Hydriastele manusii (Essig) Baker & Loo (2004: 65)

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

20. Hydriastele manusii (Essig) Baker & Loo (2004: 65) . Gronophyllum manusii Essig (1995: 100) . Type:— PAPUA NEW GUINEA. Manus Province: Manus Island, Mt. Dremsel, 740 m, 2°8’S, 146°57’E, 29 November 1975, Sands et al. 2880 (holotype USF, isotypes K!, L!)

Figure 44 (line drawing). Figure 45 (photo plate). Figure 35 (map).

Solitary, moderately robust palm to 20 m tall, bearing 9–13 leaves in crown. Stem 10–15 cm in diam.; internode not seen. Leaf ca. 1.5–2 m long including petiole; sheath ca. 100 cm long, with white bloom, crownshaft ca. 150 × 15 cm; petiole ca. 10 cm long, channelled adaxially; rachis arcuate; leaflets ca. 40 per side, arranged regularly, ascending and ± drooping at their tips, linear, truncately praemorse apically, lacking ramenta; basal leaflets multi-fold; middle leaflets 60–66 × 2–3 cm, single-fold; terminal leaflets comprising 2–4 folds. Inflorescence 60–80 cm long including 20–22 cm peduncle, branched to 2 orders, protandrous; rachillae 12–15; triads on average 3–4 mm apart, opposite and decussate; 1–5 inflorescences present. Staminate flower 6–7 × 3–4 mm at anthesis (when dry); stamens 6. Pistillate flower 3.5–4 × 2.5–3 mm in bud (when dry), with free sepals and free petals with conspicuous, triangular and valvate tips. Fruit ca. 12 × 4 mm (when dry), elongate and curved (when dry), red, with a rather inconspicuous sclerotic zone encircling apical stigmatic remains (up to ca. 1.5 mm in diam. when dry). Seed ca. 8.3 × 3.5 mm (when dry), curved; endosperm homogeneous.

Distribution:— Manus Island in the Bismarck Archipelago.

Habitat:— Premontane rainforest on steep slopes, 600–740 m.

Uses:— None recorded

Vernacular names:— None recorded

Conservation status:— Data deficient (DD). This species is insufficiently known to be assessed, but increased logging in Manus is likely to be a threat ( Shearman et al. 2008).

Specimens examined:— PAPUA NEW GUINEA. Manus Province: Manus Island, Mt. Dremsel , 740 m, 2°8’S, 146°57’E, 29 November 1975, Sands et al. 2880 (USF, K!, L!); same locality as preceding, 630 m, 2°9’S, 146°57’E, 26 March 1981, Kerenga et al. LAE 77518 (LAE!, USF) .

Notes:— Hydriastele manusii is a moderately robust canopy palm distinguished by its relatively short (1.5–2 m long), arching leaves with equally short (ca. 10 cm long) petioles.The species is further distinguished by its inflorescences with 20 cm long peduncles and relatively few (12–15) rachillae. Confusion with other species is unlikely.

Figures

FIGURE 35. Distribution map of the Longispatha group of Hydriastele in New Guinea and adjacent islands.

FIGURE 44. Hydriastele manusii. A. Leaf apex. B. Leaf mid-portion. C. Leaf base with portion of sheath. D. Peduncle. E. Portion of inflorescence with pistillate flowers. F. Portion of rachilla with pistillate flowers. G. Staminate flower. H. Pistillate flower whole and in longitudinal section. I. Fruit whole and in longitudinal section. Scale bar:A–C = 6 cm; D–E = 4 cm; F, I = 5 mm; G = 4 mm; H = 3.3 mm. All from Sands et al. 2880. Drawn by Lucy T. Smith.

FIGURE 45. Hydriastele manusii. A. Habit. B. Juvenile habit.All from Manus Island.All photos:Axel Dalberg Poulsen.