Stigmatodactylus dalagangpalawanicum, Robinson, Alastair S., Gironella, Elizabeth P. & Cervancia, Jehson M., 2016
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publication ID |
https://doi.org/ 10.11646/phytotaxa.252.2.2 |
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persistent identifier |
https://treatment.plazi.org/id/03D28788-8C72-FFEC-ABA7-EFBBFDDA34C2 |
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treatment provided by |
Felipe |
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scientific name |
Stigmatodactylus dalagangpalawanicum |
| status |
sp. nov. |
Stigmatodactylus dalagangpalawanicum View in CoL A.S.Rob., sp. nov. ( Figs. 1 View FIGURE 1 , 2 View FIGURE 2 )
Type:— PHILIPPINES. Palawan: Mount Victoria Massif, 1600 m, emergent from moss and leaf litter in thin humus layer overlying rocky ultramafic soil, 25 Jul 2007, Robinson AR002 (holotype: PPC!; transfer to PNH requested) .
Stigmatodactylus dalagangpalawanicum is distinguished from S. richardianum by its larger, flattened labellum, which is almost orbiculate with a finely erose crenulate margin, its larger, deeply channeled callus with its notched tip and short, truncated lateral margin projections, its larger, more robust plants, and the comparatively large flowers that are conspicuously red, but colourless towards the outer part of the sepals and petals.
Description: Terrestrial herbs, ca. 9.0– 15.5 cm tall from apex of tuber to inflorescence apex. Tuber globose to ovate, ca. 3.0– 4.5 mm, covered with capillary roots to 0.1 mm long, true roots few, emergent from tuber and subterranean portions of stem, 0.5–2.5 cm long. Stem erect, terete, green, glabrous, 5–8 cm long, up to ca. 1.5 mm diameter at the base, emergent from cataphyll, 3–5 mm, clasping base of stem. Leaf cordate, variably auriculate with a narrow sinus to perfoliate, ca. 1.3(–1.5) × 0.8(–1.1) cm, glabrous, green, venation darker, somewhat conspicuous, apically anastomosing. Inflorescence erect, terete, narrowing distally to ca. 0.55 mm, peduncle 3.5–8.0 cm, rachis 0.8–2.8 cm, green, with 1–7 flowers, 1–2 open simultaneously; floral bracts leaf-bearing, cordate, sessile, 4–6 mm 3–5 mm, with an acuminate tip. Flowers facing outwards, resupinate, sepals and petals spreading widely, ca. 1.77(–2.00) × 1.10(–1.72) cm, somewhat translucent. Pedicel-ovary narrow, green, glabrous, 5–7 mm long, 0.5–0.8 mm in diameter, terete, finely 6-ribbed longitudinally. Dorsal sepal erect, subulate and tubiform from involution of opposing margins, ca. 0.8–1.1 0.6 mm, but up to 1.1 mm wide at the base where opposing margins are not involute. Lateral sepals linear-subulate, narrowly ovate in section, descending, each ca. 30º from vertical, ca. 5.5–9.5 mm long. Petals subulate, almost 90º from vertical, straight to arcuate, ca. 5.35–8.45 mm long. Labellum purplish red, sometimes fading to a pale margin, petals and sepals predominantly pale, proximally flushed red, column basally red, otherwise green, flushed red immediately above anther cap, callus exterior reddish, becoming distally colourless, callus interior deep purplish red. Labellum immobile, flat, orbiculate, unlobed, ca. 0.7–0.89 mm in diameter, glabrous, surface minutely sinuate-papillate, margins markedly erose crenulate, apex in some blooms apiculate to acuminate. Callus 2–3 × 0.6–0.8 mm at base, basally fused to column for ca. 1/3 its length, thereafter deeply channeled, margins diminishing towards notched apex, lateral margins with a short, truncated projection, ca. 0.3 mm long, close to where the callus parts from the column. Column at ca. 90º to labellum, ca. 6.5–8.5 mm long, ca. 0.6 mm in diam., straight for ca. 2/3 of its length, then curved by ca. 55°, keel running ventrally along column from base, terminating in blunt-ended projection at a point 1/3 from base, 0.3–0.6 mm long, vestigial column wings emergent after projection, becoming deeply pronounced, to 0.4 mm, and angular, hyaline, subtending column apex on each side, column apex broadly clavate, rostellum blunt, ca. 0.3 × 0.4 mm, occasionally darkly coloured, stigma ovate, concave. Anther cap creamy white to slightly red suffused, cucullate, suborbiculate, with a median notch. Anther bilocular, pollinia 4, mealy, ovoid, butter yellow. Capsule narrowly oblong, ca. 4 mm in diameter, 9 mm long, 6-ribbed.
Conservation status: This species is known from three small populations across a 2 km transect in closed canopy upper montane forest.The total population across all three sites comprises ca. 18 mature individuals. Direct observations satisfy the IUCN Red List Criteria B2ac(iv);D ( IUCN, 2001) as CR (Critically Endangered). The occurrence of this taxon in the surrounding forest above 1400 metres can be inferred, potentially satisfying the criteria for an EN assessment, but the ephemeral nature of Stigmatodactylus populations and their apparent sensitivity to environmental disturbance nonetheless puts them at high risk.
Distribution and Ecology: Growing terrestrially in humus layer overlying ultramafic rock in upper montane, closed canopy forest below summit scrub zone. The known populations of Stigmatodactylus dalagangpalawanicum comprise fewer than 20 documented individuals growing within a narrow elevational range of 1400–1700 m. Plants grow singly or in sparsely scattered groups beneath stunted summit trees, 2.0– 3.5 m tall. June temperatures achieve 25 ºC in the shade during the day, 12–14 ºC at night, with frequent clouds and periodic rains (pers. obs.).Associated genera include Leptospermum ( Myrtaceae ), Vaccinium ( Ericaceae ), Rhododendron ( Ericaceae ) and Quercus ( Fagaceae ).
Phenology: Inflorescences bearing flowers observed in June, July, October, November and December, suggesting a tendency to flower following the rainy spring months into the start of the dry season, which is most pronounced from January through to April. Exploratory root excavation in October showed no apparent tubers, although they have been noted at other times of year, suggesting that these are newly produced at the end of each growing season; the noted absence of tubers in other perennating Stigmatodactylus taxa ( Kores 1991, Schlechter 1911) may thus be a function of timing, although this cannot be stated with certainty in the absence of multiple observations.
Etymology: The specific epithet, dalagangpalawanicum , is the Tagalog (Filipino) words dalaga ng Palawan (maiden of Palawan), a reference to the pretty and diminutive form of the plants and a name now adopted by the local Tagbanua tribe for the plant since our research began. This designation is made in particular honour to the second author, Elizabeth Gironella, in the year following her official retirement after decades of work as curator of the herbarium at Palawan State University.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.