NeBIO An international journal of environment and biodiversity Vol. 7, No. 4, December 2016, 133 - 137 ISSN 2278-2281(Online Version) ☼ www.nebio.info I www.neceer.org.in © 2016. NECEER, Imphal. All rights reserved Clerodendrum hexangularis D. Baro et S. K. Borthakur: A new species from Manas National Park of Assam D. Baro and S.K. Borthakur Department of Botany, Gauhati University, Guwahati-7810 14, Assam Email: skbgu1@gmail.com ABSTRACT Clerodendrum hexangularis, a new species from the grasslands of Bhuyapara and Bansbari Ranges of Manas National Park of Assam, India is described and illustrated. It is closely allied to Clerodendrum serratum (L.) Moon. but differs in its stunted habit, hexangular stem with 6 ridges and 6 furrows, sessile, dentate, slightly decurrent leaves in whorls of three, presence of bracts and bracteole, flower light blue or white in colour, fruits three or four chambered. KEYWORDS Clerodendrum hexangularis; New species; Assam; India Introduction The genus Clerodendrum L. belonging to the family Verbenaceae is widely distributed in the tropical and subtropical regions of Australia, Asia, Africa, Central and South America and the West Indies with about 400 species (Munir, 1989; Rajendran & Daniel, 2002; Mabberley, 2008). In India, the genus is represented by 23 taxa, including two varieties (Rajendran & Daniel, 2002) and in Northeast India by 18 species and 2 varieties (Deori, 2013). Assam is represented by 15 species and one variety (Barooah & Ahmed, 2014). During the course of floristic exploration in Manas National Park of Assam India, the authors collected some interesting specimens of Clerodendrum with several populations occurring in the grasslands of Bhuyapara and Bansbari Ranges of Manas National Park of Assam, India with flowers and fruits. The specimens were critically studied and compared with other described species from India, but none of them matched with the collected specimens. The closely related species to the collected specimen is Clerodendrum serratum (L.) Moon, a species widely distributed in West Bengal, Assam, Manipur, Meghalaya, Nagaland and the Andaman and Nicobar Islands. The collections being unmatched with any of the known species so far described hitherto (Munir, 1989; Rajendran & Daniel, 2002), it is described here as Clerodendrum hexangularis sp. nov. The differences between the new species with the allied Clerodendrum serratum (L.) Moon are shown in Table 1. Clerodendrum hexangularis D.Baro et S.K.Borthakur, sp. nov. (Figs.1, 2 &3) Types: India, Assam, Baksa district, Manas National Park, Bhuyapara, about 750 m, 15 May 2014, D.Baro & S.K.Borthakur 780A (Holotype: ASSAM; Isotypes: 780B, 780C, 780D GUBH). Paratype: India, Assam, Baksa district, Manas National Park, Bansbari, about 750 m, 08 May 2015, D. Baro & S.K. Borthakur 834A, 834B, 834C, 834D (GUBH). Shrubs, 1.3-1.5 m high; rootstocks woody; branches stout, hexangular with 6 ridges and 6 furrows, rarely quadrangular, pale green in colour, glabrous, internodes 10-15 cm, ternate when the stem is hexangular and opposite decussate when the stem is quadrangular, obovate-lanceolate, 24-29×13-15 cm, sessile, slightly decurrent at base, apex apiculate, margin dentate, pale green, glabrous, scabrous on both surfaces, lateral nerves 7-9 pairs. Thyrses terminal, erect, composed of 10-12 opposite- decussate cymes, 12-15×6-10 cm; peduncles greenish yellow, 2-3cm long, glandular pubescent; bract one, 1.3×0.3 cm, lorate, entire, acute at apex, pale green in colour; bractole one, 1×0.2 cm, oblong, entire acute at apex, pale green in colour; pedicels greenish white, 2-3mm, glabrous. Flower 2.5-3 cm long, light blue or white in colour, bisexual. Calyx of 5fused sepals, cupular, persistent, minutely or shallowly toothed, teeth acute, glabrous, 0.6-0.9×0.2-0.4 cm. Corolla of 5 fused petals, hypocrateriform, 5-lobed, white with deep blue blotch inside, lobes subequal, posterior lobe suborbicular or spatulate, concave, entire or