Rhododendron bhutanense D. G. Long & Bowes Lyon, Notes Roy. Bot. Gard. Edinburgh 45: 327 1988 publ. 1989.;
East Himalaya as per POWO;

An alpine Rhododendron: 1 correct image as above.
An alpine Rhododendron from Bumla pass- 14000ft, Arunachal pradesh

You mean to say that the attached image is of Rhododendron bhutanense as per your reply herein.
There are very few images of this species on the net. 
But the flowers in Rhododendron bhutanense appears to be reddish as per GBIF and Rhody garden

I am sure that this image is of Rhododendron bhutanense. I have seen it few times.



References: POWO  Catalogue of Life  The Plant List Ver.1.1  IPNI  GBIF (High resolution specimens) Bhutan Biodiversity Portal  rhodygarden
Pictorial guide to Rhododendrons of Sakteng Wildlife Sanctuary (page 7)- June 2018- Sonam Wangyel, Keesang Dorjee, Jangchu Wangdi & Thinley Wangdi