Phymatolithon sp.

Dey, Rikee, Basso, Daniela, Chakraborty, Arindam, Roy, Lopamudra, Bhaumik, Ajoy Kumar & Ghosh, Amit K., 2023, Rhodolith-forming coralline red algae in the CaCO biofactory - A case study from the Serravallian of tropical northeastern Indian Ocean, Comptes Rendus Palevol 22 (26), pp. 541-567 : 546

Phymatolithon sp.

( Fig. 3C, D)

DESCRIPTION

Growth form encrusting to foliose, thallus monomerous; the VC is non-coaxial with zonations in PF. The cells of VC more or less rectangular, measuring 16-20 µm in length and 12-14 µm in diameter ( Table 1 ). Peripheral filaments composed of 6 to 12 cells thick, each zone showing a gradual transition of long and short cells, cells of the peripheral filaments measure 8-10 µm in length and 6-9 µm in diameter. Cell fusions present in both VC and PF. Epithallial cells are visible and non-flared in some specimens. Tetra/bisporangial conceptacles are multiporate, buried within the thallus, conceptacle roof distinct, conceptacles raised above the thallus surface. Conceptacle chambers 360 to 480 µm in diameter and 140 to 180 µm in height ( Table 1 ).

REMARKS

The illustrated specimens are similar to the Phymatolithon calcareum (Pallas) Adey & McKibbin described from the upper Miocene of Santa Maria Island, Azores, NE Atlantic Ocean ( Rebelo et al. 2014), but the encrusting to foliose growth form does not match the description of P. calcareum , which is commonly fruticose. For this reason, we leave this specimen in open nomenclature. According to Rasser & Piller (1999) the genus Phymatolithon is common in the late Eocene of the Austrian Molasse Zone.