It's time of the 'big-flowered' Bifrenarias! This one I pictured in three stages: 21-oct-07, the buds with the characteristic big spur (thyrianthina was formely named magnicalcarata, 'with a big spur'), than in 23-oct-07 imature flowers, and today the fully opened flowers. The last pic shows the long spur, another distinctive characteristic of thyrianthina.