The specific epithetmikei honours Mike Hopkins, who co-discovered the species with the describing authors.[2]
Botanical history
Nepenthes mikei was discovered on Mount Pangulubao in September 1989 by Bruce Salmon, Mike Hopkins, and Ricky Maulder, during a Nepenthes expedition to Sumatra.[2] On this trip, the team also found two other undescribed Nepenthestaxa on the mountain: N.ovata and a plant they named N.xiphioides.[2] The latter is now considered a heterotypic synonym of N.gymnamphora.[6][7][8]
An early colour photograph of N.mikei was published by Mike Hopkins, Ricky Maulder, and Bruce Salmon, in a 1990 issue of the Carnivorous Plant Newsletter,[5] where the plant was identified simply as Nepenthes sp. 'New Species'.[4][5][6] The authors described it as follows:[5]
We saw another Nepenthes that is different than the others we saw in the higher highland areas. It has small pitchers slightly similar to N.tentaculata, N.tobaica and N.gracilis but tougher and thicker. The pitchers are always nicely colored with blackish lines and markings similar to N.fusca. There was very little variation with this species as all mature plants had ample rosettes on the ground and also at intervals up the stem. The stems were slimbing[sic] up to about 7 meters and had upper pitchers similar in color and shape to the lower pitchers but with the usual differences. The male inflorescences were about 20 centimeters, peduncle inclusive.
Prior to its description, N.mikei was known as N.minutissima among pitcher plant growers.[2][9] This name is a nomen nudum (naked name), as it was never formally published.[2]
Nepenthes mikei was formally described by Bruce Salmon and Ricky Maulder in a 1995 issue of the Carnivorous Plant Newsletter.[2] The herbarium specimen B.Salmon & R.Maulder 221719 is the designated holotype, and is deposited at the Auckland Institute and Museum (AK) in Auckland, New Zealand.[6][10] It was prepared on February 17, 1995, from a plant cultivated in New Zealand,[4] and consists of a vine bearing a femaleinflorescence, a lower pitcher, and a rosette.[2] The specimen was originally collected in 1989[4] from a "very steep ridge in wet mossy forest" near the summit of Mount Pangulubao, at an altitude of 2000m.[2] The authors described the plant as growing "in peatyhumus or moss at the base of 5–6m tall trees".[2] Salmon and Maulder also pressed a second specimen of N.mikei from material collected at the same elevation on Pangulubao.[2][note a] Additional herbarium specimens of N.mikei are known and these show slight morphological variability.[note b]
In 1997, Matthew Jebb and Martin Cheek published their monograph "A skeletal revision of Nepenthes (Nepenthaceae)",[3] in which they provided an emended description of N.mikei that encompassed specimens of the closely related, and at the time undescribed, N.angasanensis from Mount Leuser, Goh Lembuh, and the Kappi region.[6] Salmon and Maulder did not support this interpretation and reinstated their original description of N.mikei when they described N.angasanensis in 1999.[11] Jebb and Cheek retained N.angasanensis as a synonym of N.mikei in their 2001 monograph, "Nepenthaceae", writing: "We suspect that it [N.angasanensis] may prove not distinct from N.mikei and here treat it as a synonym."[4]
Description
A climbing stem with an upper pitcher, showing the lamina shape
Nepenthes mikei is a climbing plant growing to a height of 7m. The stem, which may be branched,[7] is up to 0.4cm in diameter and has cylindrical to angular internodes measuring up to 9cm in length.[6] Plants from Mount Bandahara are known to produce offshoots from short underground rhizomes.[6]Nepenthes mikei is noted for rapidly transitioning from a rosette to a climbing stage; sequential internodal lengths of 2–3mm and 10cm have been recorded.[6]
Leaves are sessile and coriaceous in texture.[6] The lamina (leaf blade) is linear and measures up to 10cm in length by 2cm in width. Its apex may be acute or obtuse and it is abruptly contracted at the base, clasping the stem for around half of its circumference.[6] One to two longitudinal veins are present on either side of the midrib, while pinnate veins are irregularly reticulate.[6] The upper surface of the lamina is typically green, but may be red if exposed to direct sunlight.[7]Tendrils are up to 15cm long.[6]
Rosette and lower pitchers are ovate in the basal third to quarter of the pitcher cup, becoming approximately cylindrical above and infundibular towards the pitcher mouth. They are relatively small, growing to only 12cm in height by 3cm in width. A pair of wings (≤4mm wide) typically runs down the ventral surface of the pitcher cup, with fringe elements measuring up to 8mm in length. These wings may be reduced to ribs in some plants. The glandular region on the inner surface is restricted to the ovate portion of the pitcher cup.[6] The glands are small (0.2–0.3mm in diameter) and occur at a density of around 150–180 per square centimetre.[2] The waxy zone is well developed[12] and eye spots may occasionally be present on the rear inner surface, visible through the opening.[7] The peristome is sub-cylindrical[6] to cylindrical and up to 4mm wide. It bears ribs up to 0.1mm high and spaced 0.2mm apart, which terminate in teeth up to 0.4mm long.[7] The inner portion of the peristome accounts for around 51% of its total cross-sectional surface length.[12] The pitcher lid or operculum is ovate and has a cordate base. It measures up to 3cm in length by 2.5cm in width and does not bear any appendages. The underside of the lid has an even distribution of small (0.1–0.2mm in diameter) convex glands, occurring at a density of about 40/cm2.[2] The spur, which is inserted near the base of the lid, is up to 7mm long and may be simple, forked, or fasciculate[7] with up to 12 branches.[2]
A typical upper pitcher
Upper pitchers are ovate in their basal third to fifth, becoming cylindrical above and infundibular towards the peristome. They are smaller than their lower counterparts, reaching only 8cm in height by 2cm in width. Wings are always reduced to ribs. In other respects, upper pitchers are similar to the lower traps.[7]
Nepenthes mikei has a racemoseinflorescence measuring up to 18cm in length by 1.8cm in diameter. The peduncle itself may be up to 8cm long by 1mm wide in female plants, and up to 3cm long in males.[7] The rachis is up to 8cm long.[6] The inflorescence bears one-flowered pedicels (≤6mm long), which may be bracteoleate.[6] The oblong-lanceolatetepals measure up to 4mm[6] in length. Fruits are up to 22mm long.[7]
Most parts of the plant are glabrous. An indumentum of short, white or yellowish hairs is usually present on the tendrils and some parts of the inflorescence.[7] This indumentum is a mixture of simple and stellate hairs.[6]Caducous hairs cover developing pitchers and other parts.[6]
The typical habitat of this species is summit scrub vegetation as well as lower and upper montane mossy forest.[6][7] It always grows terrestrially, often in open sites such as ridge tops and cliff sides, where it is exposed to direct sunlight.[6] The species is rare in blangs, where the lack of surrounding vegetation means the stems scramble along the ground.[6]Nepenthes mikei may be difficult to find on Mount Pangulubao,[14] where it is sympatric with N.gymnamphora (N.xiphioides), N.ovata, and N.spectabilis.[2] On Mount Bandahara, where it is common above 2400m,[6] it grows alongside N.diatas.[15]Natural hybrids with all of these species have been recorded.[6] At another location, which is undisclosed for conservation purposes, N.mikei grows alongside N.flava.[16]
The conservation status of N.mikei is listed as Vulnerable on the IUCN Red List, based on an assessment carried out in 2000.[1] This agrees with an informal assessment made by Charles Clarke in 2001, who also classified the species as Vulnerable based on the IUCN criteria. However, Clarke noted that since substantial populations of N.mikei lie within protected areas, they "are unlikely to become threatened in the foreseeable future".[6] Taking this into account, he suggested a revised assessment of Conservation Dependent.[6] The species is threatened by habitat loss and disturbance, as well as over-collection by plant collectors.[17]
In their description of N.mikei, Salmon and Maulder noted many differences between it and N.angasanensis which are now known to be unreliable.[6] For example, the authors wrote that N.angasanensis produces offshoots from underground rhizomes, while N.mikei does not;[2] populations of N.mikei from Mount Bandahara are now known to produce such offshoots.[6][7] Similarly, N.angasanensis was said to lack a fasciculatespur,[2] but this has since been recorded in lower pitchers of this species.[6] Disregarding these supposed differences leaves only a few stable distinguishing features between the species. Firstly, the teeth lining the inner margin of the peristome are shorter in N.mikei, although both have minute teeth and this difference is minor.[6] Secondly, the pedicels of N.mikei bear simple bracteoles, while those of N.angasanensis do not.[6] Finally, N.angasanensis exhibits a greater density of digestive glands on the inner pitcher surface.[6]
Offshoots from an old climbing stem bearing lower pitchers
Nepenthes angasanensis and N.mikei are more easily distinguished by their differing ecology. While N.angasanensis is generally found growing terrestrially or epiphytically in shady mossy forest, N.mikei is always terrestrial and favours more exposed sites where it receives strong sunlight.[6]Nepenthes angasanensis also typically produces longer stems, with regular offshoots from the leaf axils,[6] although these have been observed in N.mikei as well.[7]
Nepenthes tobaica differs from N.mikei in a number of floral and vegetative features. Whereas the latter has a shorter inflorescence with flowers borne singly on pedicels, N.tobaica has two-flowered partial peduncles. In addition, N.tobaica lacks the fasciculate spur of N.mikei and generally has wider laminae.[3][6][7]
In 2001, Charles Clarke performed a cladistic analysis of the Nepenthes species of Sumatra and Peninsular Malaysia using 70 morphological characteristics of each taxon. The following is a portion of the resultant cladogram, showing part of "Clade 6". The sister pair of N.angasanensis and N.mikei has 79% support.[6]
Nepenthes diatas is restricted to Mount Bandahara and thus this hybrid only occurs on that mountain.[6] This cross is common between 2300 and 2700m, where the altitudinal ranges of the two species overlap.[6][15] It was first reported in 1998.[15]
This hybrid is similar to N.mikei and also produces mostly black lower pitchers. It differs in that the terrestrial traps have a wider basal portion. The plant is also larger in stature, having broader stems and leaves, and bears a wider peristome than N.mikei.[6]
Nepenthes diatas × N.mikei has only been found at the forest margins in the summit area of Mount Bandahara. It has not been recorded from the mountain's open blangs.[6]
a.^ The second specimen of N.mikei, B.Salmon & R.Maulder 221718, was collected at the same elevation as the holotype and pressed on the same day. It consists of two lower pitchers, two upper pitchers, and a short shoot with pitchers. This specimen is also deposited at the Auckland Institute and Museum (AK).[2]
b.^ The herbarium specimen de Wilde & de Wilde-Duyfjes 13190 exhibits pitchers with forked spurs, unlike the fasciculate spurs of the holotype.[6] It is deposited at Herbarium Bogoriense (BO), the herbarium of the Bogor Botanical Gardens in Bogor, Java.[6]
Related Research Articles
Nepenthes villosa, or the villose pitcher-plant, is a tropical pitcher plant endemic to Mount Kinabalu and neighbouring Mount Tambuyukon in northeastern Borneo. It grows at higher elevations than any other Bornean Nepenthes species, occurring at elevations of over 3,200 m (10,500 ft). Nepenthes villosa is characterised by its highly developed and intricate peristome, which distinguishes it from the closely related N. edwardsiana and N. macrophylla.
Nepenthes spathulata is a tropical pitcher plant native to Java and Sumatra, where it grows at elevations of between 1100 and 2900 m above sea level. The specific epithet spathulata is derived from the Latin word spathulatus, meaning "spatula shaped", and refers to the shape of the lamina.
Nepenthes faizaliana is a tropical pitcher plant endemic to the limestone cliffs of Gunung Mulu National Park in Sarawak, Borneo. It is thought to be most closely related to N. boschiana.
Nepenthes adnata is a tropical pitcher plant endemic to the Indonesian province of West Sumatra, where it grows at elevations of 600 to 1200 m above sea level. The specific epithet adnata is Latin for "broadly attached" and refers to the base of the lamina.
Nepenthes angasanensis is a tropical pitcher plant species endemic to Sumatra, where it grows at an altitude of 1,400 metres (4,600 ft) to 3,100 metres (10,200 ft) above sea level. The status of this taxon is controversial as it is similar in morphology to N. mikei and N. tobaica. It has even been suggested that the taxon might represent a natural hybrid between N. densiflora and N. tobaica.
Nepenthes bongso is a tropical pitcher plant endemic to Sumatra, where it has an altitudinal distribution of 1000–2700 m above sea level. The specific epithet bongso refers to the Indonesian legend of Putri Bungsu, the spirit guardian of Mount Marapi.
Nepenthes glabrata is a tropical pitcher plant endemic to Sulawesi. The species grows in open, high forest at elevations of 1600 to 2100 m. It produces dainty, colourful pitchers reaching only a few centimetres in height. These traps are red speckled on a yellowish background, giving them a "hand painted" appearance.
Nepenthes gymnamphora is a tropical pitcher plant native to the Indonesian islands of Java and Sumatra. It has a wide altitudinal range of 600–2,800 metres (2,000–9,200 ft) above sea level. There is much debate surrounding the taxonomic status of this species and the taxa N. pectinata and N. xiphioides.
Nepenthes eustachya is a tropical pitcher plant endemic to Sumatra, where it grows from sea level to an elevation of 1600 m. The specific epithet eustachya, formed from the Greek words eu (true) and stachys (spike), refers to the racemose structure of the inflorescence.
Nepenthes sumatrana is a tropical pitcher plant endemic to the Indonesian island of Sumatra, after which it is named.
Nepenthes longifolia is a tropical pitcher plant endemic to Sumatra, where it grows at elevations of between 300 and 1100 m above sea level. The specific epithet longifolia, formed from the Latin words longus (long) and folius (leaf), refers to the exceptionally large leaves of this species.
Nepenthes dubia is a tropical pitcher plant endemic to the Indonesian island of Sumatra, where it grows at an altitude of 1600–2700 m above sea level. The specific epithet dubia is the Latin word for "doubtful".
Nepenthes talangensis is a tropical pitcher plant endemic to Sumatra, where it grows in upper montane forest at elevations of 1800–2500 m above sea level.
Nepenthes tobaica is a tropical pitcher plant endemic to Sumatra. It is particularly abundant around Lake Toba, after which it is named.
Nepenthes neoguineensis is a tropical pitcher plant native to the island of New Guinea, after which it is named.
Nepenthes rhombicaulis is a tropical pitcher plant endemic to Sumatra. The specific epithet rhombicaulis is formed from the Latin words rhombicus, meaning "rhomboid", and caulis, "stem". It refers to the cross-sectional shape of the stem internodes.
Nepenthes ovata is a tropical pitcher plant endemic to Sumatra. The specific epithet ovata is Latin for "ovate" and refers to the shape of the lower pitchers.
Nepenthes spectabilis is a tropical pitcher plant endemic to Sumatra, where it grows at elevations of between 1400 and 2200 m above sea level. The specific epithet spectabilis is Latin for "visible" or "notable".
Nepenthes beccariana is a tropical pitcher plant. The species was described in 1908 by John Muirhead Macfarlane based on a specimen collected from the island of Nias, which lies off the western coast of Sumatra. It appears to be closely related to both N. longifolia and N. sumatrana, and the former is possibly a heterotypic synonym of this taxon.
Nepenthes hamiguitanensis is a tropical pitcher plant endemic to a single peak on the Philippine island of Mindanao, where it grows at elevations of 1200–1600 m above sea level. Once thought to be a natural hybrid between N. micramphora and N. peltata, this plant is now considered a species of possible hybridogenic origin. It produces squat upper pitchers that vary greatly in pigmentation, from red speckled to yellow throughout.
1 2 Bauer, U., C.J. Clemente, T. Renner & W. Federle 2012. Form follows function: morphological diversification and alternative trapping strategies in carnivorous Nepenthes pitcher plants. Journal of Evolutionary Biology25(1): 90–102. doi:10.1111/j.1420-9101.2011.02406.x
Meimberg, H., A. Wistuba, P. Dittrich & G. Heubl 2001. Molecular phylogeny of Nepenthaceae based on cladistic analysis of plastid trnK intron sequence data. Plant Biology3(2): 164–175. doi:10.1055/s-2001-12897
Meimberg, H. & G. Heubl 2006. Introduction of a nuclear marker for phylogenetic analysis of Nepenthaceae. Plant Biology8(6): 831–840. doi:10.1055/s-2006-924676
Meimberg, H., S. Thalhammer, A. Brachmann & G. Heubl 2006. Comparative analysis of a translocated copy of the trnK intron in carnivorous family Nepenthaceae. Molecular Phylogenetics and Evolution39(2): 478–490. doi:10.1016/j.ympev.2005.11.023
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