Oldenlandia species ?- Cherrapunjee area, Meghalaya

Request for ID of herb : 12 posts by 4 authors. Attachments (4)
Request ID of a herb. Photographed in Cherrapunjee area, Meghalaya in September 2017; 
Plant small, about 1 ft in height; lithophytic, growing on rocks at the stream edge under semi-shaded area; about 1500 msl 

Rubiaceae member ?

Looks like Oldenlandia sps
Houstonia longifolia Gaertn.  ???

Did you check with the suggested id?
Two choices have been suggested. Both appear to be strong contenders. Couldn't decide the closer one yet!!

I think does not match with images at Houstonia longifolia (long-leaved bluet): Go Botany

I haven't worked on this yet..

Could not find any match as per comparative images at Hedyotis.