(Cleve, 1900)
Diagnosis: Long, cylindrical bowl ending in thick pedicel, always shorter than bowl. Probably the Xystonellopsis species erected by Kofoid and Campbell, 1929 (see p. 242: Fig. 480-485 therein) on the basis of Brandt (1906-1907) and Laackmann (1910) can be lumped with Xystonellopsis heros.
Ref.: Laackmann (1910).