Research on helminths from Mexican amphibians: gaps, trends, and biases

Abstract

We present a taxonomic, spatial, and thematic overview of the current state of knowledge on helminth parasites of Mexican amphibians. Sixty-six host species have been studied so far, representing 17.5% of the amphibian species distributed in Mexico. A total of 139 nominal species of helminths – 68 platyhelminths, 62 nematodes, three acanthocephalans, three annelids (hirudineans), and three arthropods (pentastomids) – have been recorded parasitizing these hosts. Most taxa found in larval stages have not been identified at the species level. The gastrointestinal nematode Aplectana itzocanensis exhibits the broadest host range, while the bladder fluke Gorgoderina attenuata and A. itzocanensis show the widest geographic distribution. Our analysis of helminthological studies evidenced gaps and biases on research efforts that have been devoted to relatively few host species, regions, and approaches. Most helminthological records come from two species, the cane toad Rhinella marina and the Montezuma's frog Lithobates montezumae, and most studies have focused on describing the helminth fauna of a host species in a particular location or on the description of new helminth species. The highest proportion of records corresponds to the Veracruzan biogeographic province, and helminth richness is significantly correlated with host richness and with total amphibian richness by biogeographic province. Only three provinces (Yucatan Peninsula, Pacific Lowlands, and Baja Californian) have positive, yet still low helminth species discovery effort. Based on our findings, we recommend pursuing research approaches unexplored in Mexico and we provide guidelines to improve research on helminths parasitizing amphibians.

Gastrointestinal parasites in bullfrogs (Lithobates catesbeianus) in aquaculture production units in the Mexican central highlands

“…Another parasite found was a nematode belonging to the genus Strongyloides sp., with a prevalence of 8.7% in the animals observed (31/360), although this nematode is not one of the most common in frogs, it has been reported parasitizing the intestine of several species of frogs and amphibians in America (Miller et al, 2009;Pessier & Mendelson, 2017). Our results shed light on the presence of two different species of parasites infecting bullfrogs, which have been reported in few studies compared to other species of cestodes, trematodes and acanthocephalans frequently reported in frogs (Cabrera-Guzmán et al, 2021;Chen et al, 2021;Kuzmin et al, 2020;Sou et al, 2018).…”

“…which, despite being widely distributed, there are few studies have focused on identification of parasites in aquaculture production units, which could present variations in their prevalence, depending on their geographical location, production systems and biosecurity, generating economic losses due to the negative effect of parasites on animal health (Antonucci et al, 2012). However, even though this species has been introduced into aquaculture production systems in Mexico, there are no published studies on the parasites that are infecting this amphibian species in the wild or in production systems in our country (Cabrera-Guzmán et al, 2021).…”

Gathering morphological and molecular data for identifying two species of trematodes from the neotropical Vaillant's frog, Lithobates vaillanti (Amphibia: Ranidae) in the highlands of Chiapas, south-eastern Mexico

“…Irrespective of their high diversity, amphibians are one of the less studied vertebrates in Mexico from the parasitological perspective. According to Cabrera-Guzmán et al (2021), about 139 nominal species of parasites have been reported parasitizing 66 amphibian species in Mexico; of these, 68 species are Platyhelminthes. These species are unevenly distributed among biogeographical provinces which may be an artefact of sampling effort bias, although Cabrera-Guzmán et al (2021) demonstrated a significant correlation between helminth and host richness by biogeographical province.…”

“…According to Cabrera-Guzmán et al (2021), about 139 nominal species of parasites have been reported parasitizing 66 amphibian species in Mexico; of these, 68 species are Platyhelminthes. These species are unevenly distributed among biogeographical provinces which may be an artefact of sampling effort bias, although Cabrera-Guzmán et al (2021) demonstrated a significant correlation between helminth and host richness by biogeographical province. One of them is the Chiapas Highlands biogeographical province in southern Mexico.…”

Community structure of the helminths of Lithobates spectabilis (Anura: Ranidae) from two localities in the Biosphere Reserve Barranca de Metztitlán, Hidalgo, Mexico

“…Approximately, 402 species of amphibians have been described from Mexico (Frots, 2018;Parra-Olea et al, 2014), of which only 66 have been studied from a helminthological perspective; this number represents only about 18% of all Mexican species (Cabrera-Guzmán et al, 2021). Most of those works have focused mainly on taxonomic descriptions, lists of species, or population level studies (Cabrera-Guzmán, 2002;Cabrera-Guzmán et al, 2007Galicia-Guerrero et al, 2000;León-Règagnon et al, 2005;Velázquez-Urrieta & León-Règagnon, 2018), and only a few reports of the ecological structure of helminth communities (Adán-Torres et al, 2018;Espínola-Novelo et al, 2017;Goldberg et al, 2001;Mata-López et al, 2013;Paredes-Calderón et al, 2004;Ruiz-Torres et al, 2017;Zelmer et al, 2004).…”