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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. The Virgin Islands dwarf sphaero has a deep brown colour on its upper side, often with a speckling of darker scales. On average, it measures from its snout to its vent, and is nearly as small as a U.S. dime. At most, it weighs . There are several stripes or bars of lighter colouration behind the eyes and at the top of the neck that help distinguish it. There are no differences in colouration between males and females, although females are slightly larger in size. Its tail will regenerate when broken off. Little is known about its population size or its biology. ==Taxonomy== The Virgin Islands dwarf sphaero, also referred to as the Virgin Islands dwarf gecko, was discovered in the summer of 1964 by biologist Richard Thomas during a collecting trip along the dry, wooded slopes of Virgin Gorda in the British Virgin Islands. The holotype for ''Sphaerodactylus parthenopion'', MCZ 77211, was an adult female collected on 12 August 1964 on a hillside above Pond Bay. A total of eight paratypes were collected on Virgin Gorda and used to describe the new species. Classified as a species of dwarf sphaero or dwarf gecko (genus ''Sphaerodactylus''), it is characterised not only by its small body size, but also by a distinctive scale colouration pattern on its head, scales that are small but keeled (having a central ridge) and imbricate on its upper (dorsal) side; a generally uniform dark colouration of the dorsal side, a lack of granular scales on the mid-dorsal area, and a lack of colouration patterns around the shoulders (scapular region) and the pelvis (sacral region). Despite striking differences in appearance, ''S. parthenopion'' may be most closely related to ''S. nicholsi''. Like the diminutive ''S. parthenopion'' in the Virgin Islands, ''S. nicholsi'', the smallest endemic sphaerodactylid in Puerto Rico, is very small. The geographic range of another species, ''S. townsendi'', divides these two closely related populations, suggesting that ''S. townsendi'' evolved after ''S. parthenopion'' and ''S. nicholsi'' diverged. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Virgin Islands dwarf sphaero」の詳細全文を読む スポンサード リンク
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