Arenaria thangoensis W.W.Sm., Rec. Bot. Surv. India 4: 180 1911. ;

World environment day is appropriate time to inform our eFI family that in last year’s botanical exploration we managed to rediscover a threatened endemic species from a remote Himalayan locale after nearly 106 years.
Arenaria thangoensis W.W.Sm. (Caryophyllaceae) is a tiny plant and this species was described in 1911 from Tangu (Thangu) area of Sikkim in the Eastern Himalaya. This species was never recollected after type collection either from type locality or anywhere in the Himalaya or Tibet and, therefore, known by the type collection only (Srivastava et al. 2015). During a floristic exploration in the Kuari Pass alpine zone (3600-3700m above sea level, Chamoli district, Uttarakhand), which happens to be the type locality of ‘Endangered and endemic’ Arenaria curvifolia Majumdar, my student Satish collected Arenaria thangoensis. This collection is a rediscovery of this threatened species after 106 years and demonstrates that it is an extant (living) species and thriving well in the area. Rediscovery from nearly 950 km (aerial distance) away from its originally known population makes it more interesting.
Image of the species attached here is a first ever photo of live specimens of this species in the world.
Rediscovering a species is a joy for me and sharing it with ardent nature lovers of eFI fraternity increases it manifolds.
This rediscovery is yet not published, though in communication with a journal.

Nice to read about the rediscovery. Thanks for sharing

No better way to celebrate World Environment day.
Thanks, Rawat ji for telling us in a nice way.

Thank you…. In fact it is Satish (my student) who deserve appreciation for this botanical exploration.
Your nice words give me strength in the arduous terrains of the Himalaya.

Celebrating this day could not have been better …

Congratulations to young explorer Satish Chandra.. who is following your footsteps, this is really a gift to discover a threatened plant after such a huge gap…many thanks for sharing these rarest pics !!

Attaching here the publication related to this rediscovery. Attachments (1) – Arenaria thangoensis.pdf

Naturally read this with interest. Checked with Flora of Bhutan Vol 1 Part 2 which covers Caryophyllaceae.
The authors have A.thangoensis W.W.Smith (and A.pharensis McNeil & Majumbar) only as a synonym of Arenaria littledalei Hemsley. What are your thoughts about this? This account for Caryophyllaceae of the region (incl. Sikkim and Chumbi) was published back in 1984.
This taxon was recorded from Sikkim (Chugya, Naku Chu and Thango) plus Chumbi (Phari plain) @ 4360-4570.
I see that ‘The Plant List’ accept A.littledalei and A.thangoensis as separate species.
There are specimens of A.littledalei (from Central Tibet and Sikkim) in the Kew herbarium, see:
Please explain how these differ from A.thangoensis?

Flora of Bhutan have taken a broad circumscription of A. littledalei giving no consideration to merosity of flowers (sepals-5 in A.pharensis while sepals 4 in A.littledalei) considering it as a variation; thus merging these species into A. littledalei. It is very similar to the case of Cotoneaster genus where Fryer consider up to 400 species worldwide while broader circumscription gives 50-70 species in world. (Pl. See note in Flora of Nepal at- All these species mentioned by you (A.pharensis (=Goringia pharensis), A.littledalei, and few others from China like A.reducta, A. saginoides etc are closely related to each other and belong to subgenus Odontostemma section ‘Reductae’ (mentioned in some Chinese works). These species are included and differentiated in Flora of China.
Arenaria thangoensis is now known as Odontostemma thangoensis (pl. See after a recent splitting of Arenaria genus following the molecular studies. 
A.thangoensis is close to A. pharensis (a 5-sepal species) but differ from it by one line of hairs on stem (2 in A.pharensis), leaves biconvex, succulent, obovate to oblanceolate (linear to linear lanceolate in A.pharensis), 2-5 stamens (2-3 in A.pharensis). However, these characters are not very convincing and a revision of this Sino-Himalayan group of Arenaria is needed. It is worth mentioning here that no species of this group (baring A.thangoensis recorded by us) are known from Indian western Himalaya.
Finally, the type specimens (Holo and iso) collected by Smith and Cave in 1909 are in Central National Herbarium, Howrah (CAL) and DD and were examined by me personally to compare our specimen. 
Arenaria s.l. has been splitted to may genera recently. We now have Arenaria s.str., Odontostemma, Shivparvatia (=Solitaria) and Eremogone.

Thanks for your response which raises a number of really important issue as to the identification of plants in general as well as specifically in connection with this taxon.
I shall respond and comment both about the general issues and about A.thangoensis but this must wait a bit as I am rather busy at present with another lecture to prepare for early next week and have an awful lot still to complete to finalise the March 2017 Journal of the Himalayan Plant Association – of which I am both Editor and major contributor!
Some of my comments will need to be worded with care….. 


The Plant List Ver.1.1
 IPNI  BSI Flora of India  India Biodiversity Portal  IBIS Flora  1997 IUCN Red List of Threatened Plants By Kerry Scott Walter, Harriet J. Gillett, World Conservation Monitoring Centre