Herpetospermum operculatum K.Pradheep, A.Pandey, K.C.Bhatt & E.R.Nayar, 2014

Herpetospermum operculatum K.Pradheep, A.Pandey, K.C.Bhatt & E.R.Nayar View in CoL , sp. nov. — Fig. 1 View Fig , 2 View Fig ; Map 1

Diagnosis: Similar to H. tonglense (C.B.Clarke) H.Schaef. & S.S.Renner , but differing in smooth yellow-striped oblong-elliptic fruits with 24 seeds arranged ascendently inside horizontally well-knitted fibre, and dispersed through opercular aperture at apex; prominent probracts and bracts; calyx with subulate sepals almost equal to the length of about-to-open flower bud; seeds ± round with irregular erose margin and subrostrate proximal end, and with prominent projections/markings on either side.

Type. K. Pradheep 1449 (holo CAL; GoogleMaps iso DD, NHCP), India, Sikkim, South District, Sadam , near river bank, N27°08ʹ, E88°25ʹ, alt. 1500 m, fl. 20 Oct. 2012 (female and male fl [in two sheets]) GoogleMaps .

Etymology. The species epithet refers to the lid-like structure (operculum) at the stylar end of the fruit, which is not found in other species of Herpetospermum .

Herbaceous, dioecious climber, up to 10 m long. Stems annual, slender, angular-sulcate, subglabrous, young shoots densely pubescent, the juvenile leaves having distinct tail-like terminal projections. Probract subulate, 7– 9 mm long, curved inwards, glabrous, green when young, turning pale yellow, caducous. Tendril 4-fid, one branch robust, elongate, puberulent. Leaves simple, highly strigose-pubescent at juvenile stage; petiole robust, angular-sulcate, 6 –10 cm long, puberulent; lamina cordate-triangular, 13 –17 by 10 –14 cm, with prominent reticulate veins, puberulent abaxially and adaxially along veins, basal sinus narrow, c. 2 cm deep; lobes 5, separated by shallow to medium sinuses, triangular-ovate with cuspidate tips, terminal one about half the length of the lamina, basal ones small; margin irregularly dentate, each tooth terminating in slightly protruding vein tips. Male inflorescence two peduncles from one axil, the first one early, 1-flowered, pedicel long, 5 – 8 cm, the second one racemose, 12–15 cm long, 5– 8(–10) flowered; flowers showy, fragrant; bract prominent, 8–12 by 4 –7 mm, varying in shape, linear-lanceolate to ovate, inflexed, with venation similar to that of leaves; young buds pilose, hairs c. 3 mm long, sepals twisted together anticlockwise at tip; peduncle robust, 8 –11 cm long, pubescent. Male flower: unopened flower bud conicalovate, (opened) flower large, corolla 6–8 cm diam, pedicel short, 6 –11(– 20) mm long, pubescent; calyx tube elongate, 4.2– 5(– 5.5) cm long, cylindric part> 3 cm long; at base 3–4 mm broad, widened to 15– 20 mm broad at apex, infundibular, subglabrous to sparsely pilose, greenish yellow; sepals 5, valvate, elongate-subulate, apex tail-like, 1–1.3(–1.8) cm, almost level with the about-to-open flower bud; corolla infundibular, petals 5, entire, connate at base, aestivation quincuncial, (ovate-) obovate with green acuminate tip, 3–3.5 by (2 –)2.5 – 2.8 cm, bright yellow, densely papillose-glandular on both sides; androecium: filaments free, inserted below the throat of the calyx tube, 7– 9 mm long, glabrous; anthers 3, connate, protruding a little above calyx tube, yellow, two 2-thecous, one 1-thecous, 8–9 mm long, connective narrow, loculi linear; pollen pale yellow, sphaerical, baculate, 125 –143 µm diam; pistillode 9 –10 mm long, base bulbous, 2 – 2.5 mm thick. Female flower solitary or seldom 2 from the same axil; pedicel robust, (3.2 –) 4– 6 cm long, pubescent; calyx tube stout, 2.5 –3.2(– 4) cm long, narrowly funnelform, at base 4 mm, at apex 12–15 mm broad; sepals and petals as in male flower. Ovary oblong, 1–1.2 cm long, ovules 8 per locule, ascendent in two rows except almost 1/3rd distal end; style firm, 2.5– 2.7 cm long; stigmas 3, each 2-lobed, oblong-ovate, 5 –6 mm long, yellow. Fruit stalk (4–)6–7(–8) cm long, puberulent; immature fruits oblong to ellipsoid-fusiform, 6–8(–10) by 3.5 –4(– 4.5) cm, smooth, green with 6 –7 (pale yellow-)yellow irregular stripes (barring operculum part), pubescent, highly foetid when crushed; mature fruit yellow, seeds packed in horizontally well-knitted fibrous saponaceous pulp, dehiscing apically through an opercular aperture followed by quick release of 24 seeds; operculum 1.5– 1.9 cm diam, umbo 2(– 3) mm long. Seed compressed, ± round with irregular acute erose margin, 1.1–1.3(–1.4) cm diam, 5 –6 mm thick, (grey-) black, proximal (hilum) end subrostrate, testa with muricate projections/markings on either side. Seedling with cotyledons elliptic-oblong, 2.2 – 2.5 by 1.6 –1.8 cm, pale green; first true leaf triangular, sublobate, pale green, tomentose.

Distribution & Ecology — North-eastern India (Nagaland, Sikkim), Myanmar (Kachin) and China (western Yunnan, southeast Xizang). Little disturbed subtropical to temperate forests: in thickets, over bushes and small trees, upon rock, in open situations, along riverbanks; 1500 –2500 m.

Conservation assessment — The first author saw 12 plants in a single population spanning about 0.01 km 2 near the vicinity of Sadam village in South District of Sikkim; the populations are unlikely to face serious habitat loss. The third author saw only two female plants near jhum (shifting cultivation) area in Mesulumi village in Phek district of Nagaland; this may be indicative of probable threat to populations due to clearing of natural habitat. T.T. Yu in 1938 (Yu 16473) annotated that he had seen these plants commonly in Shunning (Yunnan). All other studied herbarium specimens (collected in 1912, 1982 and 2010) did not reveal anything about population size, abundance, threat, etc. Therefore, it is problematical to infer any trends from these scattered observations, although the fact that this conspicuous species did not attract the attention of taxonomists from three countries suggests a drastic population decline over decades. Considering also that this new species has been confused with two other species, we conclude that sufficient information is lacking to determine the threat status, and that the ‘Data Deficient’ (DD) category is most suitable, according to the criteria of IUCN (2001, 2013).

Additional specimens. CHINA, Yunnan, Shunning, Hila, alt. 2450 m, 26 June 1938, Yu, T. T. 16473 (E, PE), (female and male fl) ((http://data.rbge. org.uk/herb/E00202140, last accessed 9 June 2013; http://www.nhpe.org/ pe/01178252, last accessed 9 June 2013); Nujiang Lisu Autonomous Pref., Bao shan, off provincial road 230 at Gang dang, Bai hua ling, Han long zhai (village) (at the end of Z003 county road), walk to Jin chang he (river), N25.30°, E98.78°, alt. 2133 m, 23 July 2010, Borosova, R., Y. Guo, S. Landrein, C. Liu , J. Osborne & T. Zhang 2046 [10CS 2046] (K[K000568578]), (female fl) (http://www.svenlandrein.com/scihort/temperate/yunnanimages/ specimensimages/images/10CS2046_a.jpg, last accessed 2 July 2013); Xizang, Medog County, alt. 1940 m, 6 Oct. 1982, Sheng, B. L. & S. Z. Cheng 1431 (PE), ((female and male fl) (http://www.nhpe.org/pe/01179183, last accessed 9 June 2013).– INDIA, Nagaland, Phek,Mesulumi, N25°34ʹ, E94°19ʹ, alt. 1838 m, 13 Oct.2011, Bhatt, K. C. 1047 (NHCP), (st). – MYANMAR, Kachin, descent from Sansi Gorge to Sadon, N25–26°, alt. 6–7000 ft, Sept. 1912, Forrest, G. 9114 (E), (male fl) (http://data.rbge.org.uk/herb/E00202141, last accessed 9 June 2013).

Note — Clarke (1877) observed a higher proportion of male to female plants in the other three species of Herpetospermum under natural conditions. However, the first author has observed an equal proportion of male and female plants in this species in South District of Sikkim. Big yellow showy flowers in clusters call for further study of its potential as ornamental. Forrest 9114 (E) recorded flower colour as bright orange; this corresponds to the observation by the first author that just before anthesis, the flower is orangish, and later turns yellow. Sheng & Cheng 1431 (PE), from Medog County in Xizang, has fruits clearly showing an operculum mark. This specimen and Yu 16473 (E) have a mixture of both male and female flowers on the same herbarium collection. Borosova, Guo, Landrein, Liu , Osborne & Zhang 2046 [10CS 2046] (K) mentioned that seeds are creamy, probably due to observations at immature stage of fruit. Fully mature seeds are (grey-)black in colour. The line diagram of Biswarea tonglensis in vol. 6 of Flora Yunnanica ( Wu et al. 1995: 343) belongs to this species. The description in Flora of China ( Lu et al. 2011: 33) for the above species with respect to length of bracts (2–3 mm), calyx segments (sometimes up to 20 mm) and pedicel of female flower (25–30 mm) indicates the likely overlap of character states of the new species with that of H. tonglense . However, we cannot exclude the possibility that true H. tonglense occurs in these countries. This new species is expected to occur in Bhutan and Indian states of Arunachal Pradesh and West Bengal (Darjeeling), and adjoining areas of Nepal.