Hydnophytum myrtifolium Merr. & L.M.Perry

33. Hydnophytum myrtifolium Merr. & L.M.Perry View in CoL — Fig. 36 View Fig ; Map 5 View Map 5

Hydnophytum myrtifolium Merr.& L.M.Perry (1945) 19. — Type: Brass 4093 (lectotype selected here A; iso BO, BRI, K, L), Papua New Guinea, Central Province, Mt Tafa , May 1933 .

Tuber irregularly subglobose to fusiform, 25 by 30 cm, sunken in moss-cushions or pendent by one to few roots to 1 m or more, surface smooth to rough, occasionally areolate, reddish brown. Entrance holes of two types: small and conical, 0.3–1 cm across; large funnel-shaped, 2–8 cm diam. Cavities of two types: large, spiral-shaped and blind-ended 2–9 cm across; or narrow, tubular, and much branched tunnels 0.1–0.5 cm across; all smooth-walled, occasionally with internally produced roots. Tuber tissue white. Stems one to many, arising from a woody stock, branching, to 1 m or more, 0.2–0.8 cm diam; pendent to upcurving. Internodes 0.5–6 cm, nodes angular, with prominent ridges decurrent from stipules. Bark grey-brown, smooth, drying ridged. Lamina elliptic to ovate, usually widest at middle; 1.4 by 0.7 to 3 by 1.7 cm; apex acute to blunt; base attenuate; gently recurved along their length; midrib prominent below, sunken above, pale green; margin recurved; stiff, leathery; dark, glossy green above, pale, dull below. Petiole short or absent, to 0.5 cm; stipules green-brown, persistent, to 0.3 cm, with central spur to 0.1 cm. Inflorescence paired, virtually sessile near stem apex, becoming shortly pedunculate with age; bracts small, papery. Flowers [5] heterostylous, club-shaped in bud. Calyx to 2.5 mm, entire to slightly dentate, much longer than disc. Corolla tube to 10 mm; lobes 4.5 by 2.5 mm, apiculate; with a dense ring of hairs at mouth of tube. Short-styled flowers with anthers to 1.8 mm, exserted; pollen 43–49 μm, wall c. 3.75 μm, brochi 1.5–2 μm, pores small; stigma 2-lobed, lobes to 2.5 mm, c. 1/2 way down corolla tube. Long-styled flowers with anthers to 1.6 mm; immediately within mouth of corolla tube; pollen 49–59 μm; stigma exserted, with lobes to 1 mm. Fruit ellipsoid, to 5 by 3.5 mm; red, with a prominent orange calyx. Pyrenes hemispherical, 3 by 2.3 mm; apex and base rounded.

Ecology & Habitat — An epiphyte of mossy forest, from 2 000–2 900 m. Tuber not inhabited by ants, but usually containing rainwater, cockroaches, myriopods and sometimes arboreal frogs and their eggs.

Distribution — Papua New Guinea (Morobe,Central and Northern Provinces).

Conservation status — Vulnerable (VU) under criteria B1ab (iii)+2ab(iii). This taxon has a geographical spread of 250 km along the Owen Stanley range. Other information: georeferenced collections 12, EOO c. 10 000 km 2, AOO 5 790 km 2 (using an auto-value cell width of 27 km), herbarium collections suggest 6 locations (subpopulations).

Note — The cavities are well adapted for collecting rainwater, with large funnel-like entrance holes. Several collectors have noticed frogs in these chambers, and MHPJ has found adults and eggs of the tree frog Cophixalus riparius Zweifel on Mt Shungol. Two other Hydnophytum species have been recorded as regularly containing frogs: H. pauper [24] and H. dauloense [29].