Cyrtandra rubribracteata Karton. & H.J.Atkins

Atkins, H. J. & Kartonegoro, A., 2021, A TAXONOMIC REVISION OF CYRTANDRA (GESNERIACEAE) IN SULAWESI, INDONESIA, Edinburgh Journal of Botany 78 (364), pp. 1-122 : 98-101

32. Cyrtandra rubribracteata Karton. & H.J.Atkins , Edinburgh J. Bot. 75(2): 29 (2018).

– Type: Indonesia, Sulawesi, Central Sulawesi, Luwuk Regency, Mt Hek , 28 ii 2004, Hendrian, Newman, Scott, Saleh. & Supriadi 968 (holotype BO, isotype E) . Figure 50 .

Shrub or small tree to 1.8 m in height. Stems cylindrical, striate, glabrous. Leaves opposite, subequal; petioles 1.5–2 cm long, glabrous; blades 14–25 × 2–3.5 cm, narrow oblong to lorate or narrow oblanceolate, base decurrent, margin serrate, occasionally biserrate, apex acuminate; 5–7 pairs of lateral veins curving sharply upwards and faint tertiary venation, dark green and glabrous above, whitish green and glabrous below. Inflorescences axillary, sessile, c.6-flowered; bracts ovate, paired, dark, dull red, c.30 × 20 mm, tough, leathery, joined very briefly at the base and forming an involucre with serrate margins, glabrous externally, enclosing the flowers and fruit; bracteoles c.40 × 10 mm, some much smaller, narrow-lanceolate with serrate margins, leathery, glabrous; pedicels 4–6 mm long, hairy. Calyx tubular, pink, 30–36 mm long, lobes 9–17 mm long, acuminate, ridged along the length of the tips, hairy externally. Corolla white, 42–45 mm long, held upright in involucre, narrow in basal 1/3, widening to mouth in upper 2/3, upper lobes rounded, 5–6 × 4–5 mm, lower and lateral lobes rounded 8–9 × 7–8 mm, distinctive ridges running along base of the tube, densely hairy externally. Stamens with filaments c. 10 mm long, attached c. 20 mm above the base of the corolla, straight at the base, curved over slightly at the top, glabrous with a few glandular hairs at the apex; anthers c. 1 mm long, glabrous, drying much darker than the filaments, with a distinctive pointed tip appearing like a hook or beak, not coherent; staminodes 3, c. 5 mm long. Gynoecium c. 30 mm long; disc cupular with undulate margin, c. 2 mm long, glabrous; ovary glabrous at the base becoming densely hairy after c. 4 mm with the margin of indumentum somewhat lobed; style densely hairy; stigma bilobed, lobes vertical or spreading, c.3 × 2 mm, with short glandular hairs. Fruits ovoid (immature), c.15 × 11 mm, glabrous at the base, more densely hairy at apex; style and calyx not persistent.

Distribution. Central Sulawesi: Banggai Regency ( Figure 51 ).

Habitat and ecology. Upland forest at an altitude of c. 980 m.

Etymology. This species is named for its distinctive red bracts ( Kartonegoro et al., 2018).

Proposed IUCN conservation category. Cyrtandra rubribracteata has an AOO of 8 km 2, based on a 2 × 2 km grid cell size ( Bachman et al., 2011). It has been possible to accurately georeference only one of the collection localities: that of the type specimen, Hendrian et al. 968, from Mount Hek. This collection was made at 980 m in upland forest, which is one of the more threatened habitat types in Sulawesi ( Cannon et al., 2007). Satellite imagery shows signs of habitat degradation at the lower altitudes of Mount Hek. The other collection (Eyma 3909) has the locality description of ‘limestone plateau’ in the subdivision of Luwuk, and no protected area has been recorded in that general area (UNEP-WCMC & IUCN, 2019). Kartonegoro et al. (2018) suggest Vulnerable (VU) for this species, but we consider there to be continuous habitat degradation and assess the species as Endangered (EN), B2ab(iii).

Additional specimen examined. INDONESIA. Central Sulawesi. Banggai: between Camp I and Camp II on limestone plateau, 28 ix 1938, Eyma 3909 ( BO, K, L) .

Cyrtandra rubribracteata can be distinguished from other Sulawesi Cyrtandra by its narrow oblong leaves with serrate margins; large, dull-red inflorescence bracts; and unusual, somewhat beaked, anthers. No other species from Sulawesi recorded so far has these distinctive anther appendages. There are, however, a number of species from Borneo recorded with a ‘conspicuous apiculus’ on the anthers, such as Cyrtandra paxiana Lauterb. and C. prostrata Kraenzl.

Figures

Figure 50. Cyrtandra rubribracteata. a, Habit; b, anthers; c, gynoecium including disc; d, opened corolla, showing position of stamens and staminodes; e, opened calyx; f, fruit; g, bracteole; h, side view of corolla; i, inflorescence. Drawn by Claire Banks from Hendrian et al. 968. Reproduced from Kartonegoro et al. (2018) with the permission of the Trustees of the Royal Botanic Garden Edinburgh.

Figure 51. Distribution of Cyrtandra rantemarioensis (black triangles), C. roseiflora (white circles) and C. rubribracteata (red circles).