Bothrostoma Stokes, 1887 (ref. ID; 2014)
Class Polyhymenophora: Subclass Spirotricha: Order Heterotrichida: Suborder Heterotrichina (ref. ID; 2014)

[ref. ID; 2014]
Body elongate, flattened dorso-ventrally, anterior narrowed to a blunt point which is slightly twisted. Buccal cavity extensive, occupying half to three quarters of the ventral body surface with the oral aperture situated equatorially or in the posterior body part. Body without armour, spines and cirri. Single rounded macronucleus with an adjacent micronucleus. Sapropelic. The genus is easily distinguished from the other two metopid genera by its absence of rib-like armour (present in Tropidoatractus) and the position of the perizonal cilia (which are on an anterior hoop in both Palmarella and Tropidoatractus.)
Quote; Colin R. Curds, Michael A. Gates and David McL. Roberts "British and other freshwater ciliated protozoa Part II Ciliophora: Oligohymenophora and Polyhymenophora" Cambridge University Press, 1983 (ref. ID; 2014)