Hydriastele wosimiensis W.J.Baker & Petoe, 2018

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

22. Hydriastele wosimiensis W.J.Baker & Petoe , sp. nov. Type:— INDONESIA. West Papua Province: vicinity of Wosimi river, Wasior Distr. , Manokwari Regency [Teluk Wondama Regency]; Sikama river , 3 km SE of Senderawoi village, 26km SSE of Wasior, 200 m, 2°57’S, 134°34’E, 27 February 2000, Baker et al. 1068 (holotype K!, isotypes AAU!, BO, BRI, L, MAN)

Diagnosis:— Distinguished by its slightly drooping leaves with pendulous leaflets in combination with a very large number of protandrous inflorescences (up to 26 at various stages of maturity) with thick rachillae (ca. 3.5 mm in diam.), staminate flowers with 12 stamens, and small ellipsoid fruits (9.5–10 × 6–8 mm).

Figure 48 (line drawing). Figure 35 (map).

Solitary, robust canopy palm to 30 m tall, bearing ca. 20 leaves in crown. Stem ca. 25 cm in diam., moderately ventricose; internode 4–25 cm long. Leaf 2.5–3 m long including petiole; sheath ca. 100 cm long with copious white indumentum, crownshaft ca. 110 × 25 cm; petiole ca. 40 cm long, flattened adaxially; rachis slightly drooping, extending beyond the terminal leaflets; leaflets ca. 50 per side, arranged regularly, single-fold, pendulous, linear, with scattered ramenta on the abaxial, basal to middle portion of the midrib; middle leaflets ca. 70 × 2.5 cm, obliquely to truncately praemorse apically; terminal leaflets briefly bifid apically. Inflorescence ca. 80 cm long including 12 cm peduncle, branched to 2 orders, protandrous; rachillae ca. 25, ca. 3.5 mm in diam.; triads on average 5 mm apart, opposite and decussate; ca. 26 inflorescences present (at various stages). Staminate flower ca. 13 × 3–4 mm in bud, cream; stamens 12. Pistillate flower 4–5 × 3.5–4 mm in bud, cream, with free sepals and free petals with conspicuous, triangular and valvate tips. Fruit 9.5–10 × 6–8 mm when ripe (7.5–9.5 × 5–5.5 mm when dry), ± ellipsoid, red, with a distinct, dark, sclerotic zone encircling apical stigmatic remains (up to ca. 3.5 mm in diam.). Seed 5.6–6.7 × 5–5.5 mm, broadly ellipsoid; endosperm homogeneous.

Distribution:— Known from the type locality in the vicinity of the Wosimi River, south of the Wandammen Peninsula in West Papua Province, western New Guinea.

Habitat:— Lowland rainforest on shallow slopes, 200 m.

Uses:— Stems used for floor boards.

Vernacular names:— Kaparo (Wandama).

Conservation status:— Data deficient (DD). More data are needed about the range and abundance of this species.

Specimens examined:— INDONESIA. West Papua Province: vicinity of Wosimi river, Wasior Distr., Manokwari Regency [Teluk Wondama Regency], Sikama river , 3 km SE of Senderawoi village, 26km SSE of Wasior, 200 m, 2°57’S, 134°34’E, 27 February 2000, Baker et al. 1068 (AAU!, BO, BRI, K!, L, MAN) .

Notes:— Hydriastele wosimiensis is a tall and robust palm with a moderately ventricose trunk. The species is distinguished by its slightly drooping leaves with pendulous leaflets in combination with protandrous inflorescences (up to 26 are present at any given time) with relatively thick rachillae (ca. 3.5 mm in diam.), staminate flowers with 12 stamens, and small fruits (7.5–9.5 × 5–5.5 mm when dry). Hydriastele wosimiensis is most similar to H. procera although that species has fewer inflorescences (ca. six present) with generally more slender rachillae (ca. 2–3 mm in diam.), larger fruits (10–15 × 6–7 mm when dry), and flowers with six stamens.

MOLUCCANA GROUP

Robust palms, leaves straight to slightly drooping with pendulous leaflets, inflorescences protogynous. The Moluccas, New Guinea, the Bismarck Archipelago and Australia.

Figures

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

FIGURE 48. Hydriastele wosimiensis.A. Portion of stem. B. Leaf apex. C. Mid-leaf portion. D. Infructescence. E. Portion of rachilla with pistillate flowers. F. Triad. G. Staminate flower in longitudinal section. H. Pistillate flower whole and in longitudinal section. I. Portion of rachilla with fruit. J. Fruit in longitudinal section. Scale bar:A = 3 cm; B–C = 8 cm; D = 6 cm; E = 1 cm; F, J = 7 mm; G = 5 mm; H = 3.3 mm; I = 1.5 cm. All from Baker et al. 1068. Drawn by Lucy T. Smith.