RESUMO
RESUMEN Objetivo. Identificar y determinar los parámetros de infección del metacestodo Parvitaenia en diferentes fases de cultivo de Dormitator latifrons y evaluar los daños histológicos. Materiales y métodos. Se revisaron 45 ejemplares, 15 en cada fase (pre-cría, pre-engorda y engorda) para identificar el metacestodo y los daños tisulares provocados. Se calculó la prevalencia, intensidad e intensidad mediana. Se evaluó la diferencia de la intensidad mediana entre fase de cultivo mediante la prueba de medianas de Mood. La longitud total, peso, factor de condición de Fulton e índice hepatosomático se correlacionó con la intensidad mediante una correlación lineal. Los daños tisulares fueron evaluados en fragmentos de hígado. Resultados. Se encontró un total de 29151 cestodos, identificados como Parvitaenia cochlearii. La prevalencia del cestodo fue de 100%, la intensidad mediana varió de 22 a 625 individuos y mostró diferencias significativas entre fases de cultivo (X2= 29.391; p<0.0001). La intensidad mostró una correlación positiva moderada con la longitud total de los peces (r2= 0.45; p<0.05) y una correlación baja con el peso (r2= 0.38; p<0.05). En hígados poco parasitados se observó fibrosis y congestión alrededor de los quistes. En hígados con altos niveles de infección se observó reducción del parénquima, fibrosis e incremento de centros melanomacrófagos. Conclusiones. Este es el primer reporte de P. cochlearii en D. latifrons de cultivo. Nuestros resultados sugieren que existe una tendencia de acumulación de cestodos durante el crecimiento de los peces, lo cual podría tener implicaciones negativas para el comercio.
ABSTRACT Objective. To identify and determine the infection parameters of the metacestode Parvitaenia in different culture stages of Dormitator latifrons and to evaluate the histological damage caused by this parasite. Materials and methods. Forty-five specimens were examined, 15 in each phase: prebreeding, pre-fattening, and fattening, to identify the metacestode and tissue damage caused using conventional parasitology and histology techniques. Prevalence, intensity, and median intensity were calculated. A Mood's median test evaluated the difference between intensity per culture phase. Total length, weight, condition factor, and hepatosomatic index were correlated with intensity by linear correlation analysis. Liver fragments were evaluated to identify the tissue damage. Results. A total of 29,151 cestodes were found and were identified as Parvitaenia cochlearii. Cestode prevalence was 100% in each culture phase. The median intensity ranged from 22 to 625 individuals and showed significant differences between culture phases (X2 = 29.391; p<0.0001). Intensity showed moderate positive correlation with total fish length (r2 = 0.45; p<0.05) and low correlation with weight (r2 = 0.38; p<0.05). In less parasitized livers, fibrosis and congestion around the cysts were observed, while in livers with high levels of infection, parenchymal reduction, fibrosis, and increase in melanomacrophage centers were observed. Conclusions. This is the first report of P. cochlearii on D. latifrons in aquaculture. We suggest that there is a tendency for cestode accumulation during fish growth, which could have negative implications for trade.
RESUMO
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.