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''Vitreorana oyampiensis'' is a South American frog species in the glassfrog family (Centrolenidae). It was first found in a restricted region of Brazil north of the lower Amazon River and in the Guyanas. Its range is bordered northeastwards by the Atlantic and in the west essentially ends at the tepui region of the Guyana Shield, barely into Venezuela where it has only been recorded once, from the Gran Sabana.〔La Marca & Reynolds (2008)〕 Formerly, it was believed to occur further westwards deep into Venezuela, but this population is now known to be a distinct species (Helena's glass frog, ''V. helenae''). But its range might extend further upstream the Amazon River, as the species also seems to occur in lowland Colombia and Ecuador. When this population was first discovered, it was compared with frogs subsequently recognized as ''V. helenae'' and thus mistakenly described as a new species ''V. ametarsia''. Its local name in French is cochranelle des Oyampis ("Wayampi glass frog").〔Guayasamin ''et al.'' (2008), Kok & Castroviejo-Fisher (2008), La Marca & Reynolds (2008)〕 ==Description== ''Vitreorana oyampiensis'' is a tiny glassfrog that lacks humeral spines in males and has a lobed liver. Adult males measure 17–21 mm from the snout to the vent, while the females are a bit larger at about 19.5-24.5 mm snout-vent length. Its snout tip is neatly rounded. The translucent eardrum is visible but not large, measuring about one-fourth to one-third of the eye's diameter; the tympanic annulus is not hidden except for the dorsal margin which is covered by the supratympanic fold.〔Guayasamin ''et al.'' (2008), Kok & Castroviejo-Fisher (2008)〕 Their color looks pale green above, but in fact this is much due to their green skeleton being visible through the weakly pigmented skin. This species has many clear and fine blackish spots decorating its upperside, which may appear as if they were suspended a bit above the greenish background in very weakly pigmented specimens. Helena's glass frog, ''V. helenae'' on the other hand has a more heavily pigmented yellowish-green upperside (but also the characteristic spots, which led to them being confused). The back has a smooth shagreen-like texture, while the entirely transparent belly skin has a grainy surface. The forward quarter to half of the parietal (outer) peritoneum is white, while the rest is transparent, allowing to see the frog's interior. The pericardium and the inner peritoneum covering the gastrointestinal tract are white, while the inner peritoneum protecting the brown lobes of the liver is also transparent except for the anterior tip (where some iridophores may be present). The iris is greyish white with a network of thin dark grey lines; in Helena's glass frog it is bright yellow. Melanophores are abundant on the dorsal surface of the two outer but absent on the two inner fingers. Preserved specimens are lavender above, with the dark spotting remaining unchanged; the white iridophores of the viscera can dissolve in preserved specimens.〔 The dentigerous process of the vomer carries one tooth at most; it can be entirely toothless. The males have a type-I nuptial pad; the prepollex stands out at the base of the first finger. The toes and the outer two fingers of ''V. oyampiensis'' are webbed; the first two fingers (of which the first is a bit longer) are completely free. The webbing formula for the outer fingers is III (2−-21/3) – (1+-2−) IV; for the toes, it is I 1 – (2−-2) II (1-1+) – (2-21/4) III (1+-11/2) – 2+ IV (2-21/3) – 1 V.〔 The disc at the tip of the third finger is mid-sized, larger than the eardrum but less than half the diameter of the eye. This species has tubercles on the thighs below the vent, but only low folds with no iridophores on the ulna and inner tarsus.〔 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「Vitreorana oyampiensis」の詳細全文を読む スポンサード リンク
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