The Old World genus Trichosanthes has flowers with strikingly fringed petals, and Linnaeus therefore placed a species from Hispaniola that he only knew from an illustration (showing such fringed petals) in that genus. The species remained hidden from the attention of subsequent workers until acquiring new relevance in the context of molecular-biogeographic work on Cucurbitaceae. Based on molecular data, it is the sister to all Sicyeae, a New World clade of about 125 species in 16 genera. We here place this species in a new genus, Linnaeosicyos, describe and illustrate it, and discuss its phylogenetic context using molecular and morphological data. Judging from Dominican amber, elements of the flora of Hispaniola date back 15–20 my, and the occurrence on the island of at least five endemic species of Cucurbitaceae (Linnaeosicyos amara, Melothria domingensis, Sicana fragrans, and the sister species Anacaona sphaerica and Penelopeia suburceolata) points to its long occupation by Cucurbitaceae.