Archidendron kalkmanii (Kosterm.) Nielsen

Takeuchi, Wayne, 2012, Modern sequels to the Kaiserin-Augusta-Fluss itinerary of Carl Ledermann: floristic discoveries from the upper Sepik of Papua New Guinea, Phytotaxa 60 (1), pp. 17-31 : 26-27

Archidendron kalkmanii (Kosterm.) Nielsen in Nielsen et al. (1984 publ. 1985: 84).

Abarema kalkmanii Kostermans (1966: 365) . Type:— INDONESIA. Papua: Hollandia, Sentani Lake , secondary forest, sloping country, 70 m, 4 September 1956, Kalkman BW 3602 (holotype BO; isotypes L, LAE!).

Additional specimen examined: — PAPUA NEW GUINEA. East Sepik Province: Ambunti District, Waskuk Hills, buttress ridge north of Garuka , foothill forest, 4°11'19"S, 142°43'37"E, 200 m, 25 November 2004, Takeuchi, Towati & Ama 17577 ( A!, LAE! [4 sheets], and 12 undistributed duplicates!) .

The Waskuk collection belongs to an alliance comprised of Archidendron arborescens ( Kostermans 1966: 365) Nielsen in Nielsen et al. (1985: 80), A. kalkmanii , and A. novoguineense ( Merrill & Perry 1942: 394) Nielsen in Nielsen et al. (1985: 84). Based on its description, A. kalkmanii is the species at Waskuk, although the corolla (to 20 mm long) is above the reported size range for that species (12–14 mm).

Except for flower size, Archidendron arborescens and A. kalkmanii are so similar that they are more like varieties, or at most, like geographic subspecies—with A. kalkmanii occurring on the north side of the Central Divide and A. arborescens on the south. There are no qualitative discontinuities in their character profiles. All the differences tabulated in Nielsen et al. (1985: 83) are quantitative. As shown by the Waskuk collection,

quantitative variation is likely to be understated and thus misleading, when taxa are characterised from small numbers of specimens.

Archidendron kalkmanii is historically known only from the Jayapura area of western New Guinea (Indonesian Papua). Its previously unknown fruits (seen on Takeuchi et al. 17577) are identical to those for A. arborescens . If accepted as a good taxon, A. kalkmanii is now recorded for PNG.