2. 中国科学院东南亚生物多样性研究中心, 内比都 耶津 05282, 缅甸;
3. 中国科学院西双版纳热带植物园, 云南 勐腊 666303;
4. 中国科学院核心植物园保护生物学协同中心, 云南 勐腊 666303
2. Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, Yezin 05282, Nay Pyi Taw, Myanmar;
3. Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, Yunnan, China;
4. Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla 666303, Yunnan, China
Agapetes D. Don ex G. Don comprises appro- ximately 100 currently recognized species, most of which are distributed in the Asian subtropical mon- soon region. It belongs to the tribe Vaccinieae Rchb., but the generic delimitation has not been solved satisfactorily due to the very closely related polyphy- letic genus Vaccinium L.[1–4]. This genus not only contains ornamentally important taxa, with enlarged and swollen rootstocks and, in most species, beautiful and delicate flowers, but also forms an important component of the evergreen broad-leaved forest, mainly as epiphytes but occasionally terrestrial trees.
During a field investigation to Yingjiang County, one specimen of an unusual Agapetes was collected. Detailed studies revealed that it did not match with any of the species so far reported from China[1, 5–7]. After examining all Agapetes species from neigh- boring countries, we found out that this species is identical to A. nana (Griff.) Hook. f., which was previously recorded only from Northeast India and North Myanmar[8–11]. Therefore, a new distributional record of A. nana for the flora of China is presented in this study.
Agapetes nana (Griff.) Hook. f. in Benth. & Hook. f. Gen. Pl. 2(2): 571, 1876. (Fig.1)
≡ Ceratostema nanum Griff., Not. Pl. Asiat. 4: 303, 1854 & Ic. Pl. Asiat.: t.505, 1854. Type: India: Assam, Naga hills, 16 Mar. 1837, W. Griffith 26 (holotype: K000729410!).
= Agapetes nana (Griff.) Hook. f. var. robusta Airy Shaw, Kew Bull. 13(3): 474, 1958. Type: Myanmar. Sumpra Bum, 5 Mar. 1953, F. Kingdon Ward 22017 (holotype: BM000752865!).
Epiphytic shrubs, up to ca. 0.8 m tall. Twigs terete, with inconspicuous pale grey lenticels, 0.3– 0.7 cm in diam., glabrous, young branches with ovate- lanceolate leaf-shaped bud scales, 0.4–0.7 cm×0.2– 0.3 cm. Leaves spirally aggregated, pseudo-verticillate; petioles short, 3–4 mm long, glabrous; leaf blades coriaceous, ovate-elliptic to elliptic-oblong, 6.5– 12.8 cm×3.0–4.5 cm, apex acute, base attenuate to obtuse, glabrous, margins entire, with unconspicuous nodulose thickening, slightly revolute when dry, midvein raised abaxially, slightly impressed adaxially, secondary veins 8–14 pairs, inconspicuous abaxially, lateral and reticulate veins forming a conspicuous intra-marginal vein. Raceme corymb-like, 12–18- flowered, 4–6 cm long, axillary or on leafless branches; peduncle stout, sub-fleshy, with sparse short glandular hairs, 1.5–2.2 cm long, bracts small, brown, triangular, ca. 0.7 mm×1.5 mm; pedicels stout, sub-fleshy, green, 1.2–1.6 cm long, ca. 1.5 mm in diam., with sparse short glandular hairs, with an epicalyx consisting of 12–18 conspicuous linear glandular ancillae (ca. 2 mm long) at the apex; bracteoles 2, brown, inserted at the base of pedicles, small, scale-like, triangular, ca. 1 mm long. Calyx narrowly campanulate, 3–3.5 mm long, glabrous; calyx tube cylindrical, slightly pale green, ca.1.5 mm long, 1.5–2 mm in diam., calyx divided to middle; lobes lanceolate, 1.5–2 mm×0.8 mm. Corolla cylindrical-conical, 1.0–1.1 cm long, glabrous, maroon (dark red); corolla tube lobed to 2/3, lobes narrowly lanceolate to linear, 7–8 mm×3–3.5 mm, strongly reflexed at anthesis. Stamens 10, ca. 1.0 cm long; filaments flat, curved at upper part, ca. 3 mm long, pubescent upper part to middle; anthers 7.5–8 mm long, thecae reddish brown, ca. 3.5 mm long, papillate, tubules brownish yellow, 4.0–4.5 mm long; with 2 spurs abaxially, spurs ca. 2 mm long, downward; Style ca. 1.1 cm long. Berry sub-globose to depressed glo- bose, 6–7 mm in diam., pinkish white when mature.
Habitat and ecology: It is an epiphytic shrub which grows on the trees in montane broad-leaved forests.
Phenology: Flowering from April to May; fruiting from May to June.
Chinese name: xiàn bāo shù luó bo (腺苞树萝卜) (新拟)
Notes: Agapetes nana is special among Agapetes because of its distinct palisade of gland-tipped hairs which forms a sort of epicalyx (Fig. 1: F, leftmost). Although Agapetes miranda Airy Shaw also has similar epicalyx[12-13], it is very different from A. nana by the whole habit. As there are very few collections of this species, the previous descriptions of its flower were based on materials with young or late flowers[9, 11]. Airy Shaw indicated that the anthers of A. nana are devoid of dorsal appendages (spurs). The most likely reason is that the dorsal appendages are not well developed when the flowers are young. Our collection possibly represents the first material with mature flowers of A. nana, so the characters of its mature flower can be described precisely, especially for the size and color of the corolla and the spurs on the back of anthers. Fortunately, we also collected the specimens with mature fruits, and the description of fruit was based on our collections from Myanmar [Yun-Hong Tan et al. M4611 (HITBC), collected on 17 June 2018].
Airy Shaw indicated that A. nana var. robusta Airy Shaw is different from A. nana by its leaf shape and size (8.8–13.5 cm×3.3–5.0 cm vs. 5.0–9.5 cm× 1.5–2.4 cm), according to our field observations and our collections from China and Myanmar, and our former discussion, the leaf shape and size with variation within population and among different popu- lations is understandable to be a universal pheno- menon, so we hold the opinion that A. nana var. robusta Airy Shaw should be resolved as a synonym of A. nana (Griff.) Hook. f.
Voucher specimen: China. Yunnan: Yingjiang County, Tongbiguan Nature Reserve, 1 May 2020, Li- Yan Wang T0494 (HITBC); ibid., 12 Jan. 2021, Bin Yang & Ping-Yuan Wang T864 (HITBC).
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