Pterygodium nigrescens flower dark median sepal

The individual Pterygodium nigrescens flower in picture has a surface roughness consisting of tiny, shiny bulges mostly in rows on the dorsal sepal and flanking lateral petals folding tightly over the top. The lateral sepals are mostly hidden on the sides with the lip and its appendage out of the light below (Liltved and Johnson, 2012; Manning, 2009; Pooley, 1998; iNaturalist).