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An inventory of parasites infecting the jaguar (Panthera onca) across its distribution range is relevant for the conservation of this threatened big cat. In this study, we report the occurrence of helminths in a jaguar from Mexico using morphological techniques (cleared and stained mounts and scanning electron microscopy) and partial sequences of the 28S ribosomal RNA (28S rRNA) gene and the cytochrome c oxidase 1 mitochondrial (COI) gene. We also provide an updated list of helminth species reported in jaguars in the Americas. Three helminth taxa are identified in the jaguar examined from Mexico: Toxocara cati, Physaloptera sp., and Taenia sp. The new 28S rRNA sequences of To. cati, Physaloptera sp., and Taenia sp. and the COI sequence of Taenia sp. corroborate the identity of the helminths isolated from this host. One hundred and twenty-nine records of helminths parasitizing jaguars from 49 studies up to May 2023 were identified in the Americas. In most of these studies (73.6%), helminths were identified using coproparasitological techniques. Sixteen helminths (7 nematodes, 5 cestodes, 3 acanthocephalans, and 1 trematode) were identified at the species level in free-ranging and captive jaguars. The study demonstrates the value of an integrative taxonomy approach to increase the accuracy of parasite identification in wildlife, especially when helminth specimens are scarce or poorly fixed.

Assuntos

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Triatoma dimidiata is a species complex, and its members are responsible for the transmission of Trypanosoma cruzi, the causative agent of Chagas disease. We present the assembly and annotation of the mitogenome of the Triatoma dimidiata (Latreille, 1811) and Triatoma huehuetenanguensis Lima-Cordón & Justi, 2019. The mitochondrial genomes were successfully sequenced using the Illumina Nextseq 500 platform, 2×75 cycles, and 5 million reads per sample. Contigs were assembled and annotated using the reference genomes of T. dimidiata and T. huehuetenanguensis available in Genbank (NC_002609 and NC_050325.1, respectively). The mitogenomes of T. dimidiata have lengths of 17,008 bp, while those of T. huehuetenanguensis are 15,910 bp and 15,909 bp. The genome comprises 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a control region. The mitogenomes will be valuable to scholars and students focused on integrative taxonomy, phylogeography, and evolutionary studies of the Triatoma dimidiata complex and the transmission of Chagas diseases.

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Trematodes of the family Allocreadiidae are primarily found in the intestines of freshwater fishes around the world. The family includes 15 genera and c. 130 species. The last 2 decades have witnessed an increase in the genetic library of its species. Molecular data have been crucial for species delimitation and species description within Allocreadiidae and for understanding their evolutionary and biogeographical history and classification. Here, the mitogenomes of 3 species of allocreadiids were obtained using high throughput sequencing methods. Mitogenomes were compared with other members of the order Plagiorchiida to determine their molecular composition, gene rearrangement and phylogenetic interrelationships. The complete circular mitogenomes of Allocreadium lobatum, Creptotrematina aguirrepequenoi and Wallinia mexicana were 14 424, 13 769 and 13 924 bp long respectively, comprising 12 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and 2 non-coding regions. Gene arrangements were identical to other Xiphidiatan trematodes. Phylogenetic analyses using the mitogenomes revealed Allocreadiidae as a monophyletic group closely related to other members of the suborder Xiphidiata; A. lobatum was yielded as the sister taxon of C. aguirrepequenoi + W. mexicana. Our study increases the complete mitochondrial genome library of trematodes and strengthens our understanding of the phylogenetic relationships and classification of this parasite group.

Assuntos

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To date, 23 species of trematodes have been reported in bats from Mexico. However, in some regions of Mexico, such as the Yucatan Peninsula, many species of bats do not have helminthological records. Here, we sampled bats in four localities in Southeastern Mexico from April 2017 to February 2022. Parasites were collected from the intestine of four species of bats: Pteronotus fulvus, Eumops nanus, Noctilio leporinus and Nyctinomops laticaudatus. Conventional morphological techniques and molecular tools with the 28S ribosomal gene were used to describe the helminths. We discovered that our parasites represent three new species and a new combination of trematodes. We found that the new species have morphological differences with their congeneric species, and we complement this information whit molecular data. Furthermore, we found morphological and molecular evidence that places Dicrocoelium rileyi within the genus Brachylecithum. This study points out the importance of comparing morphological and phylogenetic information.

Assuntos

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Astyanax mexicanus has repeatedly colonized cave environments, displaying evolutionary parallelisms in many troglobitic traits. Despite being a model system for the study of adaptation to life in perpetual darkness, the parasites that infect cavefish are practically unknown. In this study, we investigated the macroparasite communities in 18 cavefish populations from independent lineages and compared them with the parasite diversity found in their sister surface fish populations, with the aim of better understanding the role that parasites play in the colonization of new environments. Within the cavefish populations, we identified 13 parasite taxa, including a subset of 10 of the 27 parasite taxa known for the surface populations. Parasites infecting the cavefish belong to five taxonomic groups, including trematodes, monogeneans, nematodes, copepods, and acari. Monogeneans are the most dominant group, found in 14 caves. The macroparasites include species with direct life cycles and trophic transmission, including invasive species. Surprisingly, paired comparisons indicate higher parasite richness in the cavefish than in the surface fish. Spatial variation in parasite composition across the caves suggests historical and geographical contingencies in the host-parasite colonization process and potential evolution of local adaptations. This base-line data on parasite diversity in cavefish populations of A. mexicanus provides a foundation to explore the role of divergent parasite infections under contrasting ecological pressures (cave vs. surface environments) in the evolution of cave adaptive traits.

Assuntos

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This study describes a new species belonging to the genus Cathetocephalus from the spinner shark Carcharhinus brevipinna off the coast of Yucatan, Mexico. Cathetocephalus badilloi n. sp. has a soft scolex transversely positioned to the long axis of the strobila. The scolex is composed of an apical pad, papillate band and rugose base. The papillate band has two papillary segments; the upper segment has numerous papillae, positioned one next to the other in an irregular and heterogeneous way with a spongy texture that remains along the band. The lower papillary segment has numerous papillae positioned one next to the other, without space between them. This papillary band presents flattened rectangular papillae with a division located at the top of each the papilla, giving it the appearance of a molar tooth. Using the 28S rDNA gene and the method of Maximum Likelihood (ML) for phylogenetic analysis, we identified the present material as a new species. We did not collect specimens with mature or gravid proglottids, but since the specific identification of the members of this genus is based on the characteristics of the scolex, our proposal of the new species is determined by the morphology of this organ as well as the molecular results obtained.

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The phylogenetic relationships within Neodermata were examined based on putative orthologous groups of proteins (OGPs) from 11 species of Monogenea, Trematoda, and Cestoda. The dataset included OGPs from BUSCO and OMA. Additionally, peptidases were identified and evaluated as phylogenetic markers. Phylogenies were inferred using the maximum likelihood method. A network analysis and a hierarchical grouping analysis of the principal components (HCPC) of orthologous groups of peptidases were performed. The phylogenetic analyses showed the monopisthocotylean monogeneans as the sister-group of cestodes, and the polyopisthocotylean monogeneans as the sister-group of trematodes. However, the sister-group relationship between Monopisthocotylea and Cestoda was not statistically well supported. The network analysis and HCPC also showed a cluster formed by polyopisthocotyleans and trematodes. The present study supports the non-monophyly of Monogenea. An analysis of mutation rates indicated that secreted peptidases and inhibitors, and those with multiple copies, are under positive selection pressure, which could explain the expansion of some families such as C01, C19, I02, and S01. Whilst not definitive, our study presents another point of view in the discussion of the evolution of Neodermata, and we hope that our data drive further discussion and debate on this intriguing topic.

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Helminth species of Neotropical bats are poorly known. In Mexico, few studies have been conducted on helminths of bats, especially in regions such as the Yucatan Peninsula where Chiroptera is the mammalian order with the greatest number of species. In this study, we characterized morphologically and molecularly the helminth species of bats and explored their infection levels and parasite­host interactions in the Yucatan Peninsula, Mexico. One hundred and sixty-three bats (representing 21 species) were captured between 2017 and 2022 in 15 sites throughout the Yucatan Peninsula. Conventional morphological techniques and molecular tools were used with the 28S gene to identify the collected helminths. Host­parasite network analyses were carried out to explore interactions by focusing on the level of host species. Helminths were found in 44 (26.9%) bats of 12 species. Twenty helminth taxa were recorded (7 trematodes, 3 cestodes and 10 nematodes), including 4 new host records for the Americas. Prevalence and mean intensity of infection values ranged from 7.1 to 100% and from 1 to 56, respectively. Molecular analyses confirmed the identity of some helminths at species and genus levels; however, some sequences did not correspond to any of the species available on GenBank. The parasite­host network suggests that most of the helminths recorded in bats were host-specific. The highest helminth richness was found in insectivorous bats. This study increases our knowledge of helminths parasitizing Neotropical bats, adding new records and nucleotide sequences.

Assuntos

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Octopus maya is an endemic species of the Yucatan Peninsula. This species sustains the octopus' fishery in the region and is the only cephalopod cultured in Mexico. It is known that O. maya harbor a large richness and abundance of metacestodes that have been tentatively identified by light microscopy alone. Since the larval stages of some orders of marine cestodes lack the taxonomic characteristics shown by the adult stages and on which cestode taxonomy is based, identification down to the species level is often unattainable. Hence, the goal of this study was to characterize the parasites, for the first time, at morphological and molecular levels. A total of 60 octopuses were collected from September to December 2017 from four fishery landing ports in Yucatán: Sisal, Progreso, Dzilam de Bravo, and Rio Lagartos (15 hosts per locality). Morphology of metacestodes was characterized by light and Scanning Electron Microscopy (SEM), while the genes 18S and 28S rDNA were sequenced for molecular characterization. Based on phenotypic characters and molecular data, seven taxa of metacestodes were identified, four of them belonging of order Trypanorhyncha: Eutetrarhynchus sp., Kotorella pronosoma, Nybelinia sp., Prochristianella sp. 1; and the three remaining taxa belonging to the order Onchoproteocephalidea: Acanthobothrium sp., Phoreiobothrium sp., and Prosobothrium sp. This work provides, for the first time, molecular support to the morphological characterization of metacestodes recorded in Octopus maya.

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Human population is exposed to numerous parasitic ichthyozoonoses. Although Tamaulipas state (northeastern Mexico) is well known for its fishing and aquaculture industry, there are few reports of this type of zoonosis. Therefore, it is imperative to investigate whether the parasites that affect these fish may represent a zoonotic risk for the inhabitants of the area. The objective of this study was to identify molecular and/or morphologically muscle parasites of fish from coastal locations in Tamaulipas, Mexico, and assess the risk of infection for humans. Between 2017 and 2018, 764 individual fish belonging to 28 species were examined for parasites. Collected worms were processed for their identification using morphological characteristics. In addition, partial sequences of the large subunit (28S) ribosomal RNA gene were obtained from some species to corroborate their identity. Prevalence and mean intensity of all registered infections were calculated. A total of seven species of parasites were found: cestodes (Poecilancistrium caryophyllum), trematodes (Clinostomum tataxumui, Clinostomum cichlidorum), nematodes (Eustrongylides sp., Contracaecum sp.) and pentastomids (Sebekia purdieae, Sebekia sp.). Parasites infected 10 species belonging to different fish families (Ariidae, Centrarchidae, Centropomidae, Cichlidae, Eleotridae, Ictaluridae, Mugilidae and Sciaenidae). Congeneric species of parasites or related to those registered in this study have been identified as zoonotic agents in other regions of the world. Despite the low levels of infection (2.6-16.6% prevalence and 1-5.5 parasites per infected host), there is a latent risk of transmission to humans, so it is recommended to avoid eating raw or undercooked fish meat.

Assuntos