The Virgin Islands dwarf sphaero or Virgin Islands dwarf gecko (Sphaerodactylus parthenopion) is a species of gecko and also one of the smallest terrestrial vertebrates. It has only been found on three of the British Virgin Islands: Virgin Gorda, Tortola, and Moskito Island (also spelled "Mosquito Island"). It was discovered in 1964 and is suspected to be a close relative of Sphaerodactylus nicholsi, a dwarf sphaero from the nearby island of Puerto Rico. It shares its range with the big-scaled least gecko (S. macrolepis), which is found in leaf litter. Unlike this larger gecko, the Virgin Islands dwarf sphaero lives on drier hillsides, yet prefers moist microhabitats found under rocks because it lacks the adaptations necessary for preventing water loss, which is a significant problem due to its small body size.