Strobilanthes affinis (Acanthaceae): a new addition to the flora of Manipur, India

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The genus Strobilanthes Blume (1826: 781) from the family Acanthaceae (Wood & Scotland 2009) is a genus of perennial flowering herbs and shrubs with about 453 species worldwide Mabberly 2017;Thomas et al. 2019Thomas et al. , 2020Wood et al. 2019). In India, the genus is represented by ca. 150 species (Scotland 1998;Gopalan & Chitra 2008;Karthikeyan et al. 2009;Wood 2014;Biju et al. 2017), and it is found mostly in evergreen forests. The name Strobilanthes is derived from the Latin word "Strobilos" meaning cone and "anthos" meaning flower or shoot. For the first time, the genus was scientifically described by Christian Gottfried Daniel Nees Von Esenbeck in the 19 th century for the plants which bloom after long intervals, while some species of Strobilanthes bloom annually (Preethi & Suseem 2014;Josekutty et al. 2016Josekutty et al. , 2018Augustine et al. 2017). The genus is distributed in the tropical regions of Asia starting from Afghanistan through India and Southeast Asia to Australia (Josekutty et al. 2018). During 2017-2018, while surveying floral diversity around Imphal, Manipur, when the weather was clear and the vegetation was on the verge of blooming, an exciting view of a blue patch of herbs was recorded. The site was an isolated place near an abandoned old temple-like structure. It appeared like a small hill at the periphery of a human inhabitation which might have been used in the past as a sacred place where local deities may have been worshipped. It was a moist shady place with huge aged trees sheltering and nurturing vegetation beneath. A significant patch of blue coloured herbs with a height of 45-85 cm were blooming with bright blue coloured flowers in the area of around 4.5-6.5 m 2 on the slopes of a small hillock. After careful observation in the field, the first author confirmed that the specimen belongs to the genus Strobilanthes but confused it with S. auriculata or S. jeyporensis. After a detailed study of the specimen's morphology (Image 1) and pollen morphology (Image 2), and comparison with S. kunthiana, it was confirmed that the collected species was S. affinis. This specimen was again confirmed by professor John Wood, University of Oxford, United Kingdom. After confirmation, literature survey and critical characterization, it was noticed that collected plant had been earlier reported from China (Wood et al. 2003) and the species was also collected by J.D. Hooker and T. Thomson from Meghalaya as S. acrocephala more than 10 decades ago. Therefore, it was concluded that the present specimen that was collected is identified as S. affinis and reported here for J TT the first time from Manipur as an extended distribution.
During our field survey of the flora of Manipur (24.916 N & 93.961 E, 803m), some unidentified species of the genus Strobilanthes were collected. The specimens were packed in cloth bags and brought to the laboratory for analysis. The relevant floras were consulted for confirming its identity. A thorough review of the literature, detailed morphological and consultation of herbarium provided by professor Wood revealed that the specimen was Strobilanthes affinis (Griff.) Terao ex J.R.I.Wood J.R.Benn. The mounting of herbarium specimens was accomplished using standard taxonomic procedure (Jain & Rao 1977;Bridson & Forman 1998). The voucher specimens (APRF-MAN-BCD/2018-0004) were deposited in the "APRFH" Herbaria, Ambika Prasad Research Foundation, Odisha, India. The photographs of the diagnostic characteristics were taken by Stereo Microscope, (Leica MC 120 HD).
Flowering Habitat & Ecology: The collected species is Strobilanthes affinis found on a small hill top of Manipur State. The collected area lies in the Indo-Burma Biodiversity Hotspot region. It was observed that the habitat is Moist-deciduous vegetation. The most J TT common associated herbs and climbers are Passiflora foetida, Solanum nigrum, Sida cordifolia, Cissampelos pareira, and Phyllanthus reticulatus with some tree species like Bombax ceiba and Pongamia pinnata. It was found in 6.09 x 9.14 -4.57 x 7.01 m area of a hill top of said region.
Remarks: The most unique characters of collected specimen are four exerted stamens (Image 3). Wood et al. (2003) described it from China and recorded that the flowering period is only from September to November.
In the present study, however, it was observed that it flowers from August to March. It was also observed that Sida acuta is the main associate flora of the collected species. As it is found only one region of Manipur, it should be assessed for threat status using categories of IUCN, and take necessary conservation action.