Family Leptoplanidae Stimpson, 1857

Diagnosis (from Faubel, 1983): Leptoplanoidea with varying body outline and with paired clusters of cerebral and tentacular eyes. Ruffled pharynx central or anterior to the centre of the body. Male genital apparatus directed backwards behind the pharyngeal cavity. Gonopores separate. Prostatic vesicle usually with poorly differentiated glandular lining and without a distinct muscle wall, as male complex is enclosed in a massive strong muscle structure.