Calamus kostermansii W.J.Baker & J.Dransf., 2017

Baker, William J. & Dransfield, John, 2017, More new rattans from New Guinea and the Solomon Islands (Calamus, Arecaceae), Phytotaxa 305 (2), pp. 61-86 : 74-76

7. Calamus kostermansii W.J.Baker & J.Dransf. , sp. nov. Type:— INDONESIA. Papua Province: Fak-Fak, Timika,

sago swamp, between Timika and port, km 23, 10 m, 4°38’0”S, 136°54’21”E, 16 February 1998, Baker et al. 848

(holotype K!, isotypes BO!, MAN!, BH!, L!).

Diagnosis:— Similar to Calamus longipinna , but differs in the dense chocolate brown caducous indumentum on sheaths, short triangular spines on sheaths, tough ocrea that disintegrates into fibres at the margin and the more elongate and short-spiny rachis bracts.

Moderately robust, clustering rattan climbing to ca. 10 m. Stem with sheaths 18–27 mm diam., without sheaths to 15– 18 mm diam., without exudate; internodes 16–31 cm. Leaf ecirrate to ca. 1 m long; sheath yellowish green, covered with dense caducous chocolate-brown indument, bearing scattered short spines with slightly swollen bases, spines 2–7 mm, triangular, pale green with brown tips, abaxially with brown indumentum, the spines scattered or rarely in groups of 1–3; knee ca. 35 mm long, pale green unarmed or with scattered spines along margins, with scattered scales near base and sides, otherwise glabrous; ocrea ca. 16 × 2.5 cm, elongate, enclosing the stem, thick papery in texture next to the petiole and leaf rachis, disintegrating into long fibres on the opposite side, straw-coloured, unarmed or with a few scattered spines near the base, and with scattered thin caducous pale brown indumentum; flagellum 2–3 m long; petiole very short or absent; rachis ca. 100 cm long, armed distally with scattered or grouped short reflexed spines to 3 mm; leaflets ca. 50 on each side of rachis, regularly arranged, narrow lanceolate, longest leaflet in mid leaf, basal leaflets ca. 14 × 0.3 cm, mid-leaf leaflets ca. 30 × 1.4 cm, apical leaflets ca. 18 × 0.7 cm, apical leaflet pair free, leaflets armed with conspicuous black bristles to 2 mm long along 3 veins adaxially, and along margins and 3 veins abaxially with shorter bristles to 1 mm, transverse veinlets conspicuous, rather dense. Staminate inflorescence not seen. Staminate flowers not seen. Pistillate inflorescence flagelliform, ca. 4 m long including 1 m peduncle and 2 m flagelliform tip, branched to 2 orders; prophyll ca. 35 × 1.2 cm, tightly sheathing, splitting and eroding into fibres distally, glabrous, bearing 2 rows of short spines to 2 mm long along the keels; peduncular bracts absent, rachis bracts, tightly sheathing, similar to the prophyll, 15–25 × 0.7–1 cm, splitting distally into irregular fibrous lobes, glabrous, with scattered short spines; primary branches 4, to ca. 105 cm long, ca. 25 cm apart, pendulous, with up to 12 rachillae; rachillae 120–350 mm × 2–2.5 mm, terete; rachilla bracts ca. 12 × 20 mm, distichous, strictly tubular, with triangular tips, and bearing scattered very short spines and caducous dark brown indument; proximal floral bracteole acute, ca. 3 × 2 mm, distal floral bracteole acute with scattered indument, 2 × 2 mm, scar from sterile staminate flower ca. 1 mm diam.. Pistillate flowers ca. 3.5 × 1.5 mm in very early bud. Sterile staminate flowers 3 × 1 mm in very early bud. Fruit ellipsoid, ca. 15 × 7 mm including beak ca. 1 × 1 mm, with 14 longitudinal rows of pale brown, shallowly channelled, scales with dark margins, sarcotesta. Seed (sarcotesta removed) ca. 8 × 3 × 2 mm, ellipsoid; endosperm immature, probably homogeneous; embryo basal.

Etymology:— This species is named for A.J.G.H. Kostermans (1906–1994), the celebrated Dutch-Indonesian botanist whose specimen drew our attention to the existence of this species.

Distribution:— Known from only two localities in central and western Indonesian New Guinea.

Habitat:— Riverine and swamp habitats, ca. 10 m elevation.

Uses:— None recorded.

Vernacular names:— None recorded.

Specimens examined:— INDONESIA. Papua Province: Fak-Fak, Timika, sago swamp, between Timika and port, km 23, 10 m, 4°38’0”S, 136°54’21”E, 16 February 1998, Baker et al. 848 (holotype K!, isotypes BO!, MAN!, BH!, L!). West Papua Province: Manokwari, Warami, along river, 4 October 1982, Kostermans K10 (L!).

Notes:— In our paper discussing Calamus longipinna Lauterb. & K.Schum. in Schumann & Lauterbach (1900: 203) and its relatives in New Guinea ( Baker & Dransfield 2002 a), we mentioned several specimens under Calamus longipinna that differed somewhat from typical C. longipinna and were geographically isolated. One of these (Baker et al. 848) from the Timika area of southern Papua is greatly disjunct from the main area of distribution of Calamus longipinna in north-eastern New Guinea; it is also distinctive in having an ocrea that partially disintegrates into fibres, abundant indumentum on the sheath and rather elongate rachilla bracts.

Since we published this paper we have found a second collection, Kostermans K10 from Warami south of Manokwari that seems to be conspecific. With these two collections, the distinction from C. longipinna seems best reflected in its description as a separate taxon.