Revised 06/08/06
Paratripyla has been synonymized with Tripyla and the family Tripylidae currently consists of the genera Tripyla, Tripylella, Tripylina, Trischistoma, Tobrilia and Abunema (Zullini, 2006).
Major separating characters are the number of gonads, the number of teeth in the stoma, and striation of the cuticle (Tsalolikhin, 1983; Zullini, 2006)..
Tripyla has paired gonads, striated cuticle, a single stomal tooth, and the whorls of seta well separated;
Tripylella has similar characteristics, but with a dorsal tooth and two subventral denticles, and a single whorl of six long and four short setae;
Trischistoma has a single gonad, a smooth cuticle, small stomal denticles and the whorls of setae separated; and
Tripylina is similar but with a dorsal and two subventral teeth and the whorls of setae close together
Tobrilia and Abunema have some characters that seem to separate them from the other genera and various authors have proposed their removal from the family. However, since alternative families have not been suggested, Zullini (2006) has elected to retain these genera in the Tripylidae.