Anal groove on the tick's abdomen

Used to classify ticks

In the photo, the position of the anal groove on the tick's abdomen places it posterior and lateral to the anal orifice. The location of the anal groove is a characteristic used to taxonomically classify ticks. On members of the Dermacentor and Rhipicephalus genera of Ixodidae hard ticks, the groove is located posterolateral to the anal orifice.