Maesa flabellifera D. Wei, G. Hao & Utteridge, 2024

Wei, Dan, Xu, Yuan, Hao, Gang & Utteridge, Timothy M. A., 2024, Maesa flabellifera (Primulaceae), a new species from southeast Yunnan, China, PhytoKeys 248, pp. 189-197 : 189-197

Maesa flabellifera D. Wei, G. Hao & Utteridge sp. nov.

Figs 1 , 2

Type.

China • Yunnan Province: Honghe Prefecture, Pingbian County, Dawei Mountain National Nature Reserve ; 22.93, 103.69; 1871 m alt.; 26 February 2021 (fl.); D. Wei et al. Xu 210531 (Holotype: IBSC! barcode IBSC 1025516 ) .

Diagnosis.

Maesa flabellifera is morphologically similar to M. permollis , but clearly differs from the latter in the indumentum (lacking hairs vs. rusty hirsute hairs present), inflorescence structure (panicles 4.0- 6.5 cm long with 7-16 branches vs. racemes or panicles 1-3 cm long with up to 3 branches). It is also similar to M. kurzii , but can be distinguished by the indumentum (lacking hairs vs. presence of rusty tomentose and strigose hairs) and lamina texture (membranaceous vs. chartaceous).

Description.

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 scaly. 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 surface sparsely scaly; base obtuse to cuneate; margins serrulate-serrate with 20-34 teeth on each side; apex acuminate to obtuse, sometimes emarginate; mid-rib sparsely scaly adaxially and abaxially; secondary veins 10-18 pairs, craspedodromous; densely longitudinally glandular lines; petiole 1.5-3.0 cm long, sparsely scaly. Staminate inflorescences lateral (axillary), sometimes terminal, panicles, with 7-16 branches, 4.0- 6.5 cm long, axis scaly; pedicels 0.5-1.5 mm long; bracts ovate, 1.20-1.65 mm long, scaly to densely scaly, 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, scaly. 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, scaly to sparsely scaly; 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.

Distribution and habitat.

According to the specimens examined and the recent field investigations, Maesa flabellifera is presently found in Honghe Prefecture, Yunnan Province (Map 1 ). It is common in evergreen broad-leaved mixed forests at elevations of 1500-2200 m.

Phenology.

Flowering from January to March, fruiting from April to December.

Etymology.

The specific epithet ‘ flabellifera ’ is derived from the Latin ‘ flabella’ and ‘ fera’ to refer to its inflorescence with 7-16 branches of almost equal length and spreading, looking like a branching fan.

Vernacular name.

Chinese Mandarin: shan xing du jing shan (扇形杜茎山).

Preliminary conservation status.

Maesa flabellifera is widely distributed in southeast Yunnan. In the populations in the Dawei Mountain National Nature Reserves (43993 hm 2) and Huanglian Mountain National Nature Reserves (65058 hm 2), the habitats are well-protected and not threatened and individuals have been found locally common in each site. Based on currently available data, M. flabellifera is preliminarily assessed as Least Concern (LC) according to IUCN Categories and Criteria ( IUCN Standards and Petitions Committee 2024).

Additional specimens examined (paratypes).

China, Yunnan, Honghe Prefecture • Yuanyang County, Xinjie Town ; 1891 m alt.; 22 March 2023 (fl.); Wei et al. Xu 231213 ( IBSC, barcode IBSC 1025520 ) • Lüchun County, Huanglian Mountain National Nature Reserve ; 1865 m alt.; 23 March 2023 (fl.); Wei et al. Xu 231222 ( IBSC, barcode IBSC 1025523 ) • Jinping County; 2192 m alt.; 16 January 2010 (fl.); Southeast Yunnan expedition. GBOWS 956 ( KUN, barcode KUN 1279679 ) • Pingbian County; 1520 m alt.; 23 November 2009 (fr.); Qian et al. Pbdws 151 ( KUN, barcode KUN 1339632 ) .

Notes.

Based on a phylogenetic analysis of molecular data, a new infrageneric classification of Maesa was proposed, dividing it into five subgenera, based on distribution and morphological characters ( Sumanon et al. 2023). The species-level tree shows a strong signal of geographical distribution for the new infrageneric classification. It is speculated that Maesa flabellifera should be placed in the Maesa subg. Indicae Sumanon, Eiserhardt & Utteridge , by far the most species-rich subgenus in China, with species of trees or shrubs mainly from the Asian Continent, since its morphology and distribution is consistent with this clade especially the leaf morphology, such as the serrulate-serrate margins.

Maesa flabellifera belongs to the group of species with a longer corolla-tube. In the Flora Reipublicae Popularis Sinicae ( Chen 1979), Maesa was divided into two sections based on the ratio of corolla-tube length to lobe length, namely Maesa sect. Maesa and M. sect. Doraena [Thunb.] Nakai. There are eight species with a long corolla-tube similar to M. flabellifera in sect. Doraena [Thunb.] Nakai. This treatment was not adopted in the Flora of China ( Chen and Pipoly 1996). Although the long corolla-tube is a good character for species-level identification as a ‘ spot character’, the group is not monophyletic in the phylogenetic analysis ( Sumanon et al. 2023) and is used here as a comparative tool.

Maesa flabellifera is unique within the long corolla-tube species group, differing from all others by the following characters: lacking hairs on all parts; leaves thick, membranaceous and broadly elliptic to obovate, 15-35 cm long and 8-20 cm wide; long paniculate inflorescences, up to 6.5 cm long, with 7-16 branches, each branch almost equal in length, looking like a branching fan arising from the leaf axils.

In the key to Maesa in the Flora of China ( Chen and Pipoly 1996), M. flabellifera would key out close to M. permollis Kurz as they share the same leaf features and the long corolla-tube. However, M. flabellifera is unlikely to be confused with M. permollis by examination of the indumentum and inflorescence structure. Based on the herbarium and field observations, M. permollis is conspicuously hairy throughout with rusty hirsute hairs and the inflorescences are short, dense clustering of numerous flowers, forming compact, many-flowered inflorescence clusters. Moreover, M. flabellifera is found in higher elevations around 1500-2200 m, compared to M. permollis which is encountered at lower elevations around 500-1600 m.

Compared to the other Maesa species with long corolla-tubes, M. flabellifera is most similar to M. kurzii , sharing broadly elliptic to obovate leaves and long paniculate inflorescences. However, the indumentum and lamina texture make M. flabellifera very distinctive and easily separated from M. kurzii , which has chartaceous leaves, usually rusty tomentose hairs throughout and inflorescences with rusty strigose hairs. Furthermore, the distributions of these two species are distinctly different and non-overlapping. Maesa flabellifera is currently only known from southeast Yunnan, situated in Honghe Prefecture. Maesa kurzii is located within Myanmar. A detailed comparison of these three species is shown in Table 1 .

Figures

Figure 1. Holotype of Maesa flabellifera D. Wei, G. Hao & Utteridge, sp. nov. (D. Wei et al. Xu 210531, IBSC 1025516, IBSC).

Map 1. Geographical distribution of Maesa flabellifera.

Figure 2. Maesa flabellifera A habitat B habit C node with petiole and base of inflorescence D abaxial and adaxial surfaces of leaf E inflorescence F bract (borne at base of pedicel) and bracteole (borne at base of the hypanthium) G flower after removal of corolla H corolla from G, opened flat I Infructescences.