The Carolus clade recognized here is based on the phylogenetic tree published by Davis & Anderson (2010 [pdf]). The support for the clade is modest (75 bootstrap percentage), so it comes as no surprise that the morphology shows no synapomorphies for the whole clade. All the genera have interpetiolar stipules except Tricomaria, which lacks stipules, but that character is very probably plesiomorphic. The one interesting character of the clade is that all the genera except the anomalous Flabellariopsis of equatorial Africa have abaxially sericeous petals, which are almost unknown in the sister genus, Heteropterys.
Carolus – New World tropics from southern Mexico to the Lesser Antilles and South America as far south as Bolivia, Paraguay, and southern Brazil [map]
Dicella – Costa Rica, South America [maps]
Flabellariopsis – equatorial Africa [map]
Hiptage – southeastern Asia from Pakistan and India to Taiwan, the Philippines, and Indonesia [map]
Tricomaria – western Argentina [map]