Syzygium halmaherense Sunarti, Rugayah, Damayanto, Astuti, & Kusuma, 2025

Syzygium halmaherense Sunarti, Rugayah, Damayanto, Astuti, & Kusuma , sp. nov. ( Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 ).

Type:— INDONESIA. Maluku Islands: Halmahera Island, Central Halmahera, Weda Bay, Bukit Limber, elev. 204 m, 0°29’00.0”N 128°01’44.0”E, 6 August 2013, Roji Mahroji, Tjut Jul Fatisa Bangun, & Idris Haris 320 ( holotype BO! [code: BO-1934577], isotype MO! [image code: 100618320]).

Diagnosis:— Syzygium halmaherense is morphologically similar to S. perspicuinervium (Merr.) Masam. , but the leaves and flowers are slightly different. These two species have almost the same leaf size and very prominent leaf veins (very veined). However, leaves of S. halmaherense possess shorter petioles ( 3–7 mm), cordate bases, and acute to obtuse apices, lacking glandular-puncticulate abaxially. In contrast, leaves of S. perspicuinervium has longer petioles ( 10 mm), broadly acute bases, acuminate and clearly pointed apices, and numerous glandular-puncticulate abaxially. Inflorescence of S. halmaherense is panicle, possesses larger flowers ( 6–8 mm long) with four free, persistent, cream-colored sepals. The petals are subcalyptrate, four lobes, coherent and falling as a cap. In contrast, inflorescence of S. perspicuinervium is fascicled or solitary, subcorymbose, smaller flowers (approximately 3 mm long) with calyptrate or irregularly dehiscent sepals and ovate petals.

Small tree, 2.5–6.0 m tall, diameter 4–6 cm. The outer bark pale brown, and the inner bark cream. Young twigs flat. Leave opposite decussate, pinkish when young becoming green with age, lamina elliptic to ovate, 23.0–51.5 × 12–20 cm, leathery; base cordate; apex acute to obtuse; margin slightly recurved; midrib, secondary nerves, and tertiary nerve clearly prominent on the lower surface and sunken on the upper surface; secondary nerve 25–40 pairs, forms an angle of 70–80º with the midrib; intramarginal vein clearly 1, 1–7 mm from the leaf margin. Petiole 3–5(–7) mm, swollen, 5 mm thick. Stomata hypostomatic, parasitic, ca. 20 × 15 μm. Inflorescence terminally and axillary, panicle, 5–16 cm long; peduncle angled. Young inflorescences initially purplish-red, gradually changing color to whitish upon maturity. Flower buds turbinate, pale yellow, tip maroon, 2.0–6.0 × 1.0– 3.5 mm. Flowers in late bud: hypanthium torch-shaped, 6–8 × 5–6 mm, yellowish white; sepal 4, free, ca. 5 × 2 mm, purple when young, edges crack and turn cream-colored after blooming; petals subcalyptrate (4 lobes coherent and falling as a cap), ca. 4.0 × 3.5 mm, nearly round, white, soon falling after anthesis. Stamens numerous (112–115); filaments 2–7 mm long, white; anthers ca. 0.7 × 0.6 mm, pale yellow. Pollen grains monad, 10–12 μm diam. in polar view, concave triangular, 3-syncolporate, isopolar, P/E ratio sub-oblate, exine not strongly ornamented. Stylus 8–9 mm long, white. Ovary inferior, 2 locular, ovule 5–6 per locule. Fruits sphaerical, 17–24 mm diam., calyx rim ca. 3 mm diam., prominent, immature green, mature reddish yellow, stigma persistent; seed 1, 5–15 mm diam., pericarp ca. 1 mm.

Phenology:—Flowering and fruiting occur between June and August.

Distribution:— Syzygium halmaherense is endemic to the Halmahera Island, Maluku Islands, Indonesia, specifically can be found in Weda Bay ( Fig. 5 View FIGURE 5 ).

Habitat:— Syzygium halmaherense have been found in disturbed lowland forests, along stream banks, and in open areas at elevations between 204 and 302 m above sea level.

Etymology:—The specific epithet “halmaherense ” directly refers to the island of Halmahera, where the species was initially discovered.

Provisional conservation status assessment:— Syzygium halmaherense is endemic to Maluku, specifically found only around Weda Bay on Halmahera Island, Indonesia ( Fig. 5A View FIGURE 5 ). There are only five known collections from this region. The EOO of S. halmaherense is 6.792 km ², which qualifies it as Critically Endangered (CR) according to the B criterion of the IUCN. Its AOO is 16 km ², placing it in the Endangered (EN) category under the same criterion. Information on its population size, distribution, and life cycle is lacking. Discovered in 2013 in a nickel-mined forest area, the species has faced potential threats. However, Google Maps data from 2024 ( see Fig. 5B View FIGURE 5 ) shows that S. halmaherense ’s habitat still has relatively good forest cover, suggesting that the threat of habitat decline may not be fully assessed. Based on current data and IUCN Red List guidelines ( IUCN 2024), S. halmaherense is categorized as Near Threatened (NT). Ex situ conservation efforts have begun at the Bogor Botanic Gardens, West Java, Indonesia.

Additional specimens examined:— INDONESIA. Maluku Islands: Halmahera Island, Central Halmahera, Weda Bay , Bukit Limber , km 7, 00°29’49”N, 128°00’57”E, 5 August 2013, Bahar Fabanyo, Idris Hari, & Samsul Lasut 92 ( BO, code BO-1934507; MO, code 102856690) GoogleMaps ; Maluku Islands, Halmahera Island, Central Halmahera, main road to Bukit Limber , 00°29’50”N, 128°00’25”E, 10 July 2013, Iska Gushilman, Samsul Lasut, Idris Haris, & Bahar Fabanyo 770 ( BO, code BO-1934584; L, code L.3968657) GoogleMaps ; Maluku Islands, Halmahera Island, Central Halmahera, Weda Bay , Sake West , 00°30’04”N, 127°57’44”E, 17 June 2013, Tjut Jul Fatisa Bangun, Roji Mahroji, & Bahar Fabanyo 798 ( BO, code BO-1934586; L, code L.3968659) GoogleMaps ; Maluku Islands, Halmahera Island, Central Halmahera, Weda Bay , Sake West , 00°29’45”N, 127°57’30”E, 18 June 2013, Tjut Jul Fatisa Bangun, Roji Mahroji, & Bahar Fabanyo 805 ( BO, code BO-1934584; L, code L.3968658). Java, Bogor Botanic Gardens, vak VA. 202a (originated from Weda Bay , Halmahera, seeds were collected by Yayan Wahyu C. Kusuma [YY.200], 152 m above sea level ( B2011090140 ), and were planted on 22 April 2014), 12 January 2022, Siti Sunarti SS880 ( BO) GoogleMaps .