Cutaneous and conjunctival habronemosis in horses treated at the Veterinary Hospital of the Santa Catarina State University, Brazil.

Habronemosis, also known as habronemiasis or habronematidosis, is a parasitic disease of equids caused by the larval stages of Habronematidae nematodes (Habronema muscae, Habronema microstoma, and Draschia megastoma) that are transmitted by muscid flies. The presence of aberrant infective larvae in the cutaneous and conjunctival tissues of these hosts results in granulomatous, exudative, and ulcerated lesions, also known as "summer sores." In this study, we present a retrospective analysis of habronemosis cases in horses from the municipality of Lages, located on the Santa Catarina Plateau, a region with high altitudes and a temperate climate that differs from regions of Brazil where such parasitosis usually occurs. The equids were examined from 2008 to 2020 at the Veterinary Hospital of Santa Catarina State University. Sixteen patients were diagnosed and treated using macrocyclic lactones and wound cleaning. Most cases were recorded in autumn in horses (10/16, 62.5%) over 15 years of age (11/16, 68.8%), and the lesions were more frequently located in the conjunctiva (11/16, 68.8%). In scientific dissemination media, this is the first report of habronemosis on the Santa Catarina Plateau, Brazil. This information will contribute to the diagnosis, treatment and prevention of skin diseases in horses in this region.

Thubunaea acostai sp. nov. (Nematoda: Physalopteridae) from the lizard Liolaemus gracielae (Squamata: Iguania: Liolaemidae) in Argentina.

Thubunaea acostai sp. nov. is described and illustrated here, based on specimens found in the digestive tract of Liolaemus gracielae in the province of San Juan, Argentina. The new species differs from all other species assigned to Thubunaea by the number of caudal papillae. Thubunaea acostai sp. nov. has 30-31 papillae (12 pedunculated and 18-19 sessile), differing from other Neotropical species such as Thubunaea eleodori with 26 papillae (12 pedunculated and 14 sessile) and Thubunaea parkeri with 20 papillae, all pedunculated. The new species represents the third species for the Neotropics and the second described for Argentina.

Social media as a tool for detecting underdiagnosed parasitic infections: the case of spirocercosis.

Spirocercosis is a parasitic disease caused by the nematode Spirocerca lupi that affects several canids around the world. In Costa Rica, few spirocercosis cases have been reported; however, it is suspected that the infection is currently underdiagnosed. As seen during the COVID-19 pandemic, social media has sped up the spread of scientific knowledge, raising practioner's awareness of the epidemiology and signs and manifestations of infections. The aim of this work was to use social media as a tool for increasing awareness of spirocercosis among veterinarians and investigate the frequency of cases occurring in Costa Rica. Infographic material about the infection was disseminated by Whatsapp, Facebook, and Instagram from January 2021 to July 2022 using a public account of the Laboratory of Helminthology of the University of Costa Rica. In addition, Google Forms questionnaires were completed by veterinarians to report the number of spirocercosis cases in their clinics, associated manifestations, diagnosis, treatment, and outcome of the disease. Remarkably, since 2020, a six-fold increase in the number of cases per year was noted. Clinical manifestations matched those reported elsewhere, and one of every three dogs infected with S. lupi died spontaneously or required euthanasia because of the infection. This work suggests that S. lupi infection in Costa Rica may have been underdiagnosed in the last decade, and the knowledge and awareness of clinical personnel play a major role in the detection of this and other infectious diseases.

Spirocerca lupi in the stomach of two Andean foxes (Lycalopex culpaeus) from Chile.

The genus Spirocerca includes nematodes that parasitize the stomach and the oesophagus of carnivores, chiefly canids. Herein, we provide new data about the morphological, histopathological, and molecular characterization of Spirocerca sp. in Andean foxes (Lycalopex culpaeus) in Chile. Intact immature worms, identified as Spirocerca sp., were recovered in the lumen of the stomach from two foxes. Histologically, worms morphologically consistent with spirurid nematodes were present within the wall of the stomach and surrounded by nodular areas of inflammation with central necrotic debris. Molecular analysis of the cox1 gene yielded 19 sequences and 5 nucleotide sequence types with 99.95 to 99.98% similarity, being shared between both foxes. Nucleotide similarity ranged from 93.1 (with genotype 2 of S. lupi and S. vulpis) to 95.8% (with genotype 1 of S. lupi), a higher similarity than noted from sequences of S. lupi from an Andean fox from Peru (91.0 to 93.3%). However, the Poisson Tree Processes for species delineation did not support the existence of a new species Spirocerca. Phylogenetic and nucleotide analyses suggest that these specimens belong to a new variant or genotype of S. lupi or to a cryptic species. Whether the presence of the worms in the stomach has to do with genotypic differences in parasites or host or some combination is uncertain. Spirocerca lupi has never been found in Chilean dogs and must be investigated.

Subcutaneous spirocercosis in a dog from Costa Rica and first molecular confirmation of Spirocerca lupi in Central America.

Spirocerca lupi is the etiological agent of spirocercosis in canids from tropics and subtropics in the world. This parasite can lead to life threatening complications, including the formation of fibro and osteosarcomas. A 5-year-old crossbreed Maltese dog from Costa Rica was presented to a veterinary clinic with two nodules in the subcutaneous tissues of the cervical region. One of the nodules resolved with intramuscular antibiotic and anti-inflammatory treatment. However, the other nodule persisted and became purulent. The content of the nodule was excised releasing two coiled 3-cm reddish worms. Identity of the specimens was confirmed by amplifying an 850 bp fragment of the 18S rDNA. The obtained sequence showed 99.96% similarities with S. lupi from Hungary. The present study highlights the need of veterinary clinicians' awareness towards nematode aberrant migrations, and the require of molecular studies to gain insight into the parasite's evolutionary history.

An annotated checklist of the genus Pterygodermatites Wedl, 1861 (Nematoda: Rictulariidae), with notes on hosts and geographical distribution.

Species of rictulariid nematodes belonging to the genus Pterygodermatites Wedl, 1861 are parasites of mammals with a wide geographical distribution. The taxonomy of this speciose genus is complex and based mainly on morphological traits of the cephalic structures and cuticular processes. Currently, the known species are allocated to five subgenera [P. (Paucipectines), P. (Neopaucipectines), P. (Multipectines), P. (Pterygodermatites) and P. (Mesopectines)], based on the classification proposed in 1969 by Quentin. Studies on life cycles, taxonomy, biogeography and association of these parasites with mammals peaked at the end of the 1960s. Although the momentum was lost, new species and geographic records have been added in the last 50 years. Therefore, an updated checklist of species of Pterygodermatites is presented here, based on a literature survey. Information on classification, geographical distribution and host range obtained for 68 species is presented, including a distribution map. Moreover, the main differential morphological traits related to each species are tabulated. More than 140 species from 10 different mammalian orders (Carnivora, Chiroptera, Didelphimorphia, Erinaceomorpha, Macroscelidae, Microbiotheria, Paucituberculata, Primates, Rodentia and Xenarthra) have been reported as hosts of Pterygodermatites spp. The taxonomic information here compiled can contribute to future studies on the biogeography, in addition to evolutionary and ecological aspects of this diverse but poorly known genus of parasitic nematodes of mammals.

Trichlorfon for treatment of cutaneous habronemosis - evaluation of intravenous regional perfusion in the distal equine limbs

Background: Equine cutaneous habronemiasis is common in the distal regions of the limbs. Organophosphates, appliedsystemically, one previously used treatment, which is highly effective, but currently in disuse, due to the risks of intoxication. Regional perfusion is a potential technique for distal limb wounds, since, in addition to being used in low doses, itprevents systemic circulation of the drug and possible intoxication, and has a lower treatment cost. The current work aimedto perform clinical, laboratory, and venography evaluations of the use of trichlorfon in regional intravenous perfusion, asa possible form of treatment for cutaneous habronemosis in the distal region of equine limbs.Materials, Methods & Results: Twelve equines were used, divided into 2 groups, with the left thoracic limb (LTL) beingthe test limb, and the right thoracic limb (RTL) the control limb. At moment zero (M0), distal radiography and venographywere performed. The tourniquet was then loosened and after 5 min, at moment one (M1), the tourniquet was repositionedfor 1.25 mg/kg (G1) and 5.5 mg/kg (G2) trichlorfon injections into the left thoracic limb, diluted in 20 mL of Ringer’s lactate solution, and 20 mL of Ringer’s lactate solution was applied to the right thoracic limb. The tourniquet was maintainedfor 30 min after infusion in both groups. At moment 2 (M2), 4 days later, blood tests, radiography, and venography wererepeated. Every day between M0 and M2, physical examinations were performed, including measurement of the pastern,fetlock, and coronet band, and a lameness examination. There were no significant alterations in clinical parameters, behavior, and appetite. In the blood cell count, there was an increase in leukocytes on D4 in G2, although remaining withinthe reference values for the species. The biochemical tests showed no alterations. There were no changes in the circumferences evaluated and 4 equines from G2 presented lameness in the LTL and...

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

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

Taxonomic assessment of the genus Procamallanus (Nematoda) in Middle American cichlids (Osteichthyes) with molecular data, and the description of a new species from Nicaragua and Costa Rica.

Procamallanus is a species-rich genus of parasitic nematodes of marine, brackish, and freshwater fishes, occurring also occasionally in amphibians and reptiles. In the Neotropical region, this genus is highly diverse, with species described from a wide range of fish families. In this study, we reassess the taxonomic status of Procamallanus rebecae with molecular and morphological data and describe a new species endemic to Nicaragua and Costa Rica. We analyzed all Procamallanus isolated from fish from the Nicaraguan lakes and some rivers in Costa Rica after an exhaustive analysis of their freshwater fish endoparasite fauna. Procamallanus rebecae is a host-specific parasite of Middle American cichlids, previously reported in southern Mexico, Nicaragua, and Costa Rica. We therefore compared these Central American specimens with individuals of P. rebecae collected in cichlids from southeastern Mexico using two genomic regions (28S rDNA and mitochondrial cytochrome oxidase subunit 1, COI). We found high levels of sequence divergence between Procamallanus from the two geographical regions, with up to 9.8 and 10.5% for both genetic markers, respectively. We also analyzed their morphology and found conspicuous differences in the shape of the mouth and the structure of the female cauda. We therefore describe the specimens of Procamallanus from Central American cichlids as a new species. Both Procamallanus species occur in different cichlid species and are allopatrically distributed. The host specificity and ancient association patterns between cichlids and Procamallanus and the jointly colonization of both hosts and parasites during their northern dispersal from South America are briefly discussed.

Esophageal spirocercosis with pulmonary egg deposition and secondary hypertrophic osteopathy in a dog from Costa Rica.

Spirocerca lupi is the etiologic agent of spirocercosis in canids from the tropical and subtropical regions of the world. A 1-year-old dog was presented with weight loss and diarrhea. Upon examination, thickened limbs, a mass in the lung's right middle lobe and an esophageal mass were found. The pulmonary mass aspirate revealed S. lupi eggs surrounded by a purulent infiltrate. Limb bone biopsies showed irregular mineralization and cartilaginous metaplasia. Treatment with doramectin resolved the initial clinical signs. However, regurgitation was reported 5 months later. Therefore, the dog received additional doramectin and later vomited a worm morphologically consistent with a S. lupi adult. Herein we report the esophageal migration of S. lupi with egg deposition to the lung parenchyma, accompanied by secondary hypertrophic osteopathy. This report highlights the presence of S. lupi in Costa Rica and the importance of including this parasite as a differential diagnosis when compatible signs are identified.

Molecular phylogenetic study in Spirocercidae (Nematoda) with description of a new species Spirobakerus sagittalis sp. nov. in wild canid Cerdocyon thous from Brazil.

The nematode family Spirocercidae Chitwood and Wehr, 1932, comprises three subfamilies, Spirocercinae Chitwood and Wehr, 1932; Ascaropsinae Alicata and McIntosh, 1933; and Mastophorinae Quentin, 1970, which occur worldwide. Spirocercids infect canids and can cause severe illness. The crab-eating fox, Cerdocyon thous (Linnaeus, 1766), is a canid that inhabits most of South America, including Brazil and is a host for several parasitic worms, in particular, nematodes. However, few reports or genetic data are available on the spirocercids found in this host. In the present study, we describe a new species of Spirobakerus Chabaud and Bain 1981, from the intestine of two crab-eating foxes from two different biomes in Brazil. Spirobakerus sagittalis sp. nov. presents a) unequal spicules, with a long, thin left spicule with a lanceolated shape at the tip; b) a pair of sessile papillae and a median unpaired papillae located anteriorly of the cloaca, and c) a tuft without spines at the tip of the tail in females. The molecular phylogenetic analysis indicated that S. sagittalis sp. nov. is basal to the other species of the subfamily Ascaropsinae, which was not recovered as monophyletic. Our phylogenies also indicated that Spirocercidae is paraphyletic, given that Mastophorinae did not group with Ascaropsinae and Spirocercinae. We provide the first molecular data on the genus Spirobakerus and expand the molecular database of the spirocercids. However, further studies, including the sequences of other spirocercid taxa, are still needed to infer the relationships within this family more accurately.

An integrative approach assesses the intraspecific variations of Procamallanus (Spirocamallanus) inopinatus, a common parasite in Neotropical freshwater fishes, and the phylogenetic patterns of Camallanidae.

Integrative taxonomy was used to evaluate two component populations of Procamallanus (Spirocamallanus) inopinatus in Brazil and the phylogeny Camallanidae. Parasite populations were collected in the characiform Anostomoides passionis from River Xingu (Amazon basin) and Megaleporinus elongatus from River Miranda (Paraguay basin). Morphology was analysed using light and scanning electron microscopy (SEM). Genetic characterization was based on partial sequences of the 18S and 28S rDNA, and COI mtDNA. Phylogenies were based on 18S and COI due to data availability. Generalized Mixed Yule Coalescent (GMYC), Poisson Tree Process (PTP) and *BEAST were used for species delimitation and validation. SEM revealed for the first time the presence of minute denticles and pore-like structures surrounding the oral opening, phasmids in females and confirmed other important morphological aspects. Statistical comparison between the two-component populations indicated morphometric variations, especially among males. The different component population of P. (S.) inopinatus showed variable morphometry, but uniform morphology and were validated as conspecific by the GMYC, PTP and *BEAST. Some camallanid sequences in GenBank have incorrect taxonomic labelling. Host, environment and geographic aspects seem to be related to some lineages within Camallanidae; however, their real phylogenetic meanings are still unclear.

Germination capacity of the Pochonia chlamydosporia fungus after its passage through the gastrointestinal tract of domestic chickens (Gallus gallus domesticus).

This study evaluated the germination capacity of Pochonia chlamydosporia (VC4) fungus after its passage through the gastrointestinal tract of domestic chickens and its interaction with Ascaridia galli and Heterakis gallinarum eggs. Twenty-two domestic chickens were divided in two groups: control group (G1) received shredded corn substrate without VC4; and treatment group (G2) received a single dose of 29 g corn substrate containing 3.3 × 106 conidia/chlamydospores (VC4). Subsequently, chicken fecal samples were collected at intervals of 0, 6, 8, 10, 12, 18 and 24 h. Petri dishes from fecal samples of the treated group (G2) were subdivided (G2a and G2b), and then replicated in 2% agar-water medium for the microbiological test. After VC4 growth, approximately 200 eggs of A. galli (G2a) and H. gallinarum (G2b) were added to each subgroup to evaluation of ovicidal activity. There was fungal viability after passage through chicken gastrointestinal tract and egg predation of 59.9% and 43.2% for A. galli and H. gallinarum, respectively. The present work demonstrates the ability of the fungus P. chlamydosporia to survive after passing through the gastrointestinal tract of domestic chickens, an extreme environment (low pH, enzymes, microbiota and mechanical action), and still germinate after being excreted with feces.

Morphological and Molecular Evidence for a New Rhabdochonid Species (Nematoda: Rhabdochonidae) Parasitizing Profundulus oaxacae (Profundulidae) in the State of Oaxaca, Mexico.

The genus Rhabdochona Railliet, 1916 is one of the most speciose group of nematodes, parasites of freshwater fishes, with approximately 103 species described worldwide. Twenty-two species have been recorded in the Americas, 14 of them in Mexico. In this paper we describe a new species of Rhabdochona on the basis of light and scanning electron microscopy and molecular tools. Rhabdochona adentata n. sp. was recovered from the gallbladder of the freshwater Oaxaca killifish, Profundulus oaxacae (Meek, 1902) (Profundulidae) captured in the Río Grande, State of Oaxaca, Mexico. Rhabdochona adentata n. sp. differs markedly from its congeners by possessing an unusual prostom lacking anterior teeth, small simple deirids, and the location of the excretory pore at the level of the union of the muscular and glandular esophagus. Sequences of cytochrome c oxidase subunit I (COI) from mitochondrial deoxyribonucleic acid and the D2 + D3 domains of the large ribosomal subunit (28S) were obtained from 3 specimens and were analyzed using maximum likelihood and Bayesian inference analyses. Phylogenetic analyses using COI and 28S genes recovered 1 new lineage of Rhabdochona. The new species is described on the basis of a detailed morphological study. This parasite represents the first species of Rhabdochona without prostomal teeth and with a different site of infection, the gallbladder.

Atrophic Proventriculitis Associated with Gravid Females of Tetrameres sp. (Nematoda: Tetrameridae) in the Magellanic Penguin (Spheniscus magellanicus) on the Coast of Brazil.

The present study offers the first description of proventriculitis associated with the presence of gravid female nematodes of the genus Tetrameres (Nematoda: Tetrameridae) in 3 juvenile Magellanic penguins (Spheniscus magellanicus) found dead on the coast of Brazil. This study broadens knowledge on parasites associated with these hosts and the real impact of this association.

Spirocerca lupi (Spirurida: Spirocercidae) infection associated to secondary megaesophagus and obstructive process in a senile dog / Infecção por Spirocerca lupi (Spirurida: Spirocercidae) associada a megaesôfago secundário e processo obstrutivo em um cão senil

Spirocerca lupi is a nematode parasite that can be found in the esophagus and aorta of carnivores, including humans. Affected animals may develop mild to severe lesions, depending on the degree of infection, route of larval migration and the inflammatory response. The present work describes the occurrence of S. lupi in a 16-year old male Chow Chow dog, presenting a chronic esophagus infection, associated with a critical obstruction. After the identification of the parasite egg by faecal exam, the patient was treated with milbemycin in combination with praziquantel P.O., in days zero, seven and 28 after the diagnose. An esophagogram was also performed, confirming the secondary megaesophagus. The team of clinicians decide to perform a euthanasia due to the complication of the patient"s condition, even after the anthelmintic treatment. This report is important as it describes a case after 18 years of epidemiological silence in the Metropolitan region of Curitiba, PR, Brazil. The present data aims to raise awareness about the prevalence of this zoonotic disease and the importance of a specific clinical and radiographic diagnose in dogs. It is noteworthy to report the difficulty to reduce the size of the associated esophagus mass even after a potent anthelmintic treatment.(AU)

Spirocerca lupi é um parasito nematoide que pode ser encontrado no esôfago e na aorta de carnívoros, incluindo humanos. Os animais afetados pela doença podem desenvolver de lesões leves a graves, dependendo do grau de infecção, migração larval e resposta inflamatória. O presente trabalho descreve a ocorrência do parasito em um cão Chow Chow de 16 anos de idade, com infecção crônica, apresentando megaesôfago secundário associado a uma crítica obstrução do órgão. Após a identificação do ovo do parasito, foi realizado tratamento antiparasitário oral com a combinação de milbemicina e praziquantel, nos dias zero, sete e 28 após o diagnóstico. Também foi realizado esofagograma, confirmando o megaesôfago secundário. A equipe médica decidiu pela eutanásia do cão devido a sua complicação da condição clínica quando o paciente retornou, mesmo após o tratamento com anti-helmíntico. Este relato é importante porque descreve um caso após 18 anos de silêncio epidemiológico na região metropolitana de Curitiba, Paraná, Brasil. Os presentes dados visam conscientizar sobre a prevalência dessa doença zoonótica e a importância de um diagnóstico clínico e radiográfico específico em cães. É digno de nota relatar a dificuldade em reduzir o tamanho da massa esofágica associada, mesmo após um tratamento anti-helmíntico potente.(AU)

Spirocerca lupi (Spirurida: Spirocercidae) infection associated to secondary megaesophagus and obstructive process in a senile dog / Infecção por Spirocerca lupi (Spirurida: Spirocercidae) associada a megaesôfago secundário e processo obstrutivo em um cão senil

Spirocerca lupi is a nematode parasite that can be found in the esophagus and aorta of carnivores, including humans. Affected animals may develop mild to severe lesions, depending on the degree of infection, route of larval migration and the inflammatory response. The present work describes the occurrence of S. lupi in a 16-year old male Chow Chow dog, presenting a chronic esophagus infection, associated with a critical obstruction. After the identification of the parasite egg by faecal exam, the patient was treated with milbemycin in combination with praziquantel P.O., in days zero, seven and 28 after the diagnose. An esophagogram was also performed, confirming the secondary megaesophagus. The team of clinicians decide to perform a euthanasia due to the complication of the patient"s condition, even after the anthelmintic treatment. This report is important as it describes a case after 18 years of epidemiological silence in the Metropolitan region of Curitiba, PR, Brazil. The present data aims to raise awareness about the prevalence of this zoonotic disease and the importance of a specific clinical and radiographic diagnose in dogs. It is noteworthy to report the difficulty to reduce the size of the associated esophagus mass even after a potent anthelmintic treatment.

Spirocerca lupi é um parasito nematoide que pode ser encontrado no esôfago e na aorta de carnívoros, incluindo humanos. Os animais afetados pela doença podem desenvolver de lesões leves a graves, dependendo do grau de infecção, migração larval e resposta inflamatória. O presente trabalho descreve a ocorrência do parasito em um cão Chow Chow de 16 anos de idade, com infecção crônica, apresentando megaesôfago secundário associado a uma crítica obstrução do órgão. Após a identificação do ovo do parasito, foi realizado tratamento antiparasitário oral com a combinação de milbemicina e praziquantel, nos dias zero, sete e 28 após o diagnóstico. Também foi realizado esofagograma, confirmando o megaesôfago secundário. A equipe médica decidiu pela eutanásia do cão devido a sua complicação da condição clínica quando o paciente retornou, mesmo após o tratamento com anti-helmíntico. Este relato é importante porque descreve um caso após 18 anos de silêncio epidemiológico na região metropolitana de Curitiba, Paraná, Brasil. Os presentes dados visam conscientizar sobre a prevalência dessa doença zoonótica e a importância de um diagnóstico clínico e radiográfico específico em cães. É digno de nota relatar a dificuldade em reduzir o tamanho da massa esofágica associada, mesmo após um tratamento anti-helmíntico potente.

A new species of Hedruris (Nematoda: Hedruridae) from freshwater turtles, its life cycle and biogeographic distribution of the genus.

We describe Hedruris dratini n. sp. (Nematoda, Hedruridae) from Hydromedusa tectifera and Phrynops hilarii in Argentina based on morphological and molecular characters. Also, we provide information about its life cycle. The new species differs from other species of the genus by possessing the excretory pore, nerve ring and deirids at equal distance from the anterior end. Additionally, H. dratini n. sp. has mammilated eggs and males possess nine pairs of caudal papillae. The subadults and adults of H. dratini n. sp and H. orestiae were characterized by sequencing the small subunit ribosomal DNA (18S). We present for the first time a life cycle of a species of Hedruris that includes an amphipod as intermediate host and a reptile as definitive host. Furthermore, we analysed the host and geographic distribution of all Hedruris species. Although the genus has a cosmopolitan distribution and parasitizes a great host diversity, the majority of species have a Gondwanian distribution, with amphibians being the preferred hosts.

An integrative taxonomic assessment of Procamallanus (Spirocamallanus) huacraensis (Nematoda: Camallanidae), infecting the freshwater catfish Trichomycterus spegazzinii (Siluriformes: Trichomycteridae) in Argentina.

Procamallanus (Spirocamallanus) huacraensis infecting the catfish Trichomycterus spegazzinii from Escoipe River, Salta province (Argentina), is redescribed and genetically characterised for the first time, based on three genetic markers (nuclear 18S and 28S rRNA; cytochrome c oxidase subunit I [cox1] mtDNA). The phylogeny of Camallanidae was also discussed. Morphological evaluation of P. (S.) huacraensis using light and scanning electron microscopy revealed the previously undescribed features: location of deirids, accurate morphology of larvae (L1) and ovijector in females, as well as phasmids in males. Differences were found comparing the newly collected material and the type specimens, probably because the original description lacked detailing. Unfortunately, type specimens of P. (S.) huacraensis were no available for loan. The results of morphological and genetic analyses supported the validity of P. (S.) huacraensis. Inconsistencies regarding the taxonomic identification of species of Camallanidae in GenBank database were noted. Based on the current genetic database of Camallanidae, phylogenetic reconstructions using the 18S rRNA sequences were most consistent, due to the inclusion of higher number of taxa. Procamallanus (S.) huacraensis appeared as sister group of P. (S.) rarus, also isolated from a catfish in a neighbouring region. The order and habitat of hosts were also similar within some well-supported parasite lineages, but without common geographic origin. However, it is still premature to make definitive affirmations regarding the role of such features in the phylogenetic patterns of Camallanidae, given the scarcity of genetic data. The phylogenetic reconstructions also confirmed the artificiality of the morphology-based systematics of the family.