Dominikae actually comes with a close contender for second-smallest land snail, too: Angustopila subelevata, a snail described in the same paper, has a shell about .87 millimeters high on average.
An additional five new species are also described, all around 1 or 2 millimeters at the largest point in their shells.
Finding and identifying a shell the size of a (really small) piece of gravel is obviously a challenge, so it's possible that even smaller critters have evaded detection.
"Investigating tiny-shelled land snails is important for assessing biodiversity and natural history as well as for establishing the foundation for studying the evolution of dwarfism in invertebrate animals," the authors write in the study. They hope to determine the evolutionary process by which some land snails became so tiny while others have grown massive, but they write that they'll need to collect and identify more species first.
Dominikae may sound impossibly tiny, but the new species dwarfs its cousins in the sea. The smallest marine snail, Ammonicera minortalis, grows no bigger than .46 millimeters, and can be as small as .32 millimeters at the widest point of its shell.