First Occurrence of Three Species of the Genus Dactylogyrus Diesing , 1850 ( Monogenea : Dactylogyridae ) in Iraq from Some Diyala River Fishes , Diyala Province

Three monogeneans: Dactylogyrus folkmanovae from gills of Chondrostoma regium, D. reinii from gills of Mesopotamichthys sharpeyi and D. robustus from gills of Leuciscus vorax were collected from Diyala River in Diyala Province. The description, measurements and illustrations of these parasites were given.


Introduction
The fishes as a group from biodiversity view point, has the highest species variety among all vertebrate taxa.Froese and Pauly [1] have documented 32,500 fish species in the world.Fishes are of great implication in the life of mankind as a source of food, profits and employment.They are known for nutritionally wealthy source of protein, minerals and fewer saturated fats.Parasites and diseases however are known to affect the delectableness and availability of fish provisions [2], ultimately affecting the national wealth [3].
Among the fish parasites, monogeneans are the most numerous ectoparasites of fish, constituting the main class of phylum Platyhelminthes.Monogeneans mainly contaminate the gills of fishes [4], typically infecting the gills and/ or external surfaces of freshwater and marine fishes [5] and feeds on mucus, epithelial cells, tissues and blood causing different signs and symptom [6].
The most significant monogenean parasites in fishes are the dactylogyrids and gyrodactylids [7], mainly infecting cyprinid fishes [8].Dactylogyrus parasites are the cause of serious infections in gill filaments which affect respiration, their pathogenicity consequences in high mortalities [9,10] and cause important economic losses in aquaculture [11,12].
In Iraq, the first record of Dactylogyrus species from Diyala river was D. cornu on five freshwater fish species [13].So, more surveys on fish parasites are needed to recognize more species in this river.The present investigation deals with the record of three monogenean species belonging to the genus Dactylogyrus for the first time in Iraq infecting gills of some freshwater fishes from Diyala river.

Materials and Methods
A total of 84 fishes belonging to four species were collected from Diyala river, at Khan Bani Saad (situated between 33°-35° N and 36°-44° E).Sampling was done weekly twice during the period from July 2016 to February 2017.The fishes were placed in a cool box containing local river water, transferred right away to the laboratory and were examined within 24 hours after their capture.The fishes were identified according to Coad [14].In the laboratory, the gill arches were isolated from both sides, kept moist in Petri dishes and examined under dissecting microscope for the presence of dactylogyrids on each gill lamella.Parasites were isolated and then stained with aqueous neutral red and permanent slides were prepared with glycerolgelatin [15].
Drawings of the sclerotized pieces of the haptor were made by using a camera Lucida.The measurements of parasites were achieved by ocular micrometer.The morphological terminology and the parasites identification were done on basis of Pugachev et al. [16], as shown in figure (1).The information on the previous account records of parasites were checked by using the index-catalog of parasites and disease agents of fishes of Iraq [17].The mean values of all measurements (in mm) employed in this study are used in the description as in the following order: minimummaximum (mean) values.

Results and Discussion
The present investigation showed the existence of three species of monogeneans belonging to the genus Dactylogyrus.The following is an account of their measurements (in mm) which were based on five specimens of each species.

Dactylogyrus folkmanovae Ergens, 1956 (Figure (2)):
Three out of 29 Chondrostoma regium were infected with this parasite with a prevalence of 10.4% and a mean intensity of 3.This parasite was not reported before from any fish species in Iraq [17], therefore, the present parasite is considered as the first record in Iraq.
The description and measurements of the present specimens are similar to those reported by Pugachev et al. [16].This species was reported on gills of Mesopotamichthys sharpeyi of the present study with prevalence of 8.3% and the mean intensity of 8.This parasite was not reported before from any fish species in Iraq [17], therefore, the present parasite is considered as the first record in Iraq.
The description and measurements of the present specimen are similar to those reported by Pugachev et al. [16].

Dactylogyrus robustus Malewitzkaja, 1941 (Figure (4)).
The specimens of D. robustus were collected from gills of Leuciscus vorax with a prevalence of 6.3% and a mean intensity of 3.This parasite was not reported before from any fish species in Iraq [17], therefore, the present parasite is considered as the first record in Iraq.
The description and measurements of the present specimen are similar to those reported by Pugachev et al. [16].