In the province of Mendoza was recorded the scientific find, inside a cave, of a species of cave arachnid completely unknown until now. As reported by the medium «Montevideo Portal», the strange specimen would belong to the opiliones, or better known as «patonas spiders», very common in wet areas but not in more arid places, such as Mendoza, where it was found. In this regard, the National Council for Scientific and Technical Research (Conicet) of Argentina indicated that the new species of opilion was found in the basaltic region of Payunia (south of Mendoza), in a volcanic cavern of about 800 meters known as Doña Otilia.The finding of the first copies would be the product of the work of Marcela Peralta, researcher of the Miguel Lillo Foundation, who sent her material to Luis Acosta, member of the Institute of Diversity and Animal Biology to be analyzed. This is why the new opilion was baptized, paying homage to its discoverer, as «Otilioleptes Marcelae». The morphological analysis of specimens of both sexes of this new arachnid performed by Acosta, determined that it is an exclusively caveman species, that is, that develops the entirety of its life within the boundaries of the cave.As in other cases of cave species, Otilioleptes marcelae shows a series of morphological characters that are related to life within a cave. The Otilioleptes marcelae would be the second fully caveman opilion reported in Argentina. The first was Picunchenops spelaeus, found in a cave in the province of Neuquén (west), but the one found in Mendoza is the first found in a lava tube in South America.