Mazus motuoensis W.B.Ju, Bo Xu bis & X.F.Gao, 2023

Ju, Wen-Bin, Li, Xiong, Deng, Heng-Ning, Li, Meng, He, Xing-Jin, Gao, Xin-Fen & Xu, Bo, 2023, Mazus motuoensis (Mazaceae), a new species from Xizang, China, PhytoKeys 235, pp. 69-79 : 69

Mazus motuoensis W.B.Ju, Bo Xu bis & X.F.Gao sp. nov.

Figs 3 , 4 , 5

Diagnosis.

The new species is distinguished from congeneric species by its rhizomes, perennial herb covered with multicellular white villus, erect and unbranched stems, having no basal leaves, stem leaves opposite, subsessile, lower lobes margins erose-toothed.

Type.

China, Xizang, Motuo County, DeXing town, Nibi Valley , ditch edge in the forest, 29°22'27.98"N, 95°10'0.88"E, alt. 2253 m. 31 Mar 2022, WenBin JU & XIONG LI, YLZB08519 (holotype: CDBI0279767; isotypes: CDBI0279765, CDBI0279766)

Description.

Perennial herbs, 15-25 cm tall, the whole plant is covered with long white soft multicellular hairs. Rhizome white. Stems erect, unbranched. Leaves opposite, numerous, petiole inconspicuous to nearly absent; lower leaf blade scalelike and small, obovate-oblong, apex obtuse, middle and upper leaves with leaf blade elliptic to ovate, papery, 0.8-4.0 × 0.4-1.8 cm, adaxially clothed with multicellular hairs, abaxially subglabrous, multicellular hairs on veins, base cuneate, margin serrate, lateral veins 3-5 pairs. Racemes terminal, ascending to 5 cm long, lax, fewer than 5; pedicels 4-6 mm, glabrous or with a few multicellular hairs; bracts tiny, narrowly lanceolate to linear, glabrous. Calyces broadly campanulate, ca. 6 mm long, 5-veined, glabrous outside and inside, lobes 5, triangular-lanceolate, as long as tube, apex acute, midrib conspicuous, lateral veins inconspicuous. Corolla 1.2-1.5 cm long, white, but often purple on upper lobes, glabrous outside and inside apart from clavate hairs on palate; tube 0.3-0.5 cm long, shorter than calyx; limb 2-lipped, upper lip bilobed, slightly upwarp, lobes triangular ovate, apex subacute, sometimes weakly obtuse or retuse; lower lip trilobed, lobes margins erose-toothed, middle lobe usually rounded, smaller than lateral lobes, yellow palate comprising 2 longitudinal elevations extending from point of filament fusion to the base of lower lobes, with erect clavate hairs. Stamens 4, didynamous, glabrous, inserted at the same level in distal part of tube, inserted at the distal end of the tube at the same level, included; anterior pair longer, curved, appressed to corolla tube, posterior pair spreading; anthers bithecal, locules divergent, apically connivant, positioned adjacent to corolla tube on upper lip; filaments filiform, glabrous. Ovary ca. 2 mm long, glabrous, ovoid; styles ca. 7 mm long, included, glabrous, exserted beyond anthers, stigma bilobed. Fresh capsule and calyx light green, included by persistent calyx.

Distribution and habitat.

Mazus motuoensis is currently known from Nibi Valley, Motuo County, Xizang, China. It can be found under evergreen broad-leaved forest at altitudes of 2253 m.

Phenology.

Flowering was observed from May to June.

Etymology.

The specific epithet " Mazus motuoensis " refers to the locality, Motuo County, Xizang, China.

Vernacular name.

Simplified Chinese: 墨脱通泉草; Chinese pinyin: Mòtuō Tōngquáncǎo.

Conservation status.

Currently, the authors have discovered only one population of Mazus motuoensis from one single locality in Nibi Valley of Motuo County in Xizang Province, China, and ca. 30 individuals from the type locality. Evergreen broad-leaved forests are widely distributed in this area, so we speculate that this new species has a relatively wide distribution range. Due to insufficient field survey, the natural distribution of this species in the wild is not clear. Following the IUCN Red List criteria (2019), we suggest this species placement in the Data Deficient.

Figures

Figure 3. Living images of M. motuoensis A habit B inflorescence in frontal view C inflorescence in rear view D rhizome.

Figure 4. Morphology of M. motuoensis A plant B leaves C old stems D multicellular hairs attached to stem E flower F unfolded corolla, showing limb upper lip and lower lip G bract H, I calyx J anthers K ovary and style.

Figure 5. Line drawings of M. motuoensis A whole plant B multicellular hairs attached to stem C leaves D inflorescence E flower F unfolded corolla G calyx H ovary and style. Drawn by Mr. Zhen-long Liang.