Nepenthes ephippiata is a highland tropical species found only in extremely remote areas of central Borneo, such as the Hose Mountains. The species is closely related to lowii and produces upper pitchers with lid exudate in a similar manner. It's very likely that the upper pitchers have a similar excrement harvesting function like Nepenthes lowii; however, due to the extreme remoteness of their habitat this has yet to be confirmed or well studied.
The Hose Mountains form of ephippiata has a larger stature than the forms known from Gunung Raya in Kalimantan. The pitcher shape is also quite unique in that they tend to be larger and have more purple coloration. I've found they grow much more quickly and are more tolerant than the other forms circulating in cultivation. Highly recommended!