Osmanthus dechangensis J.L.Liu & Y.Yuan, 2025

Osmanthus dechangensis J.L.Liu & Y.Yuan , sp. nov. ( Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 , Table 1)

Diagnosis: The new species can be distinguished from the relatives by glabrous branchlets, relatively larger leaves, more lateral veins and involucral bracts, bracts on one side of the floret, much earlier flowering time, etc.

Types: CHINA. Heilongtan, Dawancun Village , Heilongtan Town , Dechang County, Liangshan Prefecture , Sichuan Province, 2400–2450 m a.s.l., within a pile of random stones, Feb. 1st, 2010, J. L. Liu & Q. Luo (Syntype: 5041 (male flower branch), 5042 (female flower branch), XIAS!) ; Jul. 17th,. 2021, J. L. Liu, Y. Yuan & H. Chen (Syntype: 2021-53 (fruit branch), XIAS!) .

Description: This species is a large evergreen shrub or tree, typically reaching heights of 6 to 20 meters. The bark is gray-black to black, with a diameter at breast height ranging from 9 to 40 centimeters. The trunk can be either multi-branched or unbranched at the base. Young branches are flattened near the nodes, gray to dark gray, glabrous, and

......continued on the next page exhibit prominent ridges and sparse to dense lenticels. Older branches are cylindrical, gray-black or black-gray, and feature large, raised lenticels. The leaves are opposite, sometimes arranged in whorls of 3–4, with a leathery to thickleathery texture. The leaf blades range from long-elliptic-lanceolate, narrow-elliptic-lanceolate, long-elliptic, narrowelliptic, elliptic, to broad-lanceolate, measuring (6.5–) 8.2–23.3 cm in length and 2.5–6.2 cm in width. The leaf apex varies from acuminate, long-acuminate, caudate to long-caudate, to occasionally short-acuminate, acute, or obtuse, and is either straight or slightly curved. The leaf base can be cuneate, broad-cuneate, obtuse to nearly rounded, and may sometimes be shallowly cordate to cordate, symmetrical, or distinctly asymmetrical. The upper leaf surface is dark green and glossy, while the lower surface is green; both sides are glabrous with punctate glandular dots. The midrib is flat to slightly raised on the upper surface and strongly raised on the lower surface. The lateral veins, numbering (8–) 10–25 pairs, form a reticulate pattern with finer veins, slightly raised or nearly flat on the upper surface and raised on the lower surface. The leaf margins are typically entire or exhibit sparse to dense spiny teeth (1–) 14–35 pairs, slightly recurved, and measure (0.5–) 1–4.5 mm in length. The petiole is (0.5–) 1–1.7 cm long, light green or yellow-green, glabrous, with a narrow groove on the upper side and rounded on the lower side. The cymose inflorescences are both axillary and terminal on the upper parts of the branches, with (1–) 2–3 flower buds per axil, of which only 1–2 typically mature. Each flower bud contains (3–) 5–9 flowers. The peduncle is robust, slightly flattened, (0.5–) 1–3 mm long, dark green or green, and glabrous. The Involucral bracts, either deciduous or persistent, are arranged in (5–) 6–8 layers with (10–) 12–16 bracts in total, arranged in opposite pairs. Except for the basal two bracts, which are fused at the base, the others are free. The bracts are leathery to thick papery, cup-shaped, and vary from broadly triangular, broadly ovate-triangular, broadly ovate, elliptic, obovate-lanceolate, to inverted lanceolate. They range from 2–3 mm at the base to ca. 7 mm in length and 3–4 (–5) mm in width at the upper layers. The apex is short-pointed, gradually pointed, acute, obtuse, rounded, or truncate, often with a small projection, notch, or minute teeth at the tip. The outer surface is glabrous or occasionally covered with short appressed hairs, while the inner surface is densely covered with short appressed hairs, with minute cilia along the margins. This species is dioecious, with male and hermaphroditic flowers occurring on separate plants. The flowers are pale green in the bud and transition to pale greenish-white to white upon opening. The pedicels are quadrangular, slightly flattened, (0.3–) 0.6–2 cm long, sometimes extremely short, light green or pale yellow-green, and glabrous. The calyx is 1.5–2 mm long, with a very short calyx tube or one ca. 0.5 mm long. The calyx lobes are unequal in size, typically with two larger and two smaller lobes, triangular, ovate, long-ovate to lanceolate, glabrous, with an acute, obtuse, gradually pointed, nearly truncate, or nearly rounded apex, and entire or finely toothed margins. The corolla is bell-shaped, white, glabrous, 6–7 mm long, with a corolla tube 1–2 mm long. The stamens are inserted near the mouth of the corolla tube, with two sides slightly longer, ca. 2 mm, and the other two sides shorter, ca. 1 mm. The lobes, usually 4, occasionally 5, are spreading or reflexed, elliptic to long-elliptic, 5–6 mm long, 2–4 mm wide, with a short-pointed, acute, gradually pointed, obtuse, rounded, or truncate apex, sometimes with two shallow lobes, a notch, or 1–5 minute teeth, with the margins either flat or slightly incurved at the apex and edges, forming a helmet shape. The stamens usually number 2, rarely 3 to 4, inserted near the mouth of the corolla tube ca. 0.2 mm from the edge. The filaments are slightly flattened, quadrangular, glabrous, fused to the corolla tube at the base for about 2 mm, with the upper part free and extending beyond the corolla tube for 2.5–3.5 mm. The anthers are ovate, broadly ovate, elliptic, ovoid-elliptic, rectangular-elliptic, heart-shaped, broadly heart-shaped, or broadly obovate, (2.5–) 3–3.5 mm long, (1.5–) 2–2.5 mm wide, with a rounded, obtuse, or slightly notched apex, and a heart-shaped notch at the base. In hermaphroditic flowers, the connectives do not protrude, whereas in male flowers, the connectives form a small, pointed projection. The developing pistil in hermaphroditic flowers is 3–4 mm long, with an ovary that is ovoid, broadly ovoid, ovoid-elliptic, or elliptic, (1.5–) 2–2.5 mm long, green or pale green, glabrous, with a cylindrical style ca. (0.5–) 1 mm long, pale green, glabrous, and a capitate stigma that is ovoid or elliptic, 0.5–1 mm long, with a distinctly bifid apex. The sterile pistil in male flowers is lanceolate, 2.5–3 mm long, and deeply bifid nearly to the base. The fruit is a drupe, either deciduous or persistent, elliptic, ovoid-elliptic, or sometimes long-ovoid, 1–1.7 cm long, 0.6–1 cm in diameter, often slightly oblique, with a blunt or rounded apex, sometimes with a notch or slight indentation at the tip. The fruit surface has scattered round and raised lenticels and turns from green to purple-brown, purple-black, or black upon ripening. The fruit stalk is green, glabrous, 0.5–2 cm long, quadrangular, and slightly flattened. The endocarp is (0.6–) 1–1.3 cm long and 0.5–0.7 cm in diameter, with a blunt or rounded apex, a slightly notched tip, and a rounded base, bearing 11–16 longitudinal ridges, with one prominent ridge on each side.

Habitat and Distribution: The new species grow around a mountain lake in a cool humid subalpine climate, ecologically excellent, 52 km from Dechang County seat, where the establishment of the Heilonghaizi Provincial Forest Park was approved in May 2017. More than 100 families of plants ( Ericaceae , Theaceae , Fagaceae , Pinaceae , etc.) and over 300 animal species (Sus scrofa, Moschus moschiferus , Phasianus colchicus , etc.) coexist in harmony. Up to now, only 40 living plants have been found, and of these only 25 individuals are mature.

Etymology: The epithet ‘dechangensis’ refers to the locality of the type specimen, located in Dechang County, Liangshan Prefecture, Sichuan Province, China.

Phenology: Flowering from January to February, fruiting from May to August, with mature fruits typically dropping in July to August.

Conservation status:— Osmanthus dechangensis is currently known from a single growing site, rare and vulnerable to threats, as more and more people enter its habitat with the development of local tourism. Currently, our recommended endangered status is CR according to the IUCN (2024) category. Further in field research is necessary for searching more occurring sites, studying the population dynamics and assessing the possible threats affecting the new species. These data are necessary for the correct assessment of the IUCN (2024) category, as demonstrated by different assessments of newly described species, as CR ( El Zein & Bottcher 2024), EN ( Brullo et al. 2015, Ben Mahmoud et al. 2024), VU ( Swanepoel et al. 2021), NT ( Latt et al. 2023), LC ( Siti-Munirah & Dome 2023), DD ( Chinchilla 2020).

Taxonomic remarks: The new species differs from allied species ( O. yunnanensis (Franch.) P. S. Green ) in branchlet surface, leaf morphology, inflorescence structure, floral characteristics, and flowering time ( Table 1, Figs 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 ). The main differences are as follows: As far as O. dechangensis J. L. Liu & Y. Yuan sp. nov. is concerned, the branchlets glabrous when young, leaves (6.5–) 8.2–23.3 cm long, 2.5–6.2 cm wide, lateral vein (8–) 10–25 pairs; cyme, with peduncle (0.5–) 1–3mm long; involucral bracts (10–) 12–16 arranged in (5–) 6–8 layers; bract on one side of the floret; the floret is relatively large, with calyx 1.5–2 mm long, corolla 6–7 mm long, corolla tube 1–2 mm long, corolla lobes (4.5–) 5–6 mm long, lower part of stamen filament, ca. 2 mm long, connate with corolla tube, and the upper part, ca. 2.5–3.5 mm long, distinct, anther (2.5–) 3–3.5 mm long, connective of hermaphrodite flower non-protruding, and that of male flower pointe-like protruding; flowering time Jan. to Feb. While for Osmanthus yunnanensis (Franch.) P. S. Green , the branchlets pilose when young; leaves 8–14 cm long, 2.5–4 cm wide, lateral vein 10–12 pairs; absent of peduncle; involucral bracts 2; absent of bract; the floret is relatively small, with calyx 1 mm long, corolla 5 mm long, corolla tube very short or ca. 0.5 mm long, corolla lobes 4–4.5 mm long; stamen filament not connate with corolla tube, ca. 1–1.5 mm long, anther ca. 2.5 mm long, with apex of connective pointe-like protruding; flowering time Apr. to May. In summary, the new species O. dechangensis J. L. Liu & Y. Yuan is remarkablely different from O. yunnanensis (Franch.) P. S. Green in terms of morphological structure and flowering time.

Paratypes: CHINA. Heilongtan, Dawancun Village , Heilongtan Town , Dechang County, Liangshan Prefecture , Sichuan Province, 2400–2450 m a.s.l., within a pile of random stones, Feb.1st, 2022, J. L. Liu & Y. Yuan 2021-10, 2021-11, 2021-12, 2021-13 ( XIAS!) ; CHINA. Heilongtan, Dawancun Village , Heilongtan Town , Dechang County, Liangshan Prefecture , Sichuan Province, 2400–2450 m a.s.l., within a pile of random stones, Feb. 12th, 2023, J. L. Liu, H. Chen & X. F. Teng 2023-1, 2023-2, 2023-3, 2023-4, 2023-5 ( XIAS!) .

Examined material of O. yunnanensis : CHINA. Xiling Snow Mountain , Dayi County, Sichuan Province, 1900m a.s.l., on a slope, Z. M. Tan, May 20th, 1993, 92-2, 00869621 ( PE!) ; CHINA. Renqinpeng , Motuo County, Tibet, 1800m a.s.l., in a forest, S. Z. Cheng, B. S. Li, Jan. 24th, 1983, 03532, 01506179 ( PE!) ; CHINA. Guodong Village, Aziying Town , Songming County, Yunnan Province, 2400 m a.s.l., understorey of limestone montane evergreen broad-leaved forest, L. S. Xie, May 1st, 2003, 1253091 ( KUN!) ; CHINA. Hanyuan County, Sichuan Province, 2300m a.s.l., Hanyuan Botanical Expedition, Jun. 14th, 1978, 0614, SM716301546 ( SM!) ; CHINA. Jiancao Village , Mianning County, Scihuan Province, 1700m a.s.l., in an evergreen broad-leaved forest, Z. G. Liu, Q. Q. Wang, May 4th, 1980, 21198, CDBI0114505 About CDBI ( CDBI!) ; CHINA. Houshan Scenic Area, Xiling Snow Mountain , Dayi County, Sichuan Province, 2024 m a.s.l., H. F. Wang, H. He, Y. P. Du, Apr. 28th, 2019, DY0234, CDBI0269527 About CDBI ( CDBI!) .