Nepenthes tboli 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 : 149-150

Nepenthes tboli Jebb & Cheek , sp. nov. — Fig. 2

Differs from N. saranganiensis Sh.Kurata in the stems terete (not 4-winged); leaf-blade midribs and margins hirsute (not glabrous);pitcher lid apices retuse (not rounded). — Type: Gaerlan, Sagcal & Romero in PPI 13083 (holotype BRIT!; isotype L! sh. 0099289), Philippines, Mindanao, South Cotabato Province, T’Boli, Lake Parker , 1463 m alt., male fl. & fr. Aug 1993 .

Etymology. Named, as a noun in apposition, for the T’boli people and area from whence the type specimen derives.

Terrestrial shrub or climber to at least 0.5 m tall. Rosette and climbing stems unknown. Short stems terete, 0.4–0.6 cm diam. Leaves spirally inserted, internodes 1.5–2.6 cm long, epi- dermis drying black, wrinkled, moderately densely covered in red sessile globose glands 0.05 mm diam; very young stems c. 50 % covered in red-brown, curved-erect, simple or 2(–3)-armed hairs 0.1 mm tall, concentrated in and near leaf axils; older stems with hairs 0.1–0.25 mm long c. 5 % covered and appearing glabrous. Leaf blades oblong-elliptic, 11–16 by 2.8–3.5 cm; apex attenuate, base decurrent; longitudinal and pennate nerves not conspicuous, barely visible only on lower surface, longitudinal nerves 5 –10 pairs, oblique, arising at intervals along midrib as pennate nerves, arching upwards before running along and adjacent to margin for 0.5–1 cm; indumentum absent from upper surface, except leaf edge which is densely hairy, hairs 2–3-branched from the base or from the main axis, 0.25–0.75 mm long; lower surface with red, sessile, globose glands c. 0.5 mm diam, c. 4 per mm 2; midrib moderately densely hairy, c. 50 % cover, hairs simple, or basally bi- or trifurcate 0.5–0.7 mm long, mixed with shrubby, multi-armed hairs 0.25 mm diam. Petioles with patent wings, 4.5–6 by 0.6–0.9 cm, margin with white, sparsely branched, patent hairs 0.25–0.5 mm long; base clasping the stem for 1/2–2/3 its circumference, shallowly winged, subauriculate. Lower and intermediate pitchers unknown. Upper pitchers (tendril coiled) narrowly subcylindrical, 11.5–17.5 by 3.5–4 cm; broadest at base, gradually tapering to 2.5–3 cm wide at the centre, gradually dilating towards apex, to c. 3.5 cm wide below the peristome; fringed wings absent, reduced to ridges; outer surface minutely and sparsely puberulent, c. 5 % covered with erect red hairs, c. 7 per mm 2, hairs bifurcate at base or apex, or bushy, sessile, 0.15 mm long, or (c. 1 in 20 hairs) 3 mm long, patent, with 2–3 short lateral branches. Mouth ovate, 3–5.3 by 3.7–4 cm, oblique; peristome subcylindric, 2–2.5 mm wide, ridges 0.15–0.2 mm high, 0.3 mm apart, outer edge tightly inrolled, not lobed, inner edge slightly incurved, teeth absent, perforated with holes, mostly clearly visible near the weakly developed column. Lid ovate or ovate-elliptic; 3–3.8 by 2.4–3.4 cm; apex retuse, sinus 1–2 mm deep, base shallowly and broadly cordate or rounded; lower surface with a forwarddirected pocket, 1–2 mm long, 2.5 mm wide, set back 2–3 mm from the midline apex, the pocket sides continued to apex by two ridges; mouth of pocket and marginal 2–3 mm of the lid, minutely stellate-hairy, lacking nectar glands, the hairs c. 0.1 mm diam with (2–)3–4(–5) short, thick arms, covering c. 50 % of the surface at the edge itself, giving it a grey, shaggy appearance; basal appendage conspicuous, semi-circular to oblong, asymmetric, 1.5–2 by 2 mm, arising abruptly from a ridge 6 mm long, 1.25 mm high; nectar glands trimorphic, segregated: 1. Large, elliptic-oblong, thinly bordered nectar glands 1–1.25 by 0.6–1 mm, 15–20 in number, present in a band 6 mm wide, along the midline between basal ridge and apex, sparse; smaller such glands 0.3–0.35 by 0.25 mm sparsely scattered in the distal half outside the midline and in the proximal half inside the margin, throughout the lid mixed with small sessile red globose glands c. 0.05 mm diam, c. 10 per mm 2 ( Fig. 2i );

2. small, circular, thickly rimmed (perithecoid) nectar glands, (0.15–) 0.25 mm diam, confined to the basal appendage and to two curved elliptic areas on each side of the midline in the proximal half, glands very dense, 13 per mm 2 on the appendage and abutting each other there ( Fig. 2h ); 3. small, deeply sunk borderless, circular glands 0.1–0.2 mm diam, c. 5 per mm 2 present in a small area at the junction with the peristome.

Spur simple, needle-like, tapering to a point, 10 by 0.3 mm, erect; indumentum as outer pitcher surface. Male inflorescence known from incomplete portion, rhachis 2.5 mm diam, c. 50 % covered by mainly appressed white, heterogenous hairs: bristle-like hairs 1–2-armed from base, 0.1–0.2 mm long; vermicular, septate hairs c. 0.2 mm long, and by erect, minute simple hairs 0.05 mm long; partial-peduncles 3 per mm length of rhachis, lacking bracts, 2-flowered, (1–) 2 mm long; pedicels divaricate, (8–) 9–11 mm long; sepals ‘yellow-green’, 4, elliptic, c. 0.6 by 0.4 mm, apex obtuse, inner surface densely covered in nectar glands, margin densely felted in rust-red papillae; outer surface c. 40 % covered in white appressed hairs 0.1 mm long; androphore 3 mm long, basal 1/3–2/3 with patent white hairs 0.1 mm long, distal part glabrous; anther-head subglobose, wider than long, 1.5 by 1.75 mm, anther thecae c. 15, uniseriate, dull yellow. Infructescence peduncle 25–26 cm long, 0.4–0.6 cm diam at base, very sparsely puberulent; rhachis 12–13 cm long, indumentum as midrib of leaf, c. 60 % of surface covered; partial-peduncles 30–36; 7–10 mm long, 2-flowered; bracts absent; pedicels 8–12 mm long, indumentum as midrib, c. 100 % cover; tepals 4, ovate-oblong 5–6 by 2.5 mm, outer surface with white appressed hairs c. 0.1 mm long, c. 5 % cover, absent from base; inner surface with large elliptic glands. Fruit valves 4, narrowly linear-elliptic, 2.5–3.6 by 0.2–0.3 cm, pale brown, 60 % covered by curved red hairs c. 0.4 mm long. Seeds pale brown, filiform, 14 mm long, seed body 1.25 by 0.3–0.4 mm, deeply corrugated.

Distribution & Ecology — Philippines, Mindanao, S Cotabato Province, T’boli, Lake Parker, open grassland, 1463 m.

Conservation — Here, N. tboli is assessed as Critically Endangered under criterion D of IUCN (2012) since it is currently known only from one or two mature individuals at the type locality which is threatened by plantation agriculture and tourism developments (Google Earth data). It is to be hoped that more individuals of the species will be found at other locations, hopefully in the extensive yet botanically poorly known Tiruray Highlands of the T’boli people in southern Mindanao, and that this species will be shown to be more common than present evidence suggests.

Notes — Nepenthes tboli is morphologically most similar to N. saranganiensis Sh. Kurata (2003: 41) , but lacks the strongly winged stems of N. saranganiensis , a feature unique to this species within the N. alata group. Nepenthes saranganiensis is nearly sympatric with N. tboli and is the only other species of the genus known thus far, from the extreme S of Mindanao. The two species can be differentiated using Table 2.

Nepenthes tboli is unusual in the N. alata group in possessing a pocket in the lower surface of the lid, at the apex ( Fig. 2j ). Such lid pockets occur in few other species of the genus, e.g. N. albomarginata Lindl. , and are otherwise known in Mindanao species only in N. robcantleyi Cheek (2011) and in N. graciliflora . The function of such pockets is unknown, but we speculate that they are associated with attraction of prey, possibly by holding nectar.

Figures

Fig. 2 Nepenthes tboli Jebb & Cheek. a. Habit, with upper pitchers and infructescence; b. leaf-blade midrib, lower surface, indumentum; c. hairs in axil of leaf with stem; d. hairs, on tendril; e. hairs on outer pitcher surface; f. hairs on outer pitcher wall, profile view; g. lid, lower surface, showing nectar glands (left) and venation (right); h. basal appendage of lower lid surface; i. large nectar glands of the lid midline; j. lid apex showing pocket; k. minute stellate hairs of lid margin, lower surface; l. spur; m. peristome from above; n. peristome, transverse section (outer surface: right) (all from Gaerlan et al. PPI 130838). — Scale bars: a = 5 cm; b, h–j, n, m = 2 mm; c–f = 1 mm; g, l = 1 cm; k = 0.1 mm. Drawing by Andrew Brown.