Hydnophytum fusiforme Jebb & C.R.Huxley, 2019

30. Hydnophytum fusiforme Jebb & C.R.Huxley View in CoL , sp. nov. — Fig. 33 View Fig ; Map 5 View Map 5

Tuber initio fusiforme, aetate procedente apice grandescens; superficie grisea, spinis tenuibus, flexibilibus armatum. Aperturae duo generum, vel infundibuliformes vel parvae et conicae. Caules numerosi, ramosi, ex variis locis in apice tubere enati. Lamina parva , ovata usque elliptica, 0.6 per 0.25 ad 1.2 per 0.5 cm, apice obtuso usque acuto,basi sensim attenuata.Petiolus brevissimus. Stipulae triangulares, ad 0.5 mm, satis persistentes. Inflorescentia binata, sessilis. Calyx 4-dentatis, ad 2 mm. Corollae tubus ad 2 mm, glabrum; lobi ad 2 mm.Antherae ad 1.5 mm. Stigma bifidum, pari libra cum antheris.Fructus et pyrenae ignota.

— Typus: Lloyd Hamilton in UPNG 3482 (holo UPNG; iso LAE), Papua New Guinea,West Sepik Province, Nong river .

Etymology. For the fusiform shape of the tuber in young plants.

Tuber fusiform, initially narrowly cylindrical, to 1 cm diam, becoming larger at apex with age, to 25 by 12 (30 by 30) cm, pale brown to grey. Spines slender, finely tapering and flexible, to 0.5 cm. Entrance holes of two kinds, funnel-like to 2 cm across, or small and conical to 0.2 cm internally. Cavities few, large, to 15 cm across, bulbous, smooth-walled. Stems numerous, branching, arising from various places on tuber, usually short, some to 40 cm, erect to pendulous. Internodes of main stems to 5 by 0.3 cm; those of side shoots 0.1–1.5 by 0.1–0.2 cm, nodes swollen, with a marked petiole base articulation, and a minute ridge running from below stipule. Leaves erect, recurved, clustered at apex, and often obscuring such. Lamina ovate to elliptic; 0.6 by 0.25 to 1.2 by 0.5 cm; apex blunt to acute; base tapering; dark glossy green. Petiole very short; stipules triangular, to 0.5 mm, with a hooked central process c. 0.03 cm long; somewhat persistent, though often partly detached. Inflorescence paired, sessile. Flowers [2] not heterostylous. Calyx 4-dentate, to 2 mm. Corolla tube to 2 mm, glabrous within; lobes to 2 mm, uncus to 1.5 mm. Anthers to 1.5 mm. Pollen to 75 μm, thin-walled (c. 1 μm), brochi 1.5–2.5 μm. Stigma slender, bifid, at level of anthers. Fruit and pyrenes unknown.

Ecology & Habitat — Mossy forest, 2 000–2 400 m. Tuber not inhabited by ants.

Distribution — Papua New Guinea (Southern Highlands and West Sepik Province).

Conservation status — Endangered (EN) under criteria B1ab(iii)+2ab(iii). The three known localities indicate only 2 subpopulations some 400 km distant from one another. Whilst the strict EOO covers some 820 km 2, the potential habitat is far greater. Other information:AOO 2 280 km 2 (using an auto-value cell width of 34 km).

Additional specimens examined. Jebb 271 ( LAE ), Jebb 272 ( LAE ), Jebb 293 ( LAE ), Jebb 294 ( LAE ),Southern Highlands Province, S6°07'E143°57', SE of Mt Giluwe,above Onin,‘Beechwoods No. 2’logging track; UPNG 3483 ( LAE, UPNG ), UPNG 3484 (UPNG), UPNG 3485 (UPNG), UPNG 3486 ( LAE, UPNG ), West Sepik Province, Nong river.

Note — Small specimens of this taxa have their tubers entirely buried in cushions of moss. Young tubers are narrow and fusiform in shape, later they develop a broad, blunt apical region, with stems arising from several positions. No in situ observations have been made (collections from felled trees only), but the tuber probably grows in a manner to retain its stems at the surface of the growing moss layer. Fine roots develop over the whole tuber surface, becoming short and spine-like on exposed surfaces. Some stems may grow to 30–40 cm, bearing many short side shoots. In Papua New Guinea the minute leaves readily distinguish it from all other Hydnophytum species, it differs from H. vitis -idaea [27] in its much shorter flowers.