Nepenthes baramensis C.Clarke, J.A.Moran & C.C.Lee, 2011

Clarke, C., Moran, J. A. & Lee, C. C., 2011, Nepenthes baramensis (Nepenthaceae) - a new species from north-western Borneo, Blumea 56 (3), pp. 229-233 : 230-232

Nepenthes baramensis C.Clarke, J.A.Moran & C.C.Lee , sp. nov.

Nepenthi rafflesianae similis sed ascidiis aeriis in parte superiore cylindricae et texturae chartaceae differt. — Holotypus: Hotta M . 12419 ( SAR), Brunei, Belait District, Seria, en route K . Badas to Seria along the railway of B. S. C., 7 Dec. 1963 .

Etymology. The specific epithet elongata was used by G. Beck to describe a specimen of the natural hybrid, Nepenthes × hookeriana Lindl. ( Cheek & Jebb 2001) and therefore cannot be applied to this taxon. Instead, we have chosen the specific epithet baramensis , which refers to the Baram River region of north-western Borneo.This region defines the centre of abundance for this species and extends north into the Belait District of Brunei and inland as far as Gunung Mulu National Park in Sarawak.

Terrestrial climber to 6 m tall. Stems terete, up to 8 mm diam. Internodes 0.5– 1 cm on rosettes, 10–15 cm on climbing stems. Leaves of rosettes chartaceous to thin-coriaceous, petiolate, the petioles narrow, lacking wings and canaliculate, up to 12 cm long, sheathing the stem for up to 1/2 – 3/4 of its circumference, not decurrent. Leaf blades oblong, up to 30 cm long, base abruptly contracted into the petiole; apex obtuse, acuminate, tendril insertion simple. Longitudinal nerves 3 – 5 on each side of the midrib, pennate nerves spreading towards the margins, but often inconspicuous. Tendrils uncoiled, up to 35 cm long. Leaves of climbing stems similar to those of the rosettes but smaller; petioles up to 10 cm long, not winged, sheathing the stem and not decurrent; leaf blades arising gradually from the petiole, oblong, up to 18 cm long, apex acuminate, tendril insertion simple. Lower pitchers up to 20 cm high, up to 5 cm wide, thin-chartaceous, arising abruptly from the tendril, broadly ovoid in the lower 1/3 with a pronounced hip, cylindrical above, narrowing slightly towards the mouth. Inner surfaces of the ovoid portion below the hip glandular throughout, surfaces above the hip covered in a layer of wax crystals. Two fringed wings, up to 3 cm wide (widest at the base), bearing multicellular fringe elements up to 12 mm long, run from the bottom of the pitcher to the mouth at the front. Mouth round, oblique, concave, rising at the rear into a distinct neck. Peristome sub-cylindrical, up to 8 mm wide at the front and sides, up to 12 mm wide near the apex. Outer surface entire, inner surface with distinct teeth up to 5 mm long; ribs up to 1 mm apart, up to 0.5 mm wide. Lid broadly ovate, base cordate, up to 6 cm long, up to 5 cm wide, lacking appendages on the lower surface. Large, crater-like nectar glands, up to 0.5 mm wide, scattered sparsely to densely around the outer lower surfaces. Spur simple, up to 10 mm long. Upper pitchers 18–25 cm high, 3 – 5 cm wide, thin-chartaceous, arising very gradually from the hanging end of the tendril, narrowly infundibular in the lower 1/3, becoming noticeably broader towards the hip, which is located 1/2 – 2/3 of the way up the pitcher; cylindrical above the hip to the peristome. Mouth and peristome similar to the lower pitchers, the latter sometimes with a slight kink at the front. Glandular region covers the entire inner surface below the hip; cylindrical portion above the hip covered with wax crystals. Lid ovate, generally not cordate at the base, up to 6 cm long by 4 cm wide, no appendages on the lower surface. Large, crater-like nectar glands, up to 0.5 mm wide, scattered sparsely around the outer lower surfaces. Spur simple, up to 10 mm long. Male inflorescence a raceme, peduncle up to 12 cm, rachis up to 30 cm, partial peduncles 1-flowered, bracts usually absent, pedicels 12–15 mm long, tepals elliptic, up to 7 by 5 mm; androphore 5 –6 mm long, anther head 1.2 by 2 mm. Female inflorescence similar in structure to the male, peduncle up to 12 cm, rachis up to 20 cm, partial peduncles 1-flowered, lacking bracts. Valves of fruits 50 by 10 mm. Indumentum of stem, midribs, lower surface of the leaf blade and inflorescences from base of peduncle to lower surface of the tepals white or grey arachnoid; lower surface of leaf and outer surface of pitchers with minute grey stellate hairs. Other surfaces glabrous. Colour of the leaves and pitchers drying to light green or straw brown, stem white, flowers dark brown. Pitchers on living plants pure light green throughout, or green with red-purple specks on the outer surfaces and lid; peristome green throughout to striped with varying degrees of red and green. Stems whitish grey, leaves dull green.

Distribution — Borneo: Sarawak and Brunei.

Habitat & Ecology — Sparsely-distributed terrestrial climber in peat swamp forest, kerangas and kerapah habitats, occasionally locally abundant in disturbed kerangas or along kerangas forest ecotones; below 200 metres above sea level.

Other specimens examined. BRUNEI, Tutong District,near Telamba Bridge, below 100 m, Jacobs 5684 ( SAR) ; Belait District, Sg.Topi, Operation Raleigh Path, Thomas SA 175 ( KEP). Alt range: 50– 150 m. – MALAYSIA, Sarawak,4th Division, 5 km downstream from Marudi, to the left of Batang Baram, Lobok Pasar, in the swamp area with padang vegetation, about 3 km to the west from the bank of Baram River, Fuchs H. P . 21247 ( SAR); Bintulu, Sungai Penyilam, Pengkalan Kerupok, Joanes U , Tan HS, Malcolm D, Rantai J et al. S97192 ( KEP) .

Conservation status — Many peat swamp and kerangas habitats in the Baram River region in Sarawak have been cleared in recent years, but similar habitats are still widespread in the Belait District of Brunei and in Gunung Mulu National Park in Sarawak. As long as these areas remain largely undisturbed and protected from forest clearing, we consider this taxon to be at little risk and have classified it as low risk/conservation dependent (LR(cd)) according to the IUCN Red List categories ( IUCN 2001).

Notes — It is now well established that the insect trapping capabilities of N. rafflesiana and N. baramensis are significantly different ( Table 1). In addition to the production of fragrance, the complex colour contrast pattern of its pitchers ( Fig. 2 ), that appears to be ‘tuned’ to the ultraviolet, blue and green visual sensitivity maxima typical of its insect prey, allows N. rafflesiana to attract and capture prey at higher rates than N. baramensis . For reasons that are yet to be determined, N. baramensis appears to have evolved towards an alternative supplementary nutrient acquisition strategy (i.e., capturing bat faeces). This strategy is manifested in the loss of characters that specifically attract arthropods, and thus in a syndrome of characteristics that distinguish it from N. rafflesiana . It has not yet been established whether N. baramensis pitchers possess any characteristics that specifically attract K. hardwickii to roost in them, but the cylindrical upper portion of the pitcher provides an ideal physical ‘fit’ for the bats.

The present study adds to the findings of Clarke & Moran (2011) who noted that several unique ecological relationships between highly-specialized Nepenthes species and various species of animals are facilitated by modifications to pitcher characters. However, these traits either went unnoticed, or were considered unimportant or insufficiently consistent, in previous taxonomic accounts (e.g., Danser 1928, Cheek & Jebb 2001, Clarke et al. 2010). A possible explanation for this is that important ecological interactions with animals may be facilitated by minor modifications to trap characteristics ( Clarke et al. 2010, Clarke & Moran 2011), and without the support of ecological data, the taxonomic importance of these traits is easily overlooked (especially when similar traits in other species vary to greater degrees, despite having no known ecological function). Our interpretation of the status of N. baramensis is based on both ecology and plant morphology; by linking the two, we confer taxonomic value on morphological variations that might otherwise seem unimportant.

Many aspects of the functions of the distinguishing pitcher characteristics of N. baramensis , and their relevance to this species’ interaction with K. hardwickii , have yet to be investigated in detail. This also applies to other Nepenthes species that have highly specialised interactions with animals: the use of ecological information to address taxonomic questions and hypotheses is still in its infancy with regard to Nepenthes . Although the initial outcomes of this approach are encouraging, we emphasise the need for high levels of scientific rigour in designing and conducting subsequent ecological experiments for this purpose.

Figures

Fig. 2 Colour contrast patterns between peristome and adjacent outer surface of upper pitchers of Nepenthes rafflesiana Jack and Nepenthes baramensis C.Clarke, J.A.Moran & C.C.Lee. Note the complex contrast pattern in N. rafflesiana (upper panel) and the simple pattern in N. baramensis (lower panel).