Thalictrum minshanicum Y. P. Zeng, Q. Yuan & Q. E. Yang, 2021

Zeng, You-Pai, Yuan, Qiong & Yang, Qin-Er, 2021, Thalictrum minshanicum and T. pseudoramosum (Ranunculaceae), two new species from China, Phytotaxa 502 (2), pp. 133-148 : 133-134

1. Thalictrum minshanicum Y. P. Zeng, Q. Yuan & Q. E. Yang , sp. nov. Figs. 1 , 3 , 4 .

Type:— CHINA. Sichuan: Pingwu county, along Road S205 , near Baima town , 32°44′59.83″N, 104°18′44.47″E, in forests, alt. 2090 m, 28 June 2020, Y. P. Zeng & Q. L. Huang 337 (holotype IBSC, barcode unavailable; isotypes CDBI, IBSC, PE, barcodes unavailable) .

Description:—Perennial herbs. Roots fibrous, distally tuberose. Stem to 150 cm tall, striate, puberulent, distally branched. Leaves 2‒4-ternate; blade triangular, 10‒18 cm long, 10‒18 cm broad; leaflets obovate, orbicular or broadly ovate, 1‒3 cm long, 1‒3 cm broad, herbaceous, both sides puberulent, green on adaxial side, pale green on abaxial side, base rounded or subcordate, apex obtuse or acute, 3-lobate; lobes entire or 2‒3-lobate, apex obtuse or acute; veins flat adaxially, slightly prominent abaxially; petiole slender, 3‒10 cm long; stipule membranous, margin torn. Inflorescence compound monochasia, corymbiform; rachis sparsely puberulent. Pedicels 1‒1.5 cm long, sparsely puberulent. Flowers bisexual, erect. Sepals 4‒5, caducous, elliptic, ca. 5 mm long, ca. 2.5 mm broad, white or purplish, glabrous. Stamens 45‒60, ca. 7 mm long; filament clavate, ca. 5.5 mm long, purplish; anther oblong, ca. 1.5 mm long, apex obtuse, white. Carpels 6‒10, sessile, ca. 2 mm long; ovary lunate-fusiform, shallowly ribbed, ca. 1 mm long; style slightly recurved, ca. 1 mm long; stigma conspicuous, linear, ca. 0.6 mm long. Achenes sessile, ca. 4 mm long, glabrous; body fusiform, profoundly ribbed; style persistent, slightly recurved at apex.

Distribution and habitat:— Thalictrum minshanicum is currently known from southern Gansu (Wudu, Zhugqu) and northwestern Sichuan (Beichuan, Pingwu) ( Fig. 5 ) in the Min Shan region of China. It grows in thickets or forests on slopes at altitudes of 1400‒2090 m above sea level.

Phenology:—Flowering from June to August; fruiting from August to September.

Etymology:—The specific epithet is derived from the Min Shan region, where the new species occurs.

Additional specimens examined:— CHINA. Gansu: Wudu, P.C. Kuo 5090 (WUK, barcode unavailable); Zhugqu, P.C. Kuo 5390 (WUK, barcode unavailable). Sichuan: Beichuan, C.L. Tang et al. 269 (CDBI0026275, CDBI0026276); Pingwu, Anonymous 121 (CDBI0026442, CDBI0026443), Y.P. Zeng & Q.L. Huang 330 (IBSC, barcode unavailable), Y.P. Zeng & Q.L. Huang 448 (IBSC, barcode unavailable).

Conservation status:— Thalictrum minshanicum is currently known from four populations in southern Gansu and northwestern Sichuan, China. The population in Pingwu , northwestern Sichuan, which we rediscovered recently, consists of no more than 100 individuals. The size of the other three populations remains unknown. The conservation status of T. minshanicum should therefore be considered as “Data Deficient ( DD)” before adequate information of this species is acquired ( IUCN Standards and Petitions Committee 2019) .

Notes:— Thalictrum minshanicum is most closely similar to T. brevisericeum Wang & Wang (1974: 603) ( Figs. 6 , 7 ) in habit and in having puberulent stem and leaves, but differs by having conspicuously 3-lobate (vs. slightly 3-lobate) leaflets, glabrous (vs. abaxially puberulent) sepals, longer (ca. 7 mm vs. ca. 4 mm) and clavate (vs. oblanceolate-linear) filaments, conspicuous (vs. inconspicuous) stigmas, and persistent styles slightly recurved (vs. circinate) at apex ( Figs. 3 , 4 ).

Thalictrum brevisericeum is widely distributed in China’s eastern and southern Gansu, western Henan, central and western Shaanxi, southwestern Shanxi, northwestern Sichuan, and northwestern Yunnan ( Wang & Wang 1979, Fu & Zhu 2001, Wang 2018a; Fig. 5 ). Populations of northwestern Yunnan have been treated as a variety, i.e. var. angustiantherum Wang (2018a: 88) . Another variety from Heishui in northwestern Sichuan, var. pentagynum Wang (2018a: 88) , actually should belong to T. uncinulatum Franchet ex Lecoyer (1885: 169) , a species distributed in Chongqing, Gansu, Guizhou, Hubei, Hunan, Shaanxi, Sichuan, and Yunnan, China ( Zeng et al. 2021a).

As mentioned before, specimens of Thalictrum minshanicum have been previously misidentified as T. javanicum or T. ramosum . Thalictrum minshanicum differs from T. javanicum ( Fig. 8 ) by having puberulent stem and leaves and apically slightly recurved (vs. circinate) styles. From T. ramosum ( Figs. 9 , 10 ) it differs by having puberulent (vs. glabrous) leaves, longer stamens (ca. 7 mm vs. ca. 3 mm), and elliptic-fusiform (vs. lanceolate) achenes.

It is to be noted that the true Thalictrum javanicum probably does not occur in China. The Chinese specimens previously identified as T. javanicum should belong to two recently described species. Those with a corymbiform inflorescence and widely distributed in China’s southern Chongqing, northern Guangdong, northern Guangxi, eastern Guizhou, southwestern Hubei, Hunan, Jiangxi and southern Zhejiang belong to T. xinningense Wang (2017: 408) ( Wang 2018a, Zeng et al. 2021b), and those with a paniculiform inflorescence and widely distributed in China’s northeastern Chongqing, western Guizhou, northwestern Hubei, southern Shaanxi, Sichuan, Xizang, and Yunnan, and in Nepal, belong to T. nepalense Wang (2018b: 641) . The independent specific status of T. sessile Hayata (1913: 6) from China’s Taiwan, a species previously treated as a synonym of T. javanicum ( Wang & Wang 1979, Li 1986, Liu 2000, Fu & Zhu 2001), has been reinstated by Wang (2018a). In fact, Liu & Hsieh (1976) and Yang & Huang (1989, 1996, 2008) recognized T. sessile as an independent species. Indeed, further studies are needed to clarify the delimitation and geographical distribution of T. javanicum .

Figures

FIGURE 1. Specimens of Thalictrum minshanicum (previously misidentified as T. javanicum or T. ramosum). A. China, Gansu, Wudu, P.C. Kuo 5090 (WUK, barcode unavailable). B. China, Gansu, Zhugqu, P.C. Kuo 5390 (WUK, barcode unavailable). C. China, Sichuan, Beichuan, C.L. Tang et al. 269 (CDBI0026275). D. China, Sichuan, Beichuan, C.L. Tang et al. 269 (CDBI0026276).

FIGURE 3. Holotype sheet of Thalictrum minshanicum.

FIGURE 4. Thalictrum minshanicum in the wild (Pingwu in Sichuan, China, the type locality).A. Habitat. B. Habit. C. Roots. D. Portion of stem. E. Leaf (left: adaxial side; right: abaxial side). F. Leaflet (left: adaxial side; right: abaxial side).G. Portion of abaxial side of leaflet. H. Flower, with the sepals having fallen. I. Sepals (left: adaxial side; right: abaxial side). J. Stamens. K. Carpels. L. Aggregate fruit. M. Achenes (immature).

FIGURE 5. Distribution of Thalictrum brevisericeum var. brevisericeum, T. minshanicum, T. pseudoramosum, and T. ramosum. Arrow indicates the type locality of both T. minshanicum and T. pseudoramosum, i.e. Pingwu in Sichuan, China.

FIGURE 6. Holotype sheet of Thalictrum brevisericeum.

FIGURE 7. Thalictrum brevisericeum var. brevisericeum in the wild (A‒F & L, M: Songxian in Henan, China; G‒K: Meixian in Shaanxi, China, the type locality).A. Habitat. B. Habit. C. Roots. D. Portion of stem. E. Leaf (left: adaxial side; right: abaxial side). F. Leaflet (left: adaxial side; right: abaxial side). G. Portion of abaxial side of leaflet. H. Flower, with the sepals having fallen. I. Sepals (left: adaxial side; right: abaxial side). J. Stamens. K. Carpels. L. Aggregate fruit. M. Achenes (immature).

FIGURE 8. Specimens of Thalictrum javanicum. A. Indonesia, Java, C.L. Blume s.n. (L0038655). B. Indonesia, Java, C.A. Backer 481 (BO, barcode unavailable); inset: flower. C. Indonesia, Java, J.H. Kern 7775 (BO, barcode unavailable); inset: aggregate fruit (immature). D. Indonesia, Java, W.S. Hoover et al. Deden 83 (BO, barcode unavailable); inset: aggregate fruit.

FIGURE 9. Holotype sheet of Thalictrum ramosum.

FIGURE 10. Thalictrum ramosum in the wild (Jiangkou in Guizhou, China). A. Habitat. B. Habit. C. Roots. D. Portion of stem. E. Leaf (left: adaxial side; right: abaxial side). F. Leaflet (left: adaxial side; right: abaxial side). G. Flower, with the sepals having fallen. H. Sepals (left: adaxial side; right: abaxial side). I. Stamens. J. Carpels. K. Aggregate fruit. L. Achenes (immature).