Ligictaluridus michaelalicea n. sp. (Monogenea: Dactylogyridae) from flathead catfish (Pylodictis olivaris) in the upper Mississippi River, including remarks on taxonomy influencing monogenean treatment regulation in the United States

Abstract

Ligictaluridus michaelalicea n. sp. (Monogenea: Dactylogyridae, Ancyrocephalinae) is described from the gills of Pylodictis olivaris (Siluriformes: Ictaluridae) from Wisconsin and Iowa portions of the upper Mississippi River. Diagnostic features include a relatively large, strongly curved tubular cirrus with minor terminal flare; an accessory piece with a prominent basal lobe and a simple, thick terminal limb featuring a thin lateral flange and blunt distal tip devoid of recurved hooks. The sinistral vagina, two prostatic reservoirs, and a terminal seminal vesicle of the vas deferens are prominent. The anchors, ventral and dorsal bars, and hooks are similar in overall form to those of other members of the genus. The description includes sequence data for the 18S rRNA gene, which aligned most closely with species of ancyrocephaline monogeneans, with the highest similarity being with Ligictaluridus pricei (Mueller, 1936). Other monogenean species identified from the flathead catfish examined included L. pricei and Ligictaluridus mirabilis (Mueller, 1937). L. michaelalicea n. sp. is the fourth species to be described from P. olivaris within its natural range in central and eastern North America. Implications resulting from taxonomic name changes, including species of Ligictaluridus, and United States Food and Drug Administration treatment regulations are discussed. An updated key to species of the genus Ligictaluridus is presented.

New and previously known ectoparasitic monogenoids (Platyhelminthes) on native and non-native fishes from tributaries of the Usumacinta River basin (southern Mexico), a Neotropical transition zone

“…Measurements of these specimens are consistent with those originally used to describe and redescribe this species (on P. olivaris and Ictalurus punctatus , respectively) from North America (see Table 3 ) and with the most updated taxonomic key provided by Leis et al (2018) for Ligictaluridus spp., thus separating L. mirabilis from L. floridanus (i.e., accessory piece 70–90 [from the Recreo river], 70–80 [from the Lacantún river] long, with distal tip possessing two recurved points in present specimens (see Fig. 4 ) vs 40–47 long, with single recurved point in L. floridanus (see Table 3 , and drawings/measurements of L. floridanus from the key to Leis et al, 2018 ). While not within the scope of the present study, it is noted urgent need of a formal revision of those dactylogyrids referenced as L. floridanus , L. pricei and L. mirabilis on Ictalurus spp.…”

“…Ligictaluridus mirabilis was originally described on flathead catfish Pylodictis olivaris (Rafinesque, 1818) from Mississippi River, USA from which other two Ligictaluridus spp. have also been described and/or reported, Ligictaluridus michaelalicea Leis et al (2018) , L. floridanus and L. pricei . Additionally, Ligictaluridus posthon Klassen and Beverley-Burton, 1985 has been described on Noturus flavus Rafinesque, 1818 from Ontario, being a total of seven currently known Ligictaluridus spp.…”

“…Additionally, Ligictaluridus posthon Klassen and Beverley-Burton, 1985 has been described on Noturus flavus Rafinesque, 1818 from Ontario, being a total of seven currently known Ligictaluridus spp. from North American catfishes (see Cloutman et al, 2018 ; Klassen and Beverley-Burton, 1985 ; Leis et al, 2018 ). Among these Ligictaluridus spp., L. floridanus , L. pricei and L. mirabilis have been extensively reported on native and/or introduced Ictalurus spp.…”

“…However, not any taxonomic account is described and/or provided in these reports from Mexico to support identification of these dactylogyrids, overall due to the confusion over the identity of L. mirabilis and L. floridanus. Both monogenoidean species are morphologically closer to each other and differ primarily in the size and shape of the copulatory complex (see Klassen and Beverley-Burton, 1985 ; Leis et al, 2018 ). In the present study, drawings and measurements of the morphological features (i.e., copulatory complex) of the specimens identified as L. mirabilis on I. meridionalis from southern Mexico are provided (see Fig.…”