Two new spumellarian radiolarian genera, Mendacastrum and Domuzdagia,
are described from the lower Tithonian and lower Pliensbachian
respectively. Both have a spherical cortical shell of actinommid type
and a spherical or subspherical double medullary shell with the inner
medullary shell of hagiastrid s.l. type. The inner medullary shell of
Mendacastrum is of dactyliosphaerid or higumastrid s. sit. type, whereas
that of Domuzdagia is of angulobracchiid type. Since they cannot be
assigned to any described Mesozoic pyloniacean families, they are
considered as type genera of two new families: Mendacastridae and
Domuzdagiidae respectively.