Not a species I have yet had privilege of seeing in the cellulose, but a BIG thanks to Ricardo for passing these photos my way. A Costa Rican endemic, Ruellia golfodulcensis is highly distinctive by its calyx alone. There is only one other species that, IMO, approaches a similar morphology, and it is Brazilian. I always thought Ruellia golfodulcensis had pure white flowers (based on herbarium labels), but so clearly you can see traces of anthocyanins in one of these photos. Learn something new every day!

Wild collected, Kriebel (voucher unknown); Photo by Ricardo Kriebel