Thalictrum longistipitatum Y. P. Zeng, Q. Yuan & Q. E. Yang, 2022

Zeng, You-Pai, Yuan, Qiong & Yang, Qin-Er, 2022, Thalictrum hengduanshanense and T. longistipitatum (Ranunculaceae), two new species from southeastern Xizang and northwestern Yunnan, China, Phytotaxa 571 (1), pp. 1-20 : 6-16

Thalictrum longistipitatum Y. P. Zeng, Q. Yuan & Q. E. Yang , sp. nov. (Figs. 2, 9‒11).

Type:— CHINA. Yunnan: Dêqên, Yunling town , on the way from Xidang spring to Yubeng village , in forests on mountain slopes, alt. 3450 m, 11 July 2021, Y.P. Zeng & Y.F. Luo 528 (holotype IBSC, barcode unavailable; isotypes KUN, PE, barcodes unavailable). Fig. 11 .

Diagnosis:— Thalictrum longistipitatum is closely related to T. hengduanshanense , but differs by having apically abruptly recurved (vs. straight) pedicels and shorter styles (ca. 1 mm vs. ca. 2 mm long).

Description:—Perennial herbs. Roots fibrous. Stem 35‒60 cm tall, distally branched, glandular-pubescent. Leaves 2‒3-ternate; blade triangular, 5‒10 cm long, 4‒10 cm broad; leaflets broadly obovate, obliquely broadly obovate, suborbicular or broadly ovate, 0.5‒2 cm long, 0.5‒2 cm broad, herbaceous, both sides densely glandularpubescent, adaxially green and abaxially pale green, base rounded or subcordate, apex obtuse or acute, 3-lobate; lobes entire or 1‒2-crenate, apex obtuse or acute; veins submerged adaxially, raised abaxially; petioles glandular-pubescent, 0.5‒4 cm long; stipules sheath-like or free, obliquely ovate, membranous, margin entire. Inflorescence a panicle, many-branched, sub-corymbiform, glandular-pubescent. Pedicels 2‒4 cm long, apically abruptly recurved, glandularpubescent. Flowers bisexual, drooping. Sepals 4‒5, broadly elliptic, ovate or broadly ovate, 2‒3 mm long, 1.5‒2 mm broad, abaxially glandular-pubescent, whitish or tinged with pinkish; basal nerves 3‒5, simple or branched. Stamens 9‒12, 2‒3 mm long; filaments narrowly oblanceolate-linear, 1.4‒2.0 mm long, white; anthers oblong, 0.6‒0.9 mm long, ca. 0.5 mm broad, apex obtuse, white. Carpels 3‒6, ca. 2.5 mm long, glandular-pubescent, subsessile; ovary obliquely narrowly obovate, ca. 1 mm long; style ca. 1.2 mm long, apically slightly recurved; stigma lanceolate. Achenes 7‒9 mm long, densely glandular-pubescent, long stipitate; stipe 3‒6 mm long; body narrowly lunate-fusiform, shallowly ribbed, compressed; style persistent, apically recurved, ca. 0.6 mm long. Chromosome number unknown.

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

Distribution and habitat:— Thalictrum longistipitatum is currently known only from northwestern Yunnan (Dêqên) and southeastern Xizang (Bomi, Zayu), China (Fig. 13). It grows in conifer-broadleaved forests on mountain slopes at elevations of 3100‒3450 m above sea level.

Etymology:—The specific epithet of the new species, “ longistipitatum ”, refers to its impressively long stipes of achenes.

Additional specimens examined (paratypes):— CHINA. Xizang: Bomi , W.Q. Fei 58 (IBSC, barcode unavailable) , L. Wang, X.Q. Guo & Y.P. Zeng 3350 (IBSC, barcode unavailable) ; Zayu, B.S. Li, S.Z. Cheng & Z.C. Ni 7224 (PE00767246) , Qinghai-Xizang Exped. 73-230 (KUN0690505, KUN0690506, PE00450030, PE00450031) . Yunnan: Dêqên, Qinghai-Xizang Exped. 130 (HITBC, herb. no. 074526), L. Xie & J.F. Mao 136 (PE01569411), L. Xie & J.F. Mao 137 (PE01569412), L. Xie & J.F. Mao 138 (PE01569413) .

Conservation status:— Thalictrum longistipitatum is currently known only from four populations in northwestern Yunnan (Dêqên) and southeastern Xizang (Bomi, Zayu), China. Both Bomi and Dêqên populations consist of more than 100 individuals. The size of the Zayu population remains unknown. The conservation status of T. longistipitatum should therefore be considered as “Data Deficient (DD)” before adequate information of this species is acquired ( IUCN Standards and Petitions Committee 2019).