Thrixspermum flammeum Toolmal, Schuit. & Culham, 2023

Toolmal, Nopparut, Suddee, Somran, Culham, Alastair, Utteridge, Timothy M. A. & Schuiteman, André, 2023, Taxonomic notes on Thrixspermum (Orchidaceae: Aeridinae), with five new species from Thailand, Phytotaxa 601 (3), pp. 223-262 : 248-253

5. Thrixspermum flammeum Toolmal, Schuit. & Culham , spec. nov.

( Figs. 17–19 ).

Type:— THAILAND. Eastern Thailand , Chaiyaphum Province, Phu Khieo Wildlife Sanctuary, Thung Kamang, 07 December 2020, N. Toolmal , B. Buaphong & K. Putaha 07122003 (holotype: TTM-Spirit; isotypes: BKF, QBG) .

Thrixspermum centipeda auct. non Lour.: Seidenfaden (1988: 152); Xu et al. (2010: 443); Gao & Liu (2014: 1081); Jin et al. (2019: 213).

Thrixspermum flammeum is distinguished from T. centipeda by the shorter, patent stem (rarely scandent) 3.5–14(38) cm long (vs. scandent stem 30–50 cm long), the longer peduncles 4.5–14 cm (vs. peduncles 1–3 cm), the orangish flowers, 6 cm across (vs. pale creamy yellow flowers, 4–5 cm across), the longer tepals 4.2–5.3 cm long (vs. tepals 2.2–3.0 cm long), the shorter spur 4–5 mm long, covered with orangish hairs inside (vs. spur 7–8 mm long, covered with white hairs inside), the longer lateral lobes 9 mm long (vs. lateral lobes 2 mm long), the larger mid-lobe 4 mm wide (vs. mid-lobe 2.5 mm wide), the larger callus 2.5 × 2.5 mm, pubescent, apex slightly bilobed to truncate (vs. callus 1.5 × 1.5 mm, glabrous, apex obtuse).

Epiphytic herb. Stems patent, rarely scandent, 3.5–14(38) cm long, with 5–11(30) internodes, cylindrical, slightly laterally compressed, curved upwards from the middle, covered with the leaf sheaths, 5–18-leaved; internodes 4–20 × 1.5–9.0 mm. Roots cylindrical, thick, elongate, 14 cm to at least 70 cm long, 0.5–3.1 mm diam., arising from the basal part of the stem and from nodes at the lowest leaf, not or sparsely branching. Leaves green, sometimes spotted or suffused with purplish red, patent, elliptic to oblong, 5–18 × 1.2–3.3 cm, sessile, slightly narrowed towards the base, leaves on the same side of the stem 2–3 cm apart, dorsiventrally flattened, apex unequally bilobed with obtuse lobes, with a small mucro in the middle, thick, rigid, fleshy, coriaceous, the midrib distinct on the abaxial side; leaf sheaths green, sometime spotted or suffused with purplish red, slightly bilaterally compressed, longer than the stem internodes. Inflorescences two to eight per plant, patent, racemose, 7–22 cm long, long pedunculate, arising from the nodes at the opposite side of the leaves and below the roots, green with purplish red spots; peduncle slender, slightly upwards curved from the middle, 4.5–14 cm long, 1.3–6.0 mm diam., with 3 internodes, the basal internode fairly short, stout, 1–3 cm long, 0.5–2 mm in diam., the middle internode longer, 4–8 cm long, 1.6–2.3 mm diam., the terminal internode strongly bilaterally compressed distally, 2–4 cm long, broadening to 6 mm diam. just below rachis; peduncle scales 3, green with purplish red spots, ovate to broadly triangular, incurved, concave, thickened, slightly boat-shaped, clasping the peduncle, 5.0–7.4 × 2.0– 2.2 mm, apex acuminate, keeled; rachis 1.5–12.0 cm long, depending on the age of the inflorescence, 6–29-flowered, with one or two flowers open at a time, strongly bilaterally flattened, with distichous, persistent floral bracts, 1–8 mm apart, 0.7–1.2 cm wide across the floral bracts. Floral bracts green to yellowish, sometimes with purplish red spots, bilaterally flattened, ovate to broadly triangular, incurved, concave, thickened, slightly boat-shaped, clasping the rachis, 5–9 × 2.7–3.2 mm, apex acute, keeled. Pedicel-with-ovary yellowish green, cylindrical, 6-grooved, 8–11 mm long, c. 1.5 mm diam. Flowers non-resupinate, opening widely, lasting one to two days, mildly sweet-scented, membranaceous, 6 [5] cm across; tepals orange, yellowish at the base, lip pale yellow, with reddish brown spots on both surfaces of the lip between the lateral lobes, the midlobe and apical part of the lateral lobes white, the spur with 1 mm diam. reddish brown rounded warts on the back wall which shine through on the outside, the callus creamy white tinged reddish brown abaxially, the anther, column, column-foot, stipe and viscidium creamy white. Sepals incurved at the base. Dorsal sepal linear, 48–53 [30] × 3.5–4.0 [3.0] mm, slightly tapering towards the apex, slightly concave, somewhat twisted near the base, apex acuminate, glabrous, 5-nerved. Lateral sepals linear, obliquely subhorizontal, 48–53 [30] × 4.0–4.5 [5.0] mm, slightly tapering towards the apex, rather concave, somewhat twisted and expanded near base, apex acuminate, glabrous, 5-nerved. Petals similar to sepals, slightly smaller, obliquely, 42–50 [26] × 2–3 [2] mm, apex acuminate, glabrous, 5 [3]-nerved. Lip oblong to cylindrical in outline, 3-lobed, c. 15 [12] × 4–6 [5] mm in natural position, 12 [10] mm wide when spread, with a broad, sac-like spur at the base; spur broadly conical, 4–5 [3] × 4–5 [5] mm, apex 2-lobed with obtuse lobes (0.5 × 2.5 mm), on the back wall densely covered with long orangish hairs (0.5 mm long), turning to white hairs at the base of the callus; lateral lobes narrowly triangular to slightly ovate, falcate, 9 [8] × 3–4 [3] mm, free part 2 [1] mm long, erect, curving outwards, short pubescent on both surfaces, apex acute to slightly obtuse; mid-lobe narrowly triangular, 5–7 [4] × 4 [4] mm, entirely concave (4 [3] mm long), sparsely pubescent on both surfaces, slightly convex and pubescent in apical 1.5 [1] mm, 2 [3] mm thick, more or less evenly thick from base to apex, apex obtuse; lip between the lateral lobes sparsely pubescent on both surfaces, with a tongue-shaped callus a little below the mid-lobe, callus 2.5 mm long, 2.5 mm diam., sparsely pubescent, apex slightly bilobed to truncate, decurved. Column cylindrical, short, stout, 2–3 × 2.5–3.0 mm, laterally winged; column-foot short, broad, 3–4 × 3–4 mm. Anther suborbicular in outline, glabrous, 2 × 2 mm, the median with a longitudinal ridge. Pollinia in 2 pairs, those in a pair unequal, lanceolate-ellipsoid, curved; the larger 1.7 × 0.7 mm; the smaller, 1.5 × 0.5 mm; stipe broadly ovate-elliptic, 0.5× 0.5 mm, concave along the median, slightly translucent; viscidium transverse-linear, 0.2 × 0.6 mm, bent into a crescent shape, slightly translucent. Fruit green, cylindrical, 5–9 cm long, 6.0– 8.5 mm diam., with 6 longitudinal ridges. Described from living plants and flowers, and spirit material. Measurements between square brackets refer to Kew cult. 2017-20 from Mt. Bokor, Cambodia.

Distribution:— CHINA. Yunnan. THAILAND. Northern: Mae Hong Son Province (Huai Hi, Pang Tong Palace, Boo Salee), Chiang Mai Province (Fang, Doi Pha Hom Pok National Park, Wat Chan, Doi Pha Dam, Doi Ngao, Doi Suthep-Pui National Park), Lampang Province (Khun Tan National Park), Tak Province (Umphang), Uttaradit Province (Phumiang–Phuthong Wildlife Sanctuary), Phitsanulok Province (Phu Hin Rong Kla National Park); North-Eastern: Phetchabun Province (Nam Nao National Park, Thung Salaeng Luang National Park, Loei Province (Phu Kradueng National Park, Phu Rua National Park, Phu Luang Wildlife Sanctuary); Eastern: Chaiyaphum Province (Phu Khiao Wildlife Sanctuary, Nam Prom), Nakhon Ratchasima Province (Khao Yai National Park). LAOS. Houaphanh Province (Nong Hua Pa Noi Village, Ban Na Pe), Champasak Province (near Tad Fane Waterfall). CAMBODIA. Kampot (Mt. Bokor). VIETNAM. Dak Lak (Chu Yang Sin National Park), Thua Thien Hue (Ta Lo Village), Dak Nong (Nam Nung Protected Area), Gia La-Kon Tum (Mang Den) ( Fig. 28 ).

Etymology:—From the Latin flammeus, flame-coloured, referring to the orange tepals.

Phenology:—Flowering in April, May, June, July, September and October (in natural habitat); February, March, April, October, November and December (in cultivation). Flowering is probably intermittent throughout the year, as in most species of Thrixspermum .

Habitat and ecology:—Epiphyte in deciduous dipterocarp forest, dry and wet evergreen forest, lower montane rain forest, lower montane coniferous forest, lower montane scrub and upper montane rain forest and in coffee plantations, at 500–1,700 m elevation, locally common, growing on trunks or twigs of trees, such as Pinus kesiya Royle ex Gordon (1840: 8) (Pinaceae) in coniferous forest in Thailand, in exposed positions at about 1–5 meters above the ground.

Conservation status:— Thrixspermum flammeum is a widespread species, distributed from southern China to northern Thailand, Laos, Cambodia and Vietnam, with an Extent of occurrence (EOO) of 761,461.557 km 2 and an Area of occupancy (AOO) of 124.000 km 2. It is locally common with a large number of individuals. It is, therefore, assigned the conservation status of Least Concern (LC) according to IUCN criteria.

Vernacular ( Thailand):—Maeng Mum Som (แมงมุมส̊ม), Ta Khap Som (ตะขาบส̊ม).

Additional specimens examined:— CHINA. Yunnan, A. Henry 12081 (K s.n.!). THAILAND. Northern: Mae Hong Son Province, Mueang District, Huai Hi, Pasayu Pripasertying 115, 21 April 1999 (BK s.n.!), Pang Tong Palace, P. Suksathan 4290, 05 July 2007 (QBG 30670!), Boo Salee, S. Pumicong & S. Watthana 245, 03 May 2006 (QBG 27976!), Chiang Mai Province, Fang District, Seidenfaden & Smitinand GT 2100 (C 8342!, Seidenfaden 1988: 152 as T. centipeda ), Doi Pha Hom Pok National Park, S. Damapong 25, 18 May 2006 (QBG 37287!), Galyani Vadhana District, Wat Chan, Ban Den, M. Norsaengsri 10954, 29 April 2014 (QBG 72841!), Doi Pha Dam between Hang Dong and Bo Luang, Kai Larsen et al. 2135, 05 July 1968 (AAU s.n.!, Seidenfaden 1988: 152 as T. centipeda ), Mae Chaem, Doi Ngao, A.F.G. Kerr s.n., 12 May 1921 (K s.n.!, Seidenfaden 1988: 152 as T. centipeda ), Doi Suthep-Pui National Park, A.F.G. Kerr 98, 20 May 1912 (K s.n.!, AMES s.n.!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 2645, July 1958 (C 8297!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 2394, May 1958 (C 8312!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 2943, October 1958 (C 8313!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 2388, May 1958 (C 8326!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 2822, July 1958 (C 8327!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 2228, July 1958 (C 8297!, Seidenfaden 1988: 152 as T. centipeda ), Lampang Province, Khun Tan National Park, Put 150, 12 May 1933 (BK s.n.!, BKF 15673!, Seidenfaden 1988: 152 as T. centipeda ), Tak Province, Umphang District, S. Suddee et al. 5074, 05 April 2016 (BKF s.n.!), Uttaradit Province, Nam Pat District, Phumiang–Phuthong Wildlife Sanctuary, Seidenfaden & Smitinand GT 5432, 22 May 1964 (C 8332!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 5483, 30 April 1964 (C 8341!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 5796, 30 April 1964 (C 8341!, Seidenfaden 1988: 152 as T. centipeda ), Romklao Botanical Garden 0280/2554, 11 July 2011 (QBG 59889!), Phitsanulok Province, Nakhon Thai District, Phu Hin Rong Kla National Park, S. Pumicong 229, 26 July 2006 (QBG 28803!); North-Eastern: Phetchabun Province, Nam Nao District, Nam Nao National Park, T. Smitinand 558, 24 April 1951 (BKF 4944!, P. 00324331!, Seidenfaden 1988: 152 as T. centipeda , C 8348!, P 00324331!), Seidenfaden & Smitinand GT 8714, 20 March 1980 (C 8345!, 8347!, Seidenfaden 1988: 152 as T. centipeda ), Nong Mae Na District, Thung Salaeng Luang National Park, Huay Khek, Seidenfaden & Smitinand GT 5580, 25 February 1964 (C 5580!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 5564 (C 5583!, Seidenfaden 1988: 152 as T. centipeda ), O. Phueakkhlai et al. 22, 18 May 2007, (BKF 186359!), Loei Province, Na Haew, Phusansai, Tad Hueang Waterfall, C. Maknoi 837, 16 May 2016 (QBG 27651!). Phu Kradueng National Park, Seidenfaden & Smitinand GT 747, April 1957 (C 8306!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 3748 (C 8307!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 3770, April 1957 (C 8308!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 3060, October 1958 (C 8316!, 8323!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 3062 (C s.n.!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 3063, April 1959 (C 8331!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 3764 (C s.n.!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 3765 (C 8299!, Seidenfaden 1988: 152 as T. centipeda ), Huay Tham Yai, T.Smitinand 382, 12 May 1951 (BKF 4959!, Seidenfaden 1988: 152 as T. centipeda ), Tham Saw, T. Smitinand 404, (BKF s.n.!, Seidenfaden 1988: 152 as T. centipeda ), Thum Saw Nuea waterfall, S. Suddee et al. 4460, 07 July 2013 (BKF s.n.!), Lan Pra Kaew, P. Jongsirikankha 44, 22 May 2015 (BKF 194058!), Phu Rua District, Phu Rua National Park, Camp Site 2, N. Toolmal et al. 09122001, 09 December 2020 (TTM 0006390!), Phu Luang District, Phu Luang Wildlife Sanctuary, BKF 0135 (C 8330!, Seidenfaden 1988: 152 as T. centipeda ), Seidenfaden & Smitinand GT 8561 (C 8333!, Seidenfaden 1988: 152 as T. centipeda ), Khok Nok Kra Ba, N.Toolmal et al. 10122001, 10 December 2020 (TTM 0006391!); Eastern: Chaiyaphum Province, Khon San District, Phu Khieo Wildlife Sanctuary, Seidenfaden & Smitinand GT 8120, July 1973 (C 8325!, Seidenfaden 1988: 152 as T. centipeda ), Thung Kamang, N.Toolmal et al. 07122003, 07 December 2020 (TTM 0006386!), Nam Prom, Seidenfaden & Smitinand GT 8794 (C 8336!, Seidenfaden 1988: 152 as T. centipeda ), Nakhon Ratchasima, Khao Yai National Park, Khao Khieo, Seidenfaden & Smitinand GT 5878b (C 8320!), J.Y. Vidal & Niyomdham 6373, 08 June 1979 (AAU s.n.!, P 00509691!, P 00324332!, Seidenfaden 1988: 152 as T. centipeda ), Ch. Charoenphol, Kai Larsen & E. Warncke 4230, 29 October 1970 (AAU s.n.!, P 00324330!), J.B. Comber 1645, 08 June 1986 (K s.n.!). LAOS. Houaphanh Province, Xon District, Nong Hua Pa Noi Village, N.T. Hiep et al. LA-VN 1267, 11 April 2015 (LE 01076325!), Ban Na Pe, C.J. Spire 485, 19 May 1903 (P 00324333!); Champasak Province, near Tad Fane Waterfall (photos by A. Schuiteman!). CAMBODIA. Kampot Province, Mt. Bokor, Kew cult. 2017-20 (photos by A. Schuiteman!), Angkor, C. Thorel s.n. (P 00324334!, P 00324335!, P 00324336!), Mont de Pursat, A. Godefroy 444, 10 June 1875 (P 00324337!, P 00324338!, P 00324339!). VIETNAM. Dak Lak Province, N.V. Canh s.n., 29 May 2010 (LE 01122217!), Lak and Krong Bong Districts, Chu Yang Sin National Park, Chu Yang Sin Mountain, Nuraliev s.n., 11 April 2012 (LE 01122222!, 01122223!), Thua Thien Hue Province, A Luoi District, Hong Van Municipality, Ta Lo Village, L. Averyanov et al. HAL 7640, 29 April 2005 (LE 01076332!), Dak Nong Province, Dak Song District, Nam Nung Protected Area, L. Averyanov et al. AL 1182, 25 October 2019 (LE 01066593!), Gia La-Kon Tum Province, Kon Plong District, Mang Den, L. Averyanov et al. LX-VN 2293, 28 May 1985 (LE 01076419!).

Taxonomic notes:— Thrixspermum flammeum is another species that has been confused with T. centipeda , from which it differs in the characters listed in the diagnosis. It is in general a shorter-stemmed plant with distinctly longer (4.5–14 cm long) peduncles, whereas the true T. centipeda tends to have long climbing stems and short (1–3 cm long) peduncles. Characteristic for T. flammeum is that the sepals and petals are usually curved such that the apical parts are almost parallel and pointing downwards.

Figures

FIGURE 17. Thrixspermum flammeum. A. Habit. B. Inflorescence with flowers. C. Flower (oblique view). D. Fruit. E. Dorsal sepal. F. Lateral sepals. G. Petals. H. Lip with column & column-foot (lateral view). I. Lip (adaxial view, spread out). J. Lip (lateral view). K. Lip (longitudinal section). L. Column with pedicel (ventral view). M. Anther with pollinia (ventral view). N. Pollinia (two pairs). O. Stipe & viscidium. (Drawn from holotype, N. Toolmal et al. 07122003, TTM 0006386). Illustration by Phattaravee Prommanut.

FIGURE 18. Thrixspermum flammeum.A. Flower (obliqueview).B. Flower (front view,close-up).C.Flower (ventral view).D. Dissected perianth. E. Lip, adaxial view (left & middle: natural position; right: spread out with large orange warts on the back wall of spur). F. Lip (oblique view). G. Lip (abaxial view). H. Lip (lateral view, left: natural position; right: spread out). I. Column & column-foot with pedicel (ventral, lateral & dorsal views). J. Anther with pollinia (left: ventral view; middle: ventral view; right: ventral view without pollinia). K. Pollinia (two pairs). L. Pollinia (individual). M. Stipe & viscidium. Photographed by Wattana Tanming (A–I) & Nopparut Toolmal (J & M). Illustration assembled by Yongyuth Rattanasootr. A–I from living collection (QSBG) and J–M from spirit collection of N.Toolmal et al. 07122003 TTM 0006386.

FIGURE 19. Thrixspermum flammeum. A–B. Plant habit. C. Inflorescences with flowers. D–E. Flower (ventral view). F. Flower (lateral view). Photographed by André Schuiteman (A. In situ, Champasak, Laos), Chaiwat Tunkpradit (B. In situ, Thailand), Wattana Tanming (C–E. Cultivation, QSBG) & Nopparut Toolmal (F. Cultivation, QSBG). Illustration assembled by Yongyuth Rattanasootr.

FIGURE 28. Distribution map of Thrixspermum flammeum in mainland South-East Asia.