Light and scanning electron microscopy of attachment organs of three monogeneans (Monogenoidea: Polyopisthocotylea).

Abstract

The anterior and posterior attachment organs of three species of monogeneans, Diclybothrium armatum Leuckart, 1835, Neodiscocotyle carpioditis Dechtiar, 1967, and Mazocraeoides olentangiensis Sroufe, 1958, were examined in whole-mount light-microscope preparations, and by scanning electron microscopy (SEM). Bothria with openings of gland cells were identified anterior to the oral opening in D. armatum, but sucker-like units evident in light microscopy were not seen by SEM in N. carpioditis and M. olentangiensis as these are apparently internal developments. Holdfast units of the opisthaptor of the three species are of three distinct forms: spring-like clamps in D. armatum, muscular clamps in M. olentangiensis. and suckers with sclerotized rims in N. carpioditis. Hooks in the opisthaptor appendage of D. armatum all function to form a C-shaped double-pronged hook unit. Two of the three pairs of hooks in the posterior end of M. olentangiensis project slightly from the body, while the third pair in this species and the single pair of hooks in N. carpioditis are entirely internal, probably non-functional and vestigial.