Main morphological characters of Isomermis lairdi from Jeleznitsa (A–H). A, B Mature male, anterior region with terminal mouth opening (A) and amphid (B), lateral view. C Female postparasitic juvenile, posterior end with tail appendage D Mature female, posterior end E Female, vulvar region with vagina F Male, spicules G Male postparasitic juvenile, tail region with tail appendage H Mature male, tail region. Scale bars: A, B: 50 µm; C–F: 70 µm; G, H: 100 µm.