Frenopyxis spec.

Remarks: In 2023, I received sediment samples from Najla Baković, collected from the Jopićeva cave-Bent system, Krnjak, Croatia. I found several specimens with a single strut that was not horizontal, as in F. stierlitzi, but more erect and connected to the dorsal wall (see images). The two species are probably identical or at least closely related. See also Centropyxis bipilata, discovered and described from cave systems in Croatia and Bosnia & Herzegovina (Baković et al., 2019). That species may also belong to Frenopyxis, or even be identical with this one.

The images above show that this species closely resembles Penard’s drawings of Frenopyxis (Centropyxis) laevigata. It may in fact represent the same species.