镰刀指环虫（Dactylogyrus falcatus Wu，Wang et Song，1983）是昆虫。成虫形态 虫体中等，体长0.416一0.555mm，体宽0.111一0.138mm。后吸器具2联结片。边缘小钩发育良好，长0.052一0.059mm。中央大钩Crytomerus型，全长0.059一0.070mm，基部长0.052一0.055mm，钩尖长0.014一0.017mm，内突0.008一0.014mm，外突不明显，长0.003一0.005mm。联结片棒形，两端稍膨大，大小0.007一0.009×0.042一0.052mm；副联结片中部稍突起，略成人字形，大小0.005一0.007×0.042一0.045mm。