This history reviews the information published on the controversy of the discovery of an alleged Neotropical ape, that resulted in one of the most notorious scientific frauds of the 20th Century. Ameranthropoides loysi Montandon 1929: The History of a Primatological Fraud reviews the information published on the controversy of the discovery of an alleged Neotropical anthropoid ape, that resulted in one of the most notorious scientific frauds of the 20th Century. Such finding supposedly occurred either in 1917 or 1918 while oil prospecting in the forests of the Tarra River region, located in the southwestern part of Lake Maracaibo, Zulia state, Venezuela. This case was as much discussed as it was unresolved. Detailed analysis of the archival sources suggested that the naming of such a primate was a fraud orchestrated by the Swiss physician George Montandon and de Loys himself, resulting in one of the most notorious scientific frauds of the 20th Century. This investigation provides previously unpublished information about this case -whose development seems to be resolved in Venezuela, through the account of a third witness, the Venezuelan physician Enrique Tejera. Esta historia revela la informacion publicada en torno de la controversia de un supuesto simio neotropical, que resulto ser uno de los mayores fraudes cientificos del siglo XX. Ameranthropoides loysi Montandon 1929: la historia de un fraude primatologico revela la informacion publicada en torno de la controversia del descubrimiento de un supuesto simio neotropical, que resulto ser uno de los mayores fraudes cientificos del siglo XX. Tal hallazgo presuntamente ocurrio en 1917 o 1918 durante una exploracion petrolera en la region del rio Tarra, al sur del Lago de Maracaibo, estado Zulia, Venezuela. Es un caso tan discutido como irresoluto. El analisis detallado de las fuentes documentales permite sugerir que la descripcion de dicho primate fue una farsa orquestada por el medico suizo George Montandon y por el mismo de Loys. La investigacion aporta informacion inedita sobre este particular -posiblemente uno de los fraudes cientificos mas escandalosos del siglo XX- y cuyo desarrollo parece quedar aclarado en Venezuela por el testimonio de un tercer testigo, el medico venezolano Enrique Tejera. Este texto fue escrito sin tildes ni otros caracteres especiales para evitar errores con el navegador.]