Nepenthes orbiculata
Synonymy
- Type (designated by Catalano, M. 20181): Catalano 3 (BCU 015867), Phang Nga Province, Thailand, 2017.
Description
Upright shrub, adult plants can grow up to 1.5 m tall but the species is mostly found at the rosette stage, with scrambling stems up to 50 cm long. Stems terete, 5-10 mm in diameter. Leaves chartaceous, lamina lanceolate, to 25 cm long, 3-8 cm wide, with or without fimbriate margins, apex acute or acuminate, base subpetiolate to petiolate, semiamplexicaul; longitudinal veins 3 on each side of the midrib, pinnate veins numerous; tendrils terete, up to 25 cm long, two to four times the pitcher’s length, 2 mm in diameter. Lower pitchers 8-12 cm long, 5-7 cm wide, ovoid to ellipsoid, a hip corresponding to the edge of the glandular zone runs horizontally along the base of the peristome on the front of the pitcher and about 2 cm below the lid’s base at the back; body length/mouth length: 1.7-3.3, body length/width: 1.6-2.3; two alae, 1-3 cm wide, run down ventral exterior sur- face from mouth to tendril, fringed with narrow filaments 2-10 mm long; pitcher mouth oblique, oval to broadly oval, acute towards the lid; peristome flattened, 8-10 mm wide, teeth 0.5-1 mm long, ribs to 1 mm wide; lid orbicular to elliptic, 3-5 cm long, 2.5-5 cm wide, 2/3-3/3 as large as the mouth, slightly cordate at base, 2 main longitudinal veins and 4-8 smaller radiating veins on each side of midrib, numerous crateriform glands to 1 mm in diameter densely arranged along the sides of midrib, rare or absent along the centre; a glandular boss about 2 mm long and 1 mm wide is present on the lid’s lower surface, close to the apex; spur 5-10 mm long, simple or rarely branched. Upper pitchers 10-15 cm long, 4-7 cm wide, obconic to obovoid; alae 1-20 mm wide; mouth, peristome and lid as for lower pitchers. Indumentum: plants can be glabrous or entirely covered by an arachnoid indumentum. Colour: leaves and midrib green to red, stem and tendril red; lower pitchers bright to dark red outside, often with light green to white hues especially in the upper part, light green to white inside, peristome entirely red or light green to white along the outer margin and red along the inner margin, lid green to red; upper pitchers light green outside and inside, peristome light red or green along the outer margin and red along the inner margin, lid green.A
Notes
Putative relatives: N. orbiculata is closely related to N. mirabilis, but the two are easily told apart by the shape of the lower pitchers (globose in the former, elongate in the latter) and by the position of the pitcher hip (just below the lid in the former, at the centre or in the lower half in the latter). Nepenthes orbiculata is also closely related to N. mirabilis var. globosa, and telling them apart can be tricky: the former always has globose lower pitchers with a hip just below the lid, the latter can have that same kind of pitcher but also more elongated ones, with lower hips; the former is a low shrub, 50-150 cm long, the latter can climb up to 5 m; the former is sympatric with N. mirabilis, the latter isn’t.
The glandular boss under the lid’s tip is always present in N. orbiculata and N. mirabilis var. globosa and it’s very common in N. mirabilis. All three taxa can have leaves with fimbriate margins and be glabrous.
Nepenthes growers have often pointed out the presence of a rhizome in N. orbiculata. We did observe an underground stem in the latter, which lead us to examine and compare the root systems of the three taxa, to then find out that they are too variable to draw any line of separation.
Nepenthes growers should take into account that a specimen of N. orbiculata that is immature, etiolated or introgressed with N. mirabilis has pitchers with lower hips, so it becomes even more difficult to distinguish from a specimen of N. mirabilis var. globosa.
At the only two known locations, just a few kilometres one from the other, this species is sympatric with N. andamana and N. mirabilis. Although the hybrid N. andamana x mirabilis is the most common, representing up to one third of the local Nepenthes population, the hybrids between N. orbiculata and the other two taxa are also frequent. In these very diverse colonies, N. orbiculata occupies a somehow intermediate niche: N. mirabilis grows along the edge between the forest and the savannah, N. andamana in the savannah, and N. orbiculata in the waterlogged spots of the savannah; near ponds or streams, N. mirabilis grows 0-1 m from the water, N. orbiculata 2-3 m from the water and N. andamana from 0 m from the water onwards. The inflorescence of this species has been rarely observed in the wild and it’s mostly known from photos and cultivated specimens, but it doesn’t seem to differ from the ones of N. mirabilis and N. mirabilis var. globosa.A
The glandular boss under the lid’s tip is always present in N. orbiculata and N. mirabilis var. globosa and it’s very common in N. mirabilis. All three taxa can have leaves with fimbriate margins and be glabrous.
Nepenthes growers have often pointed out the presence of a rhizome in N. orbiculata. We did observe an underground stem in the latter, which lead us to examine and compare the root systems of the three taxa, to then find out that they are too variable to draw any line of separation.
Nepenthes growers should take into account that a specimen of N. orbiculata that is immature, etiolated or introgressed with N. mirabilis has pitchers with lower hips, so it becomes even more difficult to distinguish from a specimen of N. mirabilis var. globosa.
At the only two known locations, just a few kilometres one from the other, this species is sympatric with N. andamana and N. mirabilis. Although the hybrid N. andamana x mirabilis is the most common, representing up to one third of the local Nepenthes population, the hybrids between N. orbiculata and the other two taxa are also frequent. In these very diverse colonies, N. orbiculata occupies a somehow intermediate niche: N. mirabilis grows along the edge between the forest and the savannah, N. andamana in the savannah, and N. orbiculata in the waterlogged spots of the savannah; near ponds or streams, N. mirabilis grows 0-1 m from the water, N. orbiculata 2-3 m from the water and N. andamana from 0 m from the water onwards. The inflorescence of this species has been rarely observed in the wild and it’s mostly known from photos and cultivated specimens, but it doesn’t seem to differ from the ones of N. mirabilis and N. mirabilis var. globosa.A
Distribution (General)
Peninsular Thailand, Phang Nga Province.A
Habitat
In sandy soil, in savannahs and grasslands, at sea level.A
Specimens
| Country | Date | Collector + collecting number | Herbaria | Type | Scan | Derivatives | |
|---|---|---|---|---|---|---|---|
| Catalano 3 (BCU 015867), Phang Nga Province, Thailand, 2017. | |||||||
| Citation: Catalano 3 (BCU 015867), Phang Nga Province, Thailand, 2017. | |||||||