Aryeh's field guide to the diversity of American Urinal (americanas urinalas), including related species in the porcelainas americanas family, although very thorough (he included the extremely rare horned urinal [urinalas cornu]) missed a few species. Specifically, urinalas scaphium, which can be found in the Yeshiva University's Pollack Library and Belfer Hall.
This species appears with both automatic (in the library) and manual (in Belfer) flush traits. While it is unclear which of these is the dominant trait, the automatic flush variety are notoriosly moody, and tend to flush with little provocation, so one would hope that it is reccesive. Additionally, unlike its cousins which regularly maintain a small amount of water, this species of Urinal maintains a large volume of water. For these reasons, it is suggested that perhaps this species is the missing link between the larger toilet bowls (americanas standardium) and urinals.
Although Aryeh suspects that sinks (cleanlinus basinium) have a symbiotic relationship with Urinals, it is widely accepted that urinal cakes (crustum urinalas) do in fact maintain this symbiotic relationship.
Finally, there is a species of Urinal that has proliferated in recent years which uses no water at all - the Waterless Urinal (urinalas aqualess) -which lives in more arid climates. However many experts suspect that this species is the result of genetic engineering, not a recently discovered native urinal.