Ophiorrhiza debiana Hareesh, 2017

Hareesh, Vadakkoot Sankaran, Joe, Alfred & Sabu, Mamiyil, 2017, Ophiorrhiza debiana (Rubiaceae, Rubioideae), a new species from North-East India, Phytotaxa 309 (3), pp. 291-294 : 291-293

Ophiorrhiza debiana Hareesh , A. Joe & M.Sabu sp. nov. ( Fig. 1 )

Ophiorrhiza debiana is similar to O. cordata W.L. Sha (1999: 189) but differs from the latter in having sparsely puberulous stem, persistent stipule with entire apex, lamina round to sub-cordate or attenuate at base, glabrous orbicular bracts, corolla tube 18–23 mm long, corolla tube with rusty small hairs above the villous ring within and non-keeld corolla lobes with 1 mm long horn at apex.

Type:— INDIA. Arunachal Pradesh: West Kameng district, near Sessa village, on the way to Bomdilla from Balukpong , 29 June 2015, V. S. Hareesh& A. Joe143726 (holotype, CALI; isotypes, CAL, ASSAM) .

Creeping herbs, 10–30 cm tall; stem woody at base, terete, puberulous, green in young, pale brown when mature; internodes 1.5–5.5 cm long. Stipules subulate-linear with broad base, entire, 5–7 mm long, acute, puberulous, persistent, pale brown. Petioles 0.5–3 cm long, slender, glabrous or puberulous; leaf blades ovate orovate-elliptic, 2–6 × 1.5–3 cm, rounded to sub-cordate or attenuate at base, acute or obtuse at apex, glabrous above, pale beneath; secondary veins4–7each side, glabrous or puberulous below. Inflorescence terminal, sub-corymbose, 1.5–2 cm in diameter; rachis glabrous/puberulous; peduncle 1.5–2.5 cm long, slender, glabrous/puberulous; bract orbicular, 10–12 × 8–10 mm, acute to acuminate at apex, prominently nerved, glabrous,brown, persistent; bracteoles elliptic-oblong, 9–10 × 3–4 mm, acute to obtuse, prominently nerved,persistent. Pedicels c. 0.5 mm long, glabrous. Flowers 20–25 mm long, glabrous. Hypanthium obovoid, 1.75–2 × 1.6–1.8 mm, 10-ribbed; disc 0.5–0.7 mm tall, glabrous. Calyx lobes triangular, 0.8–1 × 0.45–0.6 mm, pale brown orpale green, acute, glabrous. Corolla infundibuliform, 18–23 mm long, white, glabrous outside, rustyvillous at the middle inside and rusty small hairs above the villous ring, prominently veined; lobes ovate, 4–4.5 × 3–3.5 mm, incurved, spreading, apex acute with 1 mm long horn, pale brown. Long-styled flower: Stamens inserted at the base of corolla tube; filaments 0.60–0.75 mm long; anthers oblong-linear 1.75–1.9 mm long, white or pale yellow; style filiform, 10–11 mm long, puberulous; style branches 2, linear-lanceolate, 1.75–2 mm long, glabrous. Short-styled flower: Stamens inserted at the middle of corolla tube; filaments 2.3–2.5 mm long; anthers oblong-linear 1.85–2 mm long, white or pale yellow; style filiform, 0.75–1 mm long, glabrous; style branches 2, linear-lanceolate, 2.5–2.75 mm long, glabrous. Capsules obcordate in outline, 2–2.5 × 3–4 mm, glabrous, green; seedsmany, angular, 0.4–0.6 × 0.3–0.5 mm, brown.

Discussion: — Ophiorrhiza debiana is similar to O. cordata , a Chinese species reported from Guanxi. Both the species possess creeping habit, terminal inflorescence with foliaceous bracts, short pedicels, white infundibuliform corolla with glabrous outer surface, 10-ribbed obovoid hypanthium, triangular calyx lobes and long, filiform pubescent style. The differences are listed in the Table. 1.

Flowering and fruiting: — May–September.

Eponymy:— The species is named in honour of Dr. D.B. Deb, Botanical Survey of India, Kolkata, who revised the genus Ophiorrhiza in Indian subcontinent and also for his immense contributions to the family Rubiaceae .

Distribution and ecology: — Ophiorrhiza debiana is known only from Sessa village and Ziro point of West Kameng district of Arunachal Pradesh, North-East India. Populations were observed in the moist shady areas in association with Begonia Linnaeus (1753: 1056) sp. , Impatiens Linnaeus (1753: 937) sp., Musa cheesmannii N.W. Simmonds (1957: 479), M. sikkimensis Kurz (1878:164), Pilea Lindley (1821 : tab. 4) sp. etc.

Conservation status: — Ophiorrhiza debiana known to exist only in a single location and the area of occupancy estimated to be less than 10 km 2. Therefore, the new taxon is tentatively classified as Critically Endangered (CR B1ab(ii, iii)+B2ab(i,ii))( IUCN 2013). The major threat we observed is the clearing of roadsides and continued deforestation in the area.

Additional specimens examined (paratype): — INDIA. Arunachal Pradesh: West Kameng district, Ziro point, on the way to Bomdilla from Balukpong, 30 May 2017, V.S. Hareesh 152696.

Figures

FIGURE 1. Ophiorrhiza debiana. A. Habitat. B. Front view of flower. C & H. Inflorescence. D. & E. Bract adaxial and abaxial surface. F. & G. Bracteole adaxial and abaxial surface. I. Flower bud with bracteoles. J. Hypanthium. K. Split opened corolla of short styled flower. L. Short style with stigma andhypanthium. M. Split opened corolla of long styled flower. N Short style with stigma and hypanthium. (inset portion of style enlarged). (Photos by V.S. Hareesh & Alfred Joe).