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Nepenthes nebularum description


As published in the:
Carnivorous Plant Newsletter

Volume 45 December 2016 

Technical Refereed Contribution
 
Nepenthes Nebularum, a new species from Mindanao, Philippines
 
Geoff Mansell • 368 Hodges Road • Cordalba • QLD 4660 • Australia • info@exoticaplants.com.au
Wally Suarez • 0309 Purok 1C • Barangay Longos, Kalayaan • Laguna 4020 • Philippines
 
  Abstract: The discovery of Nepenthes nebularum sp. nov. is here reported and thereby described as
a new addition to the Philippine Nepenthes flora. This new species is closely related to both N. truncata
and N. robcantleyi, differing mainly in the smaller stature of the plants, the more pronounced
peristome teeth, and the bronzy, rather dense, and woolly indumentum found on the petiole wings,
tendrils and traps. Further distinguishing traits are discussed in the description proper. With the
description of this new species, the number of Nepenthes species in the archipelago now stands at
over 53.
 
Key words: Nepenthes, southeastern Mindanao, Philippines
 
Introduction
 
  In September 2011 participants on a trip to a remote mountain on south-eastern Mindanao, with
well-known geographer, traveller, and author Stewart McPherson, sighted epiphytically growing
black Nepenthes truncata-like plants and photos were taken from a distance; it was stated by some
of the participants on this same trip that this was evidence of the then newly described N. robcantleyi
in habitat. However, due to the distance and foggy surroundings, no real distinguishing features
could be observed in the photo except for superficial similarities to both N. truncata (Macfarlane
1911) and N. robcantleyi (Cheek 2011). On seeing the photo and noticing differences between these
plants and N. robcantleyi, Exotica Plants organized several trips to the mountain in 2012 in hope of
obtaining more details of the plants. These were undertaken by Philippine botanist and Nepenthes/
orchid taxonomist, Wally Suarez. The mountain is very foggy, as mentioned above, and leeches as
well as spiny rattans are abundant, which made the ascent difficult. After three attempts he successfully
located a colony of these plants and a set of photographs were obtained which clearly distinguished
these plants as different from both N. robcantleyi and N. truncata (Fig. 1).
 
  
 
Figure 1: Nepenthes nebularum. Two pitchers from different plants from Mt. Mayo,
Mindanao. Photos by W. Suarez.
 
  The most notable distinguishing features of these plants are the pitchers and tendrils that are
covered with a pubescence of soft bronzy hairs resembling wool, the smaller stature of the plants,
their epiphytic preference, the lack of the lid dome (“boss”) (Cheek 2011), and the lack of bracts on
the partial peduncles of the male and female flowers. Unfortunately, no specimens were collected
on this trip.
  After more discussions with Stewart McPherson and Alastair Robinson, a further trip was incorporated
as a leg of one of their Philippine excursions. In July 2013, a group climbed the same mountain.
The route taken for this trip was different from the one used on the earlier trip by Wally Suarez
organized by Exotica Plants and a different colony of these plants was located on the mountain top.
Upon examining these photos and the discovery of this additional colony on the same mountain and
noting the apparent introgression, more research was done.
  From further photos and reports of sightings of the dark N. truncata-like plants on another
mountain, also on south-eastern Mindanao, a fourth trip was organized. This second mountain was
climbed and explored in April 2015 as a part of a Philippine excursion led by Stewart McPherson
and Alastair Robinson. In the limited time available, a colony of dark N. truncata-like plants was
located and no other Nepenthes species were seen. Photographs of the plants were taken in detail
(Fig. 2 & Front Cover) and it could be seen that these plants did not represent N. robcantleyi or N.
truncata and were nearly identical to the plants found by Wally Suarez on an earlier expedition. It
should be duly noted that as previously observed, mature plants were also about one half the size of
both N. robcantleyi and N. truncata. In the opinion of the authors, these new “black” N. truncatalike
plants clearly represent a new species and are described here as N. nebularum sp. nov.
  In July 2016, another trip, organized by Exotica Plants, was undertaken to this second mountainits
location also withheld to dissuade possible poaching—and other colonies of N. nebularum sp.
nov. were observed in detail. Plants that fall within the range of N. copelandii were also observed on
the ascent trail. Plants resembling, if not the same as, N. cornuta were also found by Wally Suarez
on the 2012 trip, but on lower altitudes where N. nebularum grows.
 
  
Figure 2: Nepenthes nebularum, Mindanao. Photo by A.Bianchi.
 
Taxonomy
 
  Nepenthes nebularum Mansell and Suarez sp. nov. (Fig. 3).
  Type: From Mindanao, Philippines, sub-adult pitcher and leaf from specimen grown from seed
at Exotica Plants. Collected on 1 July 2016. Mansell EP14, ex cult. (Holotype: BRI AQ522212).
  Description: A short stemmed rosette to 60 cm diameter and up to 1.0 m long in low light, usually
much shorter. Stems terete and up to 1.5 cm in diameter. Leaves of mature plants to 16.5 cm
long by 15 cm wide, broadly truncate, apices cordate-truncate, tips decurrent to tendril, with subobtuse
and cordate bases tapering down to the petiole. Longitudinal nerves conspicuous 4-6 on each
side of midrib, not equidistant, closer together the further away they are from the midrib. Outermost
veins not full length. Pennate nerves numerous web like, inconspicuous. Petioles shallowly cana-
liculate, from 12-15 cm long × 0.6-0.8 cm in diameter near stem. Bases clasping the stem tightly, the
wings rolling evenly and tightly, one over the other, over the adaxial canal immediately after leaving
the stem, continuing smoothly and tapering slightly to the leaf blade, where they adjoin together.
Tendrils ‘D’ shaped in cross-section. At first glance, the tendril appears terete but on closer examination,
there are two raised ribs that run from the decurrent leaf tip and increase in size with the
tendril thickness as they near the pitcher, where these continue and form the pitcher wings. Pitchers
on mature plants are from 25-29 cm long × 7.5 cm at widest point, pubescent to villous with two
distinct types/lengths of ferruginous to golden hairs. Pitcher cylindrical in most part, wider in the
upper half slightly constricted in the middle, becoming elliptical in the lower part as it tapers to the
tendril attachment, with two prominent fringed wings running +/-parallel up the front of the pitcher
and terminating just below the peristome edge. Wings ca. 1.5-1.7 cm with fringe elements from
1.2-1.5 cm long. Mouth horizontal at the front angling gradually up at about 30° and then steeply
forming a narrow neck on the pitcher. Hip on pitcher rear at the back of the mouth. Peristome 6-7 cm
wide approximately midway around mouth. Flatly rounded down following the rim of the mouth at
the front with a pronounced raised triangular fold at the front of the mouth. Rest of peristome flattened
and flared, gently curving on the outer edge between several undulations forming sharp folds.
Coarse ribs – sharp inverted ‘V’ in section, ca. 2 mm high at 3 mm spacing on the outside edge of
the peristome, closer together as they enter the mouth, terminating in sharp tooth like projections
extending into the mouth several millimeters. Lid ca.7.5 × 5.5 cm, held approximately horizontal,
deltoid-ovate. Front rounded, base cordate. Margins slightly undulate. Top surface covered in short,
golden/ferruginous hairs. Noticeably, 2 prominent rows start together from the lid attachment point,
curving outwards each side of the indent created from the keel below, and curve back in, nearly
 
 
Figure 3: Nepenthes nebularum. (A) lid upper surface, (B) lid lower surface, (C) lid pleated
tip detail, (D) basal appendage gland detail, (E) Keel, basal and apical appendages
detail, (F) top view of petiole to stem attachment, (G) top view of an entire leaf, petiole and
stem attachment, (H) detail of petiole finish at leaf blade, (I) section of male inflorescence,
(J) section of lower part of female inflorescence showing single flowered to two flowered
change, (K) pitcher, (L) mature epiphytic plant. Drawn from herbarium specimens and
habitat photos by Domonick Gravine.
 
 
meeting, at the front of the lid. There is a slight domed portion near the rear of the lid over the basal
appendage below. The lid lower surface has a raised keel running longitudinally. It has a raised
vertically flattened, rounded appendage at the rear which is in the domed portion. From about half
way along the lid length the keel widens and flattens and the front part forks into a raised, partially
hollowed, semi-cone like appendage and tapers down to a stop several millimeters from the front of
the lid. The lid is folded down between this apical appendage and creates a pleated recess which can
also be seen on the top of the lid as an elongated V-shaped depression. Small, rimmed nectar glands
present and numerous on basal appendage and around its base in the recessed area. Slightly larger
similar glands sparse around appendage base and continuing sparsely along the keel to the apex of
the lid. Lid also covered, +/- evenly spaced, and with minute recessed glands. These do not seem
to be nectar glands. Keel, basal appendage recess, and apical appendage all cream/yellow colored,
the rest of the lid underside purple/maroon. Spur simple sometimes bifurcating at tip, 2-3 cm long.
Female inflorescence up to 120 cm long, 1-flowered in the lower part and then the rest is 2-flowered,
no bracts. Peduncles ca. 50 per inflorescence. Male inflorescence ca. 80 cm long, two-flowered,
no bracts. Indumentum: Ferruginous dendritic hairs dense on pitcher and tendril ca. 0.25-0.5 mm.
Tendril, pitcher lower part, pitcher bud, midrib under leaf and petiole wings densely covered also
in tufted (caespitose) ferruginous hairs, sparse on rest of pitcher, ca. 2-3 mm long. Although these
hairs are tufted the longest one(s) extend to this length others in tuft are shorter. Short ferruginous/
golden hairs are present in a row ca. 3-4 mm running along the inside edge of the lid lower surface,
possibly dendritic in shape, 0.1 mm. Leaf upper surface has simple white hairs ca. 3 mm on entire
surface. Sparse underneath blade. Leaf margin is edged with ferruginous hairs ca. 1-2 mm.
  1. Ecology: Mainly epiphytic on tall trees in sub-montane forests at altitudes to 1,800 m asl on
two mountains in southeastern Mindanao, but suspected to occur further north, where the
seed parent of N. robcantleyi was located (see Discussion below). Sometimes lithophytic on
cliff faces. They grow sympatrically, on at least one site, with lowland N. truncata and N. cfr.
cornuta, but both occur at much lower elevations than those preferred by the new species.
However, a few plants of highland N. truncata were noted growing in the same altitude as N.
nebularum, which allows the possibility that the two species may hybridize on some occasions
(again, please refer to the Discussion below).
  2. Etymology: The name originates from the Latin word nebula, meaning clouds. Inflected in
the case genitive, nebularum means “cloud loving” and “coming from the clouds”. This is
in reference to the habitat in which the plants are growing that is frequently covered in fog.
  3. Discussion: Nepenthes nebularum sp. nov. is a member of Benedictus Danser’s putative Regiae
group, and is most closely related to N. truncata, the differences of which are summarized
in Table 1. The authors are of the position that N. alata and its associated species represent a
group of its own, and does not include N. truncata and related taxa. While the readers may
be inclined to think that this new species is the same as N. robcantleyi, we believe otherwise.
While we prefer not to discuss it in length here, it is worth noting that all plants observed in
the wild never approached the sizes obtained by N. robcantleyi. As a matter of fact, we are
of the conviction that N. robcantleyi represents a lineage rooted from a hybridogenic event
involving N. truncata and N. nebularum. On this conviction it should be duly noted that the
progeny of the N. robcantleyi cultivars was not taken into consideration as they are a further
hybridization and certainly do not all fit the description of N. robcantleyi. It is also for this
reason that we are not in favour of plans to reintroduce N. robcantleyi in the wild, and for
such purposes, N. nebularum is the logical and more preferable candidate. A separate paper
on this matter is in preparation.
 
Table 1. Differences between N. nebularum, N. robcantleyi, and N. truncata.
 
  4. Conservation Notes: Nepenthes nebularum is presently known from two disjunct mountains
in south-eastern Mindanao, but there are indications that it is much more widespread on the
island, their detection limited due to the paucity of research undertaken because of uncertainties
on securities, and their preference for growing on tall trees in high-altitude, remote
areas. On the two aforementioned mountains, human disturbance is limited on the lowermost
slopes, and traces of neither clearing nor logging were observed on the upper elevations.
Even mountaineering activities are extra-limital. However, such may not be the case on other
areas where N. nebularum is suspected to be found. Indeed, if our supposition is correct that
N. robcantleyi is a natural hybrid involving N. truncata and N. nebularum, then the population
of the latter should be already extinct on the site where the seed parent of N. robcantleyi
was found (Rob Cantley, email correspondence with Wally Suarez). Awaiting a thorough
population determination of the new species on the entire island, we propose that N. nebularum
be classified as ‘Data Deficient’ under IUCN.
 
Acknowledgements: Andrea Bianchi, Mark Rouse, Andy Smith, Alastair Robinson, Stewart
McPherson, and Ryan B. Rizalda provided insights and details pertaining to N. nebularum and its
habitat. Domonick Gravine executed the line drawings. Photographs used with permission and supplied
by Exotica Plants, Wally Suarez, Andrea Bianchi.
 
References
Cheek, M. and Jebb, M. 2001. Nepenthaceae. Flora Malesiana. Vol. 15. - Foundation Flora Malesiana
Cheek, M. 2011. Nepenthes robcantleyi sp. nov. (Nepenthaceae) from Mindanao, Philippines - Nordic
Journal of Botany 29: 677-681
Cheek, M. and Jebb, M. 2014. Expansion of the Nepenthes alata group (Nepenthaceae), Philippines,
and descriptions of three new species. Blumea 59, 2014: 144-154
Macfarlane, J.M. 1911. New species of Nepenthes. Contributions from the Botanical Laboratory of
the University of Pennsylvania 3(3): 207-210
IUCN. The IUCN Red List of Threatened Species. Version 2013.2. Available online: http://www.
iucnredlist.org

 



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