Helminth fauna of Megaleporinus obtusidens (Characiformes:
Anostomidae) from Lake Guaíba: analysis of the parasite community
E. W. Wendt
C. M. Monteiro
S. B. Amato
Received: 7 September 2017 /Accepted: 15 May 2018
Springer-Verlag GmbH Germany, part of Springer Nature 2018
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,foundin
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.
Keywords Host–parasite relationship
Leporinus obtusidens,knownasBpiava,^ was recently includ-
ed in the genus Megaleporinus proposed by Ramirez et al.
(2017) after phylogenetic study of Anastomidae.
Megaleporinus obtusidens Ramirez, Birindelli and Galetti,
2017 is the only species of Megaleporinus occurring in the
State of Rio Grande do Sul, southern Brazil (Reis et al. 2003).
It is found from north to south in Brazil, as well as in
Argentina, Uruguay, and Paraguay (Britski et al. 2012).
Three genetically distinct populations can be separated: (a)
basin of the Paraná, Uruguay, and Jacui rivers; (b) São
Francisco River; and (c) Paraguay River (Ramirez et al.
2016, 2017). Zaniboni-Filho and Schultz (2003)observeda
reduction in the M. obtusidens population and related it to
agriculture and industrial practices. Thus, species survey stud-
ies in this area become crucial in evaluating threats to
Megaleporinus obtusidens was intensely studied in the
1980s, and aspects of its morphology (Sidlauskas and
Var i 2008; Britski et al. 2012), biology (Mello et al.
1999; Hartz et al. 2000; Penchaszadeh et al. 2000;
Santos 2000; Piana et al. 2003;Moraesetal.2009), and
ecology (Oldani et al. 1992;Araya1999; Araya et al.
2005) have been elucidated.
Studies dealing with the helminth fauna of this species,
however, are scarce and are concentrated mainly in the
States of Paraná and Minas Gerais (Feltran et al. 2004;
Takemoto et al. 2009;Kohnetal.2011). Knowledge about
the parasitic community can contribute to better understand-
ing host habits and behaviors and whether they may influence
the population dynamics of its host. It is known that some
Section Editor: Guillermo Salgado-Maldonado
Electronic supplementary material The online version of this article
(https://doi.org/10.1007/s00436-018-5933-4) contains supplementary
material, which is available to authorized users.
* E. W. Wendt
Laboratory of Ichthyology, Institute of Biosciences, Universidade
Federal do Rio Grande do Sul, Porto Alegre, Brazil
Laboratory of Ecology and Parasite Biology, Institute of Biology,
Universidade Federal Rural do Rio de Janeiro,
Seropédica 23897-000, Brazil
Laboratory of Helminthology, Institute of Biosciences, Universidade
Federal do Rio Grande do Sul, Porto Alegre 91501-970, Brazil