Leucas sahyadriensis Sunojk., 2019

Sunojkumar, Purayidathkandy, 2019, Leucas sahyadriensis (Lamiaceae: Lamioideae) an overlooked new endemic species from India and notes on Leucas chinensis, Phytotaxa 399 (3), pp. 187-194 : 189-191

Leucas sahyadriensis Sunojk. sp. nov. ( Figs. 1 & 2 )

Leucas sahyadriensis is morphologically similar to L. chinensis and L. biflora but differs from both by means of its long branches, broadly ovate leaves, funnel shaped calyx with bulged middle portion and wide mouth provided with stellately spreading, broadly triangular teeth and 16–17 mm long corolla.

Type:—Peninsular India Orientalis, Oct. 1882, Wight s.n. (holotype K!, barcode K 000929493)

[ Leucas chinensis sensu Bentham (1830: 62) ; (1832: 606); (1848: 524); Hooker (1885: 681); Gamble (1924: 1151); Mukerjee (1940: 182); Singh (2001: 59) non Retzius (1791: 19)].

Leucas chinensis var. lanata Hook.f. (1885: 682) syn. nov.

Lectotype (designated here):— Peninsular India Orientalis , Vellyengry hills, April 1850, Wight 2165 (lectotype K! barcode K000929492 ).

Perennial herb, basal stem and root stock thick, up to 1m high; branches straggling up to 1.5 m long, quadrangular, not grooved, dense pubescent with retrorse hairs, tender branches short tomentose; internodes 6–11 cm long. Leaves opposite, decussate, petiolate, thin, broadly ovate sometime sub-orbicular, 3–6 × 3–5 mm, usually as broad as long, base truncate to sub-cordate sometime rounded to cuneate, margin crenate or dentate with 6–13 teeth, tip obtuse to acute, dense pubescent abaxially, less pubescent adaxially; lateral veins 4–5; petiole 1.5–2.5 cm long, dense pubescent. Inflorescence in axillary clusters, each cluster 3–7 flowered, loosely arranged. Bracteoles minute, 2–3 mm long, linear, straight, ciliate, tip filiform. Flowers pedicellate; pedicels 2–3.5 mm long. Calyx widely funnel shaped; tube 10–14 mm long, basal half narrow, above suddenly bulged from middle then gradually widening and spreading out at mouth, tube longitudinally ribbed along nerves, outside short villous, hairs thin, deflexed, inside with a ring of dense long hairs at middle and hispid above, mouth 6–8 cm wide; teeth 10, equal in size, 2–3 mm long, base 1.8–2 mm broad, broadly triangular to deltoid, stellately spreading, tip spinulose, densely pubescent on both side, hairs ca. 1 mm long. Corolla white, 16–17 mm long; tube ca. 8 mm long, included in the calyx tube, inside middle annulate with an undulate ring of fleshy hair fringes, tube widening up; lower lip of corolla ca. 9 mm long, middle lobe ca. 7 mm broad, free end emarginate, each halves almost rounded on both side; lateral lobes ca. 2.5 mm broad, obliquely narrowed towards tube, front end overlap with the hind portion of middle lobe; upper lip 6 mm long, base slightly bulged, margin ciliate, apex bent, concave, dense white hairs outside. Stamens with hairy filaments; anthers bright red coloured, ca. 8 × ca. 0.5 mm, slightly longer than broad, almost rounded in appearance, theca confluent. Disc cup shaped, abaxial lobe slightly longer, other lobes equal. Ovary locules 0.5 mm high, apex rounded, trigonal, shining; style ca. 15 mm long, bent; stigma bifid, almost equal lobes, lower 0.9 mm long, upper 0.75 mm long. Nutlets black, shining, oblong, 1.8–1.9 × 1.2–1.3 mm, apex rounded middle triangular in cross section.

Phenology:— Peak season for flowering is from August to December, but also observed up to March.

Etymology:—The species is named after the type locality, Western Ghats which is also known as ‘Sahyadri’ in the regional Malayalam language.

Distribution, habitat and ecology:— Southern India; endemic to southern Western Ghats (plate 3). This species was found growing on forest openings and earth cuttings in semi evergreen forests, at an altitude above 800 m, amongst other bushy herbs and grasses. Plants prefer a cool climate, humus rich soil and shady atmosphere.

Additional specimens examined (paratypes):— INDIA. Kerala state, South Malabar , 25 January 1910, Fischer 1698 ( CAL!) ; Idukki District, Upper Vaguvarai , 18 January 2004, Sunojkumar CU88141 ( CALI!) ; Palakkad District, Parambikulam , November 1910, Meebold 12379 ( CAL!) ; Siruvani near Sadivayi , 2 July 1963, Subramaniam 774 ( FRC!) ; Palakkad District, Siruvani, Adivaram , 13 August 1960, Henry 270 ( MH!) ; Palakkad District, Thannipallam , 4 September 1960, Henry 550 ( MH!) ; Palakkad District, Nelliampathy, Seetharkundu , 26 July 1990, Sasidharan 5673 ( KFRI!) ; Palakkad District, Parambikulam, Thunakkadavu , 1 November 2002, Sujanapal 19022 ( KFRI!) ; Palakkad District, Nelliampathy, Victoria Kurisumala , 18 May 2000, Sunojkumar CU49626 ( CALI!) ; Thrissur District, Parambikulam , 22 November 1962, Sebastine 15309 ( MH!) ; Thrissur District, Thunakadavu , 28 October 1964, Sebastine 22375 ( MH!) ; Thrissur District, Sholayar , 21 March 1989, Sasidharan 5356 ( KFRI!) ; Thiruvananthapuram District, Ponmudi , 17 January 1989, Sasidharan 5270 ( KFRI!) ; Tamil Nadu state, Coimbatore District, Poonachi Anamalais , 10 October 1901, Barber 3687 ( MH!) ; Coimbatore District, Karadimalai , 31 July 1919, Raju & Ratnavelu 18662 ( CAL!) ; Coimbatore District, Vellanigiri hills, 23 February 1932, Joseph 12732 ( MH!) ; Coimbatore District, Siruvani 18 December 1956, Subramanyam 1789 ( MH!) ; Coimbatore District, Attakatti , 6 July 1961, Joseph 12732 ( CAL!) ; Coimbatore District, Anamodamalai , 31 August 1962, Sreemadhavan CPS146 ( MH!) ; Coimbatore District, Karappurayan hills 29 March 1963, Sreemadhavan CPS526 ( MH!) ; Coimbatore District, Siruvani , 24 October 1968, Deb 31086 ( MH!) ; Coimbatore District, Attakatti , 24 July 1978, Chandrabose 57274 ( MH!) ; Madurai District, Kodaikkanal Ghat , 21 July 1901, Bourne 2072 ( MH!) .

Conservational status:— Since a complete assessment cannot be performed based on the data available the status is given as Data Deficient (DD) according to IUCN (2017).

Figures

FIGURE 1. Leucas sahyadriensis. A. Habit; B. Flowering twig; C. Flower; D. Inflorescence; E. Nutlets; F. Inflorescence in Leucas biflora; G. Inflorescence in Leucas chinensis. (Photo credit: Zhu Xinxin 2012/6/7 PPBC id: 2235285.Adopted from PPBC.cn).

FIGURE 2. Leucas sahyadriensis. A. Habit; B. Flower; C. Bracteole; D. Calyx opened; E. Flower; F. Corolla opened; G. Stamens; H. Basal disc; I Gynoecium; J. Nutlets. All drawn by the author from Sunojkumar CU49626.