Hydriastele dransfieldii (Hambali,Maturb.,Wanggai&W.J.Baker) Baker&Loo (2004:64)

Petoe, Peter, Heatubun, Charlie D. & Baker, William J., 2018, A monograph of Hydriastele (Areceae, Arecaceae) in New Guinea and Australia, Phytotaxa 370 (1), pp. 448-450 : 448-450

14. Hydriastele dransfieldii (Hambali,Maturb.,Wanggai&W.J.Baker) Baker&Loo (2004:64) . Siphokentia dransfieldii Hambali, Maturb., Wanggai & W.J.Baker in Baker et al. (2000: 179). Type:— INDONESIA. Papua Province: Biak, Maturbongs 555 (holotype K!, isotypes BH, BO, L, MAN)

Figure 30 (line drawing). Figure 31 (photo plate). Figure 32 (map).

Solitary, moderately slender palm to 12 m tall, bearing 6–10 leaves in crown. Stem 5–12 cm in diam. Leaf 1.3–3 m long including petiole; sheath 35–80 cm long; petiole 10–65 cm long; lamina typically with 3 broad, multi-fold leaflets interspersed with a few single-fold leaflets each side of rachis; leaflets oblong to linear, truncately praemorse apically. Inflorescence 37–52 cm long including 2–5 cm peduncle, branched to 1 order, protandrous; rachillae 4–11, yellowishgreen; triads largely opposite and decussate. Staminate flower 9–11 × 2–5 mm in bud, green to white; stamens (9–)13–16. Pistillate flower ca. 9 × 5 mm in bud, with fused, greenish-white sepals forming a cylindrical tube, and white petals fused in lower half with conspicuous, triangular and valvate tips. Fruit ca. 18 × 12 mm when ripe, obovoid, red, with a distinct, dark, shallowly concave, sclerotic zone encircling apical stigmatic remains (up to ca. 5 mm in diam.). Seed ca. 8 × 7 mm, subglobose; endosperm ruminate.

Distribution:— Biak Islands (Biak, Supiori and Numfoor; Baker & Heatubun 2012).

Habitat:— Lowland, primary or secondary rainforest on rocky limestone ridges and slopes, often with a very thin layer of topsoil, 0–300 m.

Uses:— Leaves used for wrapping food and seeds used as a betel nut substitute.

Vernacular names:— Ombrush (Biak).

Conservation status:— Least Concern (LC). This species has a relatively narrow distribution (ca. 6,500 km 2) but has been observed to be common in many parts of Biak ( Baker & Heatubun 2012) and the AOO (20 km 2) is no doubt a low estimate resulting from under-collecting.

Specimens examined:— INDONESIA. Papua Province: Biak Island, 50 m, 1°6’S, 136°11’E, 23 July 2009, Heatubun 969 (AAU, BO, K!, MAN); Biak Island, forest around road (Jalan Manwaref) cutting through ridge., 90 m, 1°10’S, 136°10’E, 21 July 2009, Baker et al. 1331 (AAU, BO, K!, MAN); Biak Island , Sumberker Protected Forest , 110 m, 0°55’S, 135°55’E, 4 September 1998, Maturbongs 551 (BO, FTG, K!, L, MAN); Same locality as preceding, 95 m, 0°55’S, 135°55’E, 5 September 1998, Maturbongs 553 (BO, K!, MAN, NY); Same locality as preceding, 120 m, 0°55’S, 135°55’E, 5 September 1998, Maturbongs 555 (BH, BO, K!, L, MAN); Same locality as preceding, 130 m, 0°55’S, 135°55’E, 5 September 1998, Maturbongs 556 (AAU, BO, K!, MAN); Biak Island , Wari Village , Northern Biak , 50 m, 0°51’S, 136°2’E, 10 September 1998, Maturbongs 566 (BH, BO, K!, MAN); Biak Island , Adibai, Eastern Biak , 15 m, 6 September 1998, Maturbongs 557 (BO, K!, MAN); Biak Island , Sansundi village , North Biak Nature Reserve , 210 m, 0°42’S, 135°50’E, 8 September 1998, Maturbongs 561 (AAU, BO, K!, MAN); Same locality as preceding, 210 m, 0°42’S, 135°50’E, 8 September 1998, Maturbongs 562 (BO, K!, MAN); Same locality as preceding, 310 m, 0°42’S, 135°50’E, 8 September 1998, Maturbongs 563 (BO, FTG, K!, MAN); Same locality as preceding, 230 m, 0°42’S, 135°50’E, 8 September 1998, Maturbongs 564 (BO, K!, MAN, NY). CULTIVATED . INDONESIA. West Java: Bogor Botanic Gardens ex Biak Island , 1999, Hambali s.n. (K!) . UNITED STATES. Florida: Fairchild Tropical Garden ex Biak Island , 10 September 1999, Zona 822 (FTG, K!); same locality as preceeding, 26 October 1999, Zona 826 (FTG, K!) .

Notes:— Hydriastele dransfieldii is a moderately slender midstorey palm only known from the Biak Islands in western New Guinea. The species is highly distinctive vegetatively as well as in its reproductive structures. It has leaves usually consisting of three broad, multi-fold leaflets interspersed with a few single-fold leaflets and inflorescences branched to 1 order, which is unusual for Hydriastele inflorescences of more than 30 cm in length. The sepals of the pistillate flower are fused forming a conspicuous cup, and similarly the petals are fused at their bases. These features are known in only one other species, H. beguinii (Burret) Baker & Loo (2004: 62) , from North Maluku Province, which is the sister taxon of H. dransfieldii ( Loo et al. 2006) . Previously, the two species were placed in the genus Siphokentia , which was subsumed within Hydriastele ( Baker & Loo 2004) . The two species can be separated based on multiple characters of the leaves and inflorescences (see Baker et al. 2000).

LONGISPATHA GROUP

Robust palms, leaves strongly arching with ascending leaflets in combination with protandrous or protogynous inflorescences or leaves straight to slightly drooping with pendulous leaflets in combination with protandrous inflorescences, staminate flowers with 6–24 stamens enclosed by valvate petals in bud. New Guinea, Manus Island and east Melanesia.

Figures

FIGURE 30. Hydriastele dransfieldii. A. Leaf apex. B. Inflorescence with pistillate flowers. C. Portion of rachilla with pistillate flowers. D. Triad. E. Staminate flower in longitudinal section. F. Pistillate flower in longitudinal section. G. Portion of rachilla with fruit. H. Fruit in longitudinal section. Scale bar: A = 8 cm; B = 4 cm; C, H = 1 cm; D = 7 mm; E–F = 5 mm; G = 2 cm.A–B from Maturbongs 555; C–F from Zona 826; D–E from Zona 822; G–H from Hambali s.n. Drawn by Lucy T. Smith.

FIGURE 31. Hydriastele dransfieldii. A–B. Habit. C. Portion of rachilla with pistillate flowers. D. Infructescence with maturing fruit. E. Portion of rachilla with fruit. A–B from Biak Island; C, E from Baker et al. 1331; D cultivated palm, private garden, Bogor, Indonesia. All photos: W.J. Baker.

FIGURE 32. Distribution map of the Siphokentia group of Hydriastele in Biak Island.