Document Type : Research Paper
Because of the similarities in appearance between species of Oligochaeta, identify, characterize and differentiate them from each other to determine the population dynamics or molecular and phylogenies studies seems necessary. The aim of this study is to provide an identification key and diagnostic methods for the two species of genus Limnodrilus in the Anzali Wetland. In compare key features to identify and separate the two species was found in L. hoffmeisteri genital sheath is shorter and thicker than Limnodrilus claparedianus. Statistical analysis showed that this is a significant difference between the two species (P<0.05). The average length of the penial sheath in L. hoffmeister and L. claparedianus respectively were 695.31±91.63 and 1117.06±198.31 micrometer. The average length of the upper tooth and lower in L. claparedianus respectively were 9.74 ±1.82 and 6.68±0.91 micrometer, in L. hoffmeister were respectively 7.5±2.07 and 5.64±1.29 micrometer. Although in the visual observations the upper teeth of chaeta of L. claparedianus was longer than L. hoffmeisteri but a significant difference was not observed between the averages of the two species.