| 1 | Male pedicels 1-3 mm long; rachis usually straight |
| 1' | Male pedicels 5 mm long or more; rachis frequently zigzag. [Male inflorescences and flowers not known in U. arfakensis.] |
| 2 | Male perianth 5-6 mm long; filaments hairy, in-curved at apex. Leaves lobed to 1/3 to nearly to the base |
| 2' | Male perianth 5-15 mm long; filaments glabrous, straight. Leaves finely or coarsely dentate or up to 1/3 lobed |
| 3 | Male receptacle-tube shorter than broad or about as long as broad, 2-3 mm long |
| 3' | Male receptacle-tube longer than broad, c. 4 mm long. [Fruit not known.] — West Papua, Vogelkop; lowland |
| 4 | Male petals 10 mm long or more |
| 4' | Male petals 6-9 mm long |
| 5 | Male perianth c. 6 mm diameter. — Eastern Papua New Guinea; at c. 2000 m altitude |
| 5' | Male perianth c. 4 mm diameter. — Northern West Papua, Cycloop Mountains; at c. 1200 m altitude |
| 6 | Fruit 2-3 cm long (flowers not known). — West Papua, Arfak Mountains; at 850 m altitude |
| 6' | Fruit 1-1.5(-2) cm long (fruit not known in U. hippocrepicus). Flowers large, petals (5-)6 mm long or more |
| 7 | Receptacle-tube inside and filaments glabrous; anthers not cordate at base. — Whole of New Guinea, but not known from Vogelkop; at 1900-2900 m altitude |
| 7' | Receptacle-tube inside hairy (filaments glabrous); anthers deeply cordate at base. — West Papua, Baliem Valley; at 2000 m altitude |
