Acanthocystis spinosa   Cavalier-Smith and von der Heyden, 2007

Diagnosis: cell size 25 µm. Radial spine-scales (4-17 µm) numerous (unlike spinifera), cylindrical, typically strongly kinked or curved (unlike spinifera) about a quarter to one third of the way from the basal disc on which they are centrally placed, with three apical teeth. Tangential plate-scales (11-13 µm) squat ovals with a slightly elongated central areola radically different from the much more elongated bilobed non-areolate ones of A. spinifera. Differs from clavata in the squatter plate-scales and almost nontapering apically truncated and kinked spine-scales.
Type location: Windlesham Arboretum, UK.