Amentotaxus x hybridia L.M.Gao & G.L.Zhang, 2023

Gao, Lian-Ming, Zhang, Gui-Liang, Mo, Zhi-Qiong & Thomas, Philip, 2023, Amentotaxus x hybridia (Taxaceae), a new natural Amentotaxus hybrid from southeast Yunnan province, China, PhytoKeys 226, pp. 101-108 : 101

Amentotaxus x hybridia L.M.Gao & G.L.Zhang sp. nov.

Figs 1 , 2

Diagnosis.

Amentotaxus x hybridia L.M. Gao & G.L. Zhang resembles A. hekouensis L.M. Gao, but differs by its larger linear or linear-lanceolate leaves of 6-13 cm × 1.0-1.5 cm, stomatal bands with 34-40 rows on abaxial side, 2.5-3.5 mm wide, slightly wider than the green leaf margins; 3-6 seeds borne at the base of the branchlets, peduncle 1.3-1.6 cm long, 3-4 rows of persistent basal bracts (Table 1 ).

Type.

China. Yunnan: Qincaitang Mt., Longbao village , Nanxi Town , Hekou County, Honghe , 22°39'49"N, 104°01'17"E, elevation 1100 m, 15 February 2016 (with mature seeds), Zhang GL, GLM164267 (Holotype: KUN, isotype: KUN) .

Morphological description.

Small tree up to 5 m tall, bark brown gray; branch cylindric or subtetragonal, yellowish green; leafy branchlets ascending, broadly rectangular to oblong-elliptic in outline, axis green in 1st year, greenish yellow in 2nd and 3rd years, quadrangular or subterete in cross section. Leaves borne at 40-70° to the branchlet axis, distichous, twisted at the short petiolate or nearly sessile base, subsessile or petiolate, petiole to 2 mm long, almost opposite, 5-7 leaf pairs on each branchlet; Leaves leathery, linear or linear-lanceolate, 6-13 cm × 1.0-1.5 cm, straight, sometimes slightly falcate, cuneate at base, asymmetric, apex acuminate, leaf margin narrowly revolute, sometime flat; leaf marginal band green when fresh, yellowish green when dry, 2.0-3.0 mm wide; stomatal bands white when fresh and yellow white when dry, 2.5-3.5 mm wide, slightly wider than green leaf margins, stomata in 34-40 rows of each band, densely arranged; midvein slightly sunken or flat adaxially, raised abaxially, 1.5-2.0 mm wide, narrower than the stomatal and marginal bands, yellowish green, same color as the branchlet. Seed-bearing structures in clusters of 3-6 at the base of the branchlet, not from subtending leaf. Aril reddish purple when ripe. Mature seed reddish purple, obovoid-ellipsoid, 2.5-3.0 cm × 1.4-1.6 cm, mucronate at apex, naked; peduncle 1.3-1.6 cm long, compressed-quadrangular, slightly dilated below bracts; 3-4 rows of persistent basal bracts on peduncle, four bracts per row, imbricate, obovate or obovate-oblong, with a ridge in middle. Seed maturity February. Pollen cone not seen.

Distribution and ecology.

Amentotaxus x hybridia has only been found in the karst montane monsoon evergreen forest in southeast Yunnan province along the border between China (Hekou, Yunnan) and Vietnam occurring at an elevation around 1100 m.

Phenology.

Seed matures in February.

Etymology.

The specific epithet is derived from the natural hybridisation between A. yunnanensis and A. hekouensis .

Conservation status.

As a natural hybrid, Amentotaxus x hybridia is not eligible for listing under the current IUCN Categories and Criteria ( IUCN Standards and Petitions Committee 2022). However, as it occurs in areas where A. yunnanensis and A. hekouensis are sympatric, hybridisation could lead to a loss of genetic diversity for those species. In addition, the lack of a reproductive barrier between A. hekouensis and A. yunnanensis has implications for ex-situ conservation programs, especially if collections are intended to be used as a source of material for reintroduction or for long term conservation in cultivation.

Figures

Figure 1. Amentotaxus x hybridia L. M. Gao & G. L. Zhang (from the holotype, drawn by Ling Wang) A branchlet with seeds B seed with peduncle and bracts.

Figure 2. Amentotaxus x hybridia L. M. Gao & G. L. Zhang A habitat B habit C branchlet with abaxial leaves D branchlet with adaxial leaves E seeds bearing branchlet and seeds with mucronate apex F seed-bearing structure with peduncle and bracts.