Helminth fauna of Megaleporinus obtusidens (Characiformes: Anostomidae) from Lake Guaíba: analysis of the parasite community

Abstract

Structure of the helminth community of Megaleporinus obtusidens collected in Lake Guaíba was evaluated, and the results indicated that the diversity of helminth species was probably determined by fish behavior and eating habits. The influence of sex, weight, and standard length of hosts for parasitic indices was also analyzed. Sixteen helminth species were found parasitizing M. obtusidens, including the following: platyhelminths, with the highest richness, represented by one species of Aspidobothrea; four species of Digenea; and eight species of Monogenea; the latter, presented the highest prevalence. Rhinoxenus arietinus, found in nasal cavities, had the greater abundance, and was the only species classified as core. The prevalence of Urocleidoides paradoxus was significantly influenced by the sex of the host; females had the highest values. Abundance was weakly influenced by fish weight and the body length of the hosts. Urocleidoides sp. had its abundance weakly influenced by the host weight. The other helminths were not influenced by biometric characteristics of the hosts. The total species richness was similar between male and female fish, and both had 14 helminth species of parasites.

A new species of Tereancistrum (Monogenea, Dactylogyridae) from the gills of three Leporinus species (Characiformes, Anostomidae) and a revised description of Tereancistrum parvus

“…Furthermore, while Wendt et al (2015) stated that the terminal projection of the accessory piece described in the original description by Kritsky et al (1980) was absent, this characteristic was observed in the present study. In addition, the morphology of the vaginal aperture in the present study is different to that described by Wendt et al (2015) [see Figure 2d in Wendt et al (2015)], and is more closely related to that represented by Karling et al 2014[see Figure 3 in Karling et al (2014]. Wendt et al (2015) stated that the ventral bar is V-shaped, but in fact it is the dorsal bar that has this shape, as described by Kritsky et al (1980) and confirmed by Karling et al (2014).…”

“…This description was based on a single specimen and presents sclerotized structures of the haptor and MCO only. Two redescriptions of T. parvus were recently proposed and added new data on the morphology of internal organs such as the position of the vagina, testis, ovary, seminal vesicle and the egg morphology (Karling et al 2014, Wendt et al 2015. However, some morphological differences were observed in relation to these previous descriptions and they are presented herein to correct and complement the diagnosis of T. parvus.…”

“…Specimens examined: voucher specimens deposited by Karling et al (2014) (CHIOC 37863,37864,37865) and Wendt et al (2015) (CHIOC 38087,38088).…”

“…Firstly, the morphology of the MCO is different mainly in terms of the shape of the accessory piece, which consists of a rigid piece, slightly wider at the posterior region and narrower in the anterior region, where it ends in a small projection (Figure 10, present study). The plates of the accessory piece is not clear in the description by Karling et al (2014) [see Figure 4g in Karling et al (2014)], and it was represented by Wendt et al (2015) as a tube with an opening along its lateral extent [see Figure 2b in Wendt et al (2015)]. Furthermore, while Wendt et al (2015) stated that the terminal projection of the accessory piece described in the original description by Kritsky et al (1980) was absent, this characteristic was observed in the present study.…”

“…The plates of the accessory piece is not clear in the description by Karling et al (2014) [see Figure 4g in Karling et al (2014)], and it was represented by Wendt et al (2015) as a tube with an opening along its lateral extent [see Figure 2b in Wendt et al (2015)]. Furthermore, while Wendt et al (2015) stated that the terminal projection of the accessory piece described in the original description by Kritsky et al (1980) was absent, this characteristic was observed in the present study. In addition, the morphology of the vaginal aperture in the present study is different to that described by Wendt et al (2015) [see Figure 2d in Wendt et al (2015)], and is more closely related to that represented by Karling et al 2014[see Figure 3 in Karling et al (2014].…”