Arachnostega (trace fossil) on a cyclidan (Crustacea) carapace from the Pennsylvanian of Ohio, USA

We report the irregular Arachnostega gastrochaenae Bertling, 1992 burrows on the cyclidan carapace Ohioclus columbianensis Schweitzer et al., 2025, from the Upper Pennsylvanian (Missourian, ~Kasimovian) of Ohio, USA. These burrows were previously described as fungal hyphae. This is the first evidence of Arachnostega on a cyclidan carapace, and this ichnogenus itself is rare in the Upper Paleozoic. Ostracods Hollinella sp. indet. were found near the cyclidan carapace, indicating a marine genesis of the deposits. We suggest a possible relationship with ostracod-feeding burrows and Arachnosteg