Puchiumazus Bo Li, D.G. Zhang & C.L. Xiang, 2021

Xiang, Chun-Lei, Pan, Hong-Li, Min, Dao-Zhang, Zhang, Dai-Gui, Zhao, Fei, Liu, Bing & Li, Bo, 2021, Rediscovery of Mazus lanceifolius reveals a new genus and a new species in Mazaceae, PhytoKeys 171, pp. 1-24 : 1

Puchiumazus Bo Li, D.G. Zhang & C.L. Xiang gen. nov. Fig. 1

Type.

Puchiumazus lanceifolius (Hemsl.) Bo Li, D.G. Zhang & C.L. Xiang ≡ Mazus lanceifolius Hemsl., in: J. Linn. Soc., Bot. 26 (174): 181. 1890.

Diagnosis.

The new genus is characterized by having quadrangular to somewhat ribbed stems and opposite, narrowly lanceolate leaves (Figs 1 , 5A1-A3 ). Puchiumazus is sister to a clade composed of Dodartia , Lancea and Mazus . Morphologically, it is most similar to Mazus , but it differs in having quadrangular stems, lanceolate leaves (vs. terete stems and usually obovate-oblong leaves).

Description.

Perennial herbs. Rhizomes fleshy, white, horizontal. Root thin, fibrous. Stems erect, unbranched, glabrous, up to 30 cm tall, old stems quadrangular, glabrous, young stems inconspicuously quadrangular to obtusely ribbed, minutely puberulent. Leaves opposite, petiole inconspicuous to nearly absent; leaf blade narrowly lanceolate, 5.5-8.5 × 0.8-1.1 cm, submembranaceous to papery, adaxially green, pubescent, abaxially pale green, (sub)glabrous, base cuneate, margin basally entire and apically sparsely serrate, apex acute to long acuminate; lateral veins 3-5 pairs, abaxially raised and adaxially slightly depressed. Racemes terminal, 3-6 cm, flowers remarkably sparse, less than 6; pedicels 4-7 mm, sparsely puberulent; bracts tiny, narrowly lanceolate to linear. Calyx funnelform, 4-6 mm, sparsely pubescent outside, subglabrous inside, 5-lobed; lobes narrowly triangular to lanceolate, as long as tube in length, midrib conspicuous, apex acute. Corolla creamy yellow, 1.8-2.2 cm long, densely puberulent outside; tube straight, cylindric, long exserted from calyx, gradually dilated; limb 2-lipped, reddish in throat, posterior lip bilobed, lobes orbicular, anterior lip trilobed, lobes subequal, rounded. Stamens 4, didynamous, inserted on corolla tube, included, anterior pair longer; anthers bithecal, locules divergent, apically connivent; filaments filiform, glabrous. Styles included, glabrous, persistent; stigma 2-lamellate. Capsule ovoid, ca. 2 × 3 mm, glabrous.

Etymology.

The generic name is derived from " Puchiu " (in honor of Prof. Pu Chiu Tsoong (1906-1981), who was a prominent Chinese taxonomist specializing in the taxonomy of Scrophulariaceae in the traditional sense) and " mazus ", indicating that the new genus was separated from Mazus and is morphologically similar to it.

Common name

(assigned here). Bu Qiu Cao Shu (补求草属; Chinese name).

Distribution.

According to our data, this genus is endemic to Central China. It is known only from Hubei (Jianshi), Sichuan (Dayi and Dujiangyan) and Chongqing (Wushan) and can be found under evergreen broad-leaf forest at elevations of 600-1250 m.

Figures

Figure 1. Puchiumazus lanceifolius (≡ Mazus lanceifolius) A lectotype deposited at K (A. Henry 5837, barcode K 001079356) B habit C stem, showing the obtuse ribs D leaves E inflorescence F flower in lateral review G young fruits. Scale bars: 5 cm (B); 0.5 cm (C, F, G); 2 cm (D); 1 cm (E).

Figure 5. Morphological comparisons of the four genera of Mazaceae A Puchiumazus lanceifolius B Dodartia orientalis C Lancea tibetica D Mazus stachydifolius A 1, B 1, C 1, D 1 habits A 2, B 2, C 2, D 2 flowers A 3, B 3, C 3, D 3 fruits.