Thrixspermum trichoglottis (Hook.f.) Kuntze (1891: 682)

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 : 235-242

3. Thrixspermum trichoglottis (Hook.f.) Kuntze (1891: 682) ;

Schlechter (1911: 57); Smith (1921: 320); Holttum (1964: 611); Comber (1990: 322); Comber (2001: 955); Wood et al. (2011: 553) ( Figs. 8–11 , 12C–D )

— Sarcochilus trichoglottis Hook.f. (1890: 39) ; Hooker (1890: 2123).— Dendrocolla trichoglottis (Hook.f.) Ridley (1896: 381) .

Type: Singapore, icon. Ridley s.n. (lectotype K!, here designated) . Epitype (here designated): Peninsular Malaysia, Pahang, Tembeling , October 1929, C.E. Carr 185 ( K s.n.!) . Former syntypes: Malaysia, Perak, King’s Collector 5934 ( K!), icon. Scortechini s.n. ( K!) .

Epiphytic herb. Stems patent, 10–20 cm long, with 11–23 internodes, terete, slightly laterally compressed, curved upwards in upper half, covered with the leaf sheaths, 7–17-leaved; internodes 2.8–15.0 × 1.7–3.6 mm. Roots terete, thick, elongate, 9 cm to more than 20 cm long, 0.4–1.8 mm diam., arising from the basal part of the stem and from nodes opposite the leaves or near the lowest leaf, not or sparsely branching. Leaf sheaths green, slightly bilaterally compressed, longer than the stem internodes. Leaves green, patent, oblong, 3–7 × 0.7–1.8 cm, sessile, slightly narrowed towards the base, leaves on the same side of the stem 0.5–4.0 cm apart, dorsiventrally flattened, apex unequally 2-lobed with obtuse lobes, with a small mucro in the middle, thick, rigid, fleshy, coriaceous, the midrib distinct on the abaxial side. Inflorescences one to seven per plant, patent, racemose, 7–12 cm long, long pedunculate, equally or slightly longer than leaf, arising from the nodes at the lowest leaves and below the roots, yellowish green; peduncle terete, slightly upwards curved from the middle, 6–9 cm long, 0.7–2.3 mm diam., with 2–3 internodes, the basal internode fairly short, stout, c. 3 mm long, 0.7–1.5 mm diam., the middle internode normally longer, 2 cm long, 0.9 mm diam., the terminal internode swollen distally, 3.5–5.5 cm long, broadening to 2.3 mm diam. just below rachis; peduncle scales 2–3, yellowish green, broadly ovate to triangular, incurved, concave, thickened, slightly boat-shaped, clasping the peduncle, 2.2–3.0 × 0.5–1.4 mm, apex acuminate, keeled; rachis relatively short, 0.5–1.0 cm long, depending on the age of the inflorescence, densely 7–11-flowered, with 1–2 flowers open at a time, swollen, 3.5–6.3 mm diam., clearly thicker than the peduncle. Floral bracts quaquaversal, green, broadly ovate to triangular, incurved, concave, thickened, slightly boat-shaped, strongly clasping the rachis for nearly half of its length, 2.2–4.8 × 1.5–2.5 mm, apex acuminate to caudate, keeled. Pedicel-with-ovary pale yellow, cylindrical, 6-grooved, 6–8 mm long, 0.8–1.0 mm diam. Flowers resupinate, opening widely, lasting one day, membranaceous, 1.5–2.0 cm across; tepals pale yellow, lip yellow, spotted with brownish orange on both surface at the basal part of the lateral lobes, between the lateral lobes, at the basal part of the mid-lobe, and at the apex of the callus, the spur with orange warts inside on the back wall which shine through on the outside, column pale yellow, anther creamy white, pollinia bright yellow, stipe and viscidium creamy white. Dorsal sepal oblanceolate to elliptic, 8–10 × 2.5–3.0 mm, concave, slightly boat-shaped, somewhat attenuate at the base, acute, glabrous, 5-nerved, nerves reticulate branching. Lateral sepals lanceolate, 8–10 × 3.5–4 mm, obliquely dilated at the lower margin, concave, slightly boat-shaped, with a low abaxial keel, acute, glabrous, 5-nerved, nerves reticulate branching. Petals oblanceolate, 7.5–9.0 × 2.5–3.0 mm, narrower than the sepals, concave, slightly boat-shaped, acute, glabrous, 3-nerved, nerves reticulate branching. Lip rhombic-triangular in outline when spread, oblong in natural position, 3-lobed, 5–6 × 2.5–3.0 mm in natural position, 7–8 mm wide when spread, with a conical, sac-like spur at the base; spur broadly conical, 2.5 × 2.0 mm, apex obtuse, inside towards the base of the callus with large, orange, rounded warts, 1 mm diam. and densely covered with fairly long capitate hairs (0.5 mm long); lateral lobes obovate, distinctly shorter than the mid-lobe, 4–6 × 3 mm, with obtuse apex, erect, curving upwards and clasping the column, densely covered with 0.8–1.0 mm long capitate hairs on both surfaces and along the apical margins; mid-lobe short, broadly triangular, 1 × 2 mm, slightly concave at the basal part, convex at apical part (0.5 mm), glabrous or sparsely covered with 0.8–1.0 mm long capitate hairs on the adaxial surface, rather thick, fleshy, entire, apex acute, decurved; lip adaxially between the lateral lobes densely covered with long capitate hairs, glabrous abaxially, a little below the mid-lobe with a cuneate callus 1.5 mm long, 1 mm diam., apex bilobulate, decurved, glabrous. Column cylindrical, short, stout, 2.0–3.0 × 1.5–2.0 mm, laterally winged; column-foot short, broad, 2.0 × 1.5–2.0 mm. Anther suborbicular in outline, glabrous, 1.0 × 1.0 mm, the median with a longitudinal ridge. Pollinia in two pairs, those in a pair unequal, ovate, curved; the larger 0.8 × 0.5 mm; the smaller, 0.6 × 0.3 mm; stipe broadly ovate, 0.5 × 0.5 mm, concave along the median, slightly translucent; viscidium transverse-linear, 0.2 × 0.5 mm, bent into a crescent shape, slightly translucent. Fruit yellowish green, narrowly cylindrical, 6–8 cm long, 3.0 mm diam., with 6 longitudinal ridges. Described from living plants and flowers, and spirit material.

Distribution:— THAILAND. Peninsular: Narathiwat Province. SINGAPORE. Island Archipelago. MALAYSIA. Peninsular: Pahang, Kuala Lipis, Kulim, Kota Tinggi; Borneo: Sarawak, Kapit; Sabah, Sandakan, Ulu Dusun, Kota Tinggi. INDONESIA. Sumatra: West Coast, Pajokumbuh; Java: Bogor. ( Fig. 26 ).

Phenology:—Flowering in January, February, March, July, August, September, October (in natural habitat, ten records); March (in cultivation, three records). Flowering is probably intermittent throughout the year, as in most species of Thrixspermum .

Habitat and ecology:—Epiphyte in orchards and along streams, 100–150 m elev., commonly found on branches of trees, including Psidium guajava L. ( Myrtaceae ) and Baccaurea motleyana (Müll. Arg.) Müll.Arg. ( Müller Argoviensis 1866: 461) (Phyllanthaceae) at about 1–2 meters above the ground. Restricted to shady areas and somewhat exposed positions on small trees.

Conservation status:— Thrixspermum trichoglottis (Hook.f.) Kuntze is a widespread species distributed from Southern Thailand, Malaysia ( Peninsular , Borneo , Sarawak and Sabah), and Indonesia (Sumatra, Java), with an Extent of occurrence (EOO) of 1,516,886.346 km 2 and an Area of occupancy (AOO) of 60.000 km 2. As the species is quite common locally and can be found in large numbers of individuals in many sites, and is widespread from the southern part of Thailand to Java and Borneo, it is assessed as Least Concern (LC) according to IUCN criteria.

Vernacular ( Thailand):—Ta Khap Lueang Pak Lai (ตะขาบเหลืองปากลาย).

Additional specimens examined:— THAILAND. Peninsular: Narathiwat Province, Sukhirin District, Phu Khao Thong Subdistrict , N . Toolmal , A . Baka & W . Tanming 28102001, 28 October 2020 ( TTM 0006374 !), Kalubee Subdistrict , I Jue Rao village , N . Toolmal , A . Baka & W . Tanming 28102002, 28 October 2020 ( TTM 0006375 !), Phu Khao Thong Subdistrict , N . Toolmal , A . Baka & W . Tanming 28102003, 28 October 2020 ( TTM 0006376 !) . SINGAPORE. Ridley H. N . s.n., 1891 ( K 000891299 ; syntype) . MALAYSIA. Peninsular Malaysia, H. N . Ridley s.n., 1935 ( K s.n.!), Pahang, Kuala Lipis , C. E . Carr K135 , September 1929 ( K 13824 !), Kota Tinggi , Jalan Sg. Kemang, M . Shah & Noor. MS . 857, 28 September 1959 ( K s.n.!, L 1540175 !), Kulim, Ulu Paip , T . Roelfsema , APTM . Vogel, MMJ van. Balgooy s.n. ( L 0770319 , not seen), Borneo , J . Motley 484, August 1859 ( K s.n.!) , Sarawak, H. N . Ridley s.n., June 1915 ( K s.n.!), Kapit, Upper Rejang River , J. & M. S . Clemens 1164, 1929 ( K s.n.!), Clemens, J & Clemens, MS 21164 , 01 January 1929 ( L 0598061 !, L 1540177 !, L 1540178 !), Unknown s.n. ( BM 000534691 !), Sabah, Sandakan, Ulu Dusun , A . Lamb SAN 84149 ( K s.n.!), A . Lamb AL1166 / 89, 25 August 1989 ( K s.n.!) . SINGAPORE. Unknown locality, H. N . Ridley s.n., August 1891 ( BM 000534669 !), H. N . Ridley s.n., 15 February 1890 ( BM 000534670 !), H. N . Ridley s.n., 1891 ( BM 000534671 !), Hallow Road. Archipel. Ind., Unknown s.n. ( L 1540176 !) . INDONESIA. Java, J. J . Smith s.n. ( K s.n.!), Buitenzorg, Tegal Sapi , Bakhuizen van den Brink Jr, RC 1499, 23 July 1922 ( L 1469180 !), Sumatra, Posthumus 1042 ( L 1540181 !). UNKNOWN LOCALITY. Kartamah s.n. ( L 1540180 !) .

Taxonomic notes:—Although Thrixspermum trichoglottis is most similar to T. praetermissum (see the comparison above), it has also been confused with T. hystrix (Blume) Rchb.f. ( Reichenbach 1874: 145, based on Dendrocolla hystrix Blume 1825: 291 ) first described from Bogor, West Java, Indonesia, which also has pale yellow tepals. However, T. trichoglottis is distinguished by having inflorescences as long as or slightly longer than the leaves, 7–12 cm long (vs. inflorescences twice as long as the leaves, 6.5–25 cm), an obtuse spur apex (vs. spur apex distinctly bilobed), the mid-lobe adaxially sparsely covered with long capitate hairs (vs. mid-lobe adaxially densely covered with long clavate hairs).

Thrixspermum trichoglottis was described on the basis of a sterile specimen (King’s Collector 5934) and two drawings of poor quality by Scortechini and Ridley. Since several floral characters cannot be inferred from the existing type material, we here designate icon. Ridley s.n. (K s.n.!) as a lectotype, as it is the only type material that shows some floral details. To help fix the application of the name T. trichoglottis , we select C.E. Carr 185 (K s.n.) as an epitype, as this specimen was collected in the same floristic region as the type and because it has some flowers left. Although once reportedly very common in Singapore (Ridley, in sched.), it is currently considered Critically Endangered there ( Yam 2013: 118).

We note that the species reported as T. trichoglottis in Ong (2011: 95) and Ong et al. 2011 (2011: 163, the upper right figure) is T. pulchellum .

Thrixspermum album (Ridl.) Schltr. (Schlechter 1911: 56, based on Dendrocolla alba Ridl. 1905: 191 ) has been included in the synonymy of T. trichoglottis ( Seidenfaden & Wood, 1992) . Having carefully examined the protologues and type specimens of T. album (H. N. Ridley 14130, Seberang Perai Selatan, Pulau Pinang, Malaysia, 1907, K s.n.!, BM 000534632!, type of Dendrocolla alba Ridl. ) and T. pulchellum (Thwaites C.P. 2354 K 000891314!, type of Cylindrochilus pulchellus Thwaites ), we consider that T. album matches T. pulchellum in all relevant characters. Therefore, we transfer T. album from the synonymy of T. trichoglottis to that of T. pulchellum .

Figures

FIGURE 8. Lectotype of Thrixspermum trichoglottis.Illustration by H.N.Ridley, produced with permission of the Royal BotanicGardens, Kew.

FIGURE 9. Thrixspermum trichoglottis. A. Habit. B. Rachis with flowers (oblique view). C. Flower (ventral view). D. Rachis with fruit. E. Dissected perianth. F. Lip (adaxial view, natural position). G. Lip (abaxial view, natural position). H. Lip (lateral view). I. Lip (adaxial view, spread out). J. Lip (longitudinal section). K. Column & column-foot with pedicel (lateral views). L. Anther with pollinia (ventral view). M. Pollinia (two pairs). N. Stipe & viscidium. (Drawn from N. Toolmal et al. 28102001, TTM 0006374). Illustration by Phattaravee Prommanut.

FIGURE 10. Thrixspermum trichoglottis. A. Flower (front view). B. Flower (oblique view). C. Flower (ventral view). D. Dissected perianth. E. Lip (natural position, left: adaxial view; right: abaxial view). F. Lip (adaxial view, spread out). G. Lip, adaxial view (natural position, left: showing a callus; middle: showing the mid-lobe; right: showing capitate hairs inside the spur with scattered orange warts). H. Lip (lateral view). I. Column & column-foot with pedicel (ventral, lateral & dorsal views). J. Anther with pollinia (left: dorsal view; right: ventral view). K. Pollinia (two pairs). L. Stipe & viscidium. Photographed by Wattana Tanming (A–I) & Nopparut Toolmal (J–L). Illustration assembled by Yongyuth Rattanasootr. A–I from living collection (QSBG) and J–L from spirit collection of N. Toolmal et al. 28102001 (TTM 0006374).

FIGURE 11. Thrixspermum trichoglottis. A–B. Plant habit. C. Flowers (ventral view). D. Flower (front view). E. Flower (ventral view). F. Fruit. Photographed by Satawan Atdhabhan (A–C. In situ) & Wattana Tanming (D & F. Cultivation, QSBG). Illustration assembled by Yongyuth Rattanasootr.

FIGURE 12. A comparison of allied species.A–B. Thrixspermum praetermissum. C–D. Thrixspermum trichoglottis. E-F. Thrixspermum pulchellum. Photographed by Kurt Keller (A–B. Cultivation), Wattana Tanming (C–F. Cultivation, QSBG). Illustration assembled by Yongyuth Rattanasootr.

FIGURE 26. Distribution map of Thrixspermum praetermissum and T. trichoglottis in subtropical and tropical Asia.