Modelling the cortex and hypothesis for the “head” of Suppiluliumaella schlagintweitii n.sp.

We describe two new species of green algae in Dasycladales from the Lower Cretaceous of the Eastern Carpathians (Romania), Suppiluliumaella schlagintweitii n. sp. and Triploporella loducai n. sp. The two new taxa display a mineralization coating most of the thallus, possibly casting light on their growth pattern. Suppiluliumaella schlagintweitii displays a differentiated, club-shaped thallus with a very elongated vegetative part below the fertile zone (“head”) and a corticated external layer, suggesting a Neomeris type of growth. We further describe a possible mineralized juvenile growth stage. Triploporella loducai is characterized by a rather short cylindrical thallus with a reduced vegetative region (sharp tapering rounded lower end), seemingly following a growth type resembling that of spherical Bornetella.

Methods
The measurements related to the “head” of Suppiluliumaella schlagintweitii has been made on enlarged photos at 40x of specimens PSM RT37 and DiSTAR-BA.4283.2.

Biometric measurements were processed by Excel.

A procedure to evaluate the arrangement of cortical laterals is here proposed taking cortical parameters from the thin section.

Distance between the axes of two adjacent primary laterals at the cortex (dp) was computed as

dp = pDcx / w.

The area (Amesh) of a single hexagonal mesh of the “head” was computed as

Amesh= P*a/2.

The side surface (A) of the cylindrical cortical band at the equator was calculated as

A = p*Dcx*h.

The esteemed number of laterals (Nw) to be contained in the cortical band was computed as

Nw = A/Amesh.

For details see Supplementary_text.