Correct identification is a primary requirement of biodiversity management. Unfortunately, traditional taxonomies may not summarize true genetic biodiversity, a problem exemplified by the succineid land snails of the island of Hawaii. The succineids that currently occur in the study area were previously thought to belong to two relatively common species, Succinea cepulla and Succinea thaanumi. However, phylogenetic analysis of partial mitochondrial DNA cytochrome c oxidase subunit I sequences from 382 individuals from 13 sites suggests that there are at least nine robustly supported monophyletic species-level groups. Distinguishing these taxa in the field is impossible because most shell morphology characters are uninformative, and the taxa are not obligately associated with specific plant types. Of the 382 individuals sampled, 279 (73%) and 84 (21 %) belonged to two widely distributed groups. The other seven are rare (< 3 % each) and have restricted ranges. It is unclear if the rarity of these seven taxa is attributable to their cryptic ecology and behavior, or the timing of sampling. These findings demonstrate that biotic surveys remain critical even in presumed well inventoried areas and well known taxa. Assessment of these snails’ conservation status is ongoing, with a goal of providing managers with information to preserve as many distinct lineages as possible.