Nepenthes dactylifera A.S.Rob., Golos, S.McPherson & Barer, 2019

Robinson, Alastair S., Golos, Michal R., Barer, Marc, Sano, Yosuke, Forgie, Jennifer J., Garrido, Diego, Gorman, Chandler N., Luick, Adi O., Mcintosh, Nick W. R., Mcpherson, Stewart R., Palena, Gregory J., Pančo, Ivan, Quinn, Brian D. & Shea, Jeff, 2019, Revisions in Nepenthes following explorations of the Kemul Massif and the surrounding region in north-central Kalimantan, Borneo, Phytotaxa 392 (2), pp. 97-126 : 106-110

1. Nepenthes dactylifera A.S.Rob., Golos, S.McPherson & Barer , spec. nov. ( Figs. 5−6 )

Type: — Borneo, Brunei, Temburong, Amo, Bukit Belalong , 4.33°N 115.09°E, 869 m a.s.l., 24 February 1992, Prance 30548 (holotype K!, iso- L!) [K—climbing stem with upper pitchers; L —climbing stem with upper pitchers, infructescence] .

− Nepenthes sp. [“undescribed species collected from the Mulu area”] in Phillipps & Lamb (1988: 8, 1 fig.).

− Nepenthes sp. A in Clarke (1997: 141, fig. 97) and Steiner (2002: 112).

− Nepenthes fusca auct . non Danser [ Jebb & Cheek (1997: 41), partim; Cheek & Jebb (2001: 64), partim; Phillipps et al. (2008: 121), partim [figs. 151, 154−155]; McPherson (2009: 346), partim].

Diagnosis: — Nepenthes dactylifera differs from N. fusca in the long-decurrent leaf bases (vs. non-decurrent), upper pitchers tubulose to broadly infundibular (vs. narrowly infundibular), and upper pitcher lids very narrowly ovate, appearing sagittate to ligulate through marginal revolution (vs. ovate and ±complanate).

Description: —Epiphytic or terrestrial scrambling, climbing or pendent shrub, to 4 m tall. Stems of rosettes terete, 0.6–0.9 cm in diameter, internodes 0.3–1.1 cm long; vining stems ca. 0.8 cm in diameter, internodes 6–12 cm long. Leaves of rosettes coriaceous, petiolate, lamina broadly obovate-oblong to elliptic, 8–12 cm long, 5.5–8.5 cm wide, apex obtuse to truncate, not peltate, base abruptly attenuate, petiole canaliculate, 3.5–5.5 cm long, sheathing and clasping stem for>3/4 of its circumference. Longitudinal veins 2–3 on either side of midrib, restricted to outer third of lamina, where they run parallel to the laminar margin, somewhat inconspicuous. Pinnate veins numerous, irregularly reticulate, indistinct. Leaves of tall stems coriaceous, petiolate, lamina oblong to elliptic, 12–18 cm long, 6.5–9.5 cm wide, adaxial surface with sparsely scattered glands, apex acute to acuminate, occasionally obtuse, base abruptly attenuate, obtuse, petiole canaliculate, 4.5–6.5 cm long, base decurrent into two narrow wings, each 1–3 mm wide, decurrent for 1–1.3 internodes. Tendrils to 35 cm long. Lower pitchers ellipsoid in the lower half, cylindric and slightly narrower above, widening towards mouth, 8–16 cm tall, 2–3.5 cm wide, with fringed wings 2–4 mm wide, fringe elements ≤ 6 mm long, 2–5 mm apart; peristome oblique, somewhat uniform in width and strongly raised at rear to form a neck, 2.5–4 mm wide at front of pitcher, ribs very fine, ca. 0.2–0.4 mm apart, teeth minute. Lid narrowly ovate, usually complanate, 2.5–3.5 cm long, 1.4–1.8 cm wide, with a pronounced abaxial midline rib and slight basal bulge but no keel, distal part with few, large crateriform glands, rarely with terminal protuberance, abaxial surface of lid with scattered crateriform glands 0.2–0.4 mm in diameter. Spur filiform, ca. 0.8–1.2 cm long. Upper pitchers tubulose to broadly infundibular, rarely narrowly infundibular, 15–25 cm tall, 4.5–6.5 cm wide, wings absent or reduced to ridges; peristome broad, 4–8 mm wide at front of pitcher, and strongly oblique, sometimes slightly raised at the front, ribs and teeth as per lower pitchers. Lid very narrowly ovate to triangular, appearing sagittate to ligulate due to revolution or conduplication of margins about 2/5 from base, thereafter usually complanate, 3.5–6.5(–7.5) cm long, generally>4.5 times longer than wide, with pronounced abaxial midline rib, slight basal bulge or keel, rib extending into an apical protuberance 3–8 mm long; distal 2/3 of abaxial rib and protuberance with nectar glands scattered, narrowly elliptic, very thickly bordered, ocellate-crateriform, ca. 1–1.5(–2) by 0.5(–1) mm, abaxial surface of lid densely scattered with smaller ±circular, thinly bordered, crateriform nectar glands, ca. 0.3–0.6 mm in diameter. Spur filiform, 0.8–1.2 cm long. Male inflorescence to 40 cm long, ca. 180 flowers, peduncle 10–15 cm long, 4–5 mm in diameter at the base, rachis 15–25 cm long, partial peduncles 2-flowered, bifurcating 1–2 mm from base, bracts absent, pedicels to 0.8–1.2 cm long at base of rachis; tepals green, suffusing red once opened, broadly elliptic, 3–3.5 mm long, 2–2.5 mm wide, apex more or less obtuse; staminal column 2 mm long, anther head to 2.5 mm in diameter, consisting of eight fused anthers. Female inflorescence to 30 cm long, ca. 30–50 flowers, peduncle 15–20 cm long, ca. 5 mm in diameter at the base, rachis 8–12 cm long, partial peduncles 2-flowered, lowermost sometimes with filiform bracts to 6 mm long, tepals elliptic, ca. 3 mm long, 1.5–2 mm wide, apex acute, ovary ovoid, 4 mm tall, to 2.5 mm in diameter, fruit 1.5–2.5 cm long, seeds filiform, ca. 1.2 cm long, pale brown. Indumentum of short, fine brown hairs to ca. 0.5 mm scattered over exterior surface of pitchers, tendrils, abaxial midrib and leaf margins, as well as petioles of rosette leaves and all juvenile foliage, stem more or less glabrous, especially in tall stems. Inflorescences sparsely to densely pubescent, with simple, reddish-brown woolly hairs present on the main axis, pedicels and abaxial surface of tepals. Colour variable, mature stems usually reddish to black, leaves bright green, sometimes suffused with red, lower pitchers often dark, olive green blotched with deep red or black, peristome green to deep red, often suffusing to pale green on inner margin, upper pitchers from entirely pale green (almost white) to green blotched with red or, typically, green suffused with orange with a whitish peristome striped with deep red.

Etymology: —The epithet dactylifera is derived from the Greek δάκτυλος (daktylos; finger) and the Latin suffix - fer (bearing), a reference to the extremely long and narrow lid of this species, which fancifully resembles the arched fingers of the Grim Reaper in popular culture.

Phenology: —Flowering and fruiting have been observed in the months of February, March, July, August, September, and October.

Distribution and ecology: — Nepenthes dactylifera is widely distributed across the central highlands of Sarawak, its range stretching the length of the state from at least the Second Division (e.g. Bukit Bangai) in the west to the Fifth Division (e.g. Mt. Murud) in the east ( Fig. 4 ). It has also been recorded from Brunei’s eastern exclave (Temburong), from both North and East Kalimantan (Mt. Bagong), and from West Kalimantan (Mt. Keburau and Mt. Kenepai). It grows mainly as a high epiphyte in trees from about 800 m a.s.l. but widely colonises ruderal habitats such as cleared road cuttings generally above 1200 m, especially clay laterite sites in full sun. It is abundant on road embankments at ca. 1300 m in the Kelabit Highlands and on logging roads in the Hose Mountains, Sarawak (AR pers. observ.). It is only occasionally recorded above 1500 m elevation, such as on Mt. Bagong where isolated individuals were observed during this expedition at 1900 m. At the other extreme it may grow as low as 300 m a.s.l. in hill forest (see Phillipps et al. 2008: 127).

Nepenthes dactylifera is known to hybridise in nature with both N. platychila Lee (2002a: 257) and N. veitchii Hooker (1859: 421) in the Hose Mountains (see Lee 2002a, Lee 2002b) and with N. vogelii Schuiteman & de Vogel (2002: 537) in the Kelabit Highlands (AR pers. observ.).

Conservation status: — Nepenthes dactylifera is widespread in north-central Borneo above elevations of 800 m and grows within a number of protected areas, including Ulu Temburong NP in Brunei, and Batang Ai NP, Gunung Buda NP, Gunung Mulu NP and Pulong Tau NP in Sarawak. It is also likely to be present in the large Kayan Mentarang NP in North Kalimantan, which runs along the border with Sarawak and Sabah. It therefore qualifies as Least Concern when evaluated against the IUCN 3.1 criteria ( IUCN 2012).

Notes: —The ocellate crateriform glands observed on the apical protuberance of the lid of the upper pitchers ( Fig. 6G ) are variable in size, but they can be exceptionally large, in some cases exceeding 2 mm in width and 1 mm in gape, rivalling those on the much larger appendages of Nepenthes appendiculata Chi.C.Lee, Bourke, Rembold, W.Taylor & S.T.Yeo in Lee et al. (2011: 24). The glands were observed to be heavily frequented by ants on some plants, but not on others, and ants were found to be a fairly common prey type on Mt. Bagong.

A taxon belonging to Nepenthes fusca s.lat. that closely resembles N. dactylifera has been recorded from Mt. Lumarku in southern Sabah. This taxon differs in having unusually narrow, yellowish lower and upper pitchers ( Clarke 1997: fig. 58, Phillipps et al. 2008: fig. 156). In the absence of representative herbarium material and detailed field observations, it is treated as an incompletely diagnosed taxon here.

Additional specimens examined:—KALIMANTAN: Hallier 1716 (K! [4 sheets]), G. Kenepai [W. Kalimantan], no elevation data, 30 December 1893 – 5 January 1894 [separate climbing stem, leaf and upper pitcher elements]; Schmutz 7288(a) ( L!), Kalimantan Barat (W. Borneo), Mt. Keburau, 1000 m, 28 May 1989 [short stem with lower pitcher, pitcherless climbing stem]. SARAWAK: Adam 2414 ( ABD!), Miri, Mt. Mulu, 1000 m, 10 December 1987 [climbing stem with upper pitcher; originally identified as N. maxima , later as N. curtisii by J.H. Adam, 25/1/1991]; Collenette 838 (K! [2 sheets]), 2nd Div., Bukit Bangai, Sungai Lemanak, 3000 ft [= 914 m], 22 October 1961 [rosettes with lower pitchers]; Collenette 844 (K! [2 sheets]), 2nd Division, Bukit Bangai, Sungai Lemanak, 3000 ft [= 914 m], 22 October 1961 [climbing stem with upper pitcher, female inflorescence, infructescence; climbing stem with upper pitchers]; S. 19609 (Ashton) (K!, L, SAR!) Carapa Pila, Pila [Hose Mountains]/Mujong watershed, Balleh, 900 m, 7 April 1964 [K—climbing stem with upper pitchers; SAR —short stem with lower pitchers]; S. 33945 (Chai) (K!, KEP, L, MO, SAN, SAR!), 2nd Division, Lubok Antu District, Lanjak-Entimau P.F. [Protected Forest], Bukit Sengkajang, 3200 ft [= 975 m], 17 March 1974 [K, SAR —climbing stem with upper pitchers, infructescence]; S. 64997 (Yii et al.) (K, L! [2 sheets], SAR!), Bintulu div., Tatau, Ulu Sg. Sangan, Bukit Kana, 700 m, 8 October 1994 [ L —climbing stem with upper pitchers, female inflorescence; pitcherless climbing stem with male inflorescence; SAR —climbing stem with pitcher (largely missing), female inflorescence]; S. 65959 (Mohtar & Yii) (K, KEP, SAR!), Bintulu Division, Bukit Lumut, 800 m, 24 September 1992 [ SAR —climbing stem with lidless upper pitchers, male inflorescence]; S. 66985 (Yii et al.) (K, KEP, L, MO, SAN, SAR!), Bintulu Division, Tatau, Ulu Sg. Sangan, Bukit Kana, 820 m, 11 October 1994 [ SAR —climbing stem with upper pitcher bearing very broad peristome]; S. 67027 (Yii et al.) ( KEP, SAR!), Bintulu Division, Tatau, Ulu Sg. Sangan, Bukit Kana, 800 m, 13 October 1994 [ SAR —climbing stem with upper pitcher]; S. 77568 (Pearce et al.) ( SAR!), Ulu Engkari LEWS [Lanjak Entimau Wildlife Sanctuary], Bukit Pininjau, 1150 m, 1 September 1998 [climbing stem with upper pitchers]; S. 87448 (Lee & Jong) ( SAR! [2 sheets]), Limbang, Gunung Murud, side of logging road, 4°00’N 115°33’43”E, 1298 m, 24 August 2005 [climbing stem with upper pitchers, infructescence; leaf with lower pitcher]; S. 90479 (Lim & Lee) ( SAR!), Marudi, Sungai Silat Basin, SW ridge of Bukit Palutan, 2°48.00’N 115°01.33’E, 1100 m, 28 March 2003 [stem with short internodes and small laminae but bearing typical upper pitchers].

The following specimens from the Bukit Robertson area were examined as part of the assessment of N. dactylifera , but are incompletely diagnosed:— SARAWAK: S. 80625 (Julaihi et al.) ( SAR!), Belaga, ulu sungai Danum, summit of hill next [to] Bukit Robertson, 02°28’42[.]82”N 114°33’9[.]62”[E], 1100 m, 7 August 1999 [climbing stem with upper pitchers]; S. 81064 (Julaihi et al.) ( SAR!), Belaga, ulu sg[.] Danum, hill near Bukit Robertson, 02°28’7[.]10”N 114°34’2[.]98”E, 850 m, 9 August 1999 [stem with lower pitchers].

Notes on specimens examined: —The taxon from Bukit Robertson—represented by (Julaihi et al.) 80625 and 81064 —is rather distinctive, having narrowly infundibular upper pitchers with a very narrow peristome and an extremely narrow and densely hairy lid. Lower pitchers likewise have an unusually narrow peristome and lid. While N. dactylifera shows considerable variability in these characters, their expression in the plants from Bukit Robertson is extreme. Field studies are needed before a more definitive determination can be made, and we therefore treat this taxon as incompletely diagnosed at present.

At the other end of the spectrum, N. dactylifera can be a very robust species with a very broad peristome, as exemplified by (Yii et al.) 66985.

Figures

FIGURE 4. Distribution of Nepenthes dactylifera, N. fusca and N. zakriana in Borneo based on accessions held at BO, K, L and SAR herbaria, supplemented by field observations. Drawn by A.S. Robinson.

FIGURE 5. Nepenthes dactylifera A.S.Rob., Golos, S.McPherson & Barer.A—climbing stem with emerging inflorescence. B—detail of internode showing leaf base decurrency. C—lower pitcher. D—abaxial surface of lid of lower pitcher with crateriform glands. E—detail of crateriform glands along midline rib as well as adjacent scattered pitted glands. F—upper pitchers, left lateral view, right ventral view. G—lateral view of upper pitcher lid. H—detail of upper lid apical protuberance. I—inflorescence. J—seed capsules. K—male flowers. Scale bars: A, B, C, D, F, G, J = 1 cm, E, H, K = 5 mm, I = 2 cm. Based on Prance 30548, as well as on photographs and measurements made of in situ material. Illustrated by M. Barer.

FIGURE 6. Pitchers of Nepenthes dactylifera. A—lower pitcher (Kelabit Highlands). B—lower pitcher (Hose Mountains). C—upper pitcher (Kelabit Highlands). D—upper pitcher (Hose Mountains). E—exposed clay laterite habitat (Hose Mountains). F—thinly bordered crateriform nectar glands on abaxial lid surface. G—ocellate-crateriform glands in the apical region of an upper pitcher lid. F & G from Prance 30548, grids = 1 mm. Photographs A–C by A.S Robinson; D, E by M. Barer; F, G by M.R. Golos.