Boxplots showing shell widths on Potamolithus spp. Horizontal Bar, median; vertical bar, whiskers with minimal and maximum observations. 1 P. ribeirensis 2 Potamolithus sp. 1 3 P. karsticus 4 Potamolithus sp. 2 5 Potamolithus sp. 3 6 Potamolithus sp. 4 7 Potamolithus sp. 5 8 Potamolithus sp. 6 9 Potamolithus sp. 7 10 P. troglobius 11 Potamolithus aff. troglobius12 Potamolithus sp. 8 13 Potamolithus sp. 9 14 Potamolithus sp. 10 15 Potamolithus sp. 11 16 Potamolithus sp. 12. Black bars, epigean species; gray bars, troglophilic species; white bars, troglobitic species; circles, outliers; *, extremes.