Similar to Elaeocarpus luteolignum Coode, but differing from that species in glabrous (vs minutely adpressed-hairy) terminal buds and young twigs, leaf blades with black gland dots (vs leaf blades without dots), 5-merous (vs 4-merous) flowers, larger flowers (e.g. sepals 5–8 × 1.5–2.5 vs 3–4 × 1.5 mm) and more numerous stamens (29–31 vs 20).

INDONESIA. Central Sulawesi (Sulawesi Tengah): Lore Lindu National Park, Kabupaten Poso, Kecamatan Lore Utara, 7.7 km NNE of village Sedoa, Mt Rorekautimbu, tree-inventory plot “Bulu Torenali”, 1°17.2'S, 120°18.7'E, 2350 m, 21–24 Apr 2012: Brambach F, Mangopo H, Firdaus, Faber M, Tiranda R 1953 (flowers; holotype: K, 2 sheets, [K000720760]!, [K000720898]!; isotypes: BO (BO 1926842)!, CEB, L [L.2055441]!).

Trees 8–25 m tall, dbh ≤ 40 cm, without buttresses or stilt roots, flowering when full-grown. Outer bark reddish brown, verrucose; inner bark pinkish with white streaks, granular, innermost layer yellow, easily detachable from wood, wood cream to white.

Twigs glabrous, strongly angulate at first, later terete, twig bark longitudinally cracking, forming a net-like pattern, with large conspicuous leaf scars and many prominent lenticels, gummy-resinous where cut, 2.5–4.0 mm thick towards the tip, with gummy-resinous, glabrous terminal buds. Stipules caducous, linear-subulate to narrow-triangular, glabrous, often gummy, 1.5–5.0 mm long, tapering, entire.

Leaves spirally arranged, loosely to ± tightly grouped towards twig tips in older trees, in juveniles often scattered, appearing in flushes, leaves of one flush ± equal in size. Fresh leaves brownish-red when young, later dark green with contrasting paler midrib above, much lighter green and with contrasting darker green venation and the sometimes red midrib beneath, dying red. Petioles 2–14 mm long, 1–3 mm thick, glabrous or almost so, sometimes verrucose when mature, often longitudinally finely striate, usually flat in apical third above, sometimes rounded or slightly channelled above, distinct from or merging into decurrent leaf base (variable within a specimen), pulvinous or not on both ends, without pegs at apex, sometimes with elongate glands at the junction of petiole and lamina-margin, geniculate. Blades chartaceous to coriaceous, mostly oblong-obovate, some oblong-elliptic or obovate, 2.1–4.0 times as long as wide, (5–) 6–13 (–15.5) × 1.5–5.0 (–6.5) cm, acute to obtuse (80–110°) to rounded at apex, the very tip notched and with a (sometimes fused) pair of black glands, cuneate at base or tapering towards a broadly cuneate base (the larger leaves more narrowly cuneate), occasionally rounded, surface sometimes bullate, dull and glabrous above, glabrous or sometimes with some short adpressed hairs on the midrib beneath when young and then soon glabrescent, glabrous and not verrucose beneath when mature, with minute black gland dots on both sides. Midrib darker than lamina, prominent but widened and flattened towards base above, strongly prominent beneath, with 8–16 pairs of main lateral veins, diverging at 60–80° from midrib, straight for most of their length or curved, breaking up 3/4 to 7/8 inside margin, looping forward and mostly joining up; usually with intermediate veins in between, ± prominent and of same colour as or paler than lamina above and below, higher-order veins reticulate, obscure or ± clear and raised above and below, of same colour as lamina, areoles squarish, < 2 mm across, domatia absent. Margins ± entire to weakly glandular-serrate, sometimes less serrated in lower half, the teeth 2–11 mm apart, glands present regardless of serration, 0.5 mm long, spindle- or claw-shaped, sometimes elongate along margin, black.

Inflorescences in the axils of current leaves, solitary, racemose, ± of same length as subtending leaf, 3–8 cm long, axis angular, 1.2–1.5 mm thick at about halfway, with sparse, short, straight hairs between adpressed and spreading, 5–9-flowered.

Flowers bisexual, 5-merous (once 6-petalled), spiral or almost whorled on inflorescence, bracts early caducous, not seen, pedicels 6–18 mm long and 0.5–1 mm thick in flower, bent downwards and thickened at apex, buds ovoid, acute at apex. Sepals 5–8 × 1.5–2.5 mm, cream-coloured when fresh, not verrucose and ± pale adpressed-sericeous outside, densely white-velutinous next to the margins inside, otherwise short-sericeous inside but glabrous in the basalmost 1.5 mm, keeled inside for whole length. Petals thick and opaque, ivory-coloured on account of the hairs when fresh, oblong, parallel-sided almost to base, rounded to a narrow (1 mm wide) base, 6.5–7.5 mm long, 2.0–2.5 mm wide at widest point of limb, rounded at apex and divided into 9–12 narrow-triangular apical divisions 0.3–1.0 mm long, divisions unequal in length and grouped into lobes and acute at tip, not verrucose in dried material, densely white-sericeous outside, margins velvety or densely short-hairy throughout, densely short-hairy inside except for glabrous patch near base, with a low, narrow keel inside running for most of limb length, ± flat at midpoint and flat at base, without any infolding of margins. Disk golden when fresh, ± annular, 10-toothed, 0.5–0.8 mm high, densely covered with short, straight, golden hairs. Stamens 29–31, inserted in a ± single ring between disk and ovary; filaments 0.6–1.8 mm long, straight to somewhat incurved tapering from base to apex, glabrous or with a few minute hairs; anthers 1.6–2.5 mm long, khaki when fresh, minutely hairy, with outer tooth clearly much longer than inner and with a beak 0.2–0.5 mm long, beak glabrous or with a few minute hairs without setae at tip. Ovary placed above the disk, shape clearly narrowed at base, 2.0–2.5 mm long, densely short- to medium-hairy, 2–3-locular; ovules 8–12 per locule; style 2.5–3.5 mm long, stout, tapering to a point, glabrous except for the very base.

Fruits unknown.

Flowering was observed in April. No fruiting was observed.

The pollen of E. firdausii is dimorphic as two distinct morphological pollen grains were observed in the sample. The most common one is a 3-aperturate pollen grain, typical of the family Elaeocarpaceae (Coode 2004). The second, less common (4%), type presents a 2-aperturate morphology and it is clearly distinguishable from the first (Fig. 4). The two pollen types are described as follows:

3-colporate type (Fig. 4a–b):

Prolate spheroidal to spheroidal pollen grains; outline in polar view (amb) rounded semi angular; psillate; P/E: 1.0 (0.9–1.1); polar axis (P): 12.2 (11.2-13.3) µm; equatorial axis (E): 11.9 (10.4-13.1) µm; apocolpium index 3–4 µm. Colpi 7.1–11.2 × 1–2 µm long with indistinct ends. Endoaperture lalongate, c. 1 µm in diameter. Exine c. 1 µm thick, sexine as thick as nexine.

2-colporate type (Fig. 4c):

Outline in polar view (amb) circular-elliptical; equatorial axis (E): 11.6 (10.5–12.7) µm. Remaining characteristics as the 3-colporate type.

So far, only one other case of pollen dimorphism has been documented for the genus Elaeocarpus (Huang 1972). In E. firdausii, the low percentage (ca. 4%) of the 2-colporate type as compared to the 3-colporate suggests the former is an aberrant morphology, possibly associated with hybridism as reported in other species (e.g. Bhowmik and Datta 2012).

Figure 2. 

Elaeocarpus firdausii. a branch with leaves and flowers (note red leaf-galls) b bark slash c branch apex with inflorescence d underside of mature leaf e flowers with golden disc and grey anthers f reddish-brown young leaves g green young leaves h conspicuous reticulation on underside of mature leaf i clustered arrangement of leaves; j young twig with stipules k flowers on apically bent pedicels. a, c, e, g, i, and k from the type collection (Brambach et al. 1953); b, d, f, h, and j from Brambach et al. 2041.

Figure 3. 

Flower details of Elaeocarpus firdausii. a petal with hairy outer surface and apical divisions b stamen with clearly longer outer anther-tooth to the right. Drawing by Heike Culmsee from Brambach et al. 1953 (isotype, L!).

Figure 4. 

Pollen of Elaeocarpus firdausii. a the 3-colporate pollen type in equatorial view b same in polar view c the 2-colporate pollen type in polar view.

Endemic to the central part of Sulawesi. The species is so far recorded with certainty from Mt Rorekautimbu and Mt Malemo at elevations from 2150 to 2400m (Fig. 1). Both mountains are located within LLNP. During our ecological fieldwork, we recorded E. firdausii in all three inventory plots at > 2000 m, although with rather few individuals at each site. Because of its apparent association with a distinct habitat (upper montane or mossy forest above c. 2000 m) and the general lack of information from montane habitats in Sulawesi, we consider it very likely that E. firdausii occurs in many of the upper montane forests of the CSM (Fig. 1).

FB observed a sterile sapling matching all vegetative characters of E. firdausii on Mt Katopas, c. 130 km east of the other two sites (1°12.7'S, 121°26.0'E, 2450 m, 6 Sep 2014), indicating a possible occurrence on Sulawesi’s Eastern peninsula (Fig. 1, question mark).

Based on the morphological information available E. firdausii is a regular component of upper montane (mossy) forests, where its individuals can form part of the canopy. These forests occur from c. 2000 m upwards in the LLNP area and are easily distinguished because of the dominance of conifers (Podocarpaceae, mostly Dacrycarpus imbricatus (Blume) de Laub. and Phyllocladus hypophyllus Hook.f.). They have a thick layer of epiphytic mosses and ferns on trunks and branches of the trees, ± abundant undergrowth, c. 20 m tall canopies with emergents reaching > 30 m and large amounts of dead wood. The soils are characterized by excess of moisture and heavy accumulation of organic matter. They were classified as Folic Gleysols, Folic Histosols and Folic Cambisols according to the WRB classification (IUSS Working Group WRB 2014). Dominant families besides conifers include Myrtaceae (e.g. Syzygium spp., Xanthomyrtus angustifolia A.J.Scott), Fagaceae (e.g. Lithocarpus havilandii (Stapf) Barnett), Paracryphiaceae (e.g. Quintinia apoensis (Elmer) Schltr.), and other Elaeocarpaceae (e.g. Elaeocarpus steupii Coode, E. teysmannii Koord. & Valeton subsp. domatiferus Coode).

The specific epithet honours our colleague Firdaus Dg. Matta (born 1984), formerly with Herbarium Celebense in Palu, Sulawesi, who collected the type specimen and contributed greatly to the success of our fieldwork with his skills in plant collection and identification.

Based on the locations of the estimated potential habitat for E. firdausii we calculated an EOO of 58 534 km² and an AOO of 5 760 km². The latter is presumably an overestimate as not all potentially suitable sites will necessarily be occupied by the species. Nevertheless, occurrence over a relatively wide range is plausible, given the large distance (c. 55 km) between two of the collection sites. It is thus unlikely that either EOO or AOO will fall below the thresholds of criteria B1 or B2 for IUCN category VU (IUCN 2012). While deforestation is an ongoing threat to Sulawesi’s forests, upper montane forests are usually less affected because of their remote locations and difficult access (Cannon et al. 2007). Hence, we do not consider habitat destruction or exploitation by humans as an imminent threat to population levels. Given (1) the uncertainties in the estimated EOO and AOO, and (2) the recommendation to use a precautionary attitude in conservation assessments (IUCN Standards and Petitions Subcommittee 2014), we propose a preliminary extinction risk assessment of “Near Threatened” (NT) following the IUCN Red List Categories and Criteria (IUCN 2012).

Based on the morphological information available, E. firdausii is probably related to E. luteolignum, E. gambutanus Coode and E. linnaei Coode; this assemblage may be sister to the Polystachyus group from Western Malesia.

In addition to the morphological differences between E. firdausii and E. luteolignum mentioned in the diagnosis above, according to our present knowledge there are differences in habitat preference: E. firdausii occurs in mossy forest at higher elevations while E. luteolignum is known from lower to mid-montane forest dominated by Fagaceae at 1200–1800 m (Coode 1995).

Both observations in the field and examination of dried specimens show that there are morphological differences between smaller understorey plants and mature canopy-forming individuals. The former have less-clustered, longer, thicker and relatively narrower leaves with more clearly bipulvinate petioles, less-rounded tips and more clearly serrate margins. We do not know whether these differences are related to age or rather to environmental factors, e.g. stronger radiation and transpiration in the canopy. Seedlings have even narrower leaves but the very short petioles are only swollen at the base. Conspicuous cup-shaped leaf galls or their presumed scars (Fig. 2) were present in all collected specimens. All sepals and petals have a glabrous patch at the base of the otherwise hairy inner surface. These glabrous portions are apparently pressed against the 10-lobed disc before anthesis. Wood density, based on three specimens, varied from 0.45–0.56 g/cm³.

Accession numbers are given in parentheses, barcode numbers in square brackets. Barcodes of specimens in K and L link to specimen records in the respective databases (RBG Kew 2015, Wieringa 2015).

INDONESIA. Central Sulawesi (Sulawesi Tengah), Lore Lindu National Park:

Kabupaten Poso, Kecamatan Lore Utara, 8.7 km NNE of village Sedoa, Mt Rorekautimbu, tree-inventory plot “Rorekautimbu”, 1°16.7'S, 120°18.6'E, 2400 m:

Brambach F, Mangopo H, Firdaus, Faber M, Tiranda R 0721 (18–30 Jul 2011, sterile, BO (BO 1926844)!, CEB, GOET [GOET014481]!, K [K000720899]!, L [L.2055437]!);

Culmsee H 2152 (Aug–Sep 2007, sterile, GOET [GOET014482]!).

Kab. Poso, Kec. Lore Utara, 7.7 km NNE of village Sedoa, Mt Rorekautimbu, tree-inventory plot “Bulu Torenali”, 1°17.2'S, 120°18.7'E, 2350 m, 21–24 Apr 2012:

Brambach F, Mangopo H, Firdaus, Faber M, Tiranda R 2041 (flowers, BO (BO 1926843)!, CEB, GOET [GOET014478]!, K [K000720902]!, L [L.2055436]!);

Mangopo H, Firdaus, Brambach F 11 (seedling, L [L.2055440]!).

Kab. Sigi, Kec. Kulawi Selatan, 7.7 km ENE of village Moa, Mt Malemo, tree-inventory plot “Tutu Malemo”, 1°45.9'S, 120°09.6'E, 2150 m, 18–23 Oct 2011:

Brambach F, Mangopo H, Firdaus, Faber M, Tiranda R 0937 (sterile, CEB, GOET [GOET014480]!);

Brambach F, Mangopo H, Firdaus, Faber M, Tiranda R 0998 (sterile, CEB, K [K000720900]!, L [L.2055438]!),

Brambach F, Mangopo H, Firdaus, Faber M, Tiranda R 1026 (sterile, CEB, L [L.2055439]!),

Brambach F, Mangopo H, Firdaus, Faber M, Tiranda R 1028 (sterile, CEB, GOET [GOET014479]!, K [K000720901]!).