Gynochthodes betongensis Chantar., 2021

Chantaranothai, Pranom, 2021, Taxonomic notes on the genus Gynochthodes Blume (Rubiaceae) from Thailand, Phytotaxa 490 (3), pp. 291-297 : 292-295

Gynochthodes betongensis Chantar. , sp. nov. Figs. 1 & 2

Gynochthodes betongensis resembles G. cochinchinensis and G. umbellata but differs by having a cordate leaf base and slightly longer petiole (10-15 mm vs 3-10 mm).

Type:— THAILAND. Yala: Betong, Banglang National Park, Ban Chulabhorn Phattana 10, edge of evergreen forest, 5°51′48.00″N, 101°14′24.00″E, 550 m alt., 19 July 2004, R. Pooma, K. Phattarahirankanok, S. Sirimongkol, M. Poopath & S. Sangrit 4434 (holotype BKF-SN154039, isotypes AAU, E[E00210708]) .

Scandent shrub 2–3 m tall; young branchlets subterete to quadrangular, densely pubescent; older branches terete, with longitudinal furrows along the inter-petiolar medians on opposite sides, glabrescent. Leaves: lamina chartaceous, oblong to ovate-oblong or elliptic-oblong, 8.5–12 x 3–4.6 cm, base cordate, rarely with unequal sides, margin entire, apex long cuspidate to acuminate, glabrous on both surfaces, drying dark brown to black; midrib sunken to slightly prominent, sparsely puberulent on adaxial leaf surface, prominent, densely pubescent on abaxial leaf surface; lateral veins 12–14 pairs, sparsely hairy below; pit-domatia present in axils of lateral veins on abaxial leaf surface; petioles subterete, 1–1.5 cm long, slightly grooved or flattened on the upper side, densely pubescent; stipules fused along one side, forming a sheath, ca. 4 x 3.5 mm, shortly connate at base, membranous, apex acuminate with mucro ca. 1 mm long, sparsely puberulent. Flowering heads and flowers not seen. Infructescences pseudo-umbellate, terminal, consisting of 8–10 flowering heads; fruiting stipe (developing from peduncle) 11–14 mm long, hairy. Syncarps dark green turning bright orange, subglobose, (0.7–) 1–1.3 cm diameter, composed of 3–6 fruitlets, sparsely hairy.

Additional collection:— THAILAND. Yala: Betong, Ban Chulabhorn Phattana 10, trail to giant Tetrameles nudiflora R.Br. (1838: 79) tree, 21 April 2005, R. Pooma, V. Chamchumroon, K. Phattarahirankanok, S. Sirimongkol, M. Poopath & S. Machit 5106 (A, AAU, BKF-SN163540, TNS) ].

Distribution:— Thailand, known only from Betong district, Yala.

Habitat and phenology:—Margin of evergreen forest, 480–550 m alt. Fruiting specimens were collected in April– July.

Etymology:—The species is named after Betong district, Yala province, Thailand where it occurs.

Vernacular name:—Yo yan betong (ยอย่านเบตง).

IUCN Conservation status:—This species is rare, currently known only from the type locality along the margin of evergreen forest at Chulabhorn Phattana 10 village, Banglang National Park, Betong district, close to the Thai- Malaysian border. This area remains under-explored and it is possible that more populations will be discovered. The information available is insufficient for establishing the conservation status of this species. Therefore, it is classified as Data Deficient (DD) under the IUCN criteria ( IUCN, 2012); a further assessment should be carried out when more data are available.

Notes:— Gynochthodes betongensis is morphologically similar to G. cochinchinensis and G. umbellata in having flowers that are borne in heads and arranged in pseudo-umbels on terminal shoots. The new species differs in having a cordate leaf base (vs cuneate, obtuse or slightly oblique leaf base in G. cochinchinensis and G. umbellata ), slightly longer petioles (10–15 mm long vs 3–10 mm long), and more lateral veins (12–14 pairs vs 7–12 pairs in G. cochinchinensis and 6–8 pairs in G. umbellata ). In addition, G. betongensis has shorter peduncles (11–14 mm long) than G. cochinchinensis , in which the peduncles are 15–20(–40) mm long ( Table 1). The new species is known from the village of Ban Chulabhorn Phattana 10 where the two specimens above were collected.

Gynochthodes hispida (K.M.Wong) Razamfim. & B.Bremer.

— Morinda hispida K.M.Wong. Type: Malaysia, Pahang, Temambun , sandstone plateau, 600 m alt., 27 April 1986, Wong & Saw FRI 34334 (holotype KEP[KEP181740], isotypes- A[A01154973], KEP[KEP181741]).

Ecology:—Shaded in dry limestone mountain, 180 m alt., but on sandstone at 600 m alt. in Malaysia.

Vernacular name:—Yo yan bai saak (ยอย่านใบสาก).

Note:— Gynochthodes hispida is readily distinguished from all members of the genus in Thailand by having the smallest leaves among the Thai species, they also have hispid leaves and stem. This species is similar to G. calciphila (K.M. Wong 1987: 269) Razamfim. & B.Bremer (2011: 287) in having small, obovate leaves. It differs by the stipules that are triangular and connate at the base (vs fused along one side), a smaller calyx tube and lobes, and smaller anthers. Careful examination of Williams & Pooma 1489 (BKF) revealed that raphide crystals are present in the mesophyll and visible on the adaxial leaf surface. These were described by Wong (1987) as spiculate crystals. The Thai specimen was collected from a limestone mountain at 180 m alt., Huai Yot, Trang province in peninsular Thailand. It extends the range of G. hispida which had previously been thought to be restricted to the Ulu Endau area, Pahang state, Malaysia.

Gynochthodes macrophylla Kurz , Type:— INDIA. Nicobar islands , Nankowry island, February 1875, W.S. Kurz s.n. (K[K000763879]).

— G. puberula Craib , Type:— THAILAND. Surat Thani: Ko (Kow) Pa-ngan , 7 June 1927, Put 809 (lectotype K[K000763877], designated here, isolectoypes BK[ BK257347 ], K[K000763878]).

Thailand:—PENINSULAR: Surat Thani (Ko Pa-ngan) , Phangnga .

Distribution:— India ( Nicobar islands).

Ecology:—In evergreen forest.

Vernacular name:—Yo yan bai yai (ยอย่ านใบใหญ่).

Note:— Puff (2011) placed Gynochthodes puberula under G. macrophylla because of its puberulous young branches, pedicels, peduncles and ovaries which are insufficient to separate from the latter. Moreover, the indumentum is lost in older plants. Craib (1932) described G. puberula based on Put 809 which comprises three sheets. The one in Kew, [K000763877] is in good condition but it includes two specimens, the top left-hand specimen is selected as lectotype because it has more flowers.

Gynochthodes villosa (Hook.f.) Razafim. & B.Bremer.

— Morinda villosa Hook. f. Type:— INDIA. Khasia: Khasia range, de Silva (Scoudent.), July 1828, Wallich, List no. 8425 (holotype K[K000031581]).

— Morinda cinnamomea Craib. Type:— THAILAND. Satun (Satul): Khao Keo Range , ca. 700 m alt., 13 March 1928, A.F.G. Kerr 14551 (lectotype K[K001325160] designated here, isolectotypes BK[BK12300], BM[BM000945407]), syn. nov.

— Gynochthodes cinnamomea (Craib) Razafim. & B.Bremer (2011: 288) , syn. nov.

Thailand:—NORTH-EASTERN: Loei (Phu Luang Wildlife Sanctuary, Phu Suan Sai National Park); EASTERN: Nakhon Ratchasima (Khao Yai National Park, Pak Thongchai); CENTRAL: Nakhon Nayok ( Khai Yai National Park ); PENINSULAR: Chumphon (Lang Suan), Surat Thani (Phato), Satun (Khao Keo Range) ,

Distribution:— India, China (Southern Yunnan), Vietnam.

Ecology:—In mixed deciduous, dry evergreen and evergreen forests, 0−1,400 m alt. Flowering period: Mar.−Apr.

Note:— Gynochthodes villosa is similar to G. cochinchinensis in its leaf shape and size, habit and flower. It differs by having unequal calyx teeth, cuspidate stipule apices, smaller leaves and much shorter peduncles. Examination of type and non-type material of G. villosa and Morinda cinnamomea ( G. cinnamomea ) showed that the differences between them are so small and unreliable that they are best united under G. villosa . Craib (1932) described Morinda cinnamomea based on three sheets, BK12300, BM000945407 and K001325160. The specimen at K is selected here as lectotype because it has more branchlets and leaves.

Key to the species of Gynochthodes in Thailand

1. Flowers individual, in fascicles, axillary............................................................................................................................................2

1. Flowers forming in flowering heads, umbel-like, terminal................................................................................................................3

2. Leaves elliptic-lanceolate, 4.5–8(–10) by (0.5–)2.5–3.5(–5) cm, apex acute to acuminate; fruits up to 1 cm in diameter ................. ........................................................................................................................................................................................... G. coriacea

2. Leaves elliptic-oblong, 7-12 by 3–6.5 cm, apex shortly and abruptly acuminate; fruits more than 1 cm in diameter ........................ ..................................................................................................................................................................................... G. macrophylla

3. Leaves and branches glabrous......................................................................................................................................... G. umbellata

3. Leaves and branches hairy..................................................................................................................................................................4

4. Leaf base cordate. Petioles at least 1 cm long.............................................................................................................. G. betongensis

4. Leaf base cuneate, rarely subcordate. Petioles up to 1 cm long.........................................................................................................5

5. Leaves narrowly obovate to obovate, less than 2 cm wide, drying brown.......................................................................... G. hispida

5. Leaves elliptic or oblong, more than 2 cm wide, drying dark brown or black...................................................................................6

6. Abaxial leaf surface puberulous and scabrous. Calyx lobes acute........................................................................ G. cochinchinensis

6. Abaxial leaf surface villous and hispid. Calyx lobes obtuse to rounded.............................................................................. G. villosa

Figures

FIGURE 1. Gynochthodes betongensis Chantar., sp. nov. A. fruiting branch; B. abaxial leaf surface showing venation and domatia in the axils of lateral veins; C.-D. side and top views of fruiting head. Scale bars A. 3 cm, B. 2 cm, C. –D. 1 cm. Drawn by P. Kladwong from Pooma et al. 4434.

FIGURE 2. Distribution map of Gynochthodes betongensis Chantar., sp. nov. in peninsular Thailand.