Scolecia urbimetra Hook, Radtke, Campbell et Golubić, 2024

Key feature (diagnosis): S. urbimetra morphotype is composed of a shallow, regularly spaced, and branched trace, reminiscent of a city map (Figs. 2d (upper right), 17e, f), which is integrated into the substrate surface. The replicas show a serrated outline of the network of grooves that are more sparsely branching. Direct SEM of the attacked pteropod shell (Fig. 17f) illustrates that the lines created by the trace are, in fact, grooves etched into the carbonate shell, and their serrated appearance reflects the removed aragonite crystallites of the shell. These trenches are quite uniform and narrow 1.08 ± 0.25 μm (n = 123) wide. Branches occur either as alternate or opposing, with no apparent regularity, leaving large unaffected areas of the shell surface between them. The branching angle is variable, monopodial over smaller surface areas and sympodial over larger surface areas. The distances between branch points are extremely variable, ranging from 7 to 150 μm. The tracks often bend or suddenly change direction, rarely remaining straight for any distance (Fig. 17d-right)