Nepenthes hamiguitanensis

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Nepenthes hamiguitanensis
An upper pitcher of N. hamiguitanensis
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Caryophyllales
Family: Nepenthaceae
Genus: Nepenthes
Species:
N. hamiguitanensis
Binomial name
Nepenthes hamiguitanensis
Synonyms

Nepenthes hamiguitanensis is a tropical

natural hybrid between N. micramphora and N. peltata, this plant is now considered a species of possible hybridogenic origin.[1][3][4] It produces squat upper pitchers that vary greatly in pigmentation, from red speckled to yellow throughout.[2]

The

specific epithet hamiguitanensis is derived from the name of Mount Hamiguitan, to which it is endemic, and the Latin ending -ensis
, meaning "from".

Botanical history

Although only

Musuan, Bukidnon, Mindanao, Philippines.[1]

Mount Hamiguitan in 2007

Thomas Gronemeyer, Volker Heinrich and Stewart McPherson[3] carried out field studies on N. hamiguitanensis and the other species of Mount Hamiguitan between July 22–24, 2008.[1] The taxon was subsequently identified as a natural hybrid between N. micramphora and N. peltata in McPherson's two-volume monograph, Pitcher Plants of the Old World, published in May 2009.[2]

Gronemeyer returned to the site with Andreas Wistuba[3] between February 13 and 14, 2010.[1] Numerous seedlings and mature, climbing plants of N. hamiguitanensis were observed, but no intermediate plants with lower pitchers were found.[1] These field studies on Mount Hamiguitan also included observations of N. micramphora, N. justinae[5] (then regarded as a form of N. mindanaoensis), and N. peltata.[1]

Nepenthes hamiguitanensis was formally described by Thomas Gronemeyer, Andreas Wistuba, Volker Heinrich, Stewart McPherson, François Mey, and Victor B. Amoroso, in the second volume of McPherson's Carnivorous Plants and their Habitats, published in July 2010.[1][6] The herbarium specimen V.Amoroso & R.Aspiras CMUH00006494 was designated as the holotype.[1]

Description

Nepenthes hamiguitanensis is a climbing plant growing to a height of 4 m. The

internodes are 4–7 cm long.[1]

Leaves of the climbing stem are

midrib. Pinnate veins are numerous and run obliquely to the laminar margin. Tendrils are often approximately the same length as the lamina; those bearing upper pitchers are often curled.[1]

In the wild, no adult lower pitchers were recorded, and only rosette pitchers on seedling plants were recorded. For this reason they were not covered in the formal description.[1]

A typical upper pitcher

Upper pitchers are

Nectaries are evenly distributed on the underside of the lid and a prominent appendage is present at the base of the lid's lower surface. A bifurcate spur (≤4 mm long) is inserted near the base of the lid. Upper pitchers are most commonly creamy white throughout, but may also be red speckled on a yellowish background. The peristome may be creamy white, red striped, or dark red.[1]

Nepenthes hamiguitanensis has a racemose inflorescence. In the type description, the male inflorescence is recorded as being around 70 cm long by 3.5 cm wide and bearing two-flowered, ebracteate partial peduncles. These measurements are taken from field observations carried out by the describing authors at the type locality on July 23, 2008, since herbarium material of the floral structures could not be located.[1]

An coarse indumentum of short, light brown to white hairs is present on all plant parts, being particularly prominent at the laminar margins.[1]

A climbing plant with upper pitchers

Ecology

Nepenthes hamiguitanensis is

above sea level,[1] being particularly common at elevations above 1400 m.[2]

The species grows terrestrially in

ultramafic mountain, N. hamiguitanensis does not necessarily grow in an ultramafic substrate, owing to the high humus content of the forest underlayer. At the type locality, N. hamiguitanensis occurs at an average density of around two to three plants per 50 m2, as estimated by eye. Only seedlings and mature, climbing plants have been observed, with no records of larger rosette plants bearing lower pitchers.[1]

Nepenthes hamiguitanensis is

natural hybrids involving N. hamiguitanensis have been observed with certainty; it has been suggested that the flowering times of N. hamiguitanensis and the other Nepenthes species of Mount Hamiguitan may differ.[1]

The describing authors assessed the

IUCN criteria. They pointed out that N. hamiguitanensis is far more localised than N. micramphora and N. peltata, which occur at several sites on the mountain and are represented by larger populations. Mount Hamiguitan forms part of the Mount Hamiguitan Range Wildlife Sanctuary National Park and visitors are only permitted to climb the mountain with the assistance of a guide.[1][2] The future of wild populations of N. hamiguitanensis will be further secured if provincial officials of Davao Oriental are successful in their bid to gain recognition of Mount Hamiguitan as a UNESCO World Heritage Site.[1][2]

Hybrid origin

The two putative parent species of N. hamiguitanensis: an upper pitcher of N. micramphora (left) and a lower pitcher of N. peltata (right)

Nepenthes hamiguitanensis was initially assumed to represent a

natural hybrid between N. micramphora and N. peltata, both of which are also present on the upper slopes of Mount Hamiguitan.[2] It shares several morphological features with its putative parent species, such as the shape of the pitchers (with N. micramphora) and form of the indumentum (with N. peltata). However, it has distinctive light-coloured upper pitchers that neither of these species possess (N. peltata is not known to produce aerial traps at all).[1][2] In addition, N. hamiguitanensis inhabits a different ecological niche to either of these species; it typically grows in partial shade under the cover of mountain forest or at forest margins, whereas N. micramphora and N. peltata are commonly found in more exposed sites.[1]

Wild populations of N. hamiguitanensis appear to be stabilised as well as relatively

intergrades observed. The species is thought to be self-sustaining and to reproduce independently of its putative parent species, as numerous seedlings have been found at the type locality. Taking these factors into account, the describing authors wrote: "we feel that a recent hybridisation event is unlikely and that Nepenthes hamiguitanensis is not in the earlier stages of specification".[1] However, in his Carnivorous Plant Database, taxonomist Jan Schlauer treats N. hamiguitanensis as N. micramphora × N. peltata.[7]

Examples of other Nepenthes species with a putative hybrid origin include N. hurrelliana, N. murudensis, and N. petiolata.[2]

Related species

A heavily mottled upper pitcher of N. hamiguitanensis

The describing authors compared N. hamiguitanensis to N. micramphora, N. mindanaoensis, and N. peltata, which they described as "closely related species".[1] Nepenthes micramphora is smaller in all respects and is mostly glabrous (apart from the inflorescence).[1][8] Nepenthes mindanaoensis differs clearly in the shape of its upper pitchers, which are far more elongated. In addition, the species has an acute (or narrowly obtuse)[2] laminar apex as compared to the obtuse apex of N. hamiguitanensis.[1] Nepenthes peltata can be distinguished on the basis of its distinct pitchers and peltate tendril insertion. Also, unlike N. peltata, N. hamiguitanensis readily produces upper pitchers[b] and a climbing stem.[1]

In 2013,

N. kurata, N. leyte, N. mindanaoensis, N. negros, N. ramos, N. saranganiensis, and N. ultra.[9][10][11][12] These species are united by a number of morphological characters, including winged petioles, lids with basal ridges on the lower surface (often elaborated into appendages), and upper pitchers that are usually broadest near the base.[9][10] Cheek and Jebb suggested N. kitanglad and N. saranganiensis as possible close relatives of N. hamiguitanensis, these being the only other species of the N. alata group with angled stems (winged in the case of N. saranganiensis).[9]

Natural hybrids

Nepenthes hamiguitanensis has no confirmed

natural hybrids, although certain plants from Mount Hamiguitan may represent crosses involving it and N. micramphora, N. justinae[5] (previously identified as N. mindanaoensis), and N. peltata.[13]

Notes

a.^ These are the measurements for the lamina given in the formal description (diagnosis). A comparison table of related species, which was published in the same article, gives a length of 30 cm and width of 8 cm for the "leaf" of N. hamiguitanensis.[1]
b.^ An article in the September 2010 issue of the Carnivorous Plant Newsletter[14] erroneously states that N. hamiguitanensis does not produce upper pitchers.

References

  1. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab Gronemeyer, T., A. Wistuba, V. Heinrich, S. McPherson, F. Mey & A. Amoroso 2010. Nepenthes hamiguitanensis (Nepenthaceae), a new pitcher plant species from Mindanao Island, Philippines. In: S.R. McPherson Carnivorous Plants and their Habitats. Volume 2. Redfern Natural History Productions, Poole. pp. 1296–1305.
  2. ^ a b c d e f g h i j McPherson, S.R. 2009. Pitcher Plants of the Old World. 2 volumes. Redfern Natural History Productions, Poole.
  3. ^ a b c McPherson, S.R. 2010. Four new species of Nepenthes. Carnivorous Plants UK, October 11, 2010.
  4. ^ Guerini, M. 2011. "2010: new species of Carnivorous Plants" (PDF). Associazione Italiana Piante Carnivore.
  5. ^
    doi:10.3390/plants5020023
  6. ^ Nepenthes hamiguitanensis Gronem., Wistuba, V.B.Heinrich, S.McPherson, Mey & V.B.Amoroso. International Plant Names Index (IPNI).
  7. ^ Schlauer, J. N.d. Nepenthes hamiguitanensis. Carnivorous Plant Database.
  8. ^ Heinrich, V., S.R. McPherson, T. Gronemeyer & V.B. Amoroso 2009. Nepenthes micramphora (Nepenthaceae), a new species of Nepenthes L. from southern Mindanao, Philippines. In: S.R. McPherson Pitcher Plants of the Old World. Volume 2. Redfern Natural History Productions, Poole. pp. 1314–1319.
  9. ^
    doi:10.5852/ejt.2013.69
  10. ^
    doi:10.1111/j.1756-1051.2012.00099.x
  11. doi:10.3372/wi.43.43112
  12. doi:10.3767/000651913X675124
  13. Field Guide to the Pitcher Plants of the Philippines
    . Redfern Natural History Productions, Poole.
  14. ^ McPherson, S. 2010. Nepenthes palawanensis: another new species of giant pitcher plant from the Philippines. Carnivorous Plant Newsletter 39(3): 89–90.
  • Co, L. & W. Suarez 2012. Nepenthaceae. Co's Digital Flora of the Philippines.

External links

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