Hydriastele lanata 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

17. Hydriastele lanata W.J.Baker & Petoe , sp. nov. Type :— PAPUA NEW GUINEA. Western Province : North Fly Distr. , road from Tabubil to Ok Tedi Copper Mine, near mill, 10 km NW of Tabubuil, 1400 m, 5°12’S, 141°9’E, 13 December 2000, Baker et al. 1135 (holotype K!, isotypes AAU!, LAE, NY)

Diagnosis:— Distinguished by its thick and dense, lanate and somewhat fluffy indumentum on the leaf sheath, and its inflorescence with a long peduncle (11–12 cm) and relatively few rachillae (17–23). In addition, the leaves and crownshaft seem disproportionately long relative to the modest height (up to 10 m tall) and stem diameter (10 cm) of this species.

Figure 39 (line drawing). Figure 35 (map).

Solitary, moderately robust palm to 10 m tall, bearing 10–12 leaves in crown. Stem ca. 10 cm in diam.; internode ca. 15 cm long. Leaf ca. 2.4 m long including petiole; sheath ca. 120 cm long, with a thick, dense layer of fluffy, lanate, pale brown indumentum, crownshaft ca. 216 × 10 cm; petiole ca. 32 cm long, channelled adaxially; rachis arcuate; leaflets 43 per side, arranged regularly, ascending and ± drooping at their tips, linear, with ramenta on the abaxial, basal portion of the midrib; basal leaflets single-fold, obliquely praemorse apically; middle leaflets ca. 100 × 4 cm, single-fold, obliquely to truncately praemorse apically; terminal leaflets comprising ca. 4 folds, truncately praemorse apically. Inflorescence 65–70 cm long including 11–12 cm peduncle, branched to 2 orders, protandrous; rachillae 17–23; triads on average 9 mm apart, opposite and decussate. Staminate flower 13–16 × 3–4 mm in bud, white; stamens 7–10. Pistillate flower ca. 6 × 4 mm in bud, white, with free sepals and free petals with conspicuous, triangular and valvate tips. Fruit not seen. Seed not seen.

Distribution:— Known from the type locality in the northern portion of Western Province in Papua New Guinea.

Habitat:— Montane and somewhat degraded forest on steep slopes with exceptionally high epiphyte load due to unusually high rainfall, at 1400 m elevation.

Uses:— None recorded.

Vernacular names:— None recorded.

Conservation status:— Data deficient (DD). The distribution and abundance of this species are insufficiently known.

Specimens examined:— PAPUA NEW GUINEA. Western Province: North Fly Distr., road from Tabubil to Ok Tedi Copper Mine , near mill, 10 km NW of Tabubil, 1400 m, 5°12’S, 141°9’E, 13 December 2000, Baker et al. 1135 (AAU!, K!, LAE, NY) .

Notes:— Hydriastele lanata is a moderately robust tree palm immediately recognisable on account of the fluffy, lanate, pale brown indumentum on the leaf sheath, hence the choice of species epithet. The species is further distinguished by its inflorescence, which includes a long peduncle (11–12 cm) and relatively few rachillae (17–23). Hyriastele lanata is most similar to H. ledermanniana but that species is more robust, its sheaths lack thick and fluffy indumentum and it has shorter peduncles relative to the length of its inflorescences, which also comprise more rachillae.

The type locality of H. lanata is adjacent to the Ok Tedi Copper Mine in Western Province , Papua New Guinea. The palm occurred in a sparse population in a rather degraded forest with many fallen trees. The degraded nature of the forest appears to be natural rather than anthropogenic, perhaps a result of local climatic conditions (e.g. high rainfall, wind) or perhaps properties of the soil. Unfortunately, recent satellite imagery available from Google Earth (consulted January 2018) indicates that the type locality is on the verge of destruction due to expansion of the mine site .

Figures

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

FIGURE 39. Hydriastele lanata. A. Habit. B. Leaf apex. C. Mid-leaf portion. D. Inflorescence. E. Portion of rachilla with pistillate flowers. F. Triad. G. Staminate flower in longitudinal section. H. Pistillate flower in longitudinal section. Scale bar: A = 1.8 m; B–C = 8 cm; D = 6 cm; E = 1 cm; F = 7 mm; G = 5 mm; H = 3.3 mm. All from Baker et al. 1135. Drawn by Lucy T. Smith.