Two varieties cultivated in Sri Lanka.
1) variety atropurpureum [or Pseuderanthemum atropurpureum - now a synonym of Pseuderanthemum carruthersii*]- Above picture
2) variety reticulatum with white flowers with red dotted center [or Pseuderanthemum reticulatum* now a synonym of Pseuderanthemum carruthersii]
* http://www.theplantlist.org/tpl1.1/record/kew-2406673