Trichosanthes dunniana H.Lév. subsp. clarkei K.Pradheep, 2021

Pradheep, K., John, K. Joseph, Singh, P. K., Rathi, R. S. & Pandey, A., 2021, A new subspecies and new records of Trichosanthes (Cucurbitaceae) for India, and notes on T. khasiana, Blumea 65 (3), pp. 233-243 : 234-235

Trichosanthes dunniana H.Lév. subsp. clarkei K.Pradheep , subsp. nov. — Fig. 1 ; Map 1

Similar to T.dunniana H.Lév.subsp. dunniana , but differs in greenish colour of bracts and calyces (vs red in subsp. dunniana ), longer pedicels of staminate flowers (4–7 mm vs c. 2 mm in subsp. dunniana ), shorter calyx lobes (5–6 mm vs c. 9 mm in subsp. dunniana ), white staminate and pistillate flowers (vs reddish in subsp. dunniana ). — Type: K. Pradheep 2741 (holo CAL; iso DD, NHCP), India, Sikkim, East Sikkim District, Radong, near Ranipool, N27.27 E88.58, alt. 750 m, fl. 12 Aug. 2018 (♂ fl).

Etymology. The epithet ‘clarkei’ is in honour of C.B. Clarke, who contributed immensely to the understanding of Indian cucurbits.

Medium-sized perennial dioecious climber, to 10 m long. Stems slender, purplish, sulcate-striate, glabrous; probract subentire, broadly ovate, 2–4 by 3–4 mm, punctate; cystoliths obvious; tendrils 2-fid, pinkish tinged. Leaves: petiole 4–5 cm long; lamina ovate-orbicular in outline, 5(–7), deeply lobed to 4/5th, 8–15 by 7–12 cm, glabrous, membranous, scabrous, base cordate, central lobe ± elliptic, narrowed at base, margin subentire to remotely serrate, apex acuminate, upper surface dark green, lower whitish, main nerves (3–)5 radiating from petiole, glands 2–5, large, along the main nerves, 1–1.5 mm diam. Staminate racemes 12–18 cm long, shorter than or equal to corresponding leaves, 5–8-flowered, peduncle 5–6 cm long, glabrescent; bracts persistent, ovate or obovate, 20–25 by c. 20 mm, green, cucullate, glands many, dark green, c. 1 mm diam, margin serrate-lacerate. Staminate flowers: pedicel 4–7 mm long; calyx tube 1.8–2.3 cm long, widening from half-way to throat, there c. 8 mm wide, lobes ovate-triangular, 5–6 by c. 2 mm, green, often purple tinged, margin entire; corolla lobes clavate, c. 10 by 10 mm, white, frills 1.2–2 cm long. Pistillate flowers: pedicel 1–1.5 cm long; ovary ovate, more often grooved longitudinally, stigma 3-lobed, conspicuous. Fruits ovoid, 5–8.5 by 4–6.5 cm, pericarp 5–10 mm thick, orange-red, pulp greenish black. Seeds brownish, tumid, 50–65, slightly compressed, ovoid-ellipsoid, 10–12 by 5–7 by 3–5 mm, rounded at ends.

Distribution — Endemic to North-eastern India (Sikkim, northern West Bengal).

Habitat & Ecology — Common in Sikkim, at 300–1500 m altitude. Staminate plants are dominating in natural populations with an approximate sex ratio of 10–15: 1. Flowering: July to September; fruiting: October, November.

Additional specimens. INDIA, Sikkim, Sikkim Terai, between Goreedora and Kuprail , 30 Apr. 1868, S . Kurz s.n. ( CAL181081 ); 4500 ft, 17 June 1874, G . King 912 ( P06393537 ); East Sikkim District , Tadung, 3000 ft, 19 Sept. 1968, C . Majumdar 532 ( CAL); East Sikkim District, Martham Thanka , 1363 m, 17 Oct.2012, K . Pradheep & P. K . Singh 2713 ( NHCP); East Sikkim District, Radong, near Ranipool , 750 m, 12 Aug. 2018, K . Pradheep 2742 ( NHCP); East Sikkim District , Kokaley, 14 Aug. 2018, K . Pradheep 2743 ( NHCP); South Sikkim District, Temi , 1479 m, 18 Oct. 2012, K . Pradheep & P. K . Singh 2716 ( NHCP); West Sikkim District , Middle Geyzing, 1070 m, 19 Oct. 2012 (living collection IC597012 at NBPGR), K . Pradheep & P. K . Singh 2717 ( NHCP) .– West Bengal, Darjeeling District , Punkabari, 5000 ft, 4 Sept. 1870, C. B . Clarke 13329 ( CAL); Darjeeling District , Rungbee, 5000 ft, 23 July 1870, C. B . Clarke 12233 ( CAL); Darjeeling District, 12th mile to Kalimpong from Bagdogra, 1238 m, 12 Oct.2012 (living collection IC614479 at NBPGR), K . Pradheep & P. K . Singh 2715 ( NHCP); Darjeeling District, Lohapool , 11 Oct. 2012, K . Pradheep & P. K . Singh 2718 ( NHCP); Darjeeling District , near Kalimpong, 11 Oct. 2012, K . Pradheep & P. K . Singh 2719 ( NHCP) .

Note — The differences between the two subspecies of T. dunniana have been summarised in Table 1. Earlier collections of this taxon were invariably misidentified as either T. bracteata (Lam.) Voigt or T. wallichiana (Ser.) Wight. Prominence of the stigmatic lobes, bifid tendrils, claw-like corolla lobes, long pedicels of staminate flowers, and longitudinally-grooved ovaries are some field identification characters for this new taxon.

Figures

Map 1 Distribution of Trichosanthes dunniana H.Lév. subsp. clarkei K.Pradheep and T. dunniana H.Lév. subsp. dunniana in north-east India.

Fig. 1 Trichosanthes dunniana H.Lév. subsp. clarkei K.Pradheep. a. Pistilalte flowering twig; b. pistillate flower; c. staminate flower; d. staminate flowering twig; e. twig with immature fruit; f. twig with ripe fruit (inset: seeds). — Photos by K. Pradheep.