Syzygium kampotense resembles S. championii (Benth.) Merr. & L.M.Perry and S. claviflorum (Roxb.) Wall. ex Steud., in the clavate hypanthium shape, cuneate leaf base, small leaves and short petioles. The new species differs from both species in having thickly coriaceous leaves with strongly revolute leaf margins, an acute or obtuse leaf apex and fewer secondary veins (Fig. 1, Table 1).

Figure 1. 

Syzygium kampotense Chantar.: holotype, McDonal et al. 5676 (AAU). In set leaf, hypanthial cups and fruit. Photographed by B. Boonsuk.

Cambodia: Kampot Province, Kampot District, southern summit of Phnom Bokor, vicinity of Bokor, 1–2 km NE of artificial on near Church toward Prek Kaoh Toch, 13 May 1997, McDonal et al. 5676 (holotype AAU, isotype QBG).

Figure 2. 

Syzygium kampotense Chantar., showing leaf, hypanthial cups and fruit. Photographed by B. Boonsuk.

Shrub ca. 1 m tall; branching sparingly, bark corky, whitish grey or reddish. Leaves with petiole 2–3 mm long, wrinkled; lamina thickly coriaceous, 4–6.5 × 1.7– 3 cm, elliptic or elliptic-oblong, base broadly cuneate, apex acute or obtuse, margin strongly revolute; midrib impressed on the upper surface, rounded with sparse pustules on the lower surface; secondary veins in ca. 12 pairs, indistinct on upper surface and distinct on lower surface; intramarginal vein 1. Inflorescence not seen. Hypanthial cup 13–15 mm long, clavate. Pseudostipe absent. Sepals red 4, ca. 1 × 1.5 mm, triangular. Petals not seen. Stamens numerous, white. Ovary 2-locular, ca. 9 ovules per locule. Fruit purple, 8–10 mm in diameter, globose or ellipsoid, crowned with remnant of calyx lobes.

Figure 3. 

Syzygium kampotense A habit B lower surface of leaf C calyx tube (side view) D longitudinal section of calyx tube and ovary, showing two locules E fruit (from McDonald et al. 5676; drawn by N. Triyutthachai).

Endemic to Cambodia.

Dense sclerophyllous, short-tree forest, canopy 2–4 m tall, some emergent to 7 m tall; associates include Ardisia, Lithocarpus, Elaeocarpus, Melastoma, Schima, Syzygium and Vaccinum.

The species is only known from the type locality. It should be categorised as Critically endangered [CR, B1ab (iii)] according to the IUCN Red List Criteria and Categories version 3.1 (IUCN 2012). The Extent of Occurrence is estimated to be less than 20 km² and this species is found in a restricted area on open limestone hills which is a threatened ecosystem.

The name of this species is given based on the location where the plant was collected.

The new species most likely belongs to Syzygium subgenus Perikion Craven & Biffin (Craven and Biffin 2010; Hatt et al. 2023, because of its clavate hypanthium shape and ellipsoid, obovoid or globose fruit. These characteristics resemble S. claviflorum, the type of this subgenus.

Cambodia, Kampot Province, Bokor National Park, near field station, near top of plateau, 10°20.38'N, 104°01.4'E, alt. 1,045 m, 10 Mar. 2001, Midlleton & Monyrak 660 (P [P00589160]); Bokor, Dy Phon 1130 (P [P04658853]).

Based on Myrtus cerasiformis Blume.

Thailand, Cambodia, Malaysia, Java, Borneo.

In evergreen swamp forest and a drainage along river.

POWO (2023) accepts Syzygium lineatum as a synonym of S. cerasiforme and also shows the distribution of S. cerasiforme in Cambodia, Laos, Vietnam and China. I agree with Merrill and Perry (1939) that both species are not conspecific. Moreover, Parnell and Chantaranothai (2002), Chen and Craven (2007), and especially Soh and Parnell (2015) and Tagane et al. (2015, 2018) working on Cambodian taxa, indicated that Syzygium cerasiforme had never been recorded in Cambodia. Syzygium cerasiforme is similar to S. lineatum in having terminal and axillary inflorescences, leaf shape and 14 or more pairs of secondary veins. It differs by smaller leaves, sepals and petals and the outer stamens and style are shorter (4.3–6.7 mm vs 10–15 mm and 5.2–7.7 mm vs 11–13 mm, respectively). However, the Cambodian specimens were collected from Kampong Thom and Stung Treng provinces in Cambodia and I identified them as S. cerasiforme. Therefore, these two specimens are the first new record for Cambodia.

Cambodia, Kampong Thom Province, Sandan District, Rey Long, ca. 13 km south-eastern of Spong, ‘Cheum Takong’ (Takong swam; 3 × 4 km), a drainage of O Long River, Base camp 13°20.27'N, 105°36.077'E, 7 Apr. 2008, McDonald et al. 7901 (AAU) & Stung Treng Province, Prey Long Forest, Cheum Takong and O Long River, 13°20.359'N, 105°36.32'E, 7–10 April 2009, McDonald et al. PL8 (AAU).

Based on Eugena foxworthiana Ridl.

Thailand, Peninsular Malaysia, Sumatra, Borneo, Vietnam (Lao Cai (Laokhay), Pakha, 10 Dec. 1935, Poilane 25052 (K).

In evergreen forest, 50–200 m alt.

Ashton (2011) placed S. foxworthianum under S. pycnanthum (Eugenia densiflora Miq.) but I do not agree with this placement because the former differs from the latter by having a long and lax inflorescence (vs short and dense), slightly smaller and narrower leaves, 16–18.5 × 4–6.5 cm (vs larger and broader, 17.5–26 × 4.5–8.5 cm), two intramarginal veins, sometimes without the intramarginal vein and secondary veins ascending to a shallow loop (vs 2–3 intramarginal veins). Although the Vietnamese specimen Poilane 25052 (K), has young fruits, I found that it belongs to S. foxworthianum. Therefore, it is a new record of this species for Vietnam.

Eugenia densiflora var. angustifolia Ridl. was described based on two specimens from Peninsular Malaysia, Peak (Ridley s.n.) and Kelantan (Yapp s.n.). Ridley s.n. (K) is available and is designated here as the lectotype.

Thailand, Doi Inthanon (Doi Angka), 30 April 1921, Kerr 5287 (lectotype, designated by Chantaranothai and Parnell 1994, p. 35: BK; isolectotypes: BM, K, TCD).

Myanmar, Thailand, Laos, Cambodia, Vietnam and China (Yunnan province, Menghai county, Xiding country, Mt. Dahei, Hesong, 2 May 2011, Li-Jianwu 625 (HITBC no. 136852, QBG no. 64320, fruiting specimen).

In evergreen broad-leaf forest, ca. 1,960 m alt.

Syzygium angkae is characterized by having axillary or terminal inflorescences ca. 2 cm long and numerous secondary veins. It is found on mountains at an altitude of at least 1,500 m or more. The unidentified fruiting specimen at QBG belongs to S. angkae. The distribution of the species was mainly in Myanmar, Thailand, Laos, and Vietnam; it is now extended to China.

Thailand, Ubon Ratchathani, Kemmarat, Thorel 3010 (lectotype, designated by Soh and Parnell 2015, p. 261: P [P00589178]; isolectotypes: A [A00069448], P [P00589179], K [K000276196]).

Thailand, Laos, Cambodia, Vietnam, China (Yunnan Province, Mengla County, Mt. Gongbeng, Luosuo River Estuary, 500 m alt., 3 Jan. 2011, Li-Jianwu 239 (HITBG, no. 135842, QBG).

Open rock crevices in the Mekong River, partly submerged at high water or in sandy soils along the side of the river.

Syzygium thorelii is distinctive in having an obtuse or acute leaf apex and alternate leaves in the lower parts of the plant. A previously unidentified specimen seen at QBG undoubtedly belongs to S. thorelii and is a new record for China. The Chinese specimen extends the range of the species from Thailand, Laos, Cambodia and Vietnam to Yunnan.

Based on Eugenia densinevia Merr.

Philippines (Luzon) and Taiwan (South Cape).

In evergreen forest, mountain slope.

Syzygium densinervium resembles S. fastigiatum (Blume) Merr. & L.M.Perry in having paniculate inflorescence, funnel-shaped hypanthium and persistent bracts and bracteoles. It differs by its rugulose hypanthial cup. I have examined an unidentified specimen, Henry 1998 at K [K001003761] and found that it belongs to S. densinervium. I have also examined the isotype type of S. densinervium var. insulare from Taiwan and then placed it under S. densinervium. This species is distributed in the Philippines and Taiwan.

Taiwan, Botel Tobago, 7 Feb. 1980, Chang 14691 (KYO); ibid., 6 Sept. 1980, Chang 14694 (KYO).

Based on Eugenia pellucida Duthie

India, Myanmar, Thailand, Vietnam.

Along rivers or streams.

Based on three collections, Helfer 2406 (K000821333, GH00069438), Helfer 2407 and Kurz s.n., the last two have not been seen. Therefore, K000821333 is designated here as the lectotype of E. pellucida. The original description of E. pellucida var. contracta is based on Wallich 3602 which has four sheets. The specimen, K001119797 is designated here to be the lectotype because it has more leaves and inflorescences. Syzygium pellucidum was considered to be endemic to Myanmar (POWO 2023) but its distribution is now extended to Thailand, Laos and Vietnam.

Based on Eugenia prainiana King.

Thailand, Peninsular Malaysia, Borneo.

In evergreen forest, 900 m alt.

Chantaranothai and Parnell (1993) proposed subsp. minor for Thai material with a slightly shorter hypanthial cup (3–4 mm long vs 5 mm long for the typical variety), stamens and style. After examination of Gardner & Chamchumroon ST2467 K [001007729], a second new specimen collected from Trang, Thailand, I found that these characteristics are variable. Therefore, subsp. minor is here placed into synonymy of S. prainianum. This species is uncommon in Thailand but widespread in Peninsular Malaysia and Borneo.

Trang, Yanta Khao, Khao Banthat Wildlife Sanctuary, valley above Sai Rung Waterfall, Camp 2, 800 m alt., 14 Mar. 2006, Gardner & Chamchumroon ST2467 (K).