Description: Triangular-shaped nannolith formed of three blades with c-axis perpendicular to length. The median blade is wider than the two lateral blades and the c-axis lies in the plane of this blad,e hence in usual angle of rest the nannolith shows high birefringence, but inverse optical orientation (blue with gysum plate when orientated SW-NE). In alternative orientaton it is symetrical and shows low birefringence.
Typical forms are symmetrical but specimens with a spine developed from the median blade occur in upper part of range.
Remarks:
Range: NN2-6.
Synonym: Triquetrorhabdulus martinii Gartner, 1967.
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