Hydnophytum linearifolium Valeton

49. Hydnophytum linearifolium Valeton View in CoL — Fig. 52 View Fig

Hydnophytum linearifolium Valeton (1927) 135. — Type: Ledermann 9700 (lectotype selected here L; iso B presumed lost), Papua New Guinea, Sepik April River , Lager 18 , Nov. 1912 .

Hydnophytum linearifolium Valeton var. pedunculata Valeton (1927) 136. — Type: Ledermann 12455 (not seen), Papua New Guinea, Sepik Province, Felsspitze, July 1913, syn. nov.

Hydnophytum dolichophyllum Valeton (1927) 130. — Types: Ledermann 9889 (L), Papua New Guinea, Sepik Province, Lordberg, Dec. 1912 & Ledermann 12723 (L), Papua New Guinea, Sepik Province, Felsspitze, Aug. 1913, syn. nov.

Tuber unknown. Stems several (?); to 40 cm; unbranched (?); internodes 1.5–2.5 by 0.1–0.2 cm, ± quadrangular in section, but scarcely winged. Lamina linear-lanceolate to lanceolate, broadest near base; 9 by 0.8 (7 by 1.8) to 19.5 by 3.8 cm; apex acuminate-acute; base attenuate; midrib prominent below, venation obscure; matt green above, grey-green below. Petiole 0.4–2 cm; stipules minute, papery, caducous. Inflorescence paired peduncles to 1 cm. Flowers [1]?heterostylous. Calyx 0.7 mm, entire to 4-cuspidate, at level of disc. Corolla tube 1.5 mm; with a ring of hairs within mouth of tube; lobes triangular, 1.25 mm. Anthers 0.3 mm, exserted from corolla tube. Stigma bifid, below level of anthers. Fruit ovoid; to 4.5 by 2.5 mm; apex broad with prominent swollen disc surrounded by calyx remains. Pyrenes 2, ellipsoid, to 4 by 2 mm, flattened.

Ecology & Habitat — Forest (?), 200–1 500 m.

Distribution — Papua New Guinea (Sepik and Enga Provinces).

Conservation status — Near Threatened (NT). This taxon is widespread (560 km) across much of the northern Bismarck Mountains of Papua New Guinea, with herbarium collections indicating 5 locations (subpopulations). Other information: georeferenced collections 8, AOO 12 500 km 2 (using an auto-value cell width of 50 km), EOO 20 200 km 2.

Additional specimen examined. Reeve 1121 ( LAE ), Western Highlands, Enga, Pogera.

Note — This species appears to represent an analogue to H. albertisii on the northern slopes of the central mountain ranges of Papua New Guinea. As with that species it has a narrow leaf, a square stem, much reduced inflorescence peduncles, and it also belongs to the H. radicans group. We have combined a second species described from the Sepik by Valeton – H. dolichophyllum – which, although it has larger leaves and branched inflorescences, shares the same diminutive flower size. Valeton also described the variety pedunculata based on Ledermann 12455, with slightly larger leaves and pedunculate inflorescences.