Ummidia is among the most ancient, highly diversified, widespread, morphologically static, and cryptic genera of mygalomorph spiders. Therefore, it constitutes a unique subject to investigate evolutionary processes, but also a very challenging group to study. Here, we provide the description and profuse illustration of the male and female of a new species of Ummidia from the Dominican Republic, which also constitutes the first record of the family Halonoproctidae for the island of Hispaniola. With this report, the presence of Ummidia is confirmed for three of the four Greater Antillean islands (Jamaica, Cuba, and Hispaniola), as well as for Guana (with a recent common history with Puerto Rico). Thus, the Antillean Ummidia distribution is consistent with a possible ancient terrestrial dispersal from South America during the Late Eocene to Early Oligocene, a pattern also shared by other philopatric organisms.