<i>Koenigia arunachalensis</i> sp. nov. (Polygonaceae), a new species from Eastern Himalaya, India

Koenigia arunachalensis sp. nov., a new species of Polygonaceae, from Tawang district of Arunachal Pradesh, India is described and illustrated. A detailed description, illustration, color photoplate with photographs of habit and habitat, and a distribution map are provided. The new species closely resembles K. nepalensis but can be distinguished by its lanceolate leaves (versus ovate), bipartite ochrea (versus funnel‐shaped), lanceolate bract (versus elliptic‐ovate), inflorescence with 8–25 flowers (versus 5–10 flowers), pedicel 1.8–2.2 mm long (versus 1–1.5 mm), stamens 5 (versus 3) and staminodes absent (versus present, 5). It is highly abundant in the study areas and was observed from the Indo‐Bhutan border to the Indo‐Tibet border. Provisionally, the new species has been assigned as Data Deficient (DD) following IUCN guidelines.