Checklist of the monogenea (Platyhelminthes) parasitic in mexican aquatic vertebrates

Parasite infestation in red hybrid Tilapia across Sarawak: Morphological, DNA barcoding and water quality assessment under different culture systems

Red Hybrid Tilapia (RHT) is a vital species in aquaculture but remains highly vulnerable to parasitic infestations, which can compromise productivity and overall fish health. This study assessed the prevalence, intensity, and species identification of ecto- and endoparasites in RHT across different aquaculture systems in Sarawak from May to December 2022. A total of 120 RHT samples were analyzed using both morphological and molecular approaches. Results indicated a high prevalence of ectoparasites in ST1, ST2, and ST3 (100 %) compared to ST4 (96.67 %). Trichodina spp. was the most common ectoparasite (70.83 %), while molecular analysis identified Cichlidogyrus thurstonae. Endoparasites were detected only in ST1, with greater occurrence in the intestine (53 %) than in the stomach (40 %). Despite being morphologically identified as a Digenean Trematode, BLAST and phylogenetic analysis failed to provide a definitive match, suggesting a potentially novel species. Interestingly, water quality parameters did not vary significantly across sites, implying that parasite prevalence is more influenced by aquaculture system design, stocking density, and management practices rather than environmental factors alone. Poor biosecurity, high fish densities, and insufficient parasite control measures may contribute to high infestation rates. This study highlights the need for enhanced biosecurity protocols, regular parasite monitoring, and improved management strategies to mitigate parasitic infections. The findings provide valuable baseline data for sustainable RHT farming, emphasizing the importance of proactive health management to ensure long-term productivity and food security.

A Closer Look at the Choricotyle chrysophryi-like (Polyopisthocotyla: Diclidophoridae) Species Complex: Description of a New Choricotyle from the Gills of Pagellus acarne (Teleostei: Sparidae) and Revision of Choricotyle spp. from Sparids

PURPOSE

The genus Choricotyle, the largest in the diclidophoridean family, includes C. chrysophryi, whose taxonomic status remains ambiguous. This study aims to resolve this ambiguity by describing a new Choricotyle species, C. justinemusei n. sp. previously identified as C. cf. chrysophryi, and clarifying the taxonomic status of related congeneric species, particularly those reported from sparids in Mediterranean and Atlantic waters.

METHODS

Choricotyle justinemusei n. sp. was described based on Mediterranean specimens from the gills of Pagellus acarne, found in the Muséum National d'Histoire Naturelle, Paris. The species was differentiated from its congeners through morphological and anatomical features, including the presence or absence of a terminal lappet, and of ring organ, number of atrial hooks and of testes. Molecular analysis using cox1 sequences was also conducted to aid in species identification.

RESULTS

Choricotyle justinemusei n. sp. was described and distinguished from other Choricotyle species by several key morphological traits and molecular sequences. The record of C. chrysophryi from Pagellus bogaraveo in Atlantic waters was reassigned to C. chrysophryi sensu Llewellyn (1941). Furthermore, C. pagelli from P. bogaraveo was found to be distinct from C. chrysophryi sensu Llewellyn (1941), confirming the validity of both C. pagelli and C. chrysophryi as separate species, and the former was reinstated as a valid species. A differential diagnosis was also provided for C. marionis, reinstating it based on its original type-host, Spicara maena.

CONCLUSION

This study clarifies the taxonomic status of C. chrysophryi and related species, describing C. justinemusei n. sp. and reinstating C. pagelli and C. marionis as valid species. These findings contribute to a more accurate understanding of Choricotyle species and their host specificity.

Comprehensive annotated checklist of monogenean diversity and distribution in Algerian marine fish

A comprehensive checklist of monogenean parasites from marine fish in Algeria was compiled by reviewing the entire available literature, resulting in a detailed parasite-host and host-parasite list. This checklist includes 156 species across 71 genera and 23 families of monogeneans, with 136 species identified to the species level, while the remaining 20 species are identified only to the genus (19 species) or subfamily level (1 species). These parasites have been reported from 82 marine fish hosts, spanning 34 families: 15 species of Elasmobranchii, 1 of Holocephali, and 66 of Teleostei. The highest number of monogenean species was found on Teleostei (128), followed by Elasmobranchii (26), and Holocephali (2). The family Diplectanidae Monticelli, 1903 is the most prevalent, encompassing 43 species, followed by Microcotylidae Taschenberg, 1879 with 27 species. Among the most diverse genera are Lamellodiscus Johnston & Tiegs, 1922 and Microcotyle Van Beneden & Hesse, 1863, with the latter's species, Microcotyle erythrini, Van Beneden & Hesse, 1863 being the most encountered species. The class Teleostei has been the most extensively studied, with the Sparidae Rafinesque, 1818 family receiving the most attention, particularly Boops boops (Linnaeus) as the most cited fish species. Notably, Diplodus vulgaris (Geoffroy Saint-Hilaire) and Diplodus sargus (Linnaeus) exhibit high species richness. The checklist also identified seven Monogenea species, including Atriaster maillardi López-Román & De Armas Hernández, 1989, newly recorded in the Mediterranean. This checklist provides an up-to-date summary of Monogenea diversity in Algerian marine fish, reflecting nearly three decades of detailed taxonomic research. It highlights the current understanding of these parasites and underscores the need for continued research to fully explore the diversity of monogenean parasites in Algerian fish fauna.

Low similarity between parasite communities of ten sympatric carangid species

Host phylogeny and ecological convergence are two factors thought to influence the structure of parasite communities. The aims of this study were to determine the diversity of metazoan parasites of 10 sympatric fish species of the family Carangidae from the southeastern Gulf of California, and to analyze their similarity at infracommunity and component community levels, in order to determine if the host species, particularly those congeneric with similar ecological characteristics, exhibit similar assemblages of parasites. In total, 874 fish specimens were examined and 40 parasite species were identified. The component community was composed by 21 parasite species in Caranx caninus, 20 in C. caballus, 11 in C. vinctus, five in Chloroscombrus orqueta, four in Carangoides otrynter, seven in Hemicaranx leucurus, eight in Selene brevoortii, 14 in S. peruviana, and 11 in Trachinotus rhodopus. The metazoan parasite communities of C. vinctus, Ch. orqueta, H. leucurus, and S. brevoortii are reported here for the first time. The parasite communities of the remaining six carangid species have been reported from regions other than the Gulf of California. All fish species differed significantly regarding the diversity of their parasite infracommunities. This possibly is due to different patterns of habitat use among fish species, and because of the differential host specificity among parasite taxa. Nonetheless, when the analysis was restricted to common parasite species, some fish showed similar parasite infracommunities, particularly congeners of the genus Selene as well as C. caballus and C. vinctus. The component communities of species of Selene were highly similar (>65%), but the three species of Caranx were not. This result supports the hypothesis that congeneric fish species with similar ecological filters harbor similar parasite communities. However, the difference observed between C. caninus and C. caballus suggests that these species, despite being evolutionary and ecologically related, have different physiological or immunological characteristics (compatibility filters) that may result in different parasite communities.

An Annotated Checklist of Monogeneans (Platyhelminthes, Monogenea) from Aquatic Vertebrates in Peru: A Review of Diversity, Hosts and Geographical Distribution

Monogeneans are flatworm parasites that infest fish gills primarily but can also infect various other vertebrates, including amphibians, aquatic reptiles, mammals like hippos, and occasionally invertebrates like copepods, isopods, and cephalopods. Despite their remarkable diversity, our knowledge of monogenean parasites in Peru remains significantly limited, resulting in substantial gaps in our comprehension of their taxonomic identities, host associations, and geographic distribution. To address these knowledge deficits, we present an extensively curated checklist of monogeneans associated with aquatic vertebrates in Peru. This comprehensive compilation is derived from meticulous literature surveys, the examination of specimens deposited in both international and national collections, and the inclusion of additional freshly collected specimens. The checklist offers a thorough repository of data encompassing the diversity, host associations, and geographical distribution of these parasites. Taxonomic discrepancies are addressed through a critical review of the existing literature, supplemented by the direct examination of specimens, including type or voucher specimens, deposited within scientific collections. Additionally, we provide data on the DNA sequences of individual taxa. The compiled list comprises records of 358 monogenean species, including 270 valid species and 88 taxa identified at the family or generic level, all reported across 145 host species in Peru. Predominantly, these parasitic species exhibit associations within fish, with 335 infecting teleosts and 20 affecting chondrichthyans. Three monogenean species have been documented as infecting amphibians, namely Mesopolystoma samiriensis, Polistoma sp. and Wetapolystoma almae. Among the monogeneans reported, 141 were found in marine environments and 214 in freshwater environments. The most diverse families were Dactylogyridae and Diplectanidae, comprising 217 and 24 species, respectively. The hosts that harbored the highest number of monogeneans were Pygocentrus nattereri (with 23 species), followed by Stellifer minor (13 spp.) and Triportheus angulatus (11 spp.). We detected many species that do not have any material deposited in a scientific collection due to the loss or deactivation of the collection. These findings represent only a fraction of the potential diversity, considering the wide variety of aquatic vertebrate hosts inhabiting the tropical and subtropical regions of Peru.

Checklist of monogeneans from Egyptian marine fishes, including some newly collected species

A checklist of 113 monogenean species parasitizing marine fishes (60 species) from different localities in Egypt is provided. The list is supplemented by eight newly collected monogenean species from Red Sea fishes, off Safaga and El-Quseir. Five of these species are new Egyptian records: Calydiscoides euzeti Justine, 2007, Calydiscoides rohdei Oliver, 1984, Lethrinitrema austrosinense (Li & Chen, 2005) Sun, Li & Yang, 2014, Pseudohaliotrema sphincteroporus Yamaguti, 1953, and Pentatres sphyraenae Euzet & Razarihelisoa, 1959. Furthermore, Lutjanus ehrenbergii (Peters), Lethrinus nebulosus (Forsskål), Lethrinus mahsena (Forsskål), Siganus stellatus (Forsskål), and Sphyraena flavicauda Rüppell represent new host records. The current study also lists nine monogenean species from the Gulf of Aqaba for which the coordinates of the sampling localities were not clearly defined, but which could also belong to the Egyptian fauna as the gulf is part of the Red Sea basin. Dactylogyrus aegyptiacus Ramadan, 1983 is transferred to Ecnomotrema Kritsky, 2023 as E. aegyptiacum (Ramadan, 1983) n. comb. Entobdella aegyptiacus Amer, 1990, Polylabroides aegyptiacus Mahmoud & Shaheed 1998, Gotocotyla sigani Abdel Aal, Ghattas & Badawy, 2001, Neohexostoma epinepheli Abdel Aal, Ghattas & Badawy, 2001, Neothoracocotyle commersoni Abdel Aal, Ghattas & Badawy, 2001, Acleotrema maculatum Morsy, El Fayoumi & Fahmy, 2014, Diplectanum harid Morsy, El Fayoumi, Al Shahawy & Fahmy, 2014, and Pseudorhabdosynochus chlorostigma Morsy, El Fayoumi, Al Shahawy & Fahmy, 2014, are considered species inquirendae. Paranaella diplodae Bayoumy, Abd El-Hady & Hassanain, 2007 is considered incertae sedis. Allencotyla lutini El-Dien, 1995 and Lamellodiscus diplodicus Bayoumy, 2003 are regarded as nomina nuda.

Microcotylidae (Monogena) parasites of snappers (Perciformes: Lutjanidae) collected from the northeast coast of Brazil

Monogeneans are a diverse group of flatworms, being ectoparasites of marine and freshwater fish, with great morphological and ecological variety. Analyzes of monogenetics in fish with great habitat diversity such as snappers are scarce in the literature, which already emphasizes the need for an update in this regard. The presente study found, morphologically characterized and mapped the geographic distribution and in known hosts the species Microcotyloides incisa and Microcotyloides impudicus, describing the first occurrence of these monogeneans for South America and in new hosts. The survey of hosts in the literature shows that M. incisa seems to have a greater Affinity with congener species of Lutjanidae and fish from other families, which may indicate a preference or specificity for fish of this family because they are congeners of their host type. The introduction of these parasites into South American waters may have occurred due to the migratory behavior of snappers, which are well distributed along the Mexican coast, where the parasites are usually reported. Here, we also bring the first occurrence of M. incisa for Lutjanus analis and Lutjanus jocu and M. impudicus for Ocyurus chrysurus and Lutjanus synagris, helping in the mapping and distribution of these monogenetic species in the Americas.

New and previously known ectoparasitic monogenoids (Platyhelminthes) on native and non-native fishes from tributaries of the Usumacinta River basin (southern Mexico), a Neotropical transition zone

During a research on morphological diversity of gill ectoparasites on native and non-native fishes from tributaries (Palizada, El Recreo and Lacantún rivers) of the Usumacinta River Basin in the states of Campeche, Tabasco, and Chiapas (southern Mexico), the following monogenoids were found: Icelanonchohaptor tropicalis n. sp. on Usumacinta buffalo Ictiobus meridionalis (Günther, 1868) (Catostomidae); Heteropriapulus simplexiodes n. sp. and Heteropriapulus heterotylioides n. sp. on catfishes Pterygoplichthys pardalis (Castelnau, 1855) (Loricariidae) (type host) and Pterygoplichthys disyunctivus (Weber, 1991); Ligictaluridus mirabilis (Mueller 1937; Klassen and Beverley-Burton1985 from the southern blue catfish Ictalurus meridionalis (Günther, 1864) (Ictaluridae); Aristocleidus mexicanus Mendoza-Franco and Vidal-Martínez, 2001 on Eugerres mexicanus (Steindachner, 1863) (Gerreidae) (all monogenoidean species in the Dactylogyridae); and Diplectanocotyla megalopis Rakotofiringa and Oliver1987 (Diplectanidae) on tarpon Megalops atlanticus Valenciennes, 1847 (Megalopidae). The new species of Icelanonchohaptor and Heteropriapulus are herein described for the first time from a native catostomid and non-native Pterygoplichthys spp., respectively. While I. tropicalis n. sp. and L. mirabilis are morphologically comparable with their congeners from the Nearctic (i.e., United States and Canada), all other monogenoids exhibited Neotropical affinities. Present study shown that the gill monogenoids on native and non-native fishes in the Neotropical Mexican transition zone of the Usumacinta River basin are equally represented by species with Nearctic and Neotropical affinities including those adapted to freshwater environment in this area from marine ancestry.

New species of Protomicrocotyle (Monogenea: Protomicrocotylidae), and new information on P. mirabilis, parasites of Caranx spp. from Veracruz, México

During a study of the helminth parasites of carangid fish of the Gulf of Mexico, Protomicrocotyle mirabilis and a new member of that genus were found. The aim of the present study is to provide new morphological and sequences of 28s rDNA and CO1 mtDNA for P. mirabilis and describe the new species. Between 2005-2022, 73 specimens of Caranx spp. were purchased from local fishermen of the littoral waters of the Gulf of Mexico. Protomicrocotyle veracruzensis sp. nov. is most similar to P. mirabilis than to P. ivoriensis, the only members of the genus known from the Greater Atlantic Ocean Basin. Protomicrocotyle veracruzensis sp. nov. can be distinguished from those two species by the arrangement and number of testes. Measurement data on the haptoral armature for the new species is provided and the potential value and need for comparative data from these structures of other members of the genus is discussed. The results of the molecular analysis and the morphometric analysis of 91 characters confirmed that this new species belongs to Protomicrocotyle.

Morphological and molecular characterization of three new species of Gyrodactylus (Monogenea: Gyrodactylidae) infecting Sicydium salvini (Teleostei: Gobiidae) in Mexican rivers draining into the Pacific Ocean

The genus Gyrodactylus von Nordmann, 1832 is one of the most diverse within the class Monogenea; it contains mainly parasites of freshwater and marine teleost fishes. Around 40 species of Gyrodactylus have been described from gobiid fishes; mainly in Europe, as only two species are known from the Americas. In this study, we describe three new gyrodactylids from the body surface and fins of the goby Sicydium salvini (Gobiidae, Sycydiinae), which has a wide distribution on the Pacific coast, from Mexico to Panama. We describe Gyrodactylus oaxacae n. sp., G. atoyacensis n. sp. and G. salvini n. sp. collected from rivers draining to the eastern Pacific in the state of Oaxaca, Mexico. Morphologically, G. atoyacensis n. sp. and G. salvini n. sp. are very similar, and both are easily differentiated from G. oaxacae n. sp. Phylogenetic hypotheses based on sequences of the Internal Transcribed Spacers (ITS1-5.8S-ITS2 rDNA) and the D2 + D3 domains of the large ribosomal subunit (28S rDNA) support the erection of the three new taxa; and suggest that G. atoyacensis n. sp. and G. salvini n. sp. are sister species. These gyrodactylids are the first monogeneans described from gobies of the genus Sicydium in Mexico.

Neotropical sisterhood: new species of Gyrodactylus von Nordmann, 1832 (Platyhelminthes: Monogenea) infecting Rhamdia guatemalensis and Rhamdia laticauda (Siluriformes: Heptapteridae) in Mexico

We describe two new species of monogenean parasites of the genus Gyrodactylus von Nordmann, 1832 infecting Neotropical catfishes (Siluriformes) in southern Mexico: Gyrodactylus chulini n. sp. from 'chulín', Rhamdia laticauda collected in Oaxaca; and Gyrodactylus juili n. sp. from 'juil', Rhamdia guatemalensis from Veracruz. Morphologically, both new taxa are similar to Gyrodactylus spp. infecting catfishes (Siluriformes) in South America. Sequences of the internal transcribed spacers (ITS1-5.8S-ITS2 rDNA), the D2+D3 domains of the large ribosomal subunit (28S rDNA) and the cytochrome oxidase II (COII) gene were obtained from multiple parasite specimens and analysed using Bayesian inference. Phylogenetic hypotheses using ITS rDNA and COII genes, recovered two new Gyrodactylus species from Rhamdia spp.: G. chulini n. sp.; and Gyrodactylus juili n. sp., which are sister species to Gyrodactylus lilianae, a parasite of Rhamdia quelen in Brazil, and show strong affinity to other gyrodactytlids infecting Neotropical catfishes. This suggests that these new taxa, the first gyrodactylids described from Rhamdia spp. in Mexico, co-migrated to Tropical Middle America with their Neotropical catfish hosts, after the emergence of the Isthmus of Panama.

Rediscovering Monogenoids (Platyhelminthes) Parasitizing Pomacentrid and Chaetodontid Fishes from Cayo Arcas Reef, Gulf of Mexico

During a research of gill ectoparasites on damselfishes (Pomacentridae) and butterflyfishes (Chaetodontidae) from the Cayo Arcas reef in the Campeche Bank (Gulf of Mexico), the following monogenoids (Platyhelminthes) were found: Paraeuryhaliotrema pomacentris n. gen., n. sp. (Dactylogyridae) on beaugregory Stegastes xanthurus (Poey, 1860) (Pomacentridae) that is characterized, in part, by possessing a haptor armed with a dorsal, ventral anchor-bar complexes, seven pairs of similar hooks; two pairs of eyespots; overlapping gonads; a copulatory complex composed of a male copulatory organ (MCO) and an accessory piece; MCO tubular with a bulbous base from which arises a coiled shaft in the clockwise direction; and a dextral vaginal pore; Neohaliotrema variabilis n. sp. on bicolor damselfish Stegastes partitus (Poey, 1868) (type host), beaugregory Stegastes xanthurus (Poey, 1860) and beaugregory Stegastes leucostictus (Müller & Troschel, 1848); Neohaliotrema manubrium n. sp., Neohaliotrema aliamanubrium n. sp. and Neohaliotrema bifidum n. sp., Neohaliotrema bychowskii Zhukov, 1976 and Neohaliotrema macracanthum Zhukov, 1976 on Sergeant-major Abudefduf saxatilis (Linnaeus, 1758) (Pomacentridae); Neohaliotrema similium n. sp. on S. xanthurus; Haliotrema brevicirrus Zhukov 1976 on spotfin butterflyfish Chaetodon ocellatus Bloch 1787 (Chaetodontidae); Microcotyle multilineatus n. sp. (Microcotylidae) on brown chromis Chromis multilineata (Guichenot 1853) (Pomacentridae). The new species are described and illustrated; new illustrations and measurements of the haptoral structures, and new redescription and illustrations are provided for N. bychowskii, N. macracanthum and H. brevicirrus, respectively. The present study represents the first knowledge about ectoparasitic monogenoids of fishes in the Cayo Arcas reef from the Gulf of Mexico.

Checklist of The Monogenea (Platyhelminthes) Parasitic in Tunisian Aquatic Vertebrates

153 species of monogeneans have been recorded in Tunisian aquatic vertebrates (89 hosts). A list of these species with hosts is presented. A comparison of the Monogenea diversity off the coast of Tunisia with other regions of the Mediterranean Sea and the world is provided. The number of parasites depends on the number of hosts examined and their diversity in the region. This list shows that Monopisthocotylea is the richest group. In addition, new records have been reported during a survey of the diversity of monogeneans fish in the southern coast of Tunisia (Gulf of Gabes) including: Benedenia monticellii (Parona and Perugia, 1895) Johnston, 1929, Lamellodiscus bidensEuzet, 1984, Lamellodiscus confusus Amine, Euzet & Kechemir-Issad, 2007, Lamellodiscus ergensi Euzet & Oliver, 1966, Lamellodiscus hiliiEuzet, 1984, Lamellodiscus imperviusEuzet, 1984, Lamellodiscus knoepffleri Oliver, 1969, Lamellodiscus theroni Amine, Euzet & Kechemir-Issad, 2007, Ligophorus acuminatus Euzet & Suriano, 1977, Ligophorus angustus Euzet & Suriano, 1977, Ligophorus heteronchus Euzet & Suriano, 1977, Ligophorus macrocolpos Euzet & Suriano, 1977, Ligophorus minimus Euzet & Suriano, 1977, Capsala maccallumi Price, 1939 and Pseudanthocotyloides heterocotyle (Van Beneden, 1871) Euzet & Prost, 1969.

PERUANOCOTYLE PELAGICA N. SP. (MONOGENEA: MONOCOTYLIDAE), PARASITE OF THE PACIFIC COWNOSE RAY RHINOPTERA STEINDACHNERI EVERMANN AND JENKINS, 1891 (BATOIDEA: RHINOPTERIDAE) FROM THE SOUTHERN MEXICAN PACIFIC OCEAN

Peruanocotyle pelagica n. sp. is described based on specimens collected from the wall of the pharyngeal cavity of the Pacific cownose ray Rhinoptera steindachneri offshore Oaxaca and Guerrero, Mexico. The new species is distinguished from Peruanocotyle chisholmae by its anchors, which include a slender guard that curves towards the tip of the blade and which lack an accessory piece, morphological differences of the seminal vesicle, the lack of a male copulatory organ accessory piece and a greater number of spines, and an unsclerotized vagina. Molecular data of Peruanocotyle pelagica were generated to place the phylogenetic position of the genus within Monocotylidae.

Dactylogyridae 2022: a meta-analysis of phylogenetic studies and generic diagnoses of parasitic flatworms using published genetic and morphological data

Dactylogyridae is one of the most studied families of parasitic flatworms with more than 1000 species and 166 genera described to date including ecto- and endoparasites. Dactylogyrid monogeneans were suggested as model organisms for host-parasite macroevolutionary and biogeographical studies due to the scientific and economic importance of some of their host lineages. Consequently, an array of phylogenetic research into different dactylogyrid lineages has been produced over the past years but the last family-wide study was published 16 years ago. Here, we provide a meta-analysis of the phylogenetic relationships of Dactylogyridae including representatives of all genera with available molecular data (n=67). First, we investigate the systematic informativeness of morphological characters widely used to diagnose dactylogyrid genera through a parsimony analysis of the characters, character mapping, and phylogenetic comparative methods. Second, we provide an overview of the current state of the systematics of the family and its subfamilies, and summarise potentially poly- and paraphyletic genera. Third, we elaborate on the implications of taxonomic, citation, and confirmation bias in past studies. Fourth, we discuss host range, biogeographical, and freshwater-marine patterns. We found two well-supported macroclades which we assigned to the subfamilies Dactylogyrinae and Ancyrocephalinae. These subfamilies further include 16 well-supported clades with only a few synapomorphies that could be deduced from generic diagnoses in the literature. Furthermore, few morphological characters considered systematically informative at the genus level display a strong phylogenetic signal. However, the parsimony analysis suggests that these characters provide little information on the relationships between genera. We conclude that a strong taxonomic bias and low coverage of DNA sequences and regions limit knowledge on morphological and biogeographical evolutionary patterns that can be inferred from these results. We propose addressing potential citation and confirmation biases through a 'level playing field' multiple sequence alignment as provided by this study.

Helminth fauna of Scomberomorus sierra (Actinopterygii: Scombridae) in southeastern Gulf of California, Mexico

From January to May 2015, a sample of 50 individuals of the Pacific sierra Scomberomorus sierra Jordan and Starks, 1895 captured off Mazatlán (southeastern Gulf of California, Mexico) were reviewed for helminths. A total of 6, 255 parasitic worms belonging to 11 species (9 in adult stage and 2 larvae) were obtained. Trematoda was the best represented group with 6 species of Didymozoidae Monticelli, 1888 and 1 of Bucephalidae Poche, 1907. In addition, 2 monogenean species and 2 of Nematoda were collected. In this study, the first molecular sequences for didymozoid species in Mexico were generated, and for Glomeritrema sp. at worldwide level. The most prevalent species were Didymocylindrus sp. (92 %) and Didymocystis scomberomori (MacCallum & MacCallum, 1916) (88 %), whereas the monogenean Thoracocotyle crocea MacCallum, 1913 reached the highest value of mean intensity (75.2). The coincidence between the helminthological composition established in our study and that reported for the same scombrid in 4 localities from the Mexican South Pacific (sharing 10 species) suggests that this group of species persistently parasitize S. sierra throughout its distribution along the Mexican Pacific coast; furthermore, due to the richness of didymozoids and the affinity of Thoracocotylidae species for S. sierra, both groups can be considered typical parasites of this fi sh.

Characithecium spp. (Monogenea: Dactylogyridae) from Astyanax bimaculatus (Characiformes: Characidae) in Northeast Brazil, with Description of a New Species

PURPOSE

To date, seven species of Characithecium Mendonza-Franco, Reina and Torchin, 2009 (Monogenea, Dactylogyridae) are valid, parasitizing mainly fishes of the family Characidae (Characiformes) in the Neotropical region. During a parasitological study of fishes in the Batateiras River and Carás stream, Ceará state, Brazil, two species of Characithecium were collected from the gills of Astyanax bimaculatus Linnaeus, 1758 (Characidae). The purpose of the present study is to describe a new species of monogenean of the genus Characithecium and report Characithecium costaricensis Mendoza-Franco, Reina and Torchin, 2009 in A. bimaculatus, in Brazil.

METHODS

Monogeneans were isolated from the gills and stored in 70% ethanol, mounted in Gray and Wess' medium or and in a mixture of glycerin ammonium picrate (GAP) to study sclerotized structures. Morphological analyses were performed with a computerized image analysis system with differential interference contrast (DIC). The drawings were obtained with the aid of a camera lucida mounted on a Leica DMLS microscope.

RESULTS

Characithecium bifurcuprolatum n. sp. differs from its congenerics by the morphology of the accessory piece having a ventral unit articulated to cirrus base, a non-articulated dorsal and mid-ventral, and a sclerotized vaginal vestibule. Characithecium costaricensis was described from Astyanax aeneus (Günther, 1860) (Characidae) in Central America, and the present finding represents a new geographical and host records in Brazil. Furthermore, we observed the presence of a membrane at the base of the cirrus not mentioned in the original description.

CONCLUSION

Our findings increase to eight the number of known species of the genus Characithecium parasitizing characids in neotropics. We verified some additional characteristics present in the two species studied, such as the presence of a membrane at the base of the cirrus, an accessory piece with two subunits (an articulated ventral and a dorsal non-articulated) and the presence of sclerotized vaginal vestibule.

First Data on the Parasites of the Pacific Kingcroaker Menticirrhus elongatus (Perciformes: Sciaenidae): Description of a New Species of Rhamnocercoides (Dactylogyridea: Diplectanidae)

INTRODUCTION

A new monogenean, Rhamnocercoides lambayequensis n. sp. (Dactylogyridea: Diplectanidae), is described based on the specimens collected from the gills of the Pacific kingcroaker Menticirrhus elongatus (Günther 1864) (Perciformes: Sciaenidae), a demersal fish endemic to Eastern Pacific, captured off the South American Pacific coast, Lambayeque Region, Peru.

MATERIALS AND METHODS

Monogeneans were fixed in hot 4% formalin. Some monogeneans were transferred directly onto a slide in a drop of glycerin-ammonium picrate mixture (GAP). Others were mounted stained with Gomori's trichrome in Canada balsam. Drawings were made using of a drawing tube.

RESULTS

The new species is mainly characterized by its MCO, which is tubular and straight, with external (distally expanded and bifurcated) and internal tubes (distally uncovered by external tube). Rhamnocercoides lambayequensis n. sp. is also characterized by having the following features: a weakly sclerotized almost pyriform vagina; haptoral acicular spines with expanded distal portion and by having a small group of haptoral accessory spines associated with haptoral lobes arranged as spikes.

CONCLUSIONS

This is the first data on the parasites of M. elongatus, a little known, but popular fish in local markets. The present finding brings to two, the number of known species of Rhamnocercoides Luque and Iannacone 1991, and represents the sixth described marine diplectanid species infecting sciaenid fishes from Peru.

Emendation of the genus Neoheterobothrium and a proposal of a new genus Paraheterobothrium (Monogenea: Diclidophoridae) for five species of diclidophorids from Pleuronectiform fishes

Neoheterobothrium chilense González, Oliva & Acuña, 2002 is redescribed based on newly collected specimens from the type host, Hippoglossina macrops and type locality (Coquimbo, Northern Chile). Type specimens of Neoheterobothrium hippoglossini Piasecki, Wierzbicka & Kempter, 2000 and Choricotyle exilis Crane, 1972 are also redescribed. These three diclidophorid monogeneans infecting pleuronectiform flatfishes have pre-ovarian seminal receptacle, ootype inside the semicircle of ovary and elongated pharynx, differentiated from the most similar Orbocotyle Euzet & Suriano, 1975 in that members of the latter genus possess post-ovarian seminal receptacle, post-ovarian ootype and cylindrical or pyriform pharynx. Paraheterobothrium n. g. is proposed for P. chilense n. comb. (type), P. hippoglossini n. comb., P. exilis n. comb., P. papillosum n. comb. and P. syacii n. comb. A redescription of Neoheterobothrium affine (Linton, 1898), the type species of the genus, based on voucher specimens confirmed differences from the new genus in the presence of lamellate plate in the anterior jaw of clamps, absence of seminal receptacle and ovoid pharynx. The genus Neoheterobothrium was emended and N. cynoscioni (MacCallum, 1917) and N. mcdonaldi Payne, 1987 were removed from the genus. Neoheterobothrium now comprises N. affine (type), N. insulare Oliva & Luque, 1995, N. hirame Ogawa, 1999, and N. paralichthyi Suriano & Labriola, 1999, all of them parasites of flatfishes of the genus Paralichthys. Molecular analyses with the internal transcribed spacer 1 distinguished the clade for Paraheterobothrium spp. (P. chilense n. comb. and P. papillosum n. comb.) and Neoheterobothrium spp. (N. hirame, N. affine and N. paralichthyi), supporting this taxonomic emendation.

Morpho-molecular characterization of Gyrodactylus parasites of farmed tilapia and their spillover to native fishes in Mexico

Translocation of fishes for aquaculture has resulted in the co-introduction of some of their parasites. African cichlid fishes, generically called “tilapias” have been introduced worldwide, along with their monogenean parasites. In a nation-wide survey, we characterised monogeneans of the genus Gyrodactylus infecting farmed “tilapia” throughout Mexico. We also collected native fishes around farms, to look for potential parasite spillover from cultured fishes. Monogeneans were identified taxonomically using morphological and molecular characters. Originally African, pathogenic Gyrodactylus cichlidarum was recorded in every farm surveyed, infecting different “tilapia” varieties, as well as three native cichlid fish species. Previously, we had shown that G. cichlidarum also infects native, non-cichlid fishes in Mexico. We also recorded that Gyrodactylus yacatli is widely distributed in Mexico, infecting cultured “tilapia” and native fishes; and present data indicating that this is a further translocated African parasite. A third, unidentified gyrodactylid infected farmed and native fishes in Chiapas, southern Mexico; we describe the new species as Gyrodactylus shinni n. sp., and provide evidence that this is a third monogenean translocated with African fish. The wide distribution of exotic parasites co-introduced with “tilapia” and their spillover to native fishes may have an important impact on the ichthyofauna in Mexico, one the world’s megadiverse countries.

Four polyopisthocotyleans (Platyhelminthes: Monogenea) from carangid fishes in the Mediterranean, off the Algerian coasts

Four polyopisthocotyleans were collected from the gill filaments of carangids from off the Algerian coast, southern Mediterranean. Specimens of Gastrocotyle trachuri van Beneden & Hesse, 1863 (Gastrocotylidae) and Cemocotyle cf. trachuri Dillon & Hargis, 1965 (Heteraxinidae) from the Mediterranean horse mackerel Trachurus mediterraneus (Steindachner), Zeuxapta seriolae (Meserve, 1938) (Heteraxinidae) from the greater amberjack Seriola dumerili (Risso) and Pyragraphorus hollisae Euzet & Ktari, 1970 (Pyragraphoridae) from the pompano Trachinotus ovatus (Linnaeus) are redescribed based on newly collected specimens. Their taxonomically important morphological features (male copulatory organ and clamp sclerites) are described and illustrated, and the morphometric variation between Mediterranean and oceanic specimens is highlighted. Careful examination of the specimens of Cemocotyle Sproston, 1946 from the Mediterranean revealed that they exhibited unusual features compared with Cemocotyle trachuri Dillon & Hargis, 1965 from the Pacific, mainly the absence of the terminal lappet, thus questioning previous records of this species in the Mediterranean. New geographical locality records are provided for Z. seriolae and P. hollisae. The presence of C. cf. trachuri and Z. seriolae in the Mediterranean is noteworthy as these monogeneans were initially described in the Pacific Ocean. This study extends the geographical range of Z. seriolae to the southern Mediterranean.

Species delimitation of Gyrodactylus (Monogenea: Gyrodactylidae) infecting the southernmost cyprinids (Actinopterygii: Cyprinidae) in the New World

The genus Gyrodactylus von Nordmann, 1832 represents one of the most diverse and widespread taxa within Monogenea, with approximately 500 species described worldwide. Thirty-three species of Gyrodactylus have been recorded in Mexico, and in the last two decades, at least 26 new species have been described mainly from freshwater fish families such as poeciliids, goodeids, profundulids, characids, and cichlids. In this study, we describe two new species of Gyrodactylus infecting freshwater cyprinids based on morphological and molecular characteristics. Gyrodactylus ticuchi n. sp. and Gyrodactylus tobala n. sp. were recovered from Notropis moralesi de Buen and N. imeldae Cortés, respectively, captured in five localities from the State of Oaxaca, Mexico. The new species differ slightly from their congeners in the morphology of the haptoral hard parts and the male copulatory organ. Sequences of the Internal Transcribed Spacers rDNA (ITS1-5.8S-ITS2), cytochrome oxidase subunit I (cox1), and the D2 + D3 domains of the large subunit (28S rDNA) were obtained from multiple specimens and analyzed using Maximum Likelihood (ML) and Bayesian Inference (BI). Phylogenetic hypotheses using ITS rDNA, cox1, and 28S rDNA genes recovered two new species of Gyrodactylus from N. moralesi and N. imeldae; we briefly discuss their phylogenetic relationship with other congeners. These gyrodactylids represent the first species described in species of Notropis from southern Mexico, the cyprinids exhibiting the southernmost distribution in the New World.

A new species of Loimopapillosum Hargis, 1955 (Monogenea: Monocotylidae) parasitizing Hypanus dipterurus (Myliobatiformes: Dasyatidae) off the Pacific coast of South America, and its phylogenetic relationships

A new species of Loimopapillosum Hargis, 1955 is described based on specimens collected from the gills of the diamond stingray, Hypanus dipterurus (Jordan & Gilbert, 1880) (Myliobatiformes: Dasyatidae) captured off Puerto Pizarro, Tumbes Region, northern Peru. Loimopapillosum pascuali n. sp. is distinguished mainly from the type and only species, Loimopapillosum dasyatis Hargis, 1955, by its funnel-shaped male copulatory organ, with an asymmetrical base; the superficial root of the anchor with distal knobs; the deep root of the anchor with a constriction at its base; a single testis; and the number of head organs. Available sequences for members of Monocotylidae in the GenBank as well as partial sequences for the gene 28S and 18S ribosomal DNA from L. pascuali n. sp. were included in phylogenetic analyses, suggesting that Loimoinae (represented in this study by L. pascuali n. sp. and Loimosina sp.) is nested within the Monocotylidae Taschenberg, 1879. Therefore, we confirm the rejection of Loimoidae Price, 1936 and its reincorporation as a subfamily of Monocotylidae, as previously suggested. Loimopapillosum pascuali n. sp. represents the first species of this genus in South America.

Onchocleidus principalis (Monogenea: Ancyrocephalidae) Co-introduced to Europe with Centrarchid Fish

BACKGROUND

Non-native parasites are often translocated into novel areas together with their natural hosts, but the parasite diversity is frequently lower compared to the host's native range.

PURPOSE

This paper provides morphological and molecular characterisation for non-native monogenean parasite Onchocleidus principalis (Ancyrocephalidae) co-introduced with its fish host to Portugal, Europe, including new details on the species' vaginal morphology and metrics.

METHODS

Two host species, the largemouth bass Micropterus salmoides and pumpkinseed sunfish Lepomis gibbosus, were sampled from two reservoirs (Landeira, Coruche) in the Atlantic Sea drainage. Morphometric analysis and sequencing of 28S rDNA were performed.

RESULTS

Presence of O. principalis was confirmed in all individuals of largemouth bass. Accidental findings on pumpkinseed sunfish at both sampling sites represent new host records for this parasite species. The morphometric description of O. principalis showed high similarity to the species in its native range. No intraspecific sequence variation of partial 28S rDNA was observed between specimens from the two sampling sites. Presence of another North-American ancyrocephalid parasite Onchocleidus dispar was confirmed in pumpkinseed sunfish at both sites, and in largemouth bass from the Coruche Reservoir, this representing the first record of O. dispar on largemouth bass in Europe.

CONCLUSION

Onchocleidus principalis has been confirmed to parasitise both centrarchid fish species introduced to Europe. Compared to other studies, the species collected in Portugal exhibits pronounced vaginal armament.

A new species of Heterocotyle (Monogenea: Monocotylidae), a gill parasite of the diamond stingray Hypanus dipterurus (Myliobatiformes: Dasyatidae) from the Peruvian coastal zone

INTRODUCTION

A new monogenean, Heterocotyle margaritae n. sp. (Monocotylidae: Heterocotylinae), is described based on specimens collected from the gills of the diamond stingray, Hypanus dipterurus (Jordan & Gilbert, 1880) (Myliobatiformes: Dasyatidae) captured off the South Pacific coast, Lima Region, Peru.

MATERIALS AND METHODS

Monogeneans were fixed in hot 4% formalin, observed and measured as permanent mounts stained with Gomori's trichrome, and mounted in Canada balsam. Drawings were made with the aid of a drawing tube.

RESULTS

The new species is distinguished from all congeners mainly by having a funnel-shaped male copulatory organ, spatulate distally with lateral folds and by its club-shaped accessory piece. The most similar congener, H. americana Hargis, 1955, resemble H. margaritae n. sp. regarding the general structure of the male copulatory organ (funnel-shaped with an accessory piece). However, besides other features, the new species differ from H. americana by having an accessory piece without a dorsal button (vs an accessory piece with a dorsal button in H. americana).

CONCLUSIONS

This is the first report of a member of Heterocotyle Scott, 1904 in the Southeastern Pacific Ocean. The present finding brings to 20 the number of known species of Heterocotyle, and represents the fifth described monogenean species from Hypanus dipterurus.

Narcinecotyle longifilamentus n. gen., n. sp. (Monogenea: Hexabothriidae), gill parasite of the numbfish Narcine entemedor (Torpediniformes: Narcinidae) from the Mexican Pacific coast

A new genus and species of Hexabothriidae Price, 1942 is described from specimens infecting the gill of the numbfish Narcine entemedor Jordan and Starks from the Pacific coast of Mexico. In addition to the new taxon described here, species of 8 genera also display symmetrical haptors and have eggs with two polar filaments. However, they differ in the combination of the following features: distal portion of the male copulatory organ tubular, unarmed and proximally dilated confining an internal coiled duct, as well as dorsal origin of haptoral appendix. Based on molecular data derived from 3 loci, the mitochondrial Cytochrome C oxidase subunit 1 as well as the nuclear ribosomal 18S and 28S, the new species was found nested within Hexabothriidae together with the other 4 genera with representatives in GenBank. This is the first species of Hexabothriidae reported from a species of Narcinidae.

Diaphorocleidus machacae n. sp. (Monogenea) Infecting the Gill Lamellae of Brycon guatemalensis (Characiformes: Bryconidae) from the Rio Lacantún Basin in Chiapas, Mexico

BACKGROUND

There are currently nine known gill monogenean species of Diaphorocleidus Jogunoori et al. (Systematic Parasitology 58:115-124, 2004) (Dactylogyridae) which are dispersed within and/or among five fish families in the Neotropical Characiformes: Bryconidae, Acestrorhynchidae, Characidae, Iguanodectidae, and Hemiodontidae. During a fish parasitological study carried out in the Rio Lacantún from Chiapas, Mexico, a new species of Diaphorocleidus on the gill lamellae of Brycon guatemalensis Regan, 1908, was discovered.

OBJECTIVE

Our objective was to morphologically describe the new parasite species by comparing it with previously described species of Diaphorocleidus and other known dactylogyrids on Characiformes.

METHODS

Worms were fixed with 4-5% formalin solution, observed and measured as temporary or permanent mounts stained with Gomori's trichrome, and mounted in Canada balsam. In addition, some specimens were mounted on slides using a mixture of lactic acid (LA) and glycerin-ammonium picrate (GAP) and then remounted in Canada balsam to obtain measurements of the haptoral structures and copulatory complex. Drawings were made with the aid of a drawing tube using a Leica microscope DM2500 with Nomarski interference contrast.

RESULTS

The new species differs from previously described congeneric species in having comparatively biggest body size [i.e., 800-1200 µm vs. 222-340 µm in Diaphorocleidus armillatus Jogunoori et al. (Systematic Parasitology 58:115-124, 2004) (type species of the genus)]; two prostatic reservoirs; rod-shaped accessory piece; a sucker-like structure associated with the genital pore; vaginal duct looping left intestinal cecum and opening on the dextro-dorsal margin of body; anchors with conspicuous basal folds on the deep roots weakly developed.

CONCLUSIONS

Consistently with the previous phylogenetic hypotheses about the origin of bryconids (20 mya late Oligocene-early Miocene) in Central America, that morphological differentiation in D. machacae n. sp. in Mexico may somewhat reflect the insights of an early dispersal of a common ancestor of Diaphorocleidus to the area in comparison with that of a late invasion of their congeners [i.e., according to the origin of B. petrosus (10 mya) 10 mya] in Central America. The present finding brings to ten, the number of known species of Diaphorocleidus, and represents the second described species of this genus occurring in a freshwater native host in Mexico.

Morphological and molecular characterisation of a new species of Gyrodactylus von Nordmann, 1832 (Monogenoidea: Gyrodactylidae) of cichlid fishes (Perciformes) from Mexico

Gyrodactylus mojarrae n. sp. is described from the gills of the Neotropical cichlids Thorichthys maculipinnis, Rocio octofasciata, Vieja zonata and V. fenestrata from several localities across southern Mexico. The new species is erected on the basis of the morphology of the haptoral elements (anchors, bars and hooks), and its phylogenetic position within the Gyrodactylidae is evaluated based on the analysis of partial sequences of the ITS1, 5.8 rRNA gene and ITS2. Gyrodactylus mojarrae n. sp. differs from other congeneric species by having hooks with a straight shaft and recurved point, pointed toe and convex heel, presence of reduced superficial anchor roots, by the number and disposition of spinelets of the male copulatory organ, and the absence of shield and lateral processes of the superficial bar. Molecular circumscription of isolates of G. mojarrae n. sp. from different host and hydrological basins showed that these isolates are conspecific and represent a distinct lineage from other congeners, including newly sequenced isolates of Gyodactylus sp. A and Gyrodactylus sp. B from Astyanax mexicanus (Characidae) and Gobiomorus dormitor (Eleotridae), respectively. Genetic affinities of Gyodactylus sp. A and B indicate that they might represent undescribed species infecting freshwater fish from the Americas.

Morphological and molecular analyses of Pseudomazocraes sulamericana n. sp., Pseudomazocraes selene Hargis, 1957, Cemocotyle carangis (MacCallum, 1913) and Zeuxapta seriolae (Meserve, 1938) (Monogenea: Mazocraeidea) from carangid fishes in the south-western Atlantic Ocean

An integrative taxonomy approach was followed to analyse morphological and molecular characters of the monogenean species Pseudomazocraes selene, Cemocotyle carangis and Zeuxapta seriolae; specimens were collected from the gills of the carangid fishes Selene vomer, Caranx latus and Seriola lalandi caught off the coasts of the states of Rio de Janeiro and Santa Catarina, Brazil. The research revealed the presence of Pseudomazocraes sulamericana n. sp., which can be differentiated from other congeners by the shape of clamps mid-sclerite possessing a ventral piece bifurcated at the end, with large and right-angled edges of almost the same length, and by the shape of larval hooks and rounded terminal lappet. New genetic sequences include partial 28S and 18S rDNA genes for all species, ITS1 and 5.8S rDNA for Zeuxapta seriolae and Cemocotyle carangis, and ITS2 and mtDNA cox1 for C. carangis. The phylogenetic concatenated analysis based on partial 28S rDNA and 18S rDNA sequences confirmed the position of C. carangis and Z. seriolae within the Heteraxinidae. The previous phylogenetic position of Chauhaneidae was discussed based on morphological studies and it is now confirmed by molecular data that Chauhaneidae is the sister group of Allodiscocotylidae and Protomicrocotylidae.

Microcotyle visa n. sp. (Monogenea: Microcotylidae), a gill parasite of Pagrus caeruleostictus (Valenciennes) (Teleostei: Sparidae) off the Algerian coast, Western Mediterranean

Parasite biodiversity of fish of the southern part of the Mediterranean sea is still incompletely explored. We describe here Microcotyle visa n. sp. from the gill filaments of the bluespotted seabream Pagrus caeruleostictus (Valenciennes) (Sparidae) collected off the Algerian coast. The identity of fish hosts was confirmed by barcoding. Microcotyle visa n. sp. is herein described and illustrated. Analysis of the cox1 gene of the monogeneans revealed minor intraspecific variation (1.4%), an order of magnitude lower than the distance between this species and other Microcotyle species (10-15 %). Microcotyle visa n. sp. is distinguished from Microcotyle erythrini van Beneden & Hesse, 1863, a congener infesting sparids, on the basis of morphological (size of clamps, number of testes) and molecular (cox1) differences. This is the fourth member of the genus known to parasitise a sparid host. A species of Paramicrocotyle sp. included in the molecular analysis was nested within a robust Microcotyle + Paramicrocotyle clade; in the absence of demonstrated molecular and morphological differences, we consider that Paramicrocotyle Caballero & Bravo-Hollis, 1972 is a junior synonym of Microcotyle van Beneden & Hesse, 1863 and transfer two species of Paramicrocotyle as Microcotyle danielcarrioni (Martinez & Barrantes, 1977) n. comb. and Microcotyle moyanoi (Villalba & Fernandes, 1986) n. comb.

New species of Paracolpenteron n. gen. and Ancyrocephalus (Monogenea, Dactylogyridae) inhabiting the urinary bladder and gills of the Maya needlefish Strongylura hubbsi (Beloniformes, Belonidae) from Chiapas, Mexico

Parasitological examination of the maya needlefish Strongylura hubbsi Collette (Belonidae) from the Rio Lacantún basin in the Montes Azules Biosphere Reserve, Chiapas, Mexico showed that specimens were parasitized by two monogenean species in two different sites: Paracolpenteron hubbsii n. gen., n. sp in the urinary bladder and Ancyrocephalus chiapanensis n. sp in the gill lamellae. Paracolpenteron hubbsii differs from other dactylogyrid species without a haptoral anchor/bar complex infecting the urinary systems, gills and nasal cavities by the general morphology of hooks, a dextral vaginal opening, a tubular male copulatory organ comprising a base from which a coiled shaft arises in counterclockwise direction, and an unarticulated Y-shaped accessory piece. Ancyrocephalus chiapanensis n. sp. resembles Ancyrocephalus cornutus William & Rogers, 1972 from the gills of Strongylura marina from Florida from which it differs in possessing a twisted tube of the male copulatory organ (curved in A. cornutus), ventral bar with cavities on the ends (cavities absent in A. cornutus) and by the size of the ventral (length 31-34 μm vs. 24-27 μm in A. cornutus) and dorsal (length 25-28 μm vs. 18-22 μm in A. cornutus) anchors. These new monogeneans are described herein and their biogeography is briefly discussed based on the previous phylogenetic hypotheses concerning the host family.

Two new species of Gyrodactylus von Nordmann, 1832 from Profundulus oaxacae (Pisces: Profundulidae) from Oaxaca, Mexico, studied by morphology and molecular analyses

In the present study, two new species of Gyrodactylus are described from Profundulus oaxacae, a fish endemic to the Pacific slope of Oaxaca State, Mexico. Fishes were collected within their distribution range in 5 localities in the Atoyac-Verde River. Gyrodactylus montealbani n. sp. and G. zapoteco n. sp. were erected and characterized morphologically (sclerites of the attachment apparatus and the male copulatory organ) and molecularly (sequences of the Internal Transcribed Spacer region of rDNA). The haptoral sclerites of the new species are similar to those of Gyrodactylus iunuri and Gyrodactylus tepari, both recently described from the goodeid fish Goodea atripinnis, from the Mexican States of Jalisco and Querétaro, respectively; and to Gyrodactylus xtachuna described from the poeciliid Poeciliopsis gracilis in Veracruz State, Mexico - nonetheless, these species can all be discriminated based on their marginal hook morphology. Specimens of G. montealbani n. sp. and G. zapoteco n. sp. were sequenced, and were aligned with sequences of 25 other Gyrodactylus spp. Both Maximum likelihood and Bayesian inference analyses indicated that the two new species are members of independent, well-supported lineages - these are the first Gyrodactylus species described from Profundulus oaxacae.