Nepenthes leyte Jebb & Cheek, 2013

Cheek, Martin & Jebb, Matthew, 2013, Recircumscription of the Nepenthes alata group (Caryophyllales: Nepenthaceae), in the Philippines, with four new species, European Journal of Taxonomy 69, pp. 1-23 : 17-20

Nepenthes leyte Jebb & Cheek , sp. nov.

urn:lsid:ipni.org:names:77134489-1

Fig. 4

Diagnosis

Differs from N. alata B lanco in having, except in the hairy axils, glabrous stems, (not densely white hairy); upper pitchers lacking fringed wings (versus with fringed wings); nectar glands on lower surface of lid dimorphic, concentrated around margin and appendage (not monomorphic, uniformly dense and distributed).

Etymology

The specific epithet “leyte” is here used as a noun in apposition, to commemorate the island of that name, to which the species appears unique.

Type

PHILIPPINES. Eastern Visayas, Leyte, Mt Lobi, near Dagami, 7 Nov. 1999, Argent, Mendum, Fuentes, R., Belonias, B. S. 99214 (holotype K!; isotypes E!, PNH).

Description

Terrestrial climber, height 2 m (probably), drying brown. Climbing stems subterete, 4–6 mm diam., with a slight ridge below the leaf bases; the axil with a shallow groove containing a spike-like bud 1–2 mm long, inserted 5–6 mm above the axil; internodes 3–7 cm long; surface with scattered redblack, depressed-globose, sessile raised glands 0.05–0.08 mm diam.; hairs absent, except in the axillary grooves which have white, moderately dense, basally branched hairs with arms erect, ca. 1 mm long. Rosette stems and leaves unknown. Leaves of climbing stems spirally inserted, thinly leathery; blade narrowly oblong-elliptic, 13.5–16 × 2.5–3.8 cm; apex acute, not peltate; base cuneate, abruptly decurrent to the petiole; longitudinal nerves 1 pair, moderately close to the margin, inconspicuous; pennate nerves numerous, conspicuously raised on both surfaces, more or less patent, irregular; both surfaces drying brown, subglossy above, matt below; midrib on both surfaces 5–10% covered with fine white-translucent simple or 3–5-armed stellate hairs, on the upper surface 0.2–0.3 mm diam., on the lower surface 0.1–0.2 mm diam., the leaf-blade otherwise glabrous, apart from sessile red-black glands as the stem, 0.05–0.1 mm diam., 2–6 per mm 2. Petiole evenly winged along its length, the wings incurved (field notes); (2.5–)3–4.5 × 0.2–0.4 cm; clasping the stem for ½ its circumference, very shortly decurrent by 1–2 mm. Lower and intermediate pitchers unknown. Upper pitcher (tendril coiled) 12–15 × 4.5–5 cm; ovoid-ellipsoid in the lower half, upper half cylindrical, 3–3.5 cm diam., not constricted at any point; outer surface 10–30% covered in minute red stellate hairs, hairs ca. 0.1 mm diam., both sessile and shortly stalked, 4–6-armed, arms suberect or patent, density 3–5 per mm 2, mixed with sessile red-black glands 0.05 mm diam. as the leaf-blade and stem, hairs denser on lid, and towards the peristome where they are mixed with sparse erect bushy-bristle hairs 0.2–0.3 mm long; “almost uniformly green with a few purple spots mainly on the ventricose base” (Argent et al. 99214); fringed wings are absent, reduced to inconspicuous ridges; mouth ovate, 4–4.5 × 3–3.5 cm, oblique, slightly concave, “glaucous green inside with just a few red spots”; peristome (1–)2–3(–5) mm wide, narrowly subcylindrical, rounded at the front, becoming slightly flattened and widest at the sides, towards the lid, ca. 4 ridges per mm, ridges 0.075–0.15 mm high, inner edge inconspicuous, holes and teeth not visible (unless dissected: Fig. 4P ); outer edge not lobed; column weakly developed, ca. 7 × 3 mm. Lid ovate 3.2 × 2.9(–3.2) cm; apex shallowly retuse, the sinus 3–7 mm wide; base cordate, the sinus 4 mm deep, 8–15 mm wide; green; margin undulate; lower surface with convex basal appendage, 0.4–0.7 × 1–2 mm, arising from near the midpoint of the 5–6 × 0.5 mm long basal midline ridge; nectar glands slightly dimorphic, each with a different distribution: (type 1) moderately dense on the basal ridge and appendage ( Fig. 4L ) and in a ca. 2 mm band each side (but not extending along midline), glands with raised borders, shortly elliptic, 0.1– 0.2(–0.3) mm long; (type 2) slightly larger, (0.1–) 0.2–0.3 mm long, moderately dense, in bands 2–4 mm wide along the lid margins, 25–40 glands on each side, one sheet (atypical?) with a few additional large elliptic glands, 0.7 × 0.4 mm, bordered, very sparsely scattered between the margins; sessile red-black glands, as stem, leaf and outer pitcher surface, 0.005–0.01 mm diam., scattered over surface ca. 3 per mm 2; marginal part of lower surface with a few minute stellate hairs. Spur inserted 2 mm below junction of lid and pitcher on ridge; simple, stout at base tapering to a long, acute apex; 7–9.5 × 0.5–0.7 mm; completely covered in long, grey appressed hairs, hairs (0.5–)0.7–1(–1.2) mm long. Upper surface of lid with two prominent nerves, nerves densely (80–90% cover) white hairy, hairs of two types: (1) basally 1–2-branched hairs 0.3–0.4 mm long, (2) minute 3–5-armed stellate hairs 0.1 mm diam.; remainder of lid surface with type (2) hairs, but indumentum 30–40% cover, and with sparse perithecoid nectar glands 0.25 mm long. Inflorescence and infructescence unknown.

Distribution & habitat

Philippines, Visayas, Leyte; volcanic geology; “climbing on fallen tree in submontane mossy forest”, elevation 900 m (Argent et al. 99214).

Conservation

Nepenthes leyte sp. nov. is known currently from a single individual in an unprotected area, in a country, including specifically the island of Leyte, where most of the original forest habitat has been cleared for timber and agricultural land and where forest degradation and clearance are ongoing ( Myers et al. 2000; GoogleEarth viewed 2 Oct. 2013). Accordingly, it is here assessed as Critically Endangered under Criterion D of IUCN (2012). It is to be hoped that further exploration will reveal additional localities for the species, and that protection can be arranged before it becomes extinct. Currently no protected areas are believed to be present on Leyte apart from the 2193 ha Lake Danao National or Natural Park which is about 14 km to the W of the type location. However this seems to be mainly a recreational area, and within the reserve, illegal settlement, slash and burn agriculture and illegal logging are reported to be problems (http://en.wikipedia.org/wiki/Lake_Danao_(Leyte)#Threats, viewed 12 Oct. 2013). Viewing the area immediately around Lake Danao on GoogleEarth (2007 imagery, viewed 12 Oct 2013) confirms that large areas have been and were in 2007 in the process of being cleared and inhabited, and that these activities extend towards the E and the only known location for N. leyte sp. nov. Some original forest still survives along the central high ridge of Leyte, where terrain appears rugged, including the location indicated as the type location of the species, however the resolution of the imagery here is not sufficiently high to gauge how intact the habitat is. The eastern side of Leyte has higher rainfall and the forest has extensively been replaced by intensive industrial oil palm plantations which extended in 2003 to within 4 km of the type location (GoogleEarth imagery dating from 2003, viewed 2 Oct. 2013). Collection of Nepenthes leyte sp. nov. from the wild to supply the horticultural trade is considered a low risk for this species since its pitchers are not as spectacular or as bizarre as those of other members of the genus in the Philippines.

Remarks

Argent et al. 99214, here described as Nepenthes leyte sp. nov., while superficially similar to N. graciliflora , the only other species of the genus known on Leyte (Wenzel 680, GH!; Barbon et al. in PPI 8735, BRIT!; ibid. 8561, BRIT!), cannot be confused with it. This is due to the stellate hairs present on the outer pitcher surface of Nepenthes leyte sp. nov. (versus absent in N. graciliflora ), and the dimorphic nectar lid glands concentrated around the margin and appendage (not monomorphic, uniformly dense and distributed). It also has petioles that appear cylindrical since the wings are involute (not with patent wings). Apart from N. graciliflora itself, only one other member of the N. alata group is, so far, known from the Visayas: N. negros (Negros and Biliran islands). However, N. negros has densely hairy stems (versus glabrous), upper pitcher with fringed wings (not absent) and the inner peristome edge has conspicuous teeth and holes (versus conspicuous teeth absent). Nepenthes leyte sp. nov. can be distinguished from other species of the Nepenthes alata group using the key above.

Figures

Fig. 4. Nepenthes leyte sp. nov. A. Habit, climbing stem with upper pitchers. B. Stem section showing axillary hair patch and supra-axillary bud. C. Lower surface of leaf-blade, with sessile glands. D. Midrib of leaf-blade, lower surface, stellate to simple hairs. E. Midrib of leaf-blade, upper surface with stellate hairs. F. Upper lid of pitcher, upper surface. G. Indumentum of upper surface of lid, over nerve. H. As G but distant from nerve. I. Spur of upper pitcher and junction of lid with peristome (inverted). J. Lid of upper pitcher, lower surface. K. Detail of J showing large nectar glands. L. Detail of J showing midline ridge with appendage and type (1) nectar glands. M. Indumentum of outer pitcher surface. N. Peristome of upper pitcher viewed from above. O. Peristome viewed from inside pitcher. P. Peristome dissected to expose the inner edge, with teeth. Q. Peristome, transverse section (outer surface on right). All drawn from Argent et al. 99214 by Andrew Brown.