Its prostomium is epilobic, with a closed tongue, and the first dorsal pore is typically located in segments 5/6 to 6/7. The clitellum is annular. The setae are lumbricine and closely paired. Male pores are minute positioned in seminal grooves between prostatic pores. The coloration is either lacking or red on the dorsum. There are no copulatory pouches or genital markings. Gizzards are located in segments vi and vii, with no intestinal caeca present. The last heart is located in segment xii. Dero bolaui is holandric, with seminal vesicles present in segments xi and xii, and quadriprostatic in segments xvii and xix. Pineal setae can be either unornamented or ornamented with a few to several triangular teeth.