Drosera ultramafica A.Fleischm., A.S.Rob. & S.McPherson, 2011

Fleischmann, A., Robinson, A. S., McPherson, S., Heinrich, V., Gironella, E. & Madulid, D. A., 2011, Drosera ultramafica (Droseraceae), a new sundew species of the ultramafic flora of the Malesian highlands, Blumea 56 (1), pp. 10-15 : 11-14

Drosera ultramafica A.Fleischm., A.S.Rob. & S.McPherson , sp. nov. — Fig. 1 , 3 , Map 1

A Drosera spatulata Labill. caule brevi, foliis suberectis, lamina anguste oblanceolata vel oblonga, et stigmatibus spathulatis vel bilobatis recedit. — Typus: McPherson 002 (holo PPC; iso L), Philippines, Palawan, Mt Victoria , high montane forest on ultramafic soils, 1680 m alt., 24 June 2007 .

Etymology. The epithet denotes the fact that this species is confined to ultramafic soil.

Stem-forming rosetted perennial herb. Stem with short internodes, forming short stems up to 5 cm with age. Leaves narrowly oblanceolate to oblong, semi-erect, green to deep red in colour, (10–) 20–40 mm long, up to 5 mm wide near the tip; stipules papery, 3-laciniate, white to reddish (drying brown), 5–7 mm long, up to 2 mm wide at the base. Scapes 1–4; inflorescence a 1-sided raceme, rarely forked; flowers (2–)4–15; peduncle terete, slightly ascending at the base, 1–1.5 mm diam, up to 20 cm long; peduncle base with simple, appressed nonglandular hairs c. 0.5 mm long, median part of scape subglabrous; uppermost part of scape, bracts and pedicels covered with short stalked glandular trichomes or subglabrous. Pedicels terete, short, 1–4 mm long; bracts subulate to narrowly triangular with apex acute, 2–2.5 mm long, c. 0.2 mm wide; calyx subcampanulate, with subsessile glandular trichomes; sepals 5, narrowly elliptical to narrowly triangular, with apex acute, apex sometimes reflexed in fruit, 3– 6 mm long, 1–1.5 mm wide, with subsessile glands, especially near the apex; petals 5, obovate to cuneate, with crenulate margin, 8 – 9 mm long, 3.5 –4 mm wide, white or pink. Stamens 5, filaments 3–5 mm long, c. 0.1 mm wide, white; thecae 1 mm long, anthers and pollen yellow; styles 3, forked at 1/3–1/4 of their length, 3 –4 mm long, c. 0.4 mm wide near the base, stylar arms c. 0.1 mm wide, stigmatic tips lanceolate to spathulate or bifid, 0.2–0.3 mm wide; ovary subglobose; capsule subglobose, c. 3 mm long, c. 2 mm diam, opening by longitudinal slits; seed ellipsoid, apiculate, black, c. 0.4 mm long, c. 0.2 mm wide, testa reticulate.

Distribution — Malesia: Philippines, Palawan, Mt Mantalin- gahan and Mt Victoria; Malaysia, Borneo, Sabah, Mt Kinabalu; Indonesia: Sumatra, Northern Sumatra, Aceh, Gunung Bandahara and Pucuk Angasan; Sulawesi, Central Sulawesi, Buyu Katapasa. Drosera ultramafica is recorded from a number of high elevation (1500–3000 m) sites in Malesia thus far, and it is likely to be more widespread on suitable mountain ranges in the Malesian Archipelago. Drosera ultramafica has been observed and pictured growing at the summit of Buyu Kata- pasa in northern Central Sulawesi at 2700 m (U. Zimmermann, pers. obs.), but no herbarium specimens are yet available for Sulawesi ( Map 1 ).

Habitat & Ecology — High montane forest, on ultramafic soils, 1500– 3000 m.

Sparsely scattered populations in Palawan at 1600 –1700 m altitude in seepages on sharply-draining rocky soil. On Mt Mantalingahan, found growing in granular ultramafic soil on open seepages in full sun and among grasses. On Mt Victoria, found primarily among grasses and ultramafic protrusions in well-drained soils thoroughly wetted by regular downpours. Flowers and fruits observed July–August. Plants generally shaded, but exposed to intense midday sunlight and cooled by heavy cloud thereafter. June temperatures to 30 °C during the day, 16 °C at night (pers. obs.). On Mt Victoria, associated species consist predominantly of a Pleomele sp. ( Asparagaceae ), as well as Leptospermum (Myrtaceae) , Vaccinium (Ericaceae) and Medinilla spp. ( Melastomataceae ), various grasses and Nepenthes attenboroughii A.S.Rob., S.McPherson & V.B.Heinrich ( Robinson et al. 2009) .

On Mt Kinabalu in lower montane forest, growing in damp to boggy openings on ultramafic substrate from 1500–1700 m elevation ( Van Steenis 1953, Beaman et al. 2001).

In Northern Sumatra, Aceh, on Gunung (Mt) Bandahara and Pucuk Angasan (and probably other mountain summits of the Gunung Leuser National Park), D. ultramafica grows in wet ‘mountain blang vegetation’ (open montane areas with heathlike vegetation, see De Wilde & Duyfjes 2001) at altitudes of 2300– 3000 m. The soil of these mountain ‘blang’ areas is very infertile and it has been shown to be rich in heavy minerals ( Van Beek 1982), over a base of basaltic rock ( Hutchison 1975). The Sumatran plants of D. ultramafica are generally smaller in overall size, compared to the plants of Kinabalu or Palawan, with rosettes reaching 2 –3 cm diam, and scapes rarely exceeding 4 cm in height. Dwarfed plants from the summit areas of Gunung Pucuk Angasan growing in exposed areas in heavy grey clay at 3000 m (W.J.J.O. de Wilde & B.E.E. de Wilde-Duyfjes 16360) have scapes only 1 cm in length and rosettes ± 1.5 cm diam. Plants of D. ultramafica from Aceh are often associated with the locally endemic carnivorous plant Utricularia steenisii P.Taylor (e.g. intermixed in collection W.J.J.O. de Wilde & B.E.E. de Wilde-Duyfjes 15283).

Conservation status — Not threatened.

Specimens examined.

Drosera ultramafica : PHILIPPINES, Palawan, Mt Victoria, 1680 m, 24.06.2007, McPherson 002 (holo PPC;iso L) ; Palawan, Mt Mantalingahan, along slopes of Ulut Tigaplan ridge, c. 1800 m, on moss-covered rock at the depauperate heath formation, 10.04.1977, L. L . Co 1780 ( L, PNH) . – MALAYSIA, Borneo , Sabah, Mt Kinabalu, Marai Parai , 5000 ft. [1500 m], 21.03.1933, J. & M. S . Clemens 32233 ( K, L, M); 1700 m, Haviland 1268 ( K); Marai-Parai ridge, growing in exposed damp areas, flowers pink, 15.01.1983, collector unknown SNP 1025 ( K, L, PNH, SAR); 1500 m, Collenette A 95 ( BM, pho- tograph); Marai Parai Spur, M. S . Clemens 10908 ( K), 1500–1700 m; Gibbs 4040 ( BM, photograph); Topping 1886 ( K!); Mt Kinabalu , 1500 m, Low s.n. ( K) . – INDONESIA, Sumatra, North Sumatra, Gajo Lands, Gunung Leuser Nature Reserve , Atjeh [Aceh], 2300–2600 m, blang vegetation, wet, open place with very short vegetation, plant reddish, flowers pink, 28.02.1975 W. J. J. O . de Wilde & B. E. E . de Wilde-Duyfjes 15141, 15158, 15283, 16078 (all L); 2725 m, camp 2-3, P . Angasan 15969 ( L); 3000 m, 16360 ( L); moun- tain heath (‘blang’), field of Scirpus, Cladium and sedges, heavy gray clay, locally common, flowers pink, c. 2000 m, 21.02.1973, C. G. G. J . van Steenis 9085 ( L); Putjuk Angasan, spur to Mt Losir [Gunung Losir], open mountain heath, c. 2300 m, 28.01.1973, C. G. G. J . van Steenis 8332 ( L); Gunung Bandahara, camp 6, damp ‘blang’, exposed, wet places, plants reddish, flowers pink, 2600–2700 m, 24.06.1972, W. J. J. O . de Wilde & B. E. E . de Wilde-Duyfjes 13307 ( L) .

Drosera spatulata : PHILIPPINES, Luzon, Cuming 857 (L, M); Luzon, Albay Province, Mayon Volcano, road cut, open slope, 1015 m, flowers white, 04.06.1953, D.R. Mendoza 18321 (L); Mindoro, Mt Halcon, in open heaths, 2400 m, locally abundant, Merrill 5784 (?, not seen). – MALAYSIA, var. spatulata : Malay Peninsular, Kedah Peak, Holttum 14880 (SING); var. bakoensis : NW Borneo, Sarawak, Bako Plateau, J.W. Purseglove P4926 (L, SAR); P.S. Ashton S17920 (L); Telok Pandan path, c. 90 m [300'], 4.5.1959, J. Carrick & I.C. Enoch JC/473 (holotype SAR); Pedang, 90 m [300'], 22.4.1959, J. Carrick & I.C. Enoch JC/49 (SAR); Teluk Assam, heath woodland, 120 m [400'], 17.5.1955, J.W. Purseglove P4927 (spirit material) (SAR); Lintang path,sides of paths in open places free of litter, especially damp places,acid soil, 4.6.1963, P.S. Ashton S17920 (L, SAR). – PAPUA NEW GUINEA, Western Province, Wassi Kussa River, Tarara, on wet ground in savannah forest, rare herb, flowers white, Jan. 1937, L.J. Brass 8752a (A n.v., LAE n.v.); New Britain, Hoskins Sub-District, NNE slope Mt Ulawon [Mt Ulawun], on top of north-facing cliff, c. 14 feet tall, habit damp, plants in sun bright red and very conspicuous, those in shade pale green apart from red gland, corolla pink, 4300 feet [c. 1300 m], 20.02.1971, P.F.Stevens LAE51255 (L).

Notes — Plants of D. ultramafica from Palawan and Central Sulawesi have white petals, whereas plants from Northern Sumatra are pink-flowered. Specimens from Mt Kinabalu, Borneo, are reported to have both pink and white flowers.

Interestingly, seedlings of D. ultramafica bear conspicuous short-stalked glands on their cotyledons. Glandular cotyledons are occasionally found in Drosera species of section Drosera ( Conran et al. 1997) .

In the Malesian area, D. ultramafica is unlikely to be confused with any other Drosera species except D. spatulata (for differences see Table 1). In the field, sterile plants of D. ultramafica can be distinguished from D. spatulata on sight by their stem-forming habit and by the erect to semi-erect narrowly oblong to oblanceolate leaves, which give the overall plant a subglobose appearance ( Fig. 1 ). In contrast, the spathulate to cuneate leaves of D. spatulata are appressed to the ground, forming a flat rosette. Occasionally, old specimens of D. spatulata may form tall columns consisting of dried leaves (e.g. observed on Mindoro, Fig. 2), but even in these individuals, the leaves are never held erect to semi-erect as in D. ultramafica . The colour of the stipules of living plants is another useful character to tell both species apart: the membranous stipules of D. ultramafica are usually deep red in colour when alive, whereas the stipules of all varieties of D. spatulata are papery white or translucent in living plants. Unfortunately, stipules of both species turn brownish when dried, so this character is not applicable to herbarium specimens.

Drosera spatulata can be found growing in a wide range of nutrient-poor soils in Malesia, ranging from clay-based, mafic laterites, organic soils and peat to pure wet silica sand ( Van Steenis 1953, Fleischmann & Lee 2009), but it is apparently always absent in suitable habitats on ultramafic soils. Drosera spatulata is a lowland to submontane species occurring from 10–1400 m altitude ( Van Steenis 1953, Conn 1980), but reach- ing up to 2400 m on Mt Halcon, Mindoro, Philippines ( Merrill 1907, pers. obs.). In Sarawak, Borneo, in New Guinea and in eastern Australia, D. spatulata is a species of low altitude savannah and open, usually swampy, heath vegetation ( Van Steenis 1947, 1972, Conn 1980, Lowrie 1998, Fleischmann & Lee 2009). Drosera ultramafica is restricted to montane habitats (1500 – 3000 m). Due to their different ecological preferences, the species have not been reported as growing sympatrically, and they are unlikely to co-occur naturally. For the same reason, no natural hybrids involving D. ultramafica as a parent are known.

Two species of Drosera from Indochina and New Caledonia respectively are superficially reminiscent of D. ultramafica , but are not recorded from the Malesian area; these can be distinguished from the latter as follows: D. ultramafica differs from the Chinese D. oblanceolata Y.Z.Ruan , which has similar leaves and stipules, in having a glandular-hairy scape, sepals only occasionally reflexed in fruit (usually all five sepals of the calyx with reflexed tips in fruit, as in D. spatulata ) and flowers with style arms widened to the tip and a stigmatic tip that is lanceolate to spathulate or bifid (filiform style arms, stigmatic tip bifid or ramifid). In addition, D. oblanceolata is endemic to Hong-Kong ( Ruan 1981) and not expected to occur in the Malesian floristic area.

Drosera neocaledonica Raym.-Hamet , an endemic of New Caledonia, shares a similar stem-forming habit and narrowly oblanceolate leaves, but differs from D. ultramafica in having bristly white hairs on its petioles, in having a scape and sepals that are covered densely with short-stalked red glandular trichomes, and in the larger flowers (up to 2 cm diam) and styles with stigmatic tips that are branched multiple times.

Drosera neocaledonica is the only other species in the genus other than D. ultramafica that is not only tolerant of ultramafic substrates, but seemingly ecologically restricted to them ( Gibson 2001). However, both taxa can be artificially cultivated in peat-based substrates devoid of high concentrations of heavy minerals ( Gibson 2001, A. Fleischmann pers. obs.), suggesting that they are not edaphically confined to the soil chemistries of ultramafic regions. Most plant taxa endemic to ultramafites will grow well artificially on non-ultramafic soils in the absence of competition by vigorous plants or phytopathogenic fungi, thus ultramafic soils effectively provide a refuge from biotic factors present in non-ultramafic substrates ( Brooks 1987). One other species of Drosera is known to at least tolerate ultramafic sub- strates: D. arcturi Hook. can occasionally be found growing in wet soil overlying ultramafic rocks in Tasmania ( Gibson et al. 1992), but is not generally restricted to such sites, growing well in various types of non-ultramafic peaty soil ( Lowrie 1998).

Figures

Map 1 Distribution of Drosera ultramafica ($), D. spatulata var. spatulata () and D. spatulata var. bakoensis () in Malesia. Grey shading indicates areas of ultramafic rock (modified from Brooks 1987 and Hutchison 1975). Drosera spatulata is also indicated for adjacent northern Australia, Cape York, where it is locally common, see Lowrie 1998.

Fig. 1 Drosera ultramafica on Mt Mantalingahan, Palawan. Photo S. McPherson.

Fig. 3 Drosera ultramaficaA.Fleischm.,A.S.Rob.& S.McPherson.a.Habit of plant in fruit;b. leaf with stipule, adaxial view; c. leaf, abaxial view,stipule removed; d. sepal; e. petal; f. anther; g. ovary and styles; h. seed (all: McPherson 002). — Scale bars: a = 1 cm; b–g = 1 mm; h = 0.1 mm. Drawn by A. Fleischmann.