Phase-contrast micrographs of the MCOs in Dactylogyrus romuli n. sp. (a) and D. remi n. sp. (b). Characters of interest are indicated by arrows: (1) distal fold without expanded proximal portion, (2) medial fold on the opposite side to the distal fold, (3) base markedly elongated, (4) distal fold with expanded proximal portion (cornet shaped), (5) medial fold on the same side as the distal fold, (6) base slightly elongated.