Hydnophytum bracteatum Valeton

39. Hydnophytum bracteatum Valeton View in CoL — Fig. 42 View Fig

Hydnophytum bracteatum Valeton (1911) 506. — Type: Versteeg 1765 (lectotype selected here BO; iso L), New Guinea, Papua Province, Lorentz River , 28 Sept. 1907 .

Tuber to 35 cm across, irregular; surface rough, areolate. Entrance holes few, prominently lipped, and raised as much as 1 cm above tuber surface; to 2.5 cm internally. Cavities bulbous, from 0.5–15 cm across; without ants. Stems several, unbranched, to 100 cm; rounded in section, with 2 prominent, winged ridges, running from below stipule. Internodes 3–11 by 0.7 cm. Leaves sessile, spreading. Lamina , elliptic; 13.5 by 6 to 19 by 8.5 cm; apex acute; base rounded to cordate; thick and brittle; dark glossy green above, pale below. Midrib prominent above and below. Veins 15–18 including prominent secondary veins. Stipules 0.6 cm, triangular, falling before leaves. Inflorescence paired; consisting of 2 or 3 flower-producing locules covered by a dense mass of triangular leathery bracts to 1 cm long. Flowers [2] heterostylous. Calyx 3–6 mm, membraneous, margin 4-cuspidate. Corolla tube to 5 mm, with a broad ring of hairs at mouth; lobes to 3 mm overall, with an apical crest to 1.5 mm. Short-styled flowers with anthers to 1 mm, exserted; filaments to 1 mm; pollen 56 μm 3-colpate; stigma 2-lobed, at same level as anthers. Long-styled flowers with anthers to 1.5 mm, below ring of hairs; stigma above anthers, and at mouth of tube. Fruit to 5 mm, pink; calyx remains prominent to 4 mm, brown. Pyrenes obovoid to rhomboid, flattened, 3.5 by 2 mm; apex truncate-notched, with 2 lateral horns as long as or longer than true apex, giving appearance of three short teeth; abaxial surface with 2 furrows; base tapered, rounded.

Ecology & Habitat — Closed forest,100–1 000 m. Tuber rarely ant-inhabited.

Distribution — Indonesia (Papua Province) and Papua New Guinea.

Conservation status — Least Concern (LC). This taxon is remarkably widespread (2 000 km) but represented by just six locations (subpopulations). Removing the outlying island populations (Manus & New Britain) leaves the New Guinea collections with an EOO of over 100 000 km 2. Other information: georeferenced collections 7, AOO 12 500 km 2 (using an auto-value cell width of 50 km), EOO 415 200 km 2.

Note — The large leaves and inflorescence bracts, thick stem, and large-cavitied, lightweight tuber of this species distinguish it from all others. It is remarkable that such a morphologically uniform species has been collected so rarely and from such widespread localities (from the south coast of New Guinea to Manus island and New Britain). It is probably a high-level epiphyte of primary forest, accounting for its infrequent discovery.