The subgenus Aristolochia is the most diverse of the three main ones and can be further subdivided into the American section
and the Afro-Eurasian and Australasian section
reaching as far as to Australia (and maybe even across Micronesia, Samoa & Tahiti).
Hotspots of typical Gymnolobus species can be found in the Mata Atlantica in Espírito Santo, Brazil and presumably in Amazonia,
where many species have been described yet but records of unidentifiable and presumably new species continue to appear regularly.
Other mentionable regions include Hispaniola and Mexico, from where dozens of new species have been recently described and rediscovered.
The only diversity hotspot for Diplolobus in Europe is located in SW Anatolia, Turkey + adjacent regions.
About 30 species, natural hybrids and quite a number of yet undescribed ones are known.
Other hotspots to be mentioned are Thailand & Vietnam from where more than a dozen species have been described in the past decades.
Moreover, several dozens of Aristolochia occuring in the Philippines & Indonesia are leading a hidden existence since many unassignable specimens most probably new to science are completely neglected even if available in terms of herbarium specimens.