The candidate species of Otus from Príncipe A female specimen MHNC-UP-AVE7000, showing colouration in life (available also in the Macaulay library (ML): ML470442301; grey-brown morph) B female (left, sample P9-037) and male (right, sample P9-038) grey-brown morphs captured at Boca do Inferno on January 28, 2019 (ML470438621) C rufous morph individual photographed at Ribeira Porco area on July 04, 2016 D daytime sighting of a grey-brown morph individual between Rio São Tomé and Ribeira Porco on January 19, 2019 (ML470443361, only the rufous upperparts are clearly seen) E grey-brown morph individual photographed in the Ribeira Porco area on January 21, 2019 F fully developed brood patch of a female rufous morph (sample P8-001) captured in the Ribeira Porco area on January 20, 2019 (ML470440211). ML – Macaulay Library. Photographs: A – HP B, D, F – MM and BF C – PV E – Paul van Giersbergen.