Primula rebeccae A.J. Richards a synonym for Primula tenella King

Primula tenella was first discovered in the Chumbi valley, Tibet and was described by King ex Watt in Journal of the Linnean Society. Botany 20:13. 1882  (with a drawing) and also Hooker from Flora of British India 3:492.

Chumbi Valley - Reproduced by permission of Durham University Library and the Bentley Beetham Trust
W.W. Smith in The Genus Primula: Section Minutissimae. Trans. Bot. Soc. Edinb. 33:227-266. (1942),  says P. tenella was first collected in 1878 and again in 1879 in the Chumbi Valley, S. Tibet, by Dungboo, Sir George King’s collector. King recognized it as a new species and on the type (Dungaboo, anno 1878, in Herb. Calc.) has himself written the name giving the locality as Goop, 13 miles from Phari.” The holotype is presumably still at CAL, now Botanical Survey of India, Howrah, but there is no image of the type online.

At the Royal Botanic Garden Edinburgh is an isotype of a single plant with no location information or date, E00024523 and a second sheet collected by Dungboo in 1879 from Seain Chu(?), Chumbi, not available online. In Kew herbarium, there are two sheets online, K000639442, and K000639443. In Paris there is one sheet, P04907201The exact location of Goop is unknown, and access to the Chumbi Valley is restricted, so images from the approximate type location are not available.
Primula rebeccae from the original description
In 2000, Sabine and Georg Miehe found a Primula species growing near Jangothang, Bhutan (27°46'3.01"N 89°20'4.66"E) "at about 4000m and was confined to shady crevices amongst boulders in the vertically river-cut precipice between the flood-plain of the Pa Chu River and the adjoining river terrace. Here it grew in gregarious groups and clumps in a sandy-silt matrix on moss-dominated banks." The Miehe's also found similar plants higher up in the nearby Tso Phu Valley. This species was subsequently described by A.J. Richards as Primula rebeccae in Plantsman n.s., 3(1): 54. 2004. and the holotype is in Edinburgh, E00180782. The type location for P. rebeccae is about 36kms away from the type location for P. tenella.
Type location for Primula rebeccae

Subsequently, in 2008 and 2009, Margaret Thorne travelled to Jangothang and was able to photograph the population in detail showing this species to be highly variable. Notice the flower size, color, petal shape variation in the image above. Also notice how the leaves vary in shape with the exposure, back to front. See also the Species Gallery under P. tenella for more images.
Primula tenella by George Sherriff
In 1944, George Sherriff photographed Primula tenella (#16314) at the Lingshi Glacier, just 10kms away from the P. rebeccae type location. It is obviously the same species as that found by the Miehe's and even though the image is black and white, the pale eye of the flowers is apparent.

Primula caveana

In the original description of P. rebeccae, Richards compared the species to Primula caveana in Section Cordifoliae, a larger species which also grows in the same area. Differences given between the two species were the smaller calyx, filiform (thread like) pedicels, usually solitary flowers, emarginated petals and a pale eye and tube in P. rebeccae. However Richards did not compare the new species with P. tenella in Section Minutissimae, an obvious oversight. It is easy to see that P. rebeccae has the characteristic wedge shaped leaves shown in the original drawing with the original description of P. tenella and that it matches in everyway the (brief) original description of P. tenella.
Below is a map showing some historical collections and the location for P. rebeccae. 
Red- tenella, Blue - rebeccae, Yellow - caveana
(Yellow line is Tibet- Bhutan border)



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