Morphological variation of Aplectana hylambatis (Nematoda: Cosmocercidae) from different anuran hosts and localities in Argentina

Abstract

Aplectana hylambatis is a nematode with a wide geographic distribution and low host specificity. In spite of numerous reports, until this moment, the morphological variations between different hosts and localities have not been studied. We studied 401 specimens collected from five host species from seven localities in Argentina, and examined the following morphological characters: mamelon-like cuticular protuberances anterior to the vulva, structure of the gubernaculum and the spicules, number and arrangement of caudal papillae, and the measurements of twelve characters in females and eleven characters in males. The results showed that mamelon-like protuberances and caudal papillae varied in number and arrangement between different hosts and localities. The metrical study revealed that five characters in males and six in females contributed to variability; nine characters showed significant differences between host species and localities. Specimens of A. hylambatis collected from R. arenarum formed a group clearly differentiated from the rest of the specimens. The results from this study highlight the importance of examining as many specimens as possible from different host samples and from several localities to cover the intraspecific variations.

To live free or being a parasite: The optimal foraging behavior may favor the evolution of entomopathogenic nematodes

“…kraussei compared to using dead hosts [ 41 ]. These findings underscore how different host species can modify the life history traits of nematodes, as observed in the length of males of Aplectana hylambatis , which significantly varies among four anuran host species, or Nippostrongylus brasiliensis , which undergoes changes in development, lifespan, and egg production when using an alternate rodent host [ 42 , 43 ]. Collectively, our findings suggest that entomopathogenic nematodes exhibit optimal decision-making when selecting and utilizing hosts.…”

Native species Maxvachonia chabaudi Mawson, 1972 (Nematoda: Cosmocercoidea) found in the invasive marine toad Rhinella marina (Linnaeus) (Anura: Bufonidae) in Australia

“…Recently, some species of the Cosmocercoidea have been reported to exhibit remarkable morphological variation among different individuals collected from different hosts and localities or the same host in some important morphological characters (i.e., the position of the excretory pore, the structure and position of the vulva, the shape of the gubernaculum and the number and arrangement of caudal papillae - González et al 2019, Ni et al 2022. Consequently, we speculated that the presence of morphological difference in the above-mentioned respects between our specimens and Mawson's (1972) material or among different individuals of the present specimens should be considered as intraspecific variation, possibly owing to the different hosts, localities and development.…”

Nematodes of Amphibians from the South American Chaco: Distribution, Host Specificity and Ecological Aspects

“…Leptodactylus bufonius, together with R. major, was the best-studied species in both ecoregions [26,[30][31][32]42,48,49,52,67,70,71,79,81]. Therefore, we emphasize that estimates on parasite species richness are strongly influenced by sampling effort [136].…”

“…A case to highlight is that of the amphibians of the genus Pseudopaludicola. The helminth fauna of P. falcipes and P. boliviana has been analyzed in the HC [29,[79][80][81], and as a general rule, these amphibians were parasitized by a single nematode species; this contrasts with the seven species identified in P. pocoto from Caatinga [150].…”