Description of Acleotrema maculatus sp. nov. (Monogenea: Diplectanidae) infecting the spotted coral grouper Plectropomus maculatus (F:Serranidea) from the Red Sea and its histopathological impact

Acleotrema maculatus sp. nov. (Monogenea: Diplectanidae) was described from the gills of The spotted coral grouper Plectropomus maculatus (F:Serranidea, Forsskal, 1775). Fish were collected from boot landing sites and fishermen at different water locations along the Red Sea at Hurghada City, Egypt. The morphology and morphometric characterization of the recovered worms were described by means of light microscopy. Eight (53.3%) out 15 specimens of P. maculatus were infected. Most of the infected fish had very pale gills. Morphologically, the adult worm of A. maculatus sp. nov., possessed a body which was elongated, fusiform with a total length 0.86-0.90 (0.88 ± 0.02) mm, and a maximum width 0.09-0.13 (0.11 ± 0.02) mm at the level of ovary. Haptor, broad, differentiated from the rest of the body, measured 0.04-0.08 (0.06 ± 0.02) mm and provided with continuous rows of squamodiscs. Two pairs of lateral hamuli, three bars and 14 marginal hooklets were also observed. Lateral (dorsal) bars two, stout, dumbbell-shaped, measured 0.052-0.056 (0.054 ± 0.002) mm in length. Ventral bar slender, with transverse groove, measured 0.09-0.11 (0.10 ± 0.01) mm in length. Ventral hamuli measured 0.02-0.06 (0.04 ± 0.02) mm in total length with an outer root that was very long measured 0.016-0.02 (0.018 ± 0.002), stout, slightly notched at broad proximal end; inner root was conical and measured 0.013-0.017 (0.015 ± 0.002) mm, with shaft measured 0.025-0.029 (0.027 ± 0.002) mm and point length 0.007-0.009 (0.008 ± 0.002) mm. Dorsal hamuli measured 0.034-0.038 (0.036 ± 0.002) in total length; base large, stout, with only lateral rudiment of roots; blade and point were long and curved with shaft length measured 0.024-0.028 (0.026 ± 0.002) mm and 0.02-0.06 (0.04 ± 0.02) mm point length. The worm is hermaphrodite, male copulatory organ measured 0.058-0.062 (0.060 ± 0.002) mm in length with a sclerotized part composed of a well-defined, sclerotized anterior sheath. The new species was compared with those described previously from the same genus, it was shown that there were significant morphological and morphometric, which was a strong criteria for the placement these monogenean parasites as new species with new host and locality records in Egypt.