Thrixspermum indicum Vik. Kumar, D. Verma & A.N. Rao, 2017

Kumar, Vikas, Verma, Durgesh & Rao, Abbareddy Nageswara, 2017, Thrixspermum indicum (Orchidaceae), a new species from Northeast India, Phytotaxa 292 (1), pp. 79-84 : 79-83

Thrixspermum indicum Vik. Kumar, D. Verma & A.N. Rao sp. nov. ( Figs. 1–3 )

Thrixspermum muscaeflorum auct . non A.S. Rao & J. Joseph, 1971: Nanda et al. in Pleione 7(2): 560–566. 2013.

Thrixspermum indicum is more allied to T. trichoglottis ( Hooker 1890: 39) Kuntze (1891: 682) , but differs significantly from the latter in having broadly triangular lateral lobes of lip with acute incurved tips and absence of hairs on the inner surface, margins of mid-lobe and side lobes of lip instead of auricular, rounded, erect lateral lobes and presence of dense long clavate hairs on the inner surface and margins of lip.

Types: — India : Meghalaya, East Jaintia Hills, Tuber village , 25°26’19.23’’N & 92°16’29.07’’E, 1382 m, 12.07.2014, V. Kumar & D. Verma 113138 (holotype: BSD!) ; Meghalaya, East Jaintia Hills, Tuber village , 25°26’18.59’’N & 92°16’28.4’’E, 1420 m, 15.04.2014, D. Verma 127001 (paratype: BSD!) ; Manipur, Lonkhu, Tamenglong District , 25°00’28.79’’ N & 93°19’22.44’’ E, 1179 m, 04.08.2012, Y. Nanda 00015 (paratype: COGCEHR Herbarium, Hengbung, Manipur!) .

Epiphytic herb. Stem erect to horizontally spreading, short, stout, terete, 2.0– 3.5 cm long, ca. 8 mm in diameter, bearing 3–5 inflorescences. Roots long, 2–3 mm wide, greenish-white. Leaves 8.0–13.0 × 1.0– 1.5 cm, distichous, thick, more or less flat, fleshy, oblong, elliptic to linear oblong, obtusely bilobed at apex, with short mucro in sinus, dark green. Inflorescence raceme, extra axillary, sub-erect to sub-pendent, 3–6 cm long, usually with 2 sterile bracts; rachis 1.5–3.5 cm long, green, broader than the peduncle, flattened, few-flowered, opening successively, facing all sides of rachis; peduncle 1.0– 2.5 cm long. Floral bracts ca. 2.0 × 1.5 mm, broadly ovate-triangular, arranged all around on rachis, apex acute, persistent on rachis. Flowers ca. 1.5 cm long (from apex of dorsal sepal to base of ovary) and ca. 1.0 cm across (from later sepals), sub-erect, yellow, lip white tinged with purple spots at the base at side lobes. Pedicel and ovary ca. 8 mm long, erect, green. Dorsal sepal 9.0–11.0 × 4.0– 4.5 mm, elliptic, acute with a minute mucro, 5-veined, sometimes slightly hooded over the column. Lateral sepals 9–11 × ca. 5 mm, ovate-elliptic, weakly oblique, entire, cymbiform towards apex, acute, spreading, gland dotted, beaked, 5-veined. Petals 8.0–8.5 × ca. 2.0 mm, narrowly oblanceolate, entire, acute, spreading, gland dotted, beaked, 3-veined. Lip jug like, spurred, ca. 6 mm long (from apex of side lobe to base of sac) and ca. 4 mm wide, 3-lobed; lateral lobes covering the sides of the column with margins, jointed to the short foot of the column at base, short, broadly triangular with curved acute tips facing each other; mid-lobe 3.0– 3.5 mm long, thick, fleshy, transversely triangular, obtuse, glabrous; callus ca. 0.8 mm long, raised ca. 0.6 mm high, glabrous, white; spur saccate or pouch like, ca. 2 mm deep, base with a tuft of lax, small, laterally flattened pinkish hair. Column ca. 1.5 mm long, column foot ca. 2 mm long, white. Anther cap ca. 0.8 mm long, sub-orbicular, white, membranous. Pollinia 4, in two unequal pairs, ca. 0.5 mm long, ovate-triangular, stipe broadly oblong, viscidium short,

horse-shoe shaped. Capsule about transverse to the rachis, 6.8–7.5 × 0.4–0.5 cm, narrowly cylindric, ridged, with short beak at the apex.

Phenology:— Flowering July–August; fruiting September–April.

Etymology:— The specific epithet refers to the country ‘India’ from where the new species is described.

Distribution and habitat:— The species is found growing as an epiphyte on moss covered tree trunks in subtropical evergreen forests at an elevation ranging between 1100–1500 m.

Figures

FIGURE 1. Thrixspermum indicum. A. Habit. B. Flower. C. Flower (side view). D. Floral analysis. E. Lip, column, pedicel and ovary (side view). F.Lip, column, pedicel and ovary (front view). G. Lip (side view). H. Lip showing hairs inside spur. I. & J. T.S. of Lip showing hairs and raised callus. K. Column. L. Anther cap. M. Pollinia. [Photographic illustration by V. Kumar].

FIGURE 2. Thrixspermum indicum. A. Habit. B. Leaf. C. Flower. D. Fruit. E. Floral analysis. F. Lip, column, pedicel and ovary (side view). G. T.S. of Lip showing hairs inside spur and raised callus. H. Column with pedicellate ovary. I. Anther cap. J. Pollinia. [Illustration by V. Kumar].

FIGURE 3. Thrixspermum indicum. A. Habit (Flowering). B. Flower (front view). C. Habit (Fruiting). [Photographs by D. Verma].