Magnolia brunnescens K.W.Luo & XiongLi, 2022

Li, Xiong, Luo, Kai-Wen, Zhang, Zi-Bin, Tian, Jing & Wei, Xiao-Mei, 2022, Magnolia brunnescens (Magnoliaceae), a new species from Guangxi, China, Phytotaxa 544 (2), pp. 201-206 : 202-203

Magnolia brunnescens K.W.Luo & XiongLi , sp. nov. ( Figs 1 , 2 )

Type:— CHINA. Guangxi Zhuang Autonomous Region : Tian’e County, 25°04’08”N, 107°12’38”E, ca. 790 m, on the valley of broadleaved forest, flowering, 3 June 2021, Luo 21060301 (holotype: HIB!; isotypes: GXF!, IBK!) .

The new species is morphologically similar to M. dandyi Gagnepain (1939: 63) , but mainly differs in buds, twigs, stipules, petioles and peduncles densely brown-tomentose (vs. long ferruginous), vegetative buds elliptic-ovoid, ca. 1.0 cm long (vs. oblong, usually over 2.0 cm long), leaf blades adaxially villous (vs. glabrous), anthers apically semi-orbicular (vs. triangular) and carpels sparsely villous (vs. glabrous).

Evergreen trees up to 28 m high and 52 cm D. B. H., aromatic. Bark coarse with transverse lenticels when young, becoming smooth and longitudinally fissured with age. Trunk straight, branches nearly horizontal, slender, twigs robust, dotted with lenticels. Buds, twigs, stipules, petioles and peduncles densely brown-tomentose. Leaves clustered on twigs apex, vegetative buds elliptic-ovoid, ca. 1.0 cm long; blade leathery, green on both sides, oblong-elliptic to obovate-elliptic, base cuneate, apex acuminate to acute, 19–34 × 7.5–16 cm, brown villous on each side, especially thick on veins; veins conspicuous, prominent beneath, secondary veins 16–23 on each side of midvein, higher-order venation reticulate, anastomosing before margin, abaxially conspicuous, stipules caducous, petioles 2.5–5.3 cm, stipular scars 1.0– 1.8 cm long, extending 1/3–1/2 of petiole length. Flowers bisexual, solitary terminal, floral buds ellipsoid, ca. 4.0 × 3.2 cm; spathaceous bract 1, abaxially brown villous, peduncles robust, 2.5–3.3 cm long, ca. 0.8 cm in diameter; flower 9–13 cm in diameter, slightly fragrant, tepals 11(12), in 4 whorls, the outer 3 tepals green, elliptic, longitudinally 5-veined, abaxially villous at base, 5.0–7.0 × 2.8–3.5 cm, inner tepals becoming gradually smaller inwards, white, obovate to spathulate, 3.7–6.5 × 1.6–2.7 cm; stamens 250–400, purplish red, 13.4–15.0 × 2.4–3.5 mm, anthers 9.7–12.2 × 1.0– 1.5 mm, abaxially sparsely villous, introrsely dehiscent, connectives elongate into 1.0– 1.5 mm semi-orbicular appendages; gynoecium ovoid, ca. 2.4 × 1.6 cm, sparsely villous; carpels 60–80, long ca. 1.2 cm, ovules 5–6 in each side. Aggregate fruit ovoid when well-developed, ca. 8.0 × 6.0 cm, glabrous, mature follicles dehiscent along both dorsal and ventral sutures, beaks slightly recurved, seeds compressed ovoid, ca. 7.0 × 7.0 mm.

Phenology:— Flowering late May–June, fruiting late August–September.

Etymology:— From the Latin for brownish, referring to the dense, brown-tomentose indument of this plant. The Chinese name is hè-máo-mù-lián (ñ毛木Ϊ).

Distribution and habitat:— Currently known from three localities: Tian’e County; Baojia Mountain, Nandan County, Hechi City; Jiayou Town, Lingyun County, Baise City, Guangxi, China. Magnolia brunnescens is found in broad-leaved forest at approximately 800 m, growing mostly on moderate slopes with deep humus-rich soil.

Preliminary conservation status:— During fieldwork in the type locality, only two sites with a total of 16 individuals were observed, in which one critical community comprising 15 adult individuals occurs in an area not exceeding 100 m 2, and the other site has only a young tree. The prospects for this community are not optimistic. Given that most are canopy trees except for a few growing in forest margin, M. brunnescens appears to be a heliophilous species, and fewer flower buds and lower seed set are both observed on lower branches. No juveniles and seedlings were found in undergrowth and adjacent areas, indicating low natural regeneration. In addition, we noted flowering nearly overlaps the rainy season from May through August, which may contribute to difficult pollination. Furthermore, there are large plantations around the habitat in which Cunninghamia lanceolata , Phyllostachys edulis and other trees are planted.

It should be noted that two other localities are c. 85 kilometres away, and only three localities with few individuals have been thus far recorded. In fact, suitable habitat in the adjacent area is both rare and fragmented owing to locally high proportion of karst (up to 40%) and reduction of available habitat mainly caused by the replacement of extensively artificial vegetation. In view of its small population size, restricted known range, poor seedling regeneration and fragmented habitat, we preliminarily consider this species as critically endangered (CR B1ab (iii) + 2ab (iii); D) using the IUCN categories and criteria ( IUCN 2022). Further exploration and conservation studies are urgently needed.

Notes:— Indument has been recognized as a key character for delimitation of taxa in M. sect. Manglietia (Hu 2011) . In China, there are only a few species recorded with indument on carpels or stamens, and most of them also are densely tomentose on buds, twigs, stipules, peduncles and leaves: M. rufibarbata ( Dandy 1928: 128) Kumar (2006: 185) , M. ventii ( Tiêṕ 1980: 560) Kumar (2006: 185), M. zhengyiana ( Xia 2008: 55) Nooteboom (2008: 50) , M. lawii (Xia & Liao 2009: 1) Callaghan & Png (2013: 3) , M. dandyi and the new species. In addition, it needs to be mentioned that M. brunnescens is a potential aromatic plant because a strong, persistent fragrance is observed from dry branches and leaves.

Additional specimens examined:— CHINA. Guangxi: Nandan County, Baojia Mountain , 6 Nov 1980, Fu 84 ( IBK, online image) ; Lingyun County, Jiayou town , 804 m, 12 Mar 2014, Lingyun Expedition team 451027140312015 ( GXMI, online image) ; Tian’e County, ca. 790 m, 20 Nov 2019, Luo 19112001 ( HIB, GXF) ; ibidem, 11 May 2020, Luo & Li 20051101 ( HIB, GXF) ; ibidem, 28 Aug 2021, fruit, Luo 210802801 ( HIB, GXF) .

Figures

FIGURE 1. Magnolia brunnescens. A. Flowering branch. B. Petioles with stipular and scar. C. Flower in frontal view. D. Abaxial view of tepals in four whorls, from outer to internal. E. Partly dissected gynoecium with stamens below. F. Stamens. G. Carpels. H. Fruit with dehiscent follicles. I. Seeds.

FIGURE 2. Magnolia brunnescens. A. Habit. B. Leaves. C. Bark when young. D. Bark when mature. E. Indument of leaf in adaxial view. F. Indument of leaf in abaxial view.G. Vegetative bud attached to twig. H. Floral bud. I. Flower in semi-bloom. J. Open flower in side view. K. Gynoecium. L. Adaxial view of tepals in four whorls, from outer to internal. M. Stamens. N. Carpels. O. Aggregate fruit. P. Seeds.