Fig. 7

Lytvolasma aheimerensis n. sp. A External view of the specimen RA (2), showing a straight corallite with partly eroded calice and non-preserved apical part, positions of thin-sections indicated. B–D Successive transverse thin-sections in the early preserved growth stages, shows very thick major septa joining together near the centre. The cardinal septum is deformed in D. E–G Successive thin-sections in the early mature stages show the formation of a stereozone with a free axial area, shortening of the cardinal septum with maturity and the longest counter septum with a rhopaloid end. H–I Two transverse thin-sections below the calice, deformed due to rejuvenation in H and lateral compaction in I. Scale bars: 2.5 mm, except A: 5 mm. Black dots indicate the positions of cardinal septum (below), counter septum (above) and the two alar septa