Phytotaxa 413 (3): 244–250 https://www.mapress.com/j/pt/ Copyright © 2019 Magnolia Press Article PHYTOTAXA ISSN 1179-3155 (print edition) ISSN 1179-3163 (online edition) 244 Accepted by Yunfei Deng: 21 Jul. 2019; published: 1 Aug. 2019 https://doi.org/10.11646/phytotaxa.413.3.5 Strobilanthes tricostata, a new species of Acanthaceae from the Western Ghats, India SINJUMOL THOMAS 1,3 , BINCE MANI 2,* , SUSAI JOHN BRITTO 1 & PRADEEP ANNAVI VEETTIL KRISHNA PILLAI 4 1 The Rapinat Herbarium and Centre for Molecular Systematics, St. Joseph’s College (Autonomous), Tiruchirappalli–620002, India. 2 Department of Botany, St. Thomas College Palai, Kottayam–686574, India. 3 Department of Botany, Carmel College, Mala, Thrissur–680732, India. 4 WWI Innovative Solutions, Kottayam–686576, Kerala, India. * Corresponding author: BINCE MANI, E-mail: binsnm@gmail.com Abstract Strobilanthes tricostata, a new species with semelparous life history strategy, is described from the Megamalai hills, Tamil Nadu. Pollen morphology, phenology, distribution, conservation status and notes on allied taxa are provided along with illustrations. Keywords: Acanthaceae, Strobilanthes, pollen, taxonomy Introduction The genus Strobilanthes Blume (1826: 781) consists of approximately 400 species confined to the south and southeast Asia and Melanesia (Mabberley 2017). About 150 species have been reported from India and among them 61 species were reported from south India alone (Carine & Scotland 2002, Venu 2006). The Western Ghats harbours a rich biological diversity and large number of new taxa has recently been reported from this phytogeographic region including species of Strobilanthes (Carine et al. 2004, Gopalan & Chithra 2008, UNESCO 2012, Sasidharan et al. 2016, Thomas et al. 2018, 2019). The floristic exploration in the Megamalai hills of Tamil Nadu by the authors led to the collection of an interesting specimen of Strobilanthes could easily be distinguished by pubescent narrow spikes with 3-ribbed bracts. After comparing the collections with herbarium specimens in India and abroad and critical study of relevant literature, it was concluded that our collections do not match with any of the hitherto known species of Strobilanthes (Carine et al. 2004, Venu 2006). Additionally, pollen morphological characters were also studied to distinguish the species from allied species. The variability in pollen morphology is potentially useful in demarcating the species of Strobilanthes (Terao 1982, Carine & Scotland 1998, Deng et al. 2006). Taxonomy Strobilanthes tricostata S. Thomas, B. Mani, Britto & Pradeep, sp. nov. (Figs. 1 & 2) The new species is allied to Strobilanthes carnatica Carine et al. (2004: 23), but differs in the stem tawny tomentulose (not glabrous), leaves elliptic (not ovate), apex cuspidate (not long acuminate), bracts lanceolate 3-ribbed (not ovate non-ribbed), spikes non-glandular hairy at anthesis (not glabrous or glandular hairy), calyx lobes narrowly triangular (not lanceolate), pollen grains prolate (not subprolate), style pubescent (not glabrous), capsule pubescent apically (not pubescent) and seeds broadly elliptic (not orbicular). Type:—INDIA.Tamil Nadu:Theni District, Megamalai, 1400 m, 5 December 2016, Pradeep A. K. et al. 68246 (holotype RHT!, isotype RHT!).