Gyrodactylus mediotorus, King, Marcogliese, Forest, McLaughlin and Bentzen, 2013

Rahmouni, Chahrazed, Seifertová, Mária, Bean, Megan G. & Šimková, Andrea, 2024, Intraspecific variation in Gyrodactylus mediotorus and G. crysoleucas (Gyrodactylidae) from Nearctic shiners (Leuciscidae): evidence for ongoing speciation, host-switching, and parasite translocation, Parasite (Paris, France) 31 (29), pp. 1-14 : 8

Gyrodactylus mediotorus

Two fragments, the first covering the 18S rDNA region (436 bp) and the second covering the ITS region (1,010 bp), were successfully sequenced for two gyrodactylid specimens from each of C. venusta and N. cf. stramineus ( Guadalupe River) from Texas. For each gene, no intraspecific variability associated with respective fish hosts was found. Based on sequences of the 18S rDNA region, nBLAST search recovered two variants of G. mediotorus from the farmed spottail shiner N. hudsonius from Quebec ( Canada) ( KF 178302, [ 48]) and the native weed shiner N. texanus from the Upper Mississippi in Wisconsin ( USA) ( MW 666777, [ 56]) as identical matches to our specimens (respectively, 100% similarity, 100% coverage; 100% similarity, 94% coverage). Likewise, nBLAST search using the ITS sequences indicated the same variants of G. mediotorus from the USA ( MW 666182, [ 56]) and Canada ( KF 178301, [ 48]) as the closest matches to our specimens (respectively, 98.91% similarity, 99% coverage; 98.42% similarity, 99% coverage). In accordance with the morphological characterization, the parasite specimens we collected were genetically recognized as G. mediotorus following the delimitation by Ziȩtara and Lumme [116]. Yet, genetic intraspecific variation was found when comparing newly obtained and published sequences of G. mediotorus . P -distances using sequences of the ITS regions approached the limit value (1%) [116] with our specimens of G. mediotorus from C. venusta and N. cf. stramineus ( Guadalupe River) from the southcentral basin (Texas) genetically closer to those found on N. texanus from the Upper Mississippi (Wisconsin, USA) (p -distance = 0.2%; 2 bp) than to Gyrodactylus specimens parasitizing N. hudsonius from the northeastern locality ( Canada) (p -distance = 0.9%; 9 bp). With high support values ( PP = 1, BS = 100), the phylogenetic reconstruction ( Figure 3 ) indicated the monophyly of three variants of G. mediotorus with sister position to the clade of Gyrodactylus ticuchi Pinacho-Pinacho et al., 2021 ( MT 879676) and Gyrodactylus tobala Pinacho-Pinacho et al., 2021 ( MT 879671) parasitizing Notropis moralesi de Buen, 1955 and Notropis imeldae Cortés, 1968 , respectively, from Mexico [ 75].

Figures

Figure 3. Bayesian inference (BI) phylogram of Gyrodactylus spp. parasitizing Nearctic Cypriniformes based on sequences of the ITS regions (927 bp). Values above branches indicate posterior probabilities (PP) from BI analyses and bootstrap support (BS) from ML. Values below 0.80 (BI) and 70 (ML) are shown as dashes.