Photos and a line drawing are available at https://doi.org/10.3897/phytokeys.130.33956, accessed 2022.11.04.
Photos and a line drawing are available at https://doi.org/10.3897/phytokeys.130.33956, accessed 2022.11.04.
Amentotaxus hekouensis
Type specimen male, collected in Yunnan, Hekou County, Nanxi Town, Longyinchong village, +22.68581°, +104.01767° elevation 926 m, 2016.04.16, G. L. Zhang GLM-164271. The species was identified following the 2006 collection of a specimen in the same area, a limestone montane forest near Longyinchong village (Gao et al. 2019). Subsequent molecular analysis (Gao et al. 2016) classified this specimen with previously-collected specimens of Amentotaxus from Lao Cai in Viet Nam and Xiang Khoang in Laos, within a clade sister to A. formosana (Gao et al. 2019).
Dioecious evergreen tree to 5 m tall, diameter not stated; branches cylindric or subtetragonal, grey; leafy twigs ascending or sub-erect, broadly rectangular to oblong-elliptic, axis green in 1st year, greenish-yellow in 2nd and 3rd years, quadrangular or subterete in cross section. Leaves almost opposite, borne at 50–80° to twig axis, distichous, twisted at the base, petiole 2–4 mm long, 4–6 leaf pairs on each twig; leaves leathery, thin, linear or linear-lanceolate, 8–12.5 × 0.9–1.4 cm, straight, slightly falcate at the apex, cuneate at base, asymmetric, apex long-acuminate, leaf margin flat or slightly recurved, usually slightly wavy; leaf marginal band dark green, 2.5–3.2 mm wide; stomatal bands white or greenish-white, 2.1–3.0 mm wide, equal to or slight narrower than marginal bands, stomata in 25–30 rows; midvein adaxially slightly sunken or flat, abaxially raised, 1.2–2.0 mm wide, green, same color as twig. Seed cones not observed. Pollen cones borne in 1-2 racemes, ca. 8.0 cm long, with ovoid cones in 12–16 pairs, proximal cones maturing earlier than distal ones; microsporophylls 6–8, peltate, each with 4–8 pollen sacs. Pollen cones fertile March to April. Seeds not observed (Gao et al. 2019).
A. hekouensis differs from all other taxa of Amentotaxus in length and width of leaves, shape of the leaf apex, curvature of the leaf margin, stomatal band width, stomatal band ratio to leaf marginal bands, differences in the number of pollen sacs, and in the length of the pollen cone racemes (Gao et al. 2019).
China, Laos, and Viet Nam. To date, the species has been reported from 7 locations. Five are very near the China-Viet Nam border in Funing, Malipo and Hekou counties in Yunnan, and Lao Cai province in Viet Nam. There are also two more southerly collections, at Hoa Binh province in Viet Nam and at Xiang Khouang in Laos. It occurs in montane evergreen forest on limestone mountains at elevations of 850-1750 m. In part of its distribution along the border between China and Viet Nam, it is sympatric with A. yunnanensis (Gao et al. 2019).
Although the conservation status of A. hekouensis has not yet been formally assessed, the combination of a restricted, fragmented distribution with very limited area of occupancy, small population size and the threats of habitat conversion and destruction throughout its range indicate that its IUCN status should be Endangered (Gao et al. 2019).
No data as of 2023.02.23.
No data as of 2023.02.23.
In view of this species' rarity and declining conservation status, entry to its habitat should be avoided.
The epithet refers to the type locality, in Hekou County, Yunnan (Gao et al. 2019).
Gao L.-M., S.-L. Tan, G.-L. Zhang, and P. Thomas. 2019. A new species of Amentotaxus (Taxaceae) from China, Vietnam, and Laos. PhytoKeys 130:25–32. https://doi.org/10.3897/phytokeys.130.33956
Last Modified 2024-12-12
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