Which has fewer species, Rossioglossum or Bruckenthalia?
Rossioglossum:  It has 9 currently recognized species (as of May 2014), all native to Mexico, Central America, and northern and western South America. Bruckenthalia: Bruckenthalia is a genus of plants consisting of only one species, Bruckenthalia spiculifolia (spike heath) an evergreen shrub native to southeastern Europe and Asia Minor.
i don't know