Rarest within the genus is the Middle Ordovician species Gravicalymene magnotuberculata, which is also amongst the rarest of all Calymenidae and regionally confined to two exposures in New York State.
The Middle Ordovician species Gravicalymene magnotuberculata holds a unique position as the most scarce within its genus, further solidifying its rarity status alongside other Calymenidae species, which are only found in two specific locations in New York State.