Hydnophytum multituberosum Jebb & C.R.Huxley, 2019

23. Hydnophytum multituberosum Jebb & C.R.Huxley View in CoL , sp. nov. — Fig. 26 View Fig

Tuber initio solitarium, postea cum numerosis subsidiariis sphaeroideis tuberibus 1 ad 5 cm latis crescens. Caules numerosi, ramosi, quadrangulares. Lamina lanceolato-oblonga, 0.9 per 0.5 ad 2 per 0.9 cm, apice rotundo, basi obtusa, brevissime attenuata; petiolus 1 mm. Inflorescentia binati alveoli paucis papyraceis bractearum reliquiis ornati. Flores heterostyli. Calyx late obovoideus, ad 0.7 mm. Corollae tubus 2.5 mm, annulo pilorum ad faucem instructus; lobi rotundat, 1 mm. Antherae 0.6 ad 0.8 mm, intra faucem vel exsertae.Stigma 2-fidum, exsertum vel infra faucem tubi.Fructus globosus, 3.5 per 3 mm;disci reliquiae prominentes. Pyrenae,ovoideae, 2.5 per 1 mm.

— Typus: Jebb 998 (holo BO; iso K, L), New Guinea, West Papua Province, Waigeo Island , 2 km NE of Go village, 8 Sept. 1992.

Etymology. The only taxon where the tuber comprises multiple separate parts.

Tuber initially solitary, irregular in outline, brown; 10–20 cm across; further tubers develop from both stem and roots, each spheroid, 1–5 cm across. Entrance holes small, conical. Stems numerous, branching; internodes 0.6–2 by 0.2 cm, quadrangular. Leaves clustered, upright. Lamina lanceolate-oblong; 0.9 by 0.5 to 2 by 0.9 cm; apex round; base blunt, shortly-attenuate; midrib sunken above ± prominent below; veins 2 or 3, curving towards apex; thick, sclerophyllous. Petiole 0.1 cm; stipules minute, caducous. Inflorescence a socket-like depression to 2 mm across, with few, papery bract remains. Flowers [2] heterostylous. Calyx broad-obovoid, to 0.7 mm, thick-edged. Corolla tube 2.5 mm, with a band of short hairs below mouth of tube; lobes rounded, 1 mm. Anthers 0.6–0.8 mm, within mouth or exserted. Pollen 25.6 μm across in long-styled flowers, 35.6 μm in short-styled flowers, brochi c. 1.2–1.5 μm. Stigma 2-fid, exserted, or below mouth of tube. Fruit red, globose, 3.5 by 3 mm, disc remains prominent. Pyrenes ovoid, 2.5 by 1 mm.

Ecology & Habitat — Epiphytic in open scrub-like forest on ultrabasic soils, 200–400 m above sea level. Tuber inhabited by ants.

Distribution — New Guinea (West Papua Province).

Conservation status — Vulnerable (VU) under criteria D2, only known from Waigeo Island.

Additional specimens examined.Jebb 1006 (BO,L), Jebb 1007 (L),Waigeo Island, 4 km NE of Waifeo, 9 Sept. 1992.

Note — The manner in which the tuber grows is remarkable, and unmatched by any other member of the Hydnophytinae . Each tuberlet has an ordered arrangement of several enveloping cavities, each of which opens near the point of attachment to the root.