Branching fan maesa (Maesa flabellifera) similar to M. permollis and M. kurzii, but lacks hairs and long panicles

NEWS - Branching fan maesa (Maesa flabellifera D.Wei, G.Hao & Utteridge, sp. nov.) from southeastern Yunnan, China, belongs to the informal long corolla-tube species group, morphologically similar to M. permollis and M. kurzii, but lacks hairs, membranous leaves and long panicles with 7-16 branches.

Maesa Forssk. (Primulaceae) includes about 185 species, mostly distributed in the Old World tropics from southern Africa to the Pacific islands. Currently, about 35 species and two varieties (with 13 endemics) have been recorded from China and are mostly distributed in southwest China, especially in Yunnan Province.

In February 2021, during a field survey by researchers and colleagues in Pingbian, Honghe Prefecture, Yunnan, an unknown Maesa in bloom was collected. In March 2023 it was again found in Yuanyang and Lüchun. This plant is common in mixed broadleaf evergreen forests at elevations of 1500-2200 m. Flowers January-March and bears fruit April-December.

M. flabellifera is a large shrub, up to 2.5 m tall. Indumentum all parts lacking hairs, scales present on leaves, inflorescences and fruits, scales peltate, black, ± sessile, circular with irregular margins. Branches dark green with scattered lenticels, sparsely scaled.

Leaves lamina broadly elliptic to obovate, 15−35 cm long, 6−20 cm wide, membranaceous, dark green above, pale grey-green below, adaxial and abaxial surfaces sparsely scaled; base obtuse to cuneate; margins serrulate-serrate with 20−34 teeth on each side; apex acuminate to obtuse, sometimes emarginate; mid-rib sparsely scaled adaxially and abaxially; secondary veins 10−18 pairs, craspedodromous; densely longitudinally glandular lines; petiole 1.5−3.0 cm long, sparsely scaled.

Staminate inflorescences lateral (axillary), sometimes terminal, panicles, with 7−16 branches, 4.0−6.5 cm long, axis scaled; pedicels 0.5−1.5 mm long; bracts ovate, 1.20−1.65 mm long, scaled to densely scaled, margins entire, apex acute; bracteoles ± opposite, inserted at the base of the hypanthium, triangular, 0.90−1.35 mm long, 0.4−0.6 mm wide, apex acute, margins entire, scaled.

Staminate flowers pentamerous, white; calyx lobes triangular, 1.25−1.60 mm long, 0.70−1.05 mm wide, margins entire, apex acute to rounded; corolla tube 1.9−2.3 mm long, corolla lobes broadly triangular, 1.45−1.55 mm long, 1.5−1.8 mm wide, margins entire, apex rounded; stamens 5, arising 0.8−1.0 mm from the base of the corolla, filaments 1.14−1.37 mm long, anthers 0.59−0.69 mm long; hypanthium 0.75−1.20 mm long, scaled to sparsely scaled; style 1.5−2.0 mm long, stigma ± 3-lobed. Pistillate inflorescences and flowers not seen.

Fruits sub-globose, ca. 3.5 mm long, ca. 3 mm in diameter, scaly to sparsely scaly; pedicels at fruiting 0.50−1.66 mm long; bracteoles remaining ± opposite at the base of the fruit; persistent calyx lobes non-overlapping.

The new species is unique in the group of long-corolla tube species, differing from the others by the following characteristics: glabrous on all parts; leaves thick, membranous and broadly elliptic to obovate, 15−35 cm long and 8−20 cm wide; inflorescence a long panicle, up to 6.5 cm long, with 7−16 branches, each branch nearly equal in length, appearing like a branched fan emerging from the leaf axils.

M. flabellifera is similar to M. permollis, but differs in indumentum (glandular vs. with coarse hairs), inflorescence structure (panicle 4.0–6.5 cm long with 7–16 branches vs. raceme or panicle 1–3 cm long with up to 3 branches). M. flabellifera occurs at elevations of 1500–2200 m, while M. permollis occurs at elevations of 500–1600 m.

Also similar to M. kurzii, but differs in indumentum (glandular vs. with tomentose and strigose rusty hairs) and lamina texture (membranous vs. map-like). The new species is currently only known from southeastern Yunnan, while M. kurzii is found in Myanmar.

The specific epithet ‘flabellifera’ is derived from Latin ‘flabella’ and ‘fera’ to refer to its inflorescence with 7-16 branches of almost equal length and spreading, looking like a branching fan. Chinese: shan xing du jing shan (扇形杜茎山).

The population of M. flabellifera is widely distributed in Dawei Mountain National Nature Reserves (43,993 hm2) and Huanglian Mountain National Nature Reserves (65,058 hm2). The habitat is well protected, not threatened and individuals have been found commonly in each location. Based on currently available data, it is provisionally listed as Least Concern (LC) according to IUCN Categories and Criteria.

Original research

Wei D, Xu Y, Hao G, Utteridge TMA (2024). Maesa flabellifera (Primulaceae), a new species from southeast Yunnan, China. PhytoKeys 248: 189-197, DOI:10.3897/phytokeys.248.135449

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