Hydriastele apetiolata Petoe & W.J.Baker

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

4. Hydriastele apetiolata Petoe & W.J.Baker in Petoe et al. (2018: 17). Type: — INDONESIA. Papua Province: Mimika Regency, Timika , Nursery : Kuala Kencana , 50 m, 4º47’S, 136º33’E, 27 February 1998, Baker et al. 884 (holotype K!, isotypes BH, BO, L, MAN)

Figure 8 (line drawing). Figure 9 (photo plate). Figure 4 (map).

Clustering, moderately slender palm to 6 m tall, bearing 7–10 leaves per crown. Stem 4.5–6 cm in diam. Leaf to 125 cm long; sheath ca. 60 cm long; petiole lacking; leaflets 23–26 per side, arranged regularly; basal leaflets single-fold, linear and somewhat grouped, obliquely or truncately praemorse apically; terminal leaflets comprising 4–6 folds, cuneate, truncately praemorse apically; juvenile leaves entire-bifid, with or without petiole, with lamina 100–130 cm long. Inflorescence 25–35 cm long including 3.5–5.5 cm peduncle, branched to 2 orders, protogynous; primary branches ca. 8, to 27.5 cm long, bearing up to 3 rachillae each; triads opposite and decussate. Staminate flower 11–12 × 5–6 mm in bud; stamens 6–8. Pistillate flower 2–3 × 2.5–3 mm in bud, with free sepals and free, ± rounded, low petals. Fruit 7.4–9.4 × 6.6–8.2 mm when ripe, subglobose, red, with inconspicuous stigmatic apical remains lacking encircling dark sclerotic zone. Seed 5.1–7.2 × 5–6.8 mm, globose to subglobose; endosperm ruminate.

Distribution:— Known from two distinct localities on the southern coast of New Guinea.

Habitat:— Primary or secondary lowland rainforest, 20–50 m.

Uses:— None recorded.

Vernacular names:— None recorded.

Conservation status:— Data Deficient (DD; Petoe et al. 2018)

Specimens examined:— INDONESIA. Papua Province: Mimika Regency, Timika, Nursery , Kuala Kencana , ca. 50 m, 4º47’S, 136º33’E, 27 February 1998, Baker et al. 884 (BH, BO, K!, L, MAN); Mimika Regency, Timika, East Levee by drowned forest, 5 km S of Kpg Kali Kopi, Loc 11, 20 m, 4°39’S, 136°55’E, 18 February 1998, Witono 20 (BH, BO, K!, L!, MAN); Mimika Regency, Timika, East Levee by drowned forest, 5 km S of Kpg Kali Kopi, Loc 11, 20 m, 4°39’S, 136°55’E, 18 February 1998, Witono 21 (BO, K!, MAN) . PAPUA NEW GUINEA. Gulf Province: Kikori Distr., Kopi-Kikori road, 3 km NW of Kikori, 40 m, 7°24’S, 144°13’E, 21 November 2000, Baker et al. 1103 (AAU, BRI, K!, L, LAE, NY) .

Notes:— Hydriastele apetiolata is a midstorey palm with a slender stem, distinguished by its regularly pinnate, apetiolate adult leaves and entire-bifid juvenile leaves (petiolate or apetiolate in the juvenile). The combination of entire juvenile leaves and pinnate adult leaves is not known from other slender understorey to midstorey species of Hydriastele although a similar pattern in leaf dimorphism is reported for some of the bigger tree taxa, e.g. Hydriastele manusii ( Fig. 45 ) and H. boumae ( Baker & Loo 2004) . More details are given by Petoe et al. (2018).

Figures

FIGURE 4. Distribution map of the species of the Wendlandiana group of Hydriastele.

FIGURE 8. Hydriastele apetiolata. A. Leaf apex. B. Mid-leaf portion. C. Leaf base with sheath. D. Juvenile leaf. E. Infructescence. F. Portion of rachilla with triads. 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–C = 6 cm; D = 12 cm; E = 6 cm; F = 7 mm; G = 5 mm; H = 3.3 mm; I = 1.5 cm; J = 1 cm.All from Baker et al. 884. Drawn by Lucy T. Smith.

FIGURE 9. Hydriastele apetiolata. A–B, D. Habit. C. Infructescence.All from Baker et al. 884. All photos: W.J. Baker.

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