Folia Parasitologica 71:005 (2024) | DOI: 10.14411/fp.2024.005

Henneguya (Cnidaria: Myxobolidae) species infecting Oligosarcus jenynsii (Characiformes: Characidae) in a Neotropical shallow lake from Argentina: morphological and molecular characterisation

María Alejandra Rossin ORCID...^{1, *}, Delfina María Paula Cantatore ORCID...^{1, *}, Martina Lisnerová ORCID...², Verónica Taglioretti ORCID...¹, Astrid Sibylle Holzer ORCID...³

¹ Laboratorio de Ictioparasitología, Instituto de Investigaciones Marinas y Costeras (IIMyC), Facultad de Ciencias Exactas y Naturales (FCEyN), Universidad Nacional de Mar del Plata (UNMdP) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Mar del Plata, Argentina;

² Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech Republic;

³ Fish Health Division, University of Veterinary Medicine, Vienna, Austria *María Alejandra Rossin and Delfina María Paula Cantatore contributed equally to this work. Address for correspondence: Cantatore D.M.P. Laboratorio de Ictioparasitología, Instituto de Investigaciones Marinas y Costeras (IIMyC), Facultad de Ciencias Exactas y Naturales (FCEyN), Universidad Nacional de Mar del Plata (UNMdP). Deán Funes 3350, B7602AYL, Mar del Plata (7600), Argentina. E-mail: delfinacantatore@gmail.com ORCID iD: 0000-0002-2839-8319

Two previously undescribed myxozoan species, Henneguya sardellae sp. n. and H. margaritae sp. n., found infecting connective tissues of the Neotropical characid fish Oligosarcus jenynsii (Günther) from Argentina are morphologically and molecularly characterised. Mature spores of H. sardellae sp. n. are ellipsoid, with two, straight and visibly fused caudal appendages cleaved at its blunt terminal end; measuring 33.5 ± 1.2 (30.9-35.5) μm in total length, spore body 17.5 ± 0.6 (16.3-18.6) µm, 7.8 ± 0.4 (7.0-8.8) µm wide and 6.9 ± 0.2 (6.6-7.2) µm thick, with two elongated, unequally-sized polar capsules situated at anterior end, and 11-13 turns of polar tubules. Mature spores of H. margaritae sp. n. are pyriform, with two caudal appendages visible fused together and much longer than spore body, with unequal endings; measuring 35.9 ± 2.8 (29.2-40.7) µm in total length, spore body 11.5 ± 0.9 (9.2-13.0) µm long, 5.8 ± 0.4 (5.1-6.7) µm wide and 5.5 ± 0.2 (5.1-5.8) µm thick, with two polar capsules similar in size, pyriform polar capsules containing polar tubules with 4-5 coils. Both species showed a membraneous sheath surrounding the spore body and caudal appendages; in H. sardellae sp. n. this feature can deploy laterally. Phylogenetic analyses based on SSU rDNA sequences showed that H. sardellae sp. n. and H. margaritae sp. n. clustered with other myxobolids parasitising Characiformes in Brazil, Cichliformes in Mexico and Cyprinodontiformes in Mexico and the United States. The description of these two new species of Henneguya as the first described species of the genus that parasitise freshwater fish in Argentina highlights the importance of further research on the diversity and distribution of myxozoans in this region.

Keywords: Myxozoa, fish parasite, fresh water, South America

Received: May 31, 2023; Revised: December 13, 2023; Accepted: January 19, 2024; Published online: February 20, 2024  Show citation