Abstract
Thalictrum hengduanshanense and T. longistipitatum (Ranunculaceae), two new species from the southern Hengduan Mountains region in southeastern Xizang and northwestern Yunnan, China, are illustrated and described. Morphologically T. hengduanshanense is most closely similar to T. tsawarungense in having narrowly oblanceolate-linear filaments of stamens and apically slightly recurved styles, but differs by having laxly branched, corymb-like (vs. narrowly paniculiform) inflorescences and larger (ca. 9 mm vs. 4.5‒7 mm long), narrowly lunate (vs. broadly lunate) achenes (body width/body length = ca. 1/3 vs. ca. 1/2). Thalictrum longistipitatum is closely similar to T. hengduanshanense in habit and in having narrowly oblanceolate-linear filaments of stamens, apically slightly recurved styles, and long stipitate achenes, but differs by having apically abruptly recurved (vs. straight) pedicels and shorter styles (ca. 1 mm vs. ca. 2 mm long). Chromosome numbers of T. longistipitatum (2n = 14), T. rostellatum (2n = 28), T. tsawarungense (2n = 14) and T. wangii (2n = 14) are reported here for the first time.
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<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Zeng, Y.P., Yuan, Q. & Yang, Q.E. (2021f) Thalictrum bouffordii (Ranunculaceae), a new species from the Qionglai mountains region in western Sichuan, China. Phytotaxa 510: 18?28. https://doi.org/10.11646/phytotaxa.510.1.2</span></span></span>
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<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Zeng, Y.P., Fei, W.Q., Yuan, Q. & Yang, Q.E. (2021i) Thalictrum changii (Ranunculaceae), a new species from southern Xizang (Tibet), China. Phytotaxa 511: 248?260. https://doi.org/10.11646/phytotaxa.511.3.4</span></span></span>
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<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Zeng, Y.P., Yuan, Q. & Yang, Q.E. (2022b). Thalictrum daguanense (Ranunculaceae) is merged with T. omeiense, a species distributed in Sichuan and Yunnan, China. Phytotaxa 539: 130?146. https://doi.org/10.11646/phytotaxa.539.2.2</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Zeng, Y.P., Yuan, Q. & Yang, Q.E. (2022c). Thalictrum fusiforme (Ranunculaceae), described from southeastern Xizang (Tibet), China, is merged with T. rostellatum, a Sino-Himalayan species. Phytotaxa 545: 234?260. https://doi.org/10.11646/phytotaxa.545.3.1</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Zeng, Y.P., Yuan, Q. & Yang, Q.E. (2022d) Lectotypification of Thalictrum chayuense (Ranunculaceae), with its reduction to the synonymy of T. tsawarungense, both described from Zayu in southeastern Xizang, China. Phytotaxa 548: 184?198. https://doi.org/10.11646/phytotaxa.548.2.4</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Zeng, Y.P., Yuan, Q. & Yang, Q.E. (2022e) Thalictrum cuonaense (Ranunculaceae) is merged with the Himalayan T. reniforme, with notes on its morphologically similar species. Phytotaxa 554: 221?244. https://doi.org/10.11646/phytotaxa.554.3.2</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Zeng, Y.P., Yuan, Q. & Yang, Q.E. (2022f) Clarification of morphology and distribution of Thalictrum fortunei (Ranunculaceae) from China, with reduction of T. fortunei var. bulbiliferum to its synonymy on its morphologically similar species. Phytotaxa 561: 121?137. https://doi.org/10.11646/phytotaxa.561.2.1</span></span></span>
