Hydriastele ledermanniana (Becc.) 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

18. Hydriastele ledermanniana (Becc.) Baker & Loo (2004: 65) . Kentia ledermanniana Beccari (1923: 442) . Gronophyllum ledermannianum (Becc.) Moore (1963: 264) . Type:— PAPUA NEW GUINEA. East Sepik Province: Hunstein Mts., Ledermann 11229 (holotype B†). Neotype (designated here):— PAPUA NEW GUINEA. East Sepik Province: Ambunti Subdistr., Eastern ridge of Sumset (Mt. Hunstein), 1350 m, 4°31’S, 142° 39’E, 11 August 1966, Hoogland 10934 (K!, isoneotypes BH, BRI, CANB, L!, LAE)

Kentia mayrii Burret (1933: 707) . Gronophyllum mayrii (Burret) Moore (1963: 265) . Hydriastele mayrii (Burret) Baker & Loo (2004: 65) . Type:— INDONESIA. Papua Province: Cyclops Mts., 1100 m, 1928, Mayr 658 (holotype B†, isotype BO!), synon. nov.

Kentia chaunostachys Burret (1936d: 328) . Gronophyllum chaunostachys (Burret) Moore (1963: 264) . Hydriastele chaunostachys (Burret) Baker & Loo (2004: 63–64) . Type:— PAPUA NEW GUINEA. Morobe Province: Sattelberg, 750 m, 21 October 1935, Clemens 526 (holotype B†, isotype L!), synon. nov.

Figure 40 (line drawing). Figure 41 (photo plate). Figure 35 (map).

Solitary, robust to very robust, emergent palm to 30 m tall, bearing 15–19 leaves in crown. Stem 20–35 cm in diam.; internode 2.5–10 cm long. Leaf 2–3.5 m long including petiole; sheath 58–200 cm long, the upper portion with a thin layer of lanate, orange-brown indumentum, crownshaft 90–250 × 15–40 cm; petiole 30–80 cm long, flattened adaxially; rachis arcuate; leaflets 38–51 per side, arranged regularly, ascending and ± drooping at their tips, linear, with or without ramenta on the abaxial, basal portion of the midrib; basal leaflets single-fold (rarely multi-fold), obliquely praemorse apically; middle leaflets 70–130 × 2.5–5 cm, single-fold, obliquely to truncately praemorse apically; terminal leaflets comprising 2–4 folds, truncately praemorse apically. Inflorescence (50–) 65–120 cm long including 6–15 cm peduncle, branched to 2(–3) orders, protandrous; rachillae 23–66; triads 7–17 mm apart, opposite and decussate; inflorescences 5–11 present. Staminate flower 12–18 × 2–6 mm in bud, cream; stamens 9–13. Pistillate flower 7–8 × 4–5 mm in bud, cream, with free sepals and free petals with conspicuous, triangular and valvate tips. Fruit ca. 15–15.5 × 10–10.5 mm when ripe, broadly ellipsoid, brown to red, with a distinct, dark, sclerotic zone encircling apical stigmatic remains (up to ca. 4 mm in diam.). Seed ca. 10 × 8 mm, broadly ellipsoid; endosperm homogeneous.

Distribution:— Recorded from the Huon Peninsula and the central highlands of Papua New Guinea, and the Cyclops Mountains.

Habitat:— Primary or secondary, premontane to montane rainforest, on spurs and ridgetops, 700–1950 m.

Uses:— Leaves used for thatch, the split trunk used for flooring, inflorescences used for brooms, and fruits used as a betel nut substitute.

Vernacular names:— Aidjaka (Tari), Gamu (Unknown dialect), Limbom (Pidgin), Kawoisch (Mendi), Pipi (Kotte), Tuwenpeh (Wapi), Uwo (Wagu), Yauwi (Kagua)

Conservation status:— Least Concern (LC). This species is widespread (EOO> 170,000 km 2) and has been recorded as common at several localities. The relatively low AOO (48 km 2) is most likely due to under-collecting with this figure expected to increase.

Specimens examined:— INDONESIA. Papua Province: Cyclops Mts. , 1100 m, 2°30’S, 140°34’E, 1928, Mayr 658 (BO!) . PAPUA NEW GUINEA. East Sepik Province: Eastern ridge of Sumset ( Mt. Hunstein ), Ambunti Subdistr. , 1350 m, 4°31’S, 142°39’E, 11 August 1966, Hoogland 10934 (BH, BRI, CANB, K!, L!, LAE); Hunstein Mts. , 1300 m, 4°31’S, 142°39’E, Ledermann 11229 (B†) ; Eastern Highlands Province: Mt. Michael, west slopes, 1950 m, 6°25’S, 145°17’E, 28 August 1959, Brass 31196 (CANB!, K!, L!, LAE); 1 mile N of Okentenu, Kainantu subdist., 1850 m, 6°13’S, 145°55’E, 13 October 1957, Pullen 726 (A, CANB!, L!, LAE) ; Milne Bay Province: NE slopes of Mt. Simpson Massif, Mt. Wadimana , 1500 m, 10°2’S, 149°40’E, 19 July 1969, Kanis 1284 (LAE, CANB!) ; Morobe Province: Near Bulolo, Hidden Valley , near Mt. Kaindi , close to Wau , 1600 m, 7°17’S, 146°37’E, 8 November 2006, Baker et al. 1316 (AAU, K!, L, LAE); Finschhafen Distr. , Sisi village , 15 km NW of Finschhafen, 700 m, 6°29’S, 147°46’E, 4 December 2000, Banka 2000 (AAU, K!, LAE, NY); Sattelberg, 750 m, 6°29’, 147°46’, 21 October 1935, Clemens 526 (L!); Tobou, 900 m, 1 June 1937, Clemens 6561 (A!); Trig, Bulolo-Watut divide, 7 km SW of Bulolo, 1500 m, 7°15’S, 146°36’E, 13 November 1982, Kairo 536 (A, BSF, L!, LAE, USF); Hills northeast of airstrip at Wagu, 1050 m, 6°51’S, 146°48’E, 13 March 1964, Moore 9291 (BH, K!, L!, LAE) ; Sandaun Province: Torricelli Mts., Peaks ca. 4 miles N of Wigote Village, Lumi Subdistr .., 1550 m, 3°23’S, 142°9’E, 19 September 1961, Darbyshire 464 (A, BRI, CANB, K!, L!, LAE) ; Southern Highlands Province: Angga River gorge, 15 miles E of Mendi, 1700 m, 6°9’S, 143°39’E, 28 June 1961, Pullen 2646 (CANB!, LAE) .

Notes:— Hydriastele ledermanniana is a solitary, robust canopy emergent with a non-ventricose stem and a crown consisting of arching leaves. It is distinguished by its protandrous inflorescences with 6–15 cm long peduncles. Hydriastele ledermanniana is most similar to H. gibbsiana and H. calcicola but those species have short peduncles (3–5 cm in length) and in addition the former is ventricose whereas the latter is less robust. Vegetatively, H. ledermanniana can be confused with the protogynous palm H. longispatha , but it has 57–70 leaflets on each side of the rachis (rarely as few as 48 per side), whereas H. ledermanniana has 38–51 leaflets on each side of the rachis.

We failed to locate type material of H. ledermanniana and conclude that it was destroyed during the bombing of the Berlin Herbarium in 1943. Therefore, we designate a neotype here. We select Hoogland 10934 because it matches the description in the protologue of H. ledermanniana and was collected from the type locality.

We studied extensive collections, including type specimens, of H. mayrii , H. chaunostachys and H. ledermanniana . Burret (1933) noted that the difference between H. mayrii and H. ledermanniana is in the presence of strongly, apically sinuous inflorescence branches in the latter. Our neotype of H. ledermanniana does in fact display rachillae with some degree of sinuousness, but we render this too trivial a difference to merit the maintenance of H. mayrii . As noted by Burret (1936d), the type of H. chaunostachys has a much longer inflorescence (120 cm) than the destroyed type of H. ledermanniana (80 cm; Beccari 1923), but modern collections bridge the gap between these measurements (e.g. 100 cm in Banka 2000) and other differences described by Burret (1936d). Consequently, we place H. mayrii and H. chaunostachys into synonymy under H. ledermanniana here.

Figures

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

FIGURE 40. Hydriastele ledermanniana. A. Leaf apex. B. Mid-leaf portion. C. Inflorescence in part, with pistillate flowers. D. Portion of rachilla with pistillate flowers. E. Triad. F. Staminate flower. G. Pistillate flower whole and in longitudinal section. H. Portion of rachilla with fruit. I. Fruit in longitudinal section. Scale bar: A–B = 8 cm; C = 6 cm; D = 1.5 cm; E–F, I = 1 cm; G = 7 mm; H = 2 cm. All from Banka 2000. Drawn by Lucy T. Smith.

FIGURE 41. Hydriastele ledermanniana. A. Crown. B. Inflorescence with pistillate flowers. C. Portions of rachillae with triads. D. Portions of rachillae with pistillate flowers. E. Portion of rachilla with fruit. A, C, E from Baker et al. 1316; B, D from Banka 2000. All photos: W.J. Baker.