Nepenthes armin Jebb & Cheek, 2014

Cheek, M. & Jebb, M., 2014, Expansion of the Nepenthes alata group (Nepenthaceae), Philippines, and descriptions of three new species, Blumea 59 (2), pp. 144-154 : 147-149

Nepenthes armin Jebb & Cheek , sp. nov. — Fig. 1

Differs from N. graciliflora Elmer in the pitchers as wide at apex,or wider,than at base (not widest at base); convex lid appendage absent (not present); androecium: tepal length ≤ 1: 1 (not 2: 1). — Type: Argent & Reynoso 8936 (holotype K; isotypes E, PNH n.v.), Philippines, Sibuyan Island ,above Magdiwang on ridge to Mayos Peak, 750 m, male infl. 16 Aug. 1989 .

Etymology. Named after Armin Rios Marin, Municipal Councilor on Sibuyan and former World Wildlife Fund official who, on 3 October 2007, was shot and killed by a mining company official while leading a protest of his community against the clearance of forest trees to facilitate mining ( Goodland & Wickes 2008: 175); [http://www.piplinks.org/system/files/Mining+or+ Food+Case+Study+6.pdf].

Terrestrial climber 5 m tall. Rosette and short stems unknown. Climbing stem rounded-quadrangular (3 –)4 –5(–5.5) mm diam; internodes (1.2–)1.8–4.2(– 4.9) cm long; axillary buds not seen; indumentum absent apart from dense brown simple hairs in the leaf axils, otherwise only with sessile depressed-globose glands 0.04 mm diam throughout. Leaves thinly coriaceous, petiolate narrowly oblong-elliptic to narrowly elliptic-linear, (10 –)13.1–15 (–17.5) by (1.4 –)1.8– 2.6(–3.7) cm; apex acute or obtuse-rounded; base gradually decurrent to the petiole; nerves visible on the upper, not the lower, surface; longitudinal nerves 2 pairs, in the outer third of the leaf, the innermost pair arising from the midrib 1/2 –1/3 the length of the blade from the petiole; pennate nerves numerous, patent, irregular; indumentum absent except for simple hairs along the upper surface of the midrib, hairs (0.1–)0.4 – 0.6 mm long, erect, pale brown, covering (5 –)20– 40 % of the surface, densest in the distal half of the blade, otherwise with sessile glands as the stem, 10–12 glands per mm 2. Petiole (4.2 –)4.7– 5.6(–7) by (0.2–)0.3–0.4(– 0.6) cm, wings patent in life (revolute in herbarium specimens), base clasping the stem by 1/2 its circumference, not decurrent, indumentum absent apart from sessile glands, and with very sparse and inconspicuous simple hairs along the abaxial midrib. Lower and intermediate pitchers unknown. Upper pitchers (coiled tendril) green, with faint purple mottling, narrowly cylindrical in outline, 10.2 –12.9(–16) by 1.9 – 2.6(–3.2) cm, the lower half narrowly ellipsoid, gradually constricted to 1.3 –1.8(– 2.2) cm wide at the midpoint, then widening gradually to (1.7–)2.2 – 2.8(–3.2) cm wide below the peristome; fringed wings absent, reduced to inconspicuous ridges c. 1 mm wide extending from base to apex; indumentum of minutely branched hairs 0.1–1 mm long, 16–20 per mm 2, the smallest hairs with 2 – 3 branches at the base, the longer hairs with 1–2 short branches along their length, mixed with sessile depressed-globose glands 10 –12 per mm 2. Mouth broadly ovate, 1.8–2.5(– 3.8) by 1.8–2.3(– 2.4) cm, oblique, slightly concave, column not well-developed; peristome cylindric, 1–2 mm diam, ± even in width along its length, ribs 0.25 mm apart, raised 0.04 – 0.08 mm, inner edge inrolled, teeth and holes visible only when dissected ( Fig. 1h ), outer edge often with 2– 3 shallow lobes; inner surface of pitcher glaucous green with scattered purple mottling. Lid orbicular, (1.8 –)2.3– 2.7 by (1.8–)2.1– 2.6(– 3.3) cm, apex rounded, or rarely emarginate, base cordate, sinus 3–4 mm deep, 10 mm wide; lower surface brightly mottled purplish red, basal ridge c. 1 mm high 3 mm in length, convex basal appendage absent; nectar glands evenly and densely spread across the lid and ridge surface, (4 –)6–8(–10) per mm 2, monomorphic, directed to lid base (rims are asymmetric, being highest towards lid apex), orbicular, 0.2 mm diam, with membranous walls projecting vertically, 0.07 mm tall; mixed with sessile depressed-globose glands 0.04 mm diam at the edge of the lid, which are otherwise absent from the larger, central part of the surface. Spur recurved, simple, 3.5 – 5 mm long, tapering to an acute apex, base completely covered in appressed hairs 0.2 – 0.3 mm long, simple, copper-coloured, distal three-quarters 50 % covered in hairs. Male inflorescence 25– 28 by 1.2 – 1.5 cm, indumentum of appressed, simple, copper-coloured hairs 0.3–0.4 mm long covering 40 – 50 % of the surface, mixed with sessile depressed-globose glands as the stem; peduncle 7–11 by 0.1–0.2 cm; rhachis 17–18 cm long, with 70– 95, 1-flowered partial-peduncles; bracts absent; partial-peduncles/pedicels 3.5– 4.5 mm long, indumentum covering 80 –100 % of the surface; tepals 4, green at anthesis, turning red with age, 2.4 by 1.2 – 1.6 mm, outer surface completely covered in appressed, simple, copper-coloured hairs 0.2 mm long, papillae absent or inconspicuous, inner surface densely covered in elliptic nectar glands; staminal column 1–1.7 mm long, glabrous; anther-head subglobose, 0.45– 0.9 by 1.2 mm. Female inflorescence as the male, but c. 30 by 1.2 cm; peduncle c. 16 cm long; rhachis c. 14.5 cm (immature), partial-peduncles/ pedicels c. 110, 3 .5 – 6 mm long, tepals narrowly oblong 2.8 by e

1.2 mm, outer surface densely papillate with hairs sparse, scattered; ovary ellipsoid, 4-lobed, 2.2– 3 by 1.1–1.4 mm completely covered in hairs as the pedicels; stigmas glossy black, 4-lobed, 1.25 mm diam. Infructescence and seeds unknown. Data on colour and posture when live in this description is taken from the field notes of the specimens cited.

Distribution & Ecology — Philippines, Sibuyan Island, gallery forest on ultramafic rock; 750 m.

Additional material. PHILIPPINES, Sibuyan Island , Mt Giting-Giting, Madulid 6927 ( A, F, PNH n.v.), female inflor. 20 June 1987 ; ibid, Magdiwang , Barrio Hawasan , Ating River, Stone et al. in PPI 6724 ( BISH, BRIT, K, PNH n.v.) male inflor. 27 May 1992 .

Conservation — Nepenthes armin is known on current evidence from three mature individuals (specimens cited above) which occur at up to three sites on Sibuyan Island (445 km 2). Clearance of lowland forest trees on Sibuyan to facilitate mining for nickel ore is reported by Goodland & Wickes (2008: 175); [http://www.piplinks.org/system/files/Mining+or+Food+Case+ Study+6.pdf]). Lowland forest below 750 m altitude on Sibuyan has also been partially cleared for lowland agriculture (Google Earth 2014 imagery, viewed 26 Sept. 2014). The area of occupancy is a maximum of 12 km 2 using the 4 km 2 cells advocated by IUCN (2012), although the actual area occupied is far smaller. Accordingly, N. armin is here assessed as Critically Endangered under criterion D (<50 mature individuals) of the categories and criteria of IUCN (2012). None of the three records of the species indicate its frequency. However, previ- ous extensive botanical collections on Sibuyan by Elmer in the early twentieth century did not reveal this species suggesting that it is not widespread and common on the island and may be as rare and restricted as current evidence suggests. Regular visits by Nepenthes enthusiasts to Sibuyan have occurred each year in the last few years but as yet, no additional records for this species have been publicised. However, it is to be hoped that further survey work might yet result in finding numerous additional individuals in secure locations.

Taxonomic affinities — The affinities of N. armin are clearly with N. graciliflora , in the N. alata group as defined in Cheek & Jebb (2013d), in fact the two species can be easily confused owing to their superficial gross morphological similarity. It is possible that the two species are sympatric, since both occur in forest below 800 m in Sibuyan. Records of N. graciliflora on Sibuyan are: Elmer 12465 (BO, E, K, W); Sohmer 12400 (A, BISH, K, L) and Reynoso 118659 (K, PNH n.v.).

Nepenthes armin fits well within the northernmost, Luzon species of the N. alata group, namely N. alata , N. graciliflora , and N. ultra Jebb & Cheek ( Cheek & Jebb 2013f) . In com- parison with species from the southern Philippines, these four northern species share relatively smaller upper pitchers 10(–15) cm long, narrowly cylindrical peristomes, lids densely and uniformly covered in steep-walled, small, monomorphic nectar glands, and 1-flowered partial-peduncles. Nepenthes armin is easily separated from the remaining northern species due to the slightly lobed outer edge of the peristome, and the angular-terete stems. The absence of a convex basal lid appendage, although unusual in the N. alata group, is also seen in N. kitanglad Jebb & Cheek. However , in both cases a basal ridge remains. Despite the unremarkable gross morphology of its pitchers, N. armin shows several features which are, so far, unique in the N. alata group:

– The inflorescences with their very short pedicels and staminal columns, and the dense covering of short, coppercoloured appressed hairs.

– The absence of sessile depressed-globose glands from the centre of the lid.

Notes — Nepenthes armin is the fourth species of Nepenthes known from Sibuyan. All but the widespread N. graciliflora (Luzon to Mindanao) are known to be endemic to the ultramafic substrate of the island. The other endemic species are known from low shrubberies on ultramafic at higher altitudes (1300–1400 m altitude), being N. argentii Jebb & Cheek and N. sibuyanensis Nerz. Nepenthes armin is unlikely to be confused with any other species apart from N. graciliflora , which is also a climber with petiolate leaves and pitchers which are narrowly cylindrical in outline. They can be separated using Table 1. The species-richness of Nepenthes in Sibuyan, with four species of which three are endemic, equals that of the islands of Luzon, Panay and Masbate combined. Sibuyan measures less than 30 by 20 km, but has a height of 2 058 m. Due to the steep slopes, over 30 % of the island still has intact original forest habitat, unusual in the Philippines, as explained in the introduction above. In the Philippine archipelago, only Mindanao and Palawan island exceed Sibuyan for endemicity and species-richness of the genus Nepenthes . This diversity is not due to recent speciation, as has occurred on the Galapagos, for example, but is due to all of the three main Philippine Nepenthes lineages ( Cheek & Jebb 2013h) having reached Sibuyan, and then having evolved there in isolation to form unusual endemic species, including one of the most distinctive in the entire family Nepenthaceae , N. argentii . In terms of Nepenthes, Sibuyan appears to have the highest species diversity per unit area of any island in the Philippines, which may be an index of diversity for other Philippine plant species. This surprising fact is undoubtedly due to the large quantity of ultramafic substrate (unfortunately a source of metal ores), the broad altitudinal range, and also the long geological isolation of Sibuyan from other islands. The lack of disturbance and high levels of intact original habitat are also explanatory factors.

Figures

Fig. 1 Nepenthes armin Jebb & Cheek. a. Habit, male inflorescence, stem section quadrangular (inset below), and upper pitchers (detached); b. upper pitchers; c. sessile depressed-globose glands on lower surface of leaf-blade; d. hairs on midrib, adaxial surface of leaf; e. male flower; f. indumentum of lower tepal surface; g. indumentum of outer pitcher surface; h. peristome showing inner edge (dissected); i. peristome, viewed from inside pitcher, teeth not visible; j. peristome viewed from above; k. peristome, transverse section (outer surface on right); l. lower surface of lid; m. basal ridge in profile, convex appendage absent, with nectar glands, lower surface of lid; n. nectar glands, central area of lid; o. nectar glands, from lower surface of lid, lateral area; p. spur (all from Argent & Reynoso 8936). — Scale bars: a, b = 5 cm; c, d, g–k, n–p = 1 mm; e, m = 2 mm; f = 0.5 mm; l = 1 cm. Drawing by Andrew Brown.