Thalictrum pseudoramosum 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 : 134-147

2. Thalictrum pseudoramosum Y. P. Zeng, Q. Yuan & Q. E. Yang , sp. nov. Figs. 2 , 11 , 12 .

Type:— CHINA. Sichuan: Pingwu county, along Road S205 , Mupiba street, near Wugongkou , 32°28′21.99″N, 104°32′2.00″E, humid rocky cliffs, alt. 950 m, 26 June 2020, Y. P. Zeng & Q. L. Huang 326 (holotype IBSC, barcode unavailable; isotypes CDBI, IBSC, PE, barcodes unavailable) .

Description:—Perennial herbs, totally glabrous. Roots fibrous, slender. Stem to 120 cm tall, striate, single or sometimes branched. Leaves 2‒3-ternate; blade triangular, 10‒25 cm long, 10‒25 cm broad; leaflets orbicular or broadly ovate, 1‒ 3 cm long, 1‒3 cm broad, subcoriaceous, green on adaxial side, pale green on abaxial side, base rounded or subcordate, apex obtuse or acute, 3-lobate; lobes entire or inconspicuously 1‒3-crenate; veins flat adaxially, slightly prominent abaxially; petiole slender, 3‒15 cm long; stipule membranous, margin torn. Inflorescence corymbiform. Pedicels slender, 1‒4 cm long. Flowers bisexual, erect. Sepals 4‒5, caducous, elliptic, ca. 4 mm long, ca. 2.5 mm broad, purplish. Stamens 40‒60, ca. 5 mm long; filament clavate, ca. 4 mm long, purplish; anther oblong, ca. 1 mm long, apex obtuse, white. Carpels 10‒20, sessile, ca. 3 mm long, glabrous; ovary lunate-fusiform, shallowly ribbed, ca. 2 mm long; style slightly recurved, ca. 1 mm long; stigma linear, ca. 0.7 mm long. Achenes sessile, 3‒4 mm long, glabrous; body elliptic-fusiform, profoundly ribbed; style persistent.

Distribution and habitat:— Thalictrum pseudoramosum is currently known from southern Gansu (Wenxian, Wudu, Zhugqu) and northwestern Sichuan (Beichuan, Jiuzhaigou, Maoxian, Pingwu) ( Fig. 5 ). It grows on humid rocky cliffs in ravines, near streams or in forests on slopes at altitudes of 800‒2400 m above sea level.

Phenology:—Flowering from May to September; fruiting from July to October.

Etymology:—The specific epithet refers to the close similarity in habit between the new species and Thalictrum ramosum .

Additional specimens examined:— CHINA. Gansu: Precise locality unknown, G.N. Potanin s.n. (K, barcode unavailable, P00147402); Wenxian, Baishuijiang Exped.1419 (PE01859893), Baishuijiang Exped.2286 (PE01865057), Baishuijiang Exped. 5785 (PE01801238), J.Q. Fu 2604 (PE, barcode unavailable, WUK, barcode unavailable), C.Y. Chang 9831 (HNWP, barcode unavailable, WUK, barcode unavailable), C.Y. Chang 11199 (WUK, barcode unavailable), C.Y. Chang 13234 (WUK, barcode unavailable), C.Y. Chang 13250 (WUK, barcode unavailable), C.Y. Chang 13296 (WUK, barcode unavailable), C.Y. Chang 13396 (WUK, barcode unavailable), J.Q. Fu 2604 (PE00471063, WUK, barcode unavailable); Wudu, C.Y. Chang 2686 (LBG00051795, WUK, barcode unavailable); Zhugqu, Bailongjiang Exped. 1311 (PE01556428), Z.P. Wei 2439 (HHBG008570, HIMC0010481, SZ00092112, WUK, barcode unavailable). Sichuan: Beichuan, X.J. He, Q.S. Zhao & Q. Wang 134356 (SZ00375362, SZ00375363, SZ00375364), X.J. He, Q.S. Zhao & Q. Wang 140042 (SZ00375247, SZ00375347), C.L. Tang et al. 573 (CDBI0026277, CDBI0026278);

Jiuzhaigou, P.Q. Li 135 (PE00875598), C.Y. Wu et al. 86-1018 (KUN0691803); Maoxian, Sichuan Econ. Plant Exped. 8599 (CDBI0026072, CDBI0026281, CDBI0026282, PE01040895), Sichuan Econ.Plant Exped. 8700 (CDBI0026073, CDBI0026279, CDBI0026280, PE01040894).

Conservation status:— Thalictrum pseudoramosum is currently known from southern Gansu (Wenxian, Wudu, Zhugqu) and northwestern Sichuan (Beichuan, Jiuzhaigou, Maoxian, Pingwu). The population in Pingwu that we recently discovered, with no more than 50 individuals, is situated at roadside and seems vulnerable to human activities. Southern Gansu and northwestern Sichuan are two areas not yet well botanized and the information of T. pseudoramosum currently available is inadequate to make a conclusive assessment of its risk of endangerment. Therefore, the conservation status of T. pseudoramosum should be regarded as “Data Deficient (DD)” before adequate information of this species is acquired ( IUCN Standards and Petitions Committee 2019).

Notes:— Thalictrum pseudoramosum is similar to T. ramosum in habit and in having apically slightly recurved styles, but differs by having subcoriaceous (vs. herbaceous) leaflets, more numerous stamens (40‒60 vs. 16‒24), and elliptic-fusiform (vs. lanceolate-fusiform) achenes ( Figs. 11 , 12 ).

Thalictrum ramosum is widely distributed in China’s Chongqing, northwestern Guangxi, eastern Guizhou, western Hubei, western Hunan, central and southwestern Sichuan, and northeastern Yunnan ( Wang & Wang 1979, Fu & Zhu 2001, Wang 2018a), whereas T. pseudoramosum is currently known from southern Gansu and northwestern Sichuan of the Min Shan region ( Fig. 5 ).

It is to be noted that the stem and pedicels of living plants in Thalictrum ramosum are sparsely pubescent in two populations that we observed in Guizhou and Sichuan (the Jiangkou population from Guizhou shown in Figure 10 ). The hairs, however, are almost invisible on dry specimens and this species has been described as totally glabrous ( Anonymous 1972, Wang & Wang 1979, Wang 1991, Liu 2000). The hairs might have fallen off in dry specimens.

It is worth mentioning that some specimens of Thalictrum pseudoramosum have been previously annotated “ Thalictrum subramosum Péi et Shé , sp. nov. ” on the determination slips (one sheet shown in Figure 2B ). This name, however, has never been published. We name our new species as T. pseudoramosum because we designate a specimen collected by ourselves as its holotype.

Figures

FIGURE 2.Specimens ofThalictrumpseudoramosum (previouslymisidentifiedasT.javanicum orT.ramosum).A.China,Gansu,Wenxian, Baishuijiang Exped. 2286 (PE01865057). B. China, Gansu, Wudu, C.Y. Chang 2686 (WUK, barcode unavailable). C. China, Sichuan, Beichuan, C.L. Tang et al. 573 (CDBI0026277). D. China, Sichuan, Maoxian, Sichuan Econ. Plant Exped. 8599 (PE01040895).

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 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).

FIGURE 11. Holotype sheet of Thalictrum pseudoramosum.

FIGURE 12. Thalictrum pseudoramosum 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. Flower, with the sepals having fallen. H. Sepal (left: adaxial side; right: abaxial side). I. Stamens. J. Carpels. K. Aggregate fruit. L.Achenes (immature).