upper pitchers lack wings or fringe elements. Instead, they bear two prominent ribs running down the front, 3–5 mm apart. The glandular region covers the entire inner surface of the pitchers. The glands are small and occur at a density of 600-800 per square centimetre. The pitcher mouth is ovate and almost horizontal. The flattened peristome may be up to 6 mm wide, bearing ribs spaced 1/8 mm apart. The lid is narrow-elliptic, lacks appendages, and possesses two prominent veins, one on each side of the midrib. It is usually 1.5-2.5 cm long and 0.5-0.8 cm wide. Glands are evenly distributed on the underside of the lid. An unbranched, 1 mm long spur is inserted close to the base of the lid. Most parts of the plant are glabrous, although some may be covered with a sparse indumentum of simple hairs. Herbarium specimens are dark brown in colour. On living plants, the pitchers are yellow-green and often have varying amounts of red-brown blotches. The peristome may be yellow to dark brown. Taxonomy In their 1997 monograph, Matthew Jebb and Martin Cheek reduced N. tenuis to a synonym of N. dubia "with some hesitation". Material representing the natural hybrid N. inermis × N. talangensis (N. × pyriformis) was also identified by the authors as belonging to N. dubia. However, this interpretation is not followed by Charles Clarke, who does not consider the three taxa to be conspecific. Nepenthes dubia and N. tenuis can be distinguished with relative ease. Most obviously, the pitchers of N. tenuis have shorter, broader lids that are never reflexed beyond 180°, unlike those of N. dubia, which are always reflexed beyond 180°. The pitchers of N. tenuis are also differently coloured, often having red flecks on the outside, in contrast to those of N. dubia, which are usually a solid yellow or orange colour. The peristome of N. tenuis is also less tightly cylindrical than that of N. dubia. Nepenthes tenuis can be distinguished from N. jacquelineae by its linear-lanceolate leaf blade (as opposed to ovate-spathulate in the latter) and lack of large glands on the lower surface of the lid. The lid of N. jacquelineae also differs by being noticeably contracted towards the base. Finally, N. jacquelineae is far larger in stature compared with N. tenuis and its pitchers have a far more developed and broader peristome that is almost horizontal. In their description of the