Rediscovery of Rubus sikkimensis Hook. f. from Northeast India and lectotypification of its name

Rubus sikkimensis Hook. f. is an endemic species of eastern Himalaya, described from Sikkim by J. D. Hooker in 1849. Since then, the species was never collected from India until its rediscovery from Sikkim in 2019 after a gap of 170 years. Another collection from Tawang, Arunachal Pradesh, India, made by the author in 2021


Introduction
Rubus L. is one of the largest genera of Rosaceae distributed mostly in Northern Hemisphere (Lu, Boufford, 2003).Rubus is a very complex genus due to the presence of polyploidy, apomixis, and hybridization.According to Carter et al. (2019), the genus originated in North America and migrated repeatedly to the other continents.The exact number of species is uncertain due to high level of hybridization, but it is estimated that there are 1471 accepted species (POWO, 2023).The genus is classified into 12-15 subgenera (Focke, 1910(Focke, -1911(Focke, , 1914;;Jennings, 1988;Daubeny, 1996).In India, Rubus is represented by 74 species and 6 varieties which are restricted to hilly terrains and are mostly distributed at elevations between 1800 and 2200 m a. s. l. (Gupta, Dash, 2018;Gupta, 2019;Gupta, Kumar, 2023).
During the author's field exploration to Arunachal Pradesh in 2021, an unusual taxon of Rubus was collected.After examination of its morphological characters and study of relevant literature (Hooker, 1878;Long, 1987;Lu, Boufford, 2003;Boufford et al., 2011;Ansari, 2014;Gupta, 2019), it was determined as R. sikkimensis Hook.f. (subgenus Idaeobatus Focke).Comparison with the species protologue and type specimens confirmed the correctness of determination.During my study of herbarium specimens at Sikkim Himalayan Regional Centre, BSI (BSHC), another specimen of R. sikkimensis (R. Gogoi and N. Sherpa 40823) collected in 2019 from Sikkim has been traced.At the same time, the specimen D. S. C. Raju and S. Singh 5680 (BSHC, CAL) cited by Ansari (2014) in his survey of Rosaceae of Sikkim as R. sikkimensis is found to belong to R. moluccanus L.
Rubus sikkimensis was first described by Sir J. D. Hooker (1878) based on his collections made in 1849 from Lachen valley of Sikkim Himalaya (India).Later, it was also recorded from Bhutan and China (Long, 1987;Lu, Bufford, 2003).However, it was never recollected from the territory of India since 1849.Therefore, the collection of this species from Sikkim (R. Gogoi and N. Sherpa 40823) is reported here as a rediscovery of this species after a gap of 170 years, whereas the collection from Tawang (V.Kumar 20917) is a new distributional record for Arunachal Pradesh, India.A detailed description, phenology, field photographs and an image of the type specimen are provided below along with a comparison of R. sikkimensis with its allied species to facilitate its easy identification (Table ).

Materials and Methods
The specimens were collected from Tawang district of Arunachal Pradesh in 2021 and field photographs were taken using Nikon D7500 DSLR camera.Herbarium specimens were made using the standard protocol and deposited at PLP herbarium.Specimens along with dissected floral parts were examined under Olympus SZ61Tr stereo-zoom microscope and identified using relevant literature.The identity of species was confirmed by studying herbarium specimens/images deposited at BSHC, K and P. The lectotype of Rubus sikkimensis is designated here according to the International Code of Nomenclature for algae, fungi, and plants (Turland et al., 2018).

R. pungens
Cambess.Kumar V. Rediscovery of Rubus sikkimensis Hook.f. from Northeast India and lectotypification of its name