucumis metuliferus

The southern root-knot nematode, Meloidogyne incognita, is a highly serious plant parasitic nematode species that causes significant economic losses in various crops, including cucumber (Cucumis sativus L.). Currently, there are no commercial cultivars available with resistance to M. incognita in cucumber. However, the African horned melon (Cucumis metuliferus Naud.), a semi-wild relative of cucumber, has shown high resistance to M. incognita. In this study, we constructed an ultrahigh-density genetic linkage bin-map using low-coverage sequences from an F2 population generated through the cross between C. metuliferus inbred lines CM3 and CM27. Finally, we identified a QTL (quantitative trait locus, QTL3.1) with a LOD (logarithm of the odds) score of 3.84, explaining 8.4% of the resistance variation. Subsequently, by combining the results of qPCR (quantitative PCR) and VIGS (virus-induced gene silencing), we identified two genes, EVM0025394 and EVM0006042, that are potentially involved in the resistance to M. incognita in CM3. The identification of QTLs and candidate genes in this study serve as a basis for further functional analysis and lay the groundwork for harnessing this resistance trait.

Thermosensory behaviors of the free-living life stages of Strongyloides species support parasitism in tropical environments.

Soil-transmitted parasitic nematodes infect over 1 billion people worldwide and are a common source of neglected disease. Strongyloides stercoralis is a potentially fatal skin-penetrating human parasite that is endemic to tropical and subtropical regions around the world. The complex life cycle of Strongyloides species is unique among human-parasitic nematodes in that it includes a single free-living generation featuring soil-dwelling, bacterivorous adults whose progeny all develop into infective larvae. The sensory behaviors that enable free-living Strongyloides adults to navigate and survive soil environments are unknown. S. stercoralis infective larvae display parasite-specific sensory-driven behaviors, including robust attraction to mammalian body heat. In contrast, the free-living model nematode Caenorhabditis elegans displays thermosensory behaviors that guide adult worms to stay within a physiologically permissive range of environmental temperatures. Do S. stercoralis and C. elegans free-living adults, which experience similar environmental stressors, display common thermal preferences? Here, we characterize the thermosensory behaviors of the free-living adults of S. stercoralis as well as those of the closely related rat parasite, Strongyloides ratti. We find that Strongyloides free-living adults are exclusively attracted to near-tropical temperatures, despite their inability to infect mammalian hosts. We further show that lifespan is shorter at higher temperatures for free-living Strongyloides adults, similar to the effect of temperature on C. elegans lifespan. However, we also find that the reproductive potential of the free-living life stage is enhanced at warmer temperatures, particularly for S. stercoralis. Together, our results reveal a novel role for thermotaxis to maximize the infectious capacity of obligate parasites and provide insight into the biological adaptations that may contribute to their endemicity in tropical climates.

Further description of the poorly known zooparasitic nematode Abbreviata baltazardi Chabaud, 1953 (Spirurida: Physalopteridae).

Abbreviata baltazardi Chabaud, 1953 (Nematoda: Physalopteridae) is a hitherto poorly known parasitic nematode species reported from Phrynocephalus helioscopus Pallas (Squamata: Agamidae) in Iran. The current knowledge on the morphology of A. baltazardi is still very limited. In the present study, the detailed morphology of A. baltazardi was studied using light microscopy and, for the first time, scanning electron microscopy, based on newly collected specimens from the yarkand toad-headed agama P. axillaris Blanford Pallas (Squamata: Agamidae) in China. Some erroneous or previously unreported morphological features of A. baltazardi were observed using SEM, which include the presence of one large semicircular protrusion and 20-30 denticles on each pseudolabium, the absence of precloacal medioventral papilla in some individuals and the presence of 4-5 postcloacal medioventral papillae in males. SEM observations also clearly showed the detailed morphology of deirids, cloacal ornamentation, caudal papillae, vulva and egg. Abbreviata baltazardi represents the first species of Abbreviata Travassos, 1920 reported in China.

Parasitic Nematodes of Sugarcane: A Major Productivity Impediment and Grand Challenges in Management.

Sugarcane is an important cash crop grown in 137 countries, accounting for 80% of global sugar production. It supports the livelihood of more than 100 million people and up to 25% of the rural population in some countries. Plant-parasitic nematodes are one significant constraint in sugarcane production and can lead to a loss of up to 30% in productivity. More than 300 species of parasitic nematodes have been discovered in sugarcane soil. Owing to limited data, the potential damage to sugarcane crops caused by parasitic nematodes is often underestimated. The main nematodes present in sugarcane fields are root-lesion (Pratylenchus spp.), spiral (Helicotylenchus spp.), root-knot (Meloidogyne spp.), dagger (Xiphinema spp.), stunt (Tylenchorhynchus spp.), ring (Criconemella spp.), and stubby (Paratrichodorus spp.). Among these, Meloidogyne javanica and Pratylenchus zeae are the most damaging nematode species. Management of nematodes is a challenging task as there are no clear symptoms of their presence, and they often come in multiple species with varying levels of pathogenicity. Moreover, the management options available are not always effective. Integrated nematode management is a sustainable strategy for controlling nematode infestations. It involves using all possible methods to suppress the parasitic nematode population in a compatible manner and reduce it below economic threshold levels. This article focuses on the challenges of managing nematodes in sugarcane and highlights the opportunity for implementing a sustainable nematode management strategy.

Intestinal cell diversity and treatment responses in a parasitic nematode at single cell resolution

BackgroundParasitic nematodes, significant pathogens for humans, animals, and plants, depend on diverse organ systems for intra-host survival. Understanding the cellular diversity and molecular variations underlying these functions holds promise for developing novel therapeutics, with specific emphasis on the neuromuscular system’s functional diversity. The nematode intestine, crucial for anthelmintic therapies, exhibits diverse cellular phenotypes, and unraveling this diversity at the single-cell level is essential for advancing knowledge in anthelmintic research across various organ systems.ResultsHere, using novel single-cell transcriptomics datasets, we delineate cellular diversity within the intestine of adult female Ascaris suum, a parasitic nematode species that infects animals and people. Gene transcripts expressed in individual nuclei of untreated intestinal cells resolved three phenotypic clusters, while lower stringency resolved additional subclusters and more potential diversity. Clusters 1 and 3 phenotypes displayed variable congruence with scRNA phenotypes of C. elegans intestinal cells, whereas the A. suum cluster 2 phenotype was markedly unique. Distinct functional pathway enrichment characterized each A. suum intestinal cell cluster. Cluster 2 was distinctly enriched for Clade III-associated genes, suggesting it evolved within clade III nematodes. Clusters also demonstrated differential transcriptional responsiveness to nematode intestinal toxic treatments, with Cluster 2 displaying the least responses to short-term intra-pseudocoelomic nematode intestinal toxin treatments.ConclusionsThis investigation presents advances in knowledge related to biological differences among major cell populations of adult A. suum intestinal cells. For the first time, diverse nematode intestinal cell populations were characterized, and associated biological markers of these cells were identified to support tracking of constituent cells under experimental conditions. These advances will promote better understanding of this and other parasitic nematodes of global importance, and will help to guide future anthelmintic treatments.

Field testing of recombinant subunit vaccines against Teladorsagia circumcincta in lambing ewes demonstrates a lack of efficacy in the face of a multi-species parasite challenge

IntroductionWe previously demonstrated efficacy of an 8-antigen recombinant subunit vaccine against a single species homologous Teladorsagia circumcincta challenge in lambs and in lambing ewes in pen trials. We subsequently demonstrated efficacy of a simplified, 2-antigen, version of this vaccine in lambs in pen trials. Here, we test both vaccines in lambing ewes in a field setting.MethodsIn the work presented here, 12 adjacent plots were seeded with a mixed infection of several common species of parasitic nematodes of sheep in temperate regions, including T. circumcincta. Ewes (n = 144), in groups of 12, grazed for 2 years on these plots and, in the first year, six of these groups of ewes were vaccinated with a 2-antigen prototype vaccine against T. circumcincta prior to mating and then again prior to lambing. In the following year these ewes were immunised again, this time with the 8-antigen prototype vaccine against T. circumcincta prior to mating and then prior to lambing. Throughout both seasons antigen-specific serum antibody levels in ewes and faecal worm egg counts (FEC) in ewes and their lambs were monitored, along with nematode species diversity at lambing.ResultsImmunised ewes produced elevated serum antibody levels to each of the vaccine antigens following immunisation but their FEC levels were not statistically significantly impacted by vaccination with either vaccine. FEC levels were also not impacted in lambs co-grazing the pastures with these immunised ewes. Nematode species diversity was not significantly impacted by vaccination in either year.DiscussionThe immunosuppressive effects of co-infecting gastrointestinal nematodes, the absence of vaccine cross-protection against co-infecting species and the influence of the periparturient relaxation in immunity probably all contributed to the inability of either vaccine to protect against T. circumcincta infection in field trials in the work presented here.

Comparative structure activity and target exploration of 1,2-diphenylethynes in Haemonchus contortus and Caenorhabditis elegans

Infections and diseases caused by parasitic nematodes have a major adverse impact on the health and productivity of animals and humans worldwide. The control of these parasites often relies heavily on the treatment with commercially available chemical compounds (anthelmintics). However, the excessive or uncontrolled use of these compounds in livestock animals has led to major challenges linked to drug resistance in nematodes. Therefore, there is a need to develop new anthelmintics with novel mechanism(s) of action. Recently, we identified a small molecule, designated UMW-9729, with nematocidal activity against the free-living model organism Caenorhabditis elegans. Here, we evaluated UMW-9729's potential as an anthelmintic in a structure-activity relationship (SAR) study in C. elegans and the highly pathogenic, blood-feeding Haemonchus contortus (barber's pole worm), and explored the compound-target relationship using thermal proteome profiling (TPP). First, we synthesised and tested 25 analogues of UMW-9729 for their nematocidal activity in both H. contortus (larvae and adults) and C. elegans (young adults), establishing a preliminary nematocidal pharmacophore for both species. We identified several compounds with marked activity against either H. contortus or C. elegans which had greater efficacy than UMW-9729, and found a significant divergence in compound bioactivity between these two nematode species. We also identified a UMW-9729 analogue, designated 25, that moderately inhibited the motility of adult female H. contortus in vitro. Subsequently, we inferred three H. contortus proteins (HCON_00134350, HCON_00021470 and HCON_00099760) and five C. elegans proteins (F30A10.9, F15B9.8, B0361.6, DNC-4 and UNC-11) that interacted directly with UMW-9729; however, no conserved protein target was shared between the two nematode species. Future work aims to extend the SAR investigation in these and other parasitic nematode species, and validate individual proteins identified here as possible targets of UMW-9729. Overall, the present study evaluates this anthelmintic candidate and highlights some challenges associated with early anthelmintic investigation.

Influence of insectocompost obtained by cultivation of the during beetle <i>Ulomoides dermestoides</i> on the ecological-trophic composition and development of soil and phytoparasitic nematodes

The purpose of the research is to study the effect of insect compost obtained as a result of the vital activity of insects of the Coleoptera order Ulomoides dermestoides on the quantitative and qualitative composition of soil nematodes of various ecological and trophic groups, as well as on the morphological and physiological state of plants and infection of tomato plants with root-knot nematodes.Materials and methods. Under laboratory conditions, soil containing a diverse fauna of nematodes was treated with 1% dry and 0.5; 0.75 and 1% aqueous solutions of biocompost. Insect compost was obtained by keeping the U. dermestoides on a dry nutrient mixture. Then a mixture of lawn grasses was sown in the ground. After 30 days, the composition of nematodes was analyzed. The ability of insect compost to suppress parasitic nematode species was studied using the tomato-knot nematode model system. Tomatoes were infected with Meloidogyne incognita at a rate of 500 larvae (J2) per plant and simultaneously treated with a 0.5% aqueous biocompost solution.Results and discussion. The insect compost U. dermestoides has an effect on quantitative and qualitative indicators in the community of soil nematodes, increasing the number of predatory and saprobiotic nematodes and displacing parasitic ones. And due to the content of various biologically active compounds, it affects the development of rootknot nematodes in tomato roots. When tomatoes are treated with an aqueous solution of insect compost, the infection score and the number of nematodes that penetrate the roots are reduced. The introduction of compost when growing a mixture of lawn grasses and tomatoes can improve the condition of the plants.

New species of Delicata (Molineidae: Anoplostrongylinae) parasite of Cabassous tatouay (Desmarest, 1804) from the Atlantic Forest, Rio de Janeiro, Brazil.

A new species of nematode parasite of the genus Delicata (Molineidae: Anoplostrongylinae) is described from the small intestine of a road-killed Greater Naked-tailed Armadillo Cabassous tatouay (Cingulata: Chlamyphoridae) on the BR-040 highway in Rio de Janeiro state, Brazil. The genus Delicata includes 13 species of parasitizing armadillos and anteaters distributed in Brazil, Argentina, and Trinidad and Tobago. The present species is distinguished from almost all species of Delicata by the longest length of the body, except for D. khalili and D. appendiculata. However, these can be distinguished from each other by the length of the spicules. The species that closely resembles, Delicata tatouay n. sp. is D. speciosa, but it can be distinguished by a robust branch from rays 2 and 3, rays 4 larger, and rays 8 longer compared to those of the new species. The new species is the only one with a tail, characterized by a terminal spine with rattlesnake tail-like transversal striations.

Expanding automated gene summaries for Caenorhabditis and parasitic nematode species in WormBase.

WormBase and the Alliance of Genome Resources provide several types of gene data including annotations to ontology terms and controlled vocabularies. These are used to automatically generate text summaries to give users a cogent view of gene function. However, automated summaries are not available for genes that lack curated annotations. To increase the genome coverage of the summaries in WormBase, we developed a new software module that generates additional gene summaries for C. elegans and new gene summaries for nine other nematode species: four Caenorhabditis species ( C. brenneri, C. briggsae, C. japonica, C. remanei ), P. pacificus , and four parasitic species ( B. malayi, O. volvulus, S. ratti and T. muris ).

Semperula wallacei (Mollusca, Veronicellidae) um hospedeiro natural recém-descoberto de Angiostrongylus cantonensis (Nematoda, Angiostrongylidae) na Bacia do Pacífico.

Semperula wallacei (Issel, 1874) is a species of terrestrial slug that occurs in southeast China and the Pacific Basin and is the only species of its genus that occurs beyond the Oriental region and to the east of Wallace's line in the Australian region, where it has probably been introduced. In this study, we report for the first time S. wallacei as an intermediate host for Angiostrongylus cantonensis (Chen, 1935) based on histological and molecular analyses of slugs from Tuamasaga, Samoa, deposited at the Medical Malacological Collection (Fiocruz-CMM). DNA was obtained from the deparafinized tissues scraped from specimen slides. Polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) targeted to the internal transcribed spacer 2 (ITS2) region were carried out using the restriction enzyme Cla I. The RFLP profile observed for our larval specimen of S. wallacei was identical to the profile previously established for A. cantonensis, demonstrating that S. wallacei can be naturally infected with A. cantonensis and is likely to be an intermediate host for this parasitic nematode species in the field. The potential for geographical range expansion of S. wallacei in the Pacific Basin, its small size, and the general role of veronicellids as crop pests and hosts of nematodes, indicate the significance of S. wallacei as an invasive species in the Pacific Basin. Our work also highlights the importance of biological collections for investigating the environmental impact of invasive species on agriculture, public health, and biodiversity conservation.

Evaluation of botanicals for the management of Meloidogyne incognita infecting carrot and volatile nematicidal metabolite profiling

Plant-parasitic nematodes infect and cause substantial yield losses in numerous crops. Growing concern over chemical nematicides has attracted attention to safe alternatives. Meloidogyne incognita is one of the plant parasitic nematode species in the tropics and subtropics, which have a drastic economic effect on crops. This nematode is polyphagous, attacking both monocotyledons and dicotyledons crops. This study aimed to investigate the management of M. incognita using six botanical viz., Commelina benghalensis, Evolvulus nummularius, Gomphrena celosioides, Lindenbergia indica, Scoparia dulcis, and Vernonia cinerea under the pots condition. It was found that the pots treated with the amendment of fresh leaves (60 g) of selected botanicals with dried powder 10 g of L. indica efficiently reduced the infestation caused by M. incognita on carrots along with significantly increased growth and biochemical attributes. Out of the six botanicals, GC–MS analysis was performed with the two most effective plants, namely, L. indica and S. dulcis. Results from GC–MS analysis showed various volatile compounds in leaves extract of both plants, out of which phytol was a major compound. Our study concluded that various compounds, along with phytol shown by GC–MS analysis, suppress the infestation of M. incognita and increase the yield of carrots.

Identification of broadly-conserved parasitic nematode proteins that activate immunity

IntroductionSoil transmitted nematodes are impediments to human health and agricultural production. Poor anthelmintic efficiencies, the emergence of resistant strains, and the persistence of infective stages highlight the need for more effective control strategies. Parasitic nematodes elicit a Th2-type immune response that most often is not protective. Vaccination has thus far been unsuccessful due to unrealized antigenic characters and unknown mechanisms that nematodes use to circumvent host immunity.MethodsHere, we used a genomics/proteomics approach (including immunoblot experiments from pigs infected with T. suis) to prioritize putative immunogenic excretory/secretory (E/S) proteins conserved across and specific to several gastrointestinal (GI) parasitic nematode species. A cocktail of five recombinant proteins optimized for conserved GI nematode targets was used immunize pigs and test for active antibody responses in both the serum and intestinal ileal fluid of immunized pigs. An antibody-protein array of putative immunogenic proteins was developed from a combined bioinformatic, experimental, and literature-based prioritization of homologous parasite proteins.ResultsScreening the array with sera and ileal fluid samples from immunized pigs suggested cross-reactivity among homologous proteins and a general activation of immunity. PCA clustering showed that the overall immune responses were altered by immunization, but no substantial changes were observed following direct worm challenge with either Ascaris suum or Trichuris suis.DiscussionProteins that activated immunity are potential antigens for immunization and the multi-omics phylum-spanning prioritization database that was created is a valuable resource for identifying target proteins in a wide array of different parasitic nematodes. This research strongly supports future studies using a computational, comparative genomics/proteomics approach to produce an effective parasite vaccine.

Türkiye’de Isparta ili yağ gülü yetiştirilen bazı alanlarında bitki paraziti nematodların belirlenmesi

The study was carried out to investigate plant parasitic nematodes in oil rose growing areas in Isparta province in July-August 2022. Soil samples were collected from 4 districts and the study was carried out with 65 samples. Plant parasitic nematodes were extracted by the modified Baermenn funnel technique. A total of 12 genera of plant parasitic nematodes were determined in the study. These are Tylenchus spp., Aphelenchus spp., Pratylenchus spp., Ditylenchus spp., Dorylaimus spp., Paratylenchus spp., Longidorus spp., Xiphinema spp., Meloidogyne spp., Helicotylenchus spp., Tylenchorhynchus spp., and Merlinius spp. The Pratylenchus (52.3%), Paratylenchus (38.5%), and Helicotylenchus (41.5%) seemed to be the most prevailing genera. The least common genus is Meloidogyne (7.6%). Meloidogyne species were identified molecularly by using species-specific primers from second-stage juveniles. The 5 samples taken from cultivated oil rose fields were infected and detected with Meloidogyne hapla Chitwood, 1949. Densities of M. hapla varied between 60-480/100 g soil. This is the first report of M. hapla on oil rose (Rosa damascena Mill.) in Türkiye.

Prevalence of Gastrointestinal Parasites in Slum Children of Dhaka City: Comparison of Two Coprological Methods

The present study aimed to measure the prevalence of intestinal parasites among children with gastrointestinal tract infections from different slum areas of Dhaka. Furthermore, a comparison was made of the accuracy of direct smear (DS) and formol-ether concentration (FEC) techniques in the detection of infection. The overall prevalence of parasitic infection was 72.46% with a combined method. By direct smear, 2 species of protozoa (11.59%), 2 species of cestode (5.07%) and 4 species of nematode (18.12%) parasites were detected whereas by formol – ether concentration method, 5 species of protozoa (28.26%), 1 species of Trematode (1.44%), 2 species of cestode (17.39%) and 5 species of nematode (79.71%) parasites were detected. By direct smear (DS) and formol-ether concentration (FEC) the prevalence of intestinal parasites was 42% and 58% respectively. Ascaris lumbricoides was the most common parasite detected by both formol-ether concentration (37.68%) and direct smear method (7.97%). A statistically significant association (P < 0.001) was found between the test methods, age groups and months with parasitic infection. Direct smear showed less sensitivity than formol-ether concentration technique (100%). The diagnostic performance of formol-ether technique for the diagnosis of intestinal parasites in slum children was remarkably higher as related to direct smear in the present study. Therefore, the DS and FEC combined techniques should be used as routine investigative techniques for the identification of intestinal parasites. Henceforth, it is advantageous to use the formol-ether method to complement the direct smear method. Bangladesh J. Zool. 50(3): 353-361, 2022

Resolving the origins of secretory products and anthelmintic responses in a human parasitic nematode at single-cell resolution.

Nematode excretory-secretory (ES) products are essential for the establishment and maintenance of infections in mammals and are valued as therapeutic and diagnostic targets. While parasite effector proteins contribute to host immune evasion and anthelmintics have been shown to modulate secretory behaviors, little is known about the cellular origins of ES products or the tissue distributions of drug targets. We leveraged single-cell approaches in the human parasite Brugia malayi to generate an annotated cell expression atlas of microfilariae. We show that prominent antigens are transcriptionally derived from both secretory and non-secretory cell and tissue types, and anthelmintic targets display distinct expression patterns across neuronal, muscular, and other cell types. While the major classes of anthelmintics do not affect the viability of isolated cells at pharmacological concentrations, we observe cell-specific transcriptional shifts in response to ivermectin. Finally, we introduce a microfilariae cell culture model to enable future functional studies of parasitic nematode cells. We expect these methods to be readily adaptable to other parasitic nematode species and stages.

Microsatellite profiling of hosts from parasite-extracted DNA illustrated with raccoons (Procyon lotor) and their Baylisascaris procyonis roundworms

BackgroundImportant information on movement pathways and introduction routes of invasive parasites can be obtained by comparing the genetic makeup of an invader with its spatial genetic structure in other distribution areas. Sometimes, the population genetic structure of the host might be more informative than that of the parasite itself, and it is important to collect tissue samples of both host and parasite. However, host tissue samples are frequently not available for analysis. We aimed to test whether it is possible to generate reliable microsatellite profiles of host individuals by amplifying DNA extracted from a nematode parasite, using the raccoon (Procyon lotor) and the raccoon roundworm (Baylisascaris procyonis) as a test case.MethodsBetween 2020 and 2021, we collected tissue as well as a single roundworm each from 12 raccoons from central Germany. Both the raccoon and the roundworm DNA extracts were genotyped using 17 raccoon-specific microsatellite loci. For each roundworm DNA extract, we performed at least eight amplification reactions per microsatellite locus.ResultsWe extracted amplifiable raccoon DNA from all 12 roundworms. We obtained at least two amplification products for 186 of the 204 possible genotypes. Altogether 1077 of the 1106 genotypes (97.4%) matched the host-DNA derived reference genotypes and thus did not contain genotyping errors. Nine of the 12 roundworm-derived genetic profiles matched the reference profiles from the raccoon hosts, with one additional genetic profile containing genotyping errors at a single locus. The remaining two genetic profiles were deemed unsuitable for downstream analysis because of genotyping errors and/or a high proportion of missing data.ConclusionsWe showed that reliable microsatellite-based genetic profiles of host individuals can be obtained by amplifying DNA extracted from a parasitic nematode. Specifically, the approach can be applied to reconstruct invasion pathways of roundworms when samples of the raccoon hosts are lacking. Further research should assess whether this method can be replicated in smaller species of parasitic nematodes and other phyla of parasites more generally.Graphical

Ferron L. Andersen (1931-2022).

Nematodes of the family Molineidae are the most frequent helminths reported infecting the digestive tract of South American amphibians. The molineid genus Kentropyxia Baker, 1982 includes only 2 nominal species of parasitic nematodes: Kentropyxia sauria Baker, 1982 and Kentropyxia hylae Feitosa et al., 2015 both from the eastern Amazon. We describe a new nematode species of Kentropyxia parasitizing Boana boans, Boana geographica, and Boana wavrini from 2 different locations in the eastern Amazon. Kentropyxia bakeri n. sp. has corona radiata composed of unequal lappets, a smooth cephalic vesicle, a claviform esophagus, and well-developed cuticular longitudinal ridges composing the synlophe. Females have a well-developed ovojector, with amphidelphic uteri, and a simple tail. Males have a type I copulatory bursa and complex robust spicules divided into an outer process and fan-like branches (1 dorsolateral and 1 ventrolateral) divided into numerous projections. We observed intraspecific variation among specimens from different hosts, which can be related to factors regarding the hosts, the parasite, their location, and/or their ecology. The new species differs from its congeners by the presence of cervical alae composed of a series of modified oblique ridges which are absent in K. sauria but are composed of single expanded cuticle projections in K. hylae. This species is the third described for the genus and the second reported for a hylid host in the Neotropics.

Molecular characterisation and histopathological study of Eustrongylides excisus nematode in the northern pike (Esox lucius)

Eustrongylides excisus is a parasitic nematode species whose life cycle requires two intermediate hosts, an aquatic oligochaete and a benthophagous fish. In the present study, 100 specimens of Esox lucius Linnaeus weighing 550-800 g were collected from Freidoonkenar, south of the Caspian Sea (Mazandaran province, Iran) and were examined for the presence of Eustrongylides. The bright red nematode larvae were found in the testes and encapsulated in the body musculature of 90% of E. lucius fish. The larvae were diagnosed as Eustrongylides excisus. Tissue samples were collected from the muscles and testes for histopathological examination of the lesions caused by the parasitic larvae. For molecular analysis, the nematode larvae genomic DNA was extracted and molecular characterisation of Eustrongylides and comparison with the corresponding sequences available in the GenBank was done. The histopathological damages caused by parasites in the muscle included external nodules, inflammation, necrosis, and granulomas. Granulomas containing multi-nucleated giant cells, epithelioid cells, lymphoid cells, macrophages and necrotic debris were observed. Microscopic examination of the testes revealed mild vacuolar degeneration in some Sertoli cells. Molecular analysis confirmed obtained larvae as E. excisus. Comparison of DNA sequences showed that isolated nematodes were very similar to those obtained from freshwater fish in China. The present study reported Eustrongylides nematodes in Esox lucius, and inflammatory lesions caused by E. excisus larvae in the muscle and testis of this species of fish for the first time. In addition, molecular characterization and phylogenic analysis of recovered larvae showed presence of microvarients.

New Annotated Records of Helminth Parasites, Mostly from North America, with Light Microscopy. I. Trematoda (Digenea), Cestoda, Nematoda

We give an account of 13 species of trematode, cestode, and nematode parasites collected from various hosts in different geographical locations mostly in North America. Each species account is annotated and morphologically presented using light microscopy showing characteristic diagnostic features. None of these accounts has been previously published. All geographical records and many host associations are new. This treatment includes the digeneans Brachylaima fuscatum (Rudolphi, 1819), and Echinostomum coalitum Barker and Beaver 1915, the cestodes Anonchotaenia quiscali Rausch & Morgan, 1947), Choanotaenia musculosa (Fuhrmann, 1896), Isoglaridacris calentinei Mackiewicz, 1974, Isoglaridacris chetekensis Williams, 1977, Isoglaridacris folius Fredrickson and Ulmer, 1965, Isoglaridacris longus, Fredrickson and Ulmer, 1965, Nybelinia Poche, 1926, and the nematodes Anisakis simplex (Rudolphi, 1809) Dujardin, 1845 type I, Camallanus ancylodirus Ward and Magath, 1916, Rhabdochona cascadilla Wigdor, 1918, and Subulura Molin, 1860.