Morphological and molecular description of eight new species of Gyrodactylus von Nordmann, 1832 (Platyhelminthes: Monogenea) from poeciliid fishes, collected in their natural distribution range in the Gulf of Mexico slope, Mexico

Abstract

Eight new species of Gyrodactylus are described from Poecilia mexicana, Poeciliopsis gracilis, Pseudoxiphophorus bimaculatus [syn. = Heterandria bimaculata], and Xiphophorus hellerii collected in the Nautla and La Antigua River Basins in Veracruz, and in the Tecolutla River Basin in Puebla, Mexico. Analyzing the morphology of the marginal hooks, Gyrodactylus pseudobullatarudis n. sp. and Gyrodactylus xtachuna n. sp. are both very similar to Gyrodactylus bullatarudis; Gyrodactylus takoke n. sp. resembles Gyrodactylus xalapensis; Gyrodactylus lhkahuili n. sp. is similar to Gyrodactylus jarocho; and both Gyrodactylus microdactylus n. sp. and Gyrodactylus actzu n. sp. are similar to Gyrodactylus poeciliae in that all three species possess extremely short shaft points. A hypothesis of the systematic relationships of the eight new Gyrodactylus species and some of the known gyrodactylids infecting poeciliids was constructed with sequences of the Internal Transcribed Spacers (ITS1 and ITS2) and the 5.8S ribosomal gene of the rRNA. Phylogenetic trees showed that the new and previously described species of Gyrodactylus infecting poeciliid fishes do not form a monophyletic assemblage. Trees also showed that the eight new species described morphologically correspond to well-supported monophyletic groups; and that morphologically similar species are also phylogenetically close. Additionally, we correct previous erroneous records of the presence of Gyrodactylus bullatarudis on wild Poecilia mexicana and Xiphophorus hellerii collected in Mexico, as re-examination of the original specimens indicated that these corresponded to Gyrodactylus pseudobullatarudis n. sp. (infecting Poecilia mexicana and Xiphophorus hellerii) and to Gyrodactylus xtachuna n. sp. (on Xiphophorus hellerii). Finally, given the widespread anthropogenic translocation of poeciliid fishes for the aquarium trade and mosquito control programs, as well as the existence of invasive, feral poeciliid populations worldwide, we discuss the possibility that gyrodactylid parasites could be introduced along with the fish hosts-this work provides taxonomic information to assess that possibility, as it describes parasites collected from poeciliid fishes within their native distribution range.

Ecto- and endo-parasitic monogeneans (Platyhelminthes) on cultured freshwater exotic fish species in the state of Morelos, South-Central Mexico

“…These fishes were introduced to Central America (i.e., Mexico and Honduras) for aquaculture purposes from 1965-1980s (Salgado-Maldonado and Rubio-Godoy 2014, Salgado-Maldonado et al 2015) and the presence of species of Dactylogyrus and G.kobayashii (see Table 1, 3) in Morelos might be originally related to these introductions. Poeciliids (known as guppies, mollies, platies, and swordtails) have been studied for ectoparasitic monogeneans in Mexico and mainly gyrodactylids have been reported on the skin and/or gills on these fishes (García-Vásquez et al 2015). Currently, there are 11 gyrodactylid species described and/or reported from poeciliids.…”

“…This monogenean species has been reported on Poeciliacaucana (Steindachner) and P.reticulata from their natural ranges of distribution (Venezuela and Trinidad, respectively). Among all species of Gyrodactylus mentioned above, only G.bullatarudis Turnbull, 1956 and G.turnbulli Harris, 1986 have been reported on six poeciliid host species ( Gambusiaholbrooki Girard, Poeciliasphenops Valenciennes, P.reticulata , P.bimaculata , Poeciliopsis sp., and X.hellerii ) from Mexico, Canada, Costa Rica, Peru, Trinidad, Australia, and Singapore (see García-Vásquez et al 2015). Given the low host specificity of both gyrodactylid species and the invasive characteristic of poeciliids, the potential transfer of these gyrodactylids to native poeciliids and other ecologically-associated hosts in Mexico is high (see García-Vásquez et al 2017, Mendoza-Franco et al 2015).…”

“…In the literature, there are a number of reports dealing with the introduction of parasites by ornamental fish from which the consequences of parasite introduction can be detrimental to native fish. For example, epizootics that may lead to extensive mortality (i.e., D.vastator on cyprinids, see Cone 1999) as shown for several species of monogeneans introduced into farms or aquariums, and from there to natural populations (Bakke et al 2002, 2007; García-Vásquez et al 2017). In addition to the identification of invasive host fish species, it is recommended that all freshwater fish imported into the country for food (farmed) or ornamental purposes must comply, at least, with quarantine regulations.…”

“…In addition, some specimens were mounted in a mixture of lactic-acid (LA) and glycerin- ammonium picrate (GAP) and then remounted in Canada balsam as permanent preparations (Mendoza-Franco et al 2013). Parasite identifications were made using a Leica microscope DM2500 with Nomarski interference contrast and based on descriptions provided in the following references: García-Vásquez et al 2007, 2015, Jogunoori et al 2004, Kritsky et al 1989, Lim 1996, Mendoza-Palmero et al 2012, Pariselle and Euzet 1995, Yamaguti 1963. Reference specimens were deposited in the National Helminthological Collection of Mexico ( CNHE ).…”

To each his own: no evidence of gyrodactylid parasite host switches from invasive poeciliid fishes to Goodea atripinnis Jordan (Cyprinodontiformes: Goodeidae), the most dominant endemic freshwater goodeid fish in the Mexican Highlands

“…Trade of ornamental poeciliids has also contributed to the wide dissemination of their monogenean parasites: several gyrodactylid species have been recorded to infect aquarium fishes in Canada, UK, Czech Republic, Singapore, Korea, India, Australia, etc. [10, 12, 14]. In fact, five of the 19 species of Gyrodactylus known to infect poeciliid fishes were originally obtained from exotic fishes reared in aquaria (reviewed in [14]).…”