A new species of Hedruris Nitzsch, 1821 (Nematoda: Hedruridae) parasitic in the freshwater fish Oligosarcus jenynsii (Günther, 1864) (Characidae) from Argentina

Abstract

Nematodes belonging to genus Hedruris Nitzsch, 1821 (Nematoda: Hedruridae) were found in the stomach of the freshwater fish Oligosarcus jenynsii (Günther, 1864) (Characidae) from a shallow eutrophic lake in Argentina. Morphological comparisons with congeneric relatives showed that these nematodes belong to a new species, for which H. bifida n. sp. is proposed. Hedruris bifida n. sp. can be distinguished from its congeners by the following combination of characters: bifid deirids, absence of precloacal papillae and nine pairs of postcloacal papillae and non-mammillated eggs. The new species closely resembles Hedruris suttonae Brugni & Viozzi, 2010¸ the only known species from Argentina; however, the bifid deirids in the new species and the distribution pattern of perianal spines in females clearly distinguish both species. Hedruris bifida n. sp. represents the second nominal species of the genus in Argentina and the eighth species described in the Neotropical region.

Seasonal variation of Hedruris dratini (Nematoda) parasitizing Hydromedusa tectifera (Chelidae), with focus on host’s torpor state

“…In addition, the sex ratio of H. dratini remains constant throughout the year being not altered by climatic seasonal variations. Females of H. dratini are bigger than males, a feature which was also noted in several species of the genus (e.g., [ 7 , 20 , 34 ]). There are differences in the average size of males and females between seasons, being larger in cold seasons and smaller in the warm ones.…”

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

“…(i.e. 18–0:0:18), all of them from the Neotropics: H. orestiae , H. basilichtensis , H. moniezi , H. suttonae and H. bifida (Bursey & Goldberg, 2000; Rossin & Timi, 2016). However, none of them possess mammilated eggs.…”

“…Additionally, females of H. moniezi are described as opistodelphic, those of H. suttonae and H. bifida are monodelphic, but Hedruris dratini n. sp. females are didelphic, prodelphic (Ibañez & Córdova, 1976; Brugni & Viozzi, 2010; Rossin & Timi, 2016).…”

“…Females attach to the epithelial wall using a characteristic eversible hook situated in their caudal end, while males are found either coiled around the female ones or free in the stomach lumen (Baker, 1982, 1986; Blair, 1984). The genus is widely distributed and comprises 28 species, four of which are considered doubtful, that is, Hedruris iheringi Pereira & Vaz, 1933, H. hylae Johnston & Mawson, 1941, H. scabra Freitas & Lent, 1941 and H. marinus Kurochkin & Korotaeva, 1974 (Baker, 1982, 1986; Ramadan et al ., 2014; Jones & Resasco, 2016; Rossin & Timi, 2016). In the Neotropical region, nine species of Hedruris were recorded: H. siredonis Baird, 1858, H. orestiae Moniez, 1889, H. mucronifer Schuurmans Stekhoven, 1951, H. basilichtensis Mateo, 1971, H. juninensis Bendezú, 1976, H. moniezi Ibañez & Córdova, 1976, H. heyeri Bursey & Goldberg, 2007, H. suttonae Brugni & Viozzi, 2010 and H. bifida Rossin & Timi, 2016.…”

“…In the Neotropical region, nine species of Hedruris were recorded: H. siredonis Baird, 1858, H. orestiae Moniez, 1889, H. mucronifer Schuurmans Stekhoven, 1951, H. basilichtensis Mateo, 1971, H. juninensis Bendezú, 1976, H. moniezi Ibañez & Córdova, 1976, H. heyeri Bursey & Goldberg, 2007, H. suttonae Brugni & Viozzi, 2010 and H. bifida Rossin & Timi, 2016. Among them, only H. mucronifer , H. suttonae , H. bifida and H. orestiae occur in Argentina (Bursey & Goldberg, 2000; Palumbo et al ., 2016; Rossin & Timi, 2016; Serrano-Martinez et al ., 2017).…”