Pleuranthodium corniculatum Lofthus & A.D.Poulsen, 2020

Lofthus, Ø., Newman, M. F., Jimbo, T. & Poulsen, A. D., 2020, The Pleuranthodium (Zingiberaceae) of Mount Wilhelm, Papua New Guinea, Blumea 65 (2), pp. 95-101 : 96-101

1. Pleuranthodium corniculatum Lofthus & A.D.Poulsen , sp. nov. — Fig. 1a , 2 , 3

This species is distinguished from Pleuranthodium piundaundense (P.Royen) R.M.Sm. by having a dark reddish brown calyx with at least 2 appendices at the apex, dark reddish brown corolla lobes and a pale yellow-green labellum with reddish centre (vs pale yellow-green calyx lacking appendices, pale orange-yellow corolla lobes and an orange labellum). The lamina has strigose hairs on the veins beneath while the other species on Mt Wilhelm are glabrous. — Type: A.D. Poulsen, T. Jimbo, W. Banda & T. Muanda 3019 (holo LAE; iso E), Papua New Guinea, Chimbu Province, slope of Mt Wilhelm, Wonn , montane forest, S5°48'48.2" E145°4'57.6", 2875 m, 18 Apr. 2016, flowering and fruiting .

Etymology. The epithet is derived from the Latin diminutive, corniculata, describing the presence of small horn-like structures, in this case on the apex of the calyx.

Terrestrial herb in clump. Rhizome stout, fleshy, deeply subterranean, moderately creeping. Leafy shoot to 5 m long with up to 25 leaves per shoot; bases to 25 cm apart, to 8 cm across, smooth, shiny, green; pseudostem distinctly flattened; sheath smooth, mid-green, with scattered hairs transitioning to pubescent towards the ligule; ligule truncate to irregularly lobed, to 1.5 mm long, reddish brown when young, pubescent, margin pubescent; petiole to 15 mm long, pale green, pubescent; lamina narrowly ovate, c. 80 by 19 cm, dark to mid-green above, pale green beneath, glabrous above, strigose along veins beneath, base obtuse, margin strigose, apex acuminate. Inflorescence subterminal by 30–40 cm, to 40 cm long; free part of peduncle pendulous, round in cross-section, to 10 cm long, yellowish green to pale reddish brown, tomentose; peduncular bracts to 3, cucullate, enclosing the young inflorescence, decreasing in size towards inflorescence, most distant bract to 47 cm long, persistent until fruiting (sometimes with laminoid apex of c. 9 by 2 cm), proximate bracts shorter and caducous,all bracts red when young, dark brown when old, tomentose; spike cylindrical, to 30 cm long with a rachis of similar length with numerous flowers, flowering starting from middle of spike and continuing towards base and apex. Flower 4.6–5 cm long, resupinate; pedicel 12–15 mm long, reddish brown, puberulous; calyx 14–16 mm long, dark reddish brown, puberulous, especially on lateral ridges and increasingly towards apex, apex with 2 appendages, ± horn-shaped, to 4 mm long, usually bent, sometimes reflexed, sometimes reduced to distinct knobs (rarely a third appendage present, horn-like or reduced to a knob); floral tube c. 11 mm long, pale red, externally and internally glabrous; corolla lobes dark purple, minutely pubescent along margin; dorsal lobe cymbiform with cucullate and acuminate apex, reaching middle or apex of anther, c. 13 by 5 mm; lateral lobes triangular, with broad cucullate apex, overlapping each other and clasping apex of labellum, attached at a c. 30° angle to tube, inserted alongside dorsal lobe, 10–12 by c. 5.5 mm; staminal tube c. 3 mm long; labellum rounded, cucullate, c. 8 by 5 mm, apex slightly bifid (incision c. 0.5 mm deep), pale yellow-green with reddish centre, densely pubescent throat and mouth, otherwise glabrous; stamen c. 11 mm long, cream to pale yellow-green; filament ventral side flattened with a broad groove, dorsal side rounded, c. 5 by 3.5–4.5 mm, hirsute in and on edges of groove and below thecae, anther parallel-sided, c. 6 by 4 mm, glabrous, apex shallowly incised; thecae dehiscing along their entire length, cream, glabrous; ovary narrowly pyriform, c. 10 by 5 mm, orange-red to reddish brown at base and apex, sparsely puberulous; epigynous gland enclosing style from one side, bilobed conical, c. 4 by 3 mm long, apex acute, surface verrucose; style 2.5 cm long, cream, glabrous; stigma claviform, glabrous, 0.9 by 1.3 by 0.5 mm, pointing downwards, at apex with a transverse, bilabiate ostiole, glabrous, c. 0.25 mm wide. Infructescence subterminal, pendulous, free part of peduncle to 10 cm long, distal peduncular bract persistent, others caducous leaving scars; fruit head cylindrical, to c. 25 by 8 cm; pedicel 1.3–1.5 cm long; capsule pyriform, fleshy, c. 2 by 1.1 cm, orange-yellow, very sparsely pubescent, splitting lengthwise from apex downwards in 3 parts along the locules; seeds 4–10 per locule, rounded outwards but flattened when in contact with others, c. 5.5 by 4 mm, green, smooth, shiny; aril pinkish red, covering only base, leaving apex of seed exposed.

Distribution — Only known from Mt Wilhelm, Chimbu Province, Papua New Guinea.

Habitat & Ecology — This species occurs in montane forest and on a grassy slope. Budding, flowering and fruiting were recorded in early February and flowering and fruiting continued at least till mid-April. The altitudinal range of this species is 2580–2875 m.

Ethnobotany — The vernacular name is merutamban in the Kuman language. This information was given by William Banda,

with reddish midrib, glabrous, base rounded to cuneate, margin ± pilose with antrorse hairs, apex acutely subcaudate.

Inflorescence terminal, 12–26 cm long; free part of peduncle ascending at first, later pendulous, slightly trigonous in crosssection, 6–13 cm long, pale green, very minutely to minutely pilose; peduncular bracts 3, cucullate, enclosing the young inflorescence, decreasing in size towards inflorescence: most distant one leaf-like, to 18 by 6 cm, rounded at apex, proximate bracts linear, 1.5–4.5 cm long, with involute appendage,

caducous, all bracts yellow, turning reddish brown when dead,

glabrous except for dense silky pubescence on apical appendage; spike ovoid-ellipsoid, 6.5–13 by 5–7 cm, composed of a

4–12 cm long rachis with numerous flowers, flowering starting from base. Flower c. 5 cm long, not resupinate; pedicel 2–3.5

mm long, pale red, minutely pilose; calyx 18–20 mm long, pale yellow-green, glabrous, smooth, leathery, margins scarious,

sometimes sparsely fimbriate, bilobed, without appendages; Fig. 3 William Banda demonstrating how to extract the strong fibres from floral tube 22–28 mm long, yellow to pale orange-yellow, ex- the sheaths of Pleuranthodium corniculatum (Poulsen et al. 3019; E, LAE). ternally glabrous, internally glabrous near base, colliculate to — Photo by Axel Dalberg Poulsen. echinate towards insertion of lobes; corolla lobes bright yellow or orange, sometimes tinged green at base, glabrous, slightly who demonstrated that fibres taken from the sheath can be longer than labellum; dorsal lobe 15–17 by 5–8 mm, c. 2 mm used to make ropes and snares (Fig. 3). He also said that the shorter than anther, oblong-elliptic, with rounded and cucullate leaves are used for making mumu (ground oven with hot rocks). apex; lateral lobes c. 11 by 7–8 mm, dorsal margin involute; Conservation status — With only two collections, which were labellum infundibuliform, c. 6 by 10 mm almost entirely adnate made in the same area, the population size is unknown, though to stamen, pale orange, margin erect, wavy and glabrous, these collections were made 52 years apart, which indicates central lobe bilobed (incision c. 3 mm deep); stamen 7–8 mm that the population is somewhat stable in that area. A potential long, cream; filament ventrally colliculate along central furrow, threat to the species is extraction by the local people but, as c. 3 by 4–5 mm, glabrous; anther broadly elliptic, c. 5 by 4 only the vegetative parts are used, it is unlikely that this will mm, apex emarginate; thecae dehiscing along their entire pose a major threat to the species and the conservation status length, cream, glabrous; ovary ellipsoid or ovoid, trigonous, can be assessed as Least Concern (LC; IUCN 2019). 4–7 by 3.5–5 mm, red, glabrous; epigynous gland enclosing the style from one side, irregularly bilobed, verrucose, c. 1.2 by Additional specimen. P

APUA

N

EW

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UINEA

, Chimbu, Keglsugl , S6° E145° ,

2 mm; style c. 4.7 cm long, cream, glabrous; stigma claviform, 2580 m, 2 Feb. 1964, flowering and fruiting, Millar NGF 23122 (LAE).

glabrous, 0.8 by 1.3 by 0.7 mm, pointing downwards, apex Note — This species, first collected at Mt Wilhelm by Millar with a transverse, bilabiate ostiole, glabrous, c. 0.4 mm wide. in 1964, is the only one of the three species so far recorded Infructescence terminal, pendulous, free part of peduncle 10–17 at this site, that does not have yellowish orange flowers. The cm long, bracts caducous leaving scars except for most distal emerging vegetative shoots are thick with conspicuous yellow 1 (or 2); fruit head cylindrical, to 18 by 6 cm; pedicel to 1 cm scales with a red margin, which is a sterile character easy to long, spreading, capsule ellipsoid, clearly trigonous (with 3 dis- recognise.A peculiar trait to this species is that it starts flowering tinct ridges), fleshy, 3–3.5 by 1–1.3 cm, red, glabrous, splitting in the middle of the inflorescence, as opposed to the other two, lengthwise from apex in 3 parts along ridges, calyx persistent; where flowering starts at the base. Furthermore, the flowers seeds 3–5 per locule, irregularly folded to ruminate, 3–5 by are resupinate, they turn 180°. In effect the dorsal corolla lobe 4–5 mm, green with small red aril at base. is still upwards even though the spike is pendulous. This is Distribution — Pleuranthodium piundaundense is endemic an unusual trait in Pleuranthodium and further investigation is to Papua New Guinea and has mainly been recorded on the needed to clarify how many species have resupinate flowers. lower slopes of Mt Wilhelm, Chimbu Province, but also at

Mt Kerigomna (Eastern Highlands Province) and at Mt Hagen 2. Pleuranthodium piundaundense (P.Royen) R.M.Sm. — (Western Highlands Province) .

Habitat & Ecology — This species occurs in montane for- Fig. 4

est and on stream banks in moss forest. At Mt Wilhelm it has Pleuranthodium piundaundense (P.Royen) R.M.Sm. (1991) 65. — Riedelia been collected between 3000–3600 m. During the collecting piundaundensis P. Royen (1979) 875,t. 294. — Psychanthus piundaunden- of A.D. Poulsen et al. 3023 in April 2016, it was found fruiting sis (P.Royen) R.M.Sm. (1990) 81. — Type: M.M.J. van Balgooy 584 (holo only at 3100 m and the only flowering shoot was encountered L (barcodes L 0041159–61); iso A, CANB n.v., K, LAE, SING),Papua New

200 m higher. It has also been collected once at Mt Hagen at Guinea, Eastern Highlands, Pindunde [corrected to Piundaunde in Van Royen (1979)] Valley, above Kombugomambuno, 3350 m, 7 June 1965. 2580 m. Flowering and fruiting occur from mid-March to mid-

October. Etymology. The epithet refers to the Piundaunde valley with the two lakes Ethnobotany — When collecting A.D. Poulsen et al. 3023, Piunde (c. 3600 m) and Aunde (c. 3700 m) on the slopes of Mt Wilhelm above

the local guide, William Banda, relayed the information that this the type locality.

species is called anger keneh yaundo (in the Kuman language: Terrestrial herb in clump. Rhizome fleshy, 3–4 cm across, short- anger = arrow, keneh = head, yaundo = leaf). This refers to the creeping. Leafy shoot to 3–4.3 m long; bases 6–7 cm apart, shape of the spike resembling an arrowhead. The leafy shoots to 3 cm across; sheath longitudinally ribbed, pale yellow-green are used for constructing walls of bush huts. tinged brown, glabrous except pubescent below ligule, lower- Conservation status — The species is well documented, most sheaths decaying with age; ligule shallowly bilobed, grows in areas with low human impact and is not harvested 2–3.5 mm long, reddish brown, pubescent, margin finely ciliate; beyond subsistence scale, which would not involve destrucpetiole to 6 mm long, reddish brown, glabrous; lamina ovate tion of whole individuals. It is therefore to be considered Least to elliptic, 15–33 by 5–11 cm, mid-green, beneath pale green Concern (LC) according to IUCN (2019).

Additional specimens. PAPUA NEW GUINEA, Chimbu Prov., Pengagl Creek, 25 Aug.1964, A.N. Millar & C.D. Sayers NGF 23778 ( LAE); Mt Wilhelm, Keg- elsugl–Pindaunde trail, 2 June 1966, L.K. Wade ANU 7269 ( LAE); Mt Wilhelm , North side of Pindaunde Valley , 8 Oct. 1971, J.M.B. Smith ANU 15214 ( LAE); ibid., 12 Mar. 1981, J. Sterly 80648 (E); Mt Wilhelm , Kambuglo Mabuno, 19 Apr. 2016, A.D. Poulsen et al. 3023 (E, LAE); Kundiawa subdistrict, near walking track 1.5 miles from field station, 13 June 1968, J. Vandenberg NGF 39516 ( LAE) . – Eastern Highlands Prov., Goroka, Mt Kerigomna , 22 June 1971, P.F. Stevens & P. Grubb LAE 54646 (E) . – Western Highlands Prov., Mt Hagen , 18 July 1970, P.F. Stevens LAE 50250 (E).

Note — The original description of Riedelia piundaundensis was thorough and elaborate but, as it was placed in Riedelia , the diagnostic characters emphasized were selected to distinguish it from other species of that genus. The description above incorporates the description by Van Royen (1979) and has been amended, taking into account the additional collections presently known.

Figures

Fig. 1 a. Pleuranthodium corniculatum Lofthus & A.D.Poulsen. Lateral view. — b. Pleuranthodium sagittatum Lofthus & A.D.Poulsen. Lateral view (a: Poulsen et al. 3019; pickled material at E; b: Poulsen et al. 3017; pickled material at E). — Drawing by Øystein Lofthus.

Fig. 2 Pleuranthodium corniculatum Lofthus & A.D.Poulsen. a. Habit (Thomas Mundua demonstrating the size of the plant); b. bases of leafy shoots and new shoot; c. cross-section of pseudostem; d. ligule; e. inflorescence; f. flower, lateral view; g. flower, dorsal view; h. calyx; i. stamen, dorsal and ventral view; j. infructescence; k. fruit; l. fruit, part of capsule removed exposing green seeds and pinkish red aril; m. fruit, cross-section (Poulsen et al. 3019; E, LAE). — Photos by Axel Dalberg Poulsen.

Fig. 4 Pleuranthodium piundaundense (P.Royen) R.M.Sm. a. Habit (Thomas Mundua demonstrating the size of the plant); b. ligule; c. inflorescence; d. whole flowers; e. calyx; f. stamen, ventral view; g. ovary, style and stigma; h. infructescence; i. fruit; j. fruit, part of capsule removed; k. fruit, cross-section; l. seeds and aril (Poulsen et al. 3023; E, LAE). — Photos by Axel Dalberg Poulsen.