Hengduan adder's-tongue (Whittieria hengduanensis) from eastern Himalayas similar to the American Whittieria engelmannii
NEWS - Hengduan adder's-tongue (Whittieria hengduanensis Z.L.Liang & Li Bing Zhang, sp. nov.) from Sichuan, Xizang, and Yunnan, Southwest China (eastern Himalayas) shows that the genus has members that are intercontinentally separated between the Himalayas and America, a unique pattern that has not been documented in the literature.
Ophioglossaceae is divided into 4 subfamilies and 15 genera. The seven recognized genera within Ophioglossoideae are Cheiroglossa C. Presl.; Goswamia Li Bing Zhang & Liang Zhang; Haukia Li Bing Zhang & Liang Zhang; Ophioderma (Blume) Endl.; Ophioglossum L.; Rhizoglossum C. Presl; and Whittieria Li Bing Zhang & Liang Zhang.
During field trips in western Sichuan and southeastern Xizang in 2021, the researchers collected several species from several locations. This species has pronounced complex reticulate venation, similar to the American W. engelmannii, but is about 8000 km away from the latter species' distribution in aerial distance.
Whittieria hengduanensis is plant 10–13 cm tall. Rhizomes erect, cylindrical, quiescent. 6–7 mm, with numerous black residual trophophore stalks. Leaves 1–2 per rhizome. Roots fleshy, up to 25 (–50) per rhizome, ca. 0.6mm dia. Leaf stalks 4.5–7.5 cm long, 1.5–2 mm diameter; the lower part is buried in the soil, grey.
Trophophores nearly circular to ovate, papery, 1.6–6 cm long, 1–3 cm broad at the middle, apex acute, narrowed toward the base. Venation complex-reticulate (also called “double venation” with small areolae inside a large areola), with included veinlets.
Sporophores arising at ground level, the base is slightly attached to sporophores; stalks 3.5–7 cm long; spike 1.2–1.8 cm long, ca. 2.5 mm diam., 16–23 pairs of sporangia per spike.
W. hengduanensis is similar to W. engelmannii but has up to 25 (–50) roots per rhizome and 10–20 large areoles per trophophore (vs. less than 15 roots per rhizome and 0–8 areoles per trophophore in W. engelmannii).
The new species was discovered in western Sichuan (Batang, Daocheng, Daofu, Derong, Maerkang, Xiangcheng, Yajiang, Yuexi), northwestern Yunnan (Lijiang, etc.), and eastern Xizang (Mangkang, Zayu). It grows on bottom soil under bushes in dry and hot river valleys at elevations of 2500–4000 m.
Original research
Liang Z-L, Zhang L-B (2024). Discovery of Whittieria hengduanensis sp. nov. (Ophioglossaceae) from Southwest China demonstrates a unique intercontinental disjunct pattern in plants between the Himalaya and the Americas. PhytoKeys 249: 27-36, DOI:10.3897/phytokeys.249.135379
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