False Eranthemum (Pseuderanthemum maculatum [Syn: Pseuderanthemum carruthersii])

Introduced ornamental shrub cultivated in gardens. Native of Polynesia. Flowering throughout the year.
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