Monogenea of Marine Fishes From Hainan Island Ⅴ.One New Species of The Genus Ligophorus From The South China Sea

In the present paper one new species of Ligophorus Euzet & Suriano,1977 (Monogenea,Ancyrocephalidae) are described.Type specimens are deposited in the Department of Biology,Hainan Normal University. Ligophorus hamulosus Pan & Zhang,sp.nov.(Figs.1-4) Type specimens No.:HHK9605-15.Host:Liza macrolepis.Location:Gills.Locality:Haikou (20′06°N,110′38°E),Hainan Island.Date:Nov.5,1996. Body of medium size,0.560-0.702×0.127-0.146 mm.Pharynx 0.015-0.018×0.015-0.020 mm.Opisthohaptor 0.075-0.118×0.068-0.070 mm in size.Marginal hooklets 0.012-0.015 mm in length.Ventral central large anchors 0.027-0.029 mm in total length,basal portion 0.020-0.023 mm,point about 0.003 mm,inner root 0.009-0.013 mm,outer root 0.004-0.050 mm.Ventral connective plate 0.007-0.009×0.033-0.038 mm.Dorsal central large anchors 0.020-0.023 mm in total length,basal portion 0.015-0.018 mm,point about 0.003 mm,inner root 0.009-0.013 mm,outer root 0.004-0.005 mmDorsal connective plate 0.004-0.005×0.038-0.040 mm in size. Copulatory organ 0.025-0.043 mm in total length.Copulatory tube thin,C-shaped curved,0.055-0.063 mm in length according to its curvature,diameter of middle part about 0.002 mm.Supporting apparatus 0.020-0.030 mm in length.Vagina being funnel like and thin,0.020-0.023 mm in length.Eggs 0.065-0.098×0.050-0.078 mm in size. Description is based on 10 specimens. This worm is similar to Ligophorus imitans Euzet & Suriano,1977,but differs from the latter by 1)the shape and the structure of the central anchors,2)the different size and the chitinous measurement between the ventral and the dorsal central large anchors and 3)the structure of the copulatory apparatus.