THREE NEW SPECIES OF DACTYLOGYRUS FROM GILLS OF XENOCYPRIS ARGENTEA

The present paper describes three new species of Dactylogyrus,collected from Xeno- cypris argentea Gunther in the River Siyan of the Pearl River System.Syntypespecimens are deposited in the Department of Biology,South China Normal University. 1.Dactylogyrus paracymbidioides sp.nov.(Fig.1,A—C) Worm of medium size,body width 0.088—0.107mm;length 0.520—0.728 mm.Mar- ginal booklets 0.023—0.039 mm in total length.Central large anchors of D.wunderi type, total length 0.031—0.034 mm,basal portion 0.027—0.029 mm,point 0.007—0.010 mm,in- ner root 0.008—0.009 mm,outer root 0.001—0.003 mm.Connective plate is 0.003—0.004 ×0.032—0.036 mm in size.Supplementary plate omega-like,0.008×0.031—0.036 mm in size. Copulatory organ 0.057—0.062 mm in total length.Copulatory tube 0.050—0.060 mm due to its cuvature.Supporting apparatus lambda-like,0.049—0.052 mm long.Vagina 0.039 —0.047×0.031—0.039 mm in size. Description is basend on 4 specimens. Remarks:The new species is similar to both D.leucisculus Gussev,1955 and D. hainanensis Lang,1981 in the opisthohaptor and copulatory organ,but it differs from the latter two species in the shape of the supporting apparatus and the measurement of cuticu- lar structures of the opisthohaptor,the copulatory organ and also in the structure of vagina. 2.Dactylogyrus polycheirodactylus sp.nov.(Fig.1,a—b) Minute worm,body width 0.031—0.049 mm,length 0.233—0.420 mm.Marginal hook- lets 0.017—0.029 mm in total length.Central large anchors of D.wunderi type,with only one connective plate,0.029—0.032 mm in total length,basal portion 0.023—0.028 mm, point 0.010mm,inner root 0.010—0.013 mm,outer root 0.003 mm.Connective plate 0.003×0.026—0.028 mm in size. Copulatory organ 0.020—0.023 mm in total length.Copulatory tube 0.017—0.020 mm.Supporting apparatus pincers-like,with a thumb-shape piece in the middle,0.015— 0.020 mm measuring in length. No eggs and vagina have been discovered after examination. Remarks:The worm is closely related to D.chernyshevae Jukhimenko,1981 in the chitinous armature on the fastenting disk,but differs from the latter by the structure and length of the male copulatory organ and also in the absence of supplementary plate,in the ratio between total length of central large anchors and basal portion. 3.Dactylogyrus hemivolutus sp.nov.(Fig.3,A—B) Minute worm,body width 0.057—0.080 mm;length 0.481—0.576 mm.Marginal hook- lets 0.019—0.025 mm in total length.Central large anchors of D.wunderi type,with only one connective bar,total length 0.026—0.037 mm,basal portion 0.022—0.024 mm, point 0.012—0.013 mm,inner root 0.010—0.013 mm outer root 0.003—0.005 mm,Con- nective plate 0.003—0.006×0.030—0.038 mm in size. Copulatory organ 0.023—0.026 mm in total length.Copulatory tube 0.018—0.022 mm.Supporting apparatus 9-shape,0.023—0.026 mm in length. No eggs and vagina have been discovered after examination. Description is based on 2 specimens. Remarks:The new species is closely related to D.junckisi Jukhimenko,1981 in chi- tinoun armature on the opisthohaptor,but differs from the latter by the structure and mea- surement of the male genitalia.