Uncovering the monogenean species diversity of cyprinoid fish in Iraq using an integrative approach.

The freshwaters of Iraq harbour a high diversity of endemic and phylogenetically unique species. One of the most diversified fish groups in this region is cyprinoids, and although their distribution is relatively well known, their monogenean parasites have only rarely been investigated. Herein, we applied an integrative approach, combining morphology with molecular data, to assess the diversity and phylogeny of cyprinoid-associated monogenean parasites. A total of 33 monogenean species were collected and identified from 13 endemic cyprinoid species. The highest species diversity was recorded for Dactylogyrus (Dactylogyridae, 16 species) and Gyrodactylus (Gyrodactylidae, 12 species). Four species of Dactylogyrus and 12 species of Gyrodactylus were identified as new to science and described. Two other genera, Dogielius (Dactylogyridae) and Paradiplozoon (Diplozoidae), were represented only by 4 and 1 species, respectively. Phylogenetic analyses of the Dactylogyrus and Gyrodactylus species revealed that the local congeners do not form a monophyletic group and are phylogenetically closely related to species from other regions (i.e. Europe, North Africa and Eastern Asia). These findings support the assumption that the Middle East served as an important historical crossroads for the interchange of fauna between these 3 geographic regions.

Monogeneans and chubs: Ancient host-parasite system under the looking glass.

Host-parasite coevolution is one of the fundamentals of evolutionary biology. Due to the intertwined evolutionary history of two interacting species and reciprocal coadaptation processes of hosts and parasites, we can expect that studying parasites will shed more light onto the evolutionary processes of their hosts. Monogenea (ectoparasitic Platyhelminthes) and their cyprinoid fish hosts represent one of the best models for studying host-parasite evolutionary relationships using a cophylogenetic approach. These parasites have developed remarkably high host specificity, where each host species often serves as a potential host for its own host-specific monogenean species. Here, the cophylogenetic relationships in the Dactylogyrus-Squalius system was investigated, as Squalius is one of several cyprinoid genera with puzzling phylogeography and inhabits all four major peri-Mediterranean peninsulas. Of 29 endemic Squalius species examined for the presence of Dactylogyrus parasites, a total of 13 Dactylogyrus species were collected from the gills of 20 Squalius species across a wide range of distribution. Phylogenetic reconstruction revealed a polyphyletic origin for Dactylogyrus species parasitizing congeneric Squalius, with four major clades being recognized. On the basis of the delimitation of host specificity, strict specialists parasitizing single host species, geographic specialists parasitizing congeners in a limited geographical region, and true generalists parasitizing congeners in various geographical regions were recognized in Dactylogyrus species parasitizing Squalius. The phylogenetic reconstruction of Squalius hosts revealed two major clades, the first encompassing only peri-Mediterranean species and the second including species from other Euro-Asian regions. Distance-based cophylogenetic methods did not reveal a statistically significant global cophylogenetic structure in the studied system; however, several host-parasite links among Iberian endemic species contributed significantly to the overall structure. The widest host range and associated genetic variability were recorded for D. folkmanovae, parasitizing nine Squalius species, and D. vistulae, parasitizing 13 Squalius species. Two different dispersion mechanisms and morphological adaptations to Squalius hosts were clearly reflected in the contrasting cophylogenetic patterns for these two species with different levels of host specificity. While host-parasite cospeciation plays an important role in diversification within D. folkmanovae, diversification within D. vistulae is driven mainly by host switching.

Helminth fauna of the Eurasian beaver in the Czech Republic with remarks on the genetic diversity of specialist Stichorchis subtriquetrus (Digenea: Cladorchiidae).

Eurasian beaver (Castor fiber) is a well-established faunal element in the Czech Republic, even though, historically, its populations were almost eradicated in this region. Nowadays, its distribution and population density are well monitored; nonetheless, the beaver's parasites, as potential threats to the environment, are often neglected in wildlife management. Therefore, we investigated the endoparasitic helminth diversity of 15 beaver individuals from three collection sites in the Czech Republic. Three parasite species were collected: Stichorchis subtriquetrus (Digenea), Travassosius rufus, and Calodium hepaticum (Nematoda), of which the two nematode species were reported for the first time from C. fiber in the Czech Republic. The highest prevalence and intensity of infection were observed in S. subtriquetrus (P = 93%, I = 1-138), while the two other species were collected only from one beaver individual. Subsequent analysis of the genetic diversity of the specimens using highly variable genetic markers revealed a weak population structure among the individuals collected from different beaver hosts. There was only a weak association of COI haplotypes with geography, as the haplotypes from the Berounka basin formed homogeneous groups, and individuals from the Dyje basin and Morava partially shared a haplotype. Even though common population genetic markers (i.e., microsatellites) did not reveal any structure in the hosts, our results suggest that the genetic diversity of their parasites may shed more light on population partition and the historical migration routes of Eurasian beavers.