Very nice picture! Agree with it being made by Ero sp. According to Roberts, two of the Ero species that produce circular (as opposed to elongated) egg sacs are E. cambridgei and E. furcata.#9 Really looks like an Ero sp. eggsac
E. tuberculata makes the elongated sac, so you can rule it out as having produced the one you photographed. Of course, there might still be one in your cellar.In my country live :
Ero aphana (Walck. 1802)
Ero cambridgei Kulcz. 1911
Ero furcata (Vill. 1789)
Ero tuberculata (De Geer 1778)
tomorow I will try to take some new pictures