A new section in Nepenthes ( Nepenthaceae ) and a new species from Sulawesi

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INTRODUCTION
While identifying loans and gifts of Nepenthes specimens at the Royal Botanic Gardens, Kew, in preparation for a monograph of the genus, the following taxon new to science was discovered in a consignment from the Royal Botanic Garden Edinburgh. It is named below as N. maryae Jebb & Cheek, and is included, with eight other species from Sulawesi and Borneo, in a new section of Nepenthes.
The newly described N. maryae has blade-like peristome ridges, similar to those of N. hamata J.R. Turnbull & A.T.Middleton (1984), which, along with the fasciculate spur, the perfoliateadnate leaves, and the rhombic mouth, all confirm the placement of this taxon in a group of species including N. tentaculata Hook.f. (Cheek & Jebb 2001), formally named below as section Tentaculatae Cheek & Jebb. The diagnostic characters separating N. hamata and N. maryae are presented in Table 1 Nepenthes maryae is unique among the species of section Tentaculatae in that the lower surface of the lid is hairy, and also because the majority (c. 75 %) of the flowers are bracteate. Bracts are otherwise absent in the group except in N. nigra Nerz, Wistuba, Chi.C.Lee, Bourke, U.Zimm. & S.McPherson (Nerz et al. 2011a), where c. 5 % of the flowers, those at the base of the inflorescence, are bracteate.
Putative novel species in Nepenthes always need to be scrutinised to determine whether they might merely be interspecific hybrids, which often occur at low frequency wherever species co-occur. Hybrids in Nepenthes are intermediate in character between the two parent species. A hybrid origin for this species can be ruled out, since no other species of Nepenthes on Sulawesi has the lower surface of the upper pitcher lid hairy, and of the Sulawesi species of section Tentaculatae, only in N. undulatifolia Nerz, Wistuba, U.Zimm., Chi.C.Lee, Pirade & Pitopang (Nerz et al. 2011b) are the stems simple-hairy as in N. maryae, but N. undulatifolia has strongly infundibular upper pitchers and oblanceolate, peltate leaf blades, characters which do not occur in N. maryae.
Although only a single specimen of N. maryae is known so far, this is not unusual in the genus, in which most species have first been described from a single specimen, and in which many species are known from single mountains. This paper forms part of studies towards a World Monograph of Nepenthes L. building on a Skeletal Revision of Nepenthes (Jebb & Cheek 1997) and the Flora Malesiana account (Cheek & Jebb 2001).
Section Tentaculatae Cheek & Jebb, sect. nov. Terrestrial climbers, lower pitchers with multicellular, filamentous projections (or 'tentacles') from the upper surface of the lid; spur usually fasciculate; most species with leaf bases of climbing stems more or less perfoliate and/ or adnate; pitcher mouth rounded to rhombic. -Type species: Nepenthes tentaculata Hook.f.
Habitat & Distribution -Submontane forest in Borneo and Sulawesi.
Some of the characters that delimit this section appear to be neotenous. The presence of multicellular projections from the upper surface of the lid, and the fasciculate spur are widespread, perhaps ubiquitous, in the seedlings of species of Nepenthes, but rarely expressed in the lower pitchers of any species except those of section Tentaculatae, possibly the only exception being N. weda Cheek (Cheek 2015). In some species of section Tentaculatae, such as N. tentaculata and N. hamata, these neotenous features are also expressed in the upper pitchers, together with fringed wings which are normal in lower pitchers (and also seedlings) but in most other species of the genus usually absent or reduced to inconspicuous ridges in the upper pitchers.
Besides being 'tentaculate', the majority of the section is also distinctive for the (sub)perfoliate-adnate leaf bases, unique in the genus apart from N. adnata Tamin  Section Tentaculatae is an addition to the six sections of the genus proposed by Danser (1928). Of the nine species included in Tentaculatae here, only one, N. tentaculata was known to Danser, which he placed in section Vulgatae Danser (1928) with 21 other species of diverse affinities. There is good molecular phylogenetic support for the section Tentaculatae. Mullins (2000) included N. muluensis, N. murudensis, N. tentaculata, N. glabrata and N. hamata in his sampling of 85 Nepenthes species. In his analysis of the biparentally inherited nuclear gene region 5S-NTS, all five species were retrieved in a crown clade with 99 % jack-knife support, while in the analysis of the maternally inherited chloroplast gene region trnL-trnF, N. muluensis, N. murudensis, N. glabrata and N. hamata form a clade with 87 % jack-knife support which is sister to a clade with a single species, N. tentaculata (Mullins 2000: 43).  Fig. 1 Differing from N. hamata in the stems densely and persistently brown patent hairy (not glabrous); the blade-like peristome ridges 1.8 -2.5 mm in length (not 12 -16 mm); leaves of climbing stems (12.5 -)14 -17(-21.5) by 2.7-3.2 cm (not 5-7(-15) by 1.8-2.5 cm); male inflorescence partial peduncles short, < 7.5 mm (not > 10 mm) and bracteate. Etymology. Named for Mary Mendum, born Bates (1945Bates ( -2004, staff botanist of the Royal Botanic Gardens, Edinburgh, botanical artist and taxonomist, specialising in Gesneriaceae of Southeast Asia, especially the genus Aeschynanthus Jack. She co-collected many specimens on expeditions in the Philippines and Indonesia, often with George Argent, including the type and currently only known specimen of Nepenthes maryae.
Conservation -Currently no imminent threats are known at the only known location of this species. According to the lead collector, only one or two plants were seen at the single known location for N. maryae (Argent pers. comm. to Cheek). It is possible that less than 50 mature individuals are present. In the same section, and also from Sulawesi, N. pitopangii has a small population size reported of 13 individuals at just two widely separated sites, despite lengthy and dedicated searching (McPherson 2011: 507-515).
Nepenthes maryae, like other species of the genus, may be restricted to the single mountain on which it was discovered, or to a small number of peaks. This is supported by the fact that so much dedicated exploration for Nepenthes novelties has taken place in the last 10 years on the mountains of Sulawesi that, had the species been present elsewhere, it would probably already have been discovered. Since on current evidence N. maryae is known only from a small population at a single site, it is here assessed as Vulnerable under criterion D2 of IUCN (2001).

DISCUSSION
The conspicuously hairy lower surface of the pitcher lid seen in N. maryae (Fig. 1i), is otherwise recorded only in N. lowii Hook.f. and N. ephippiata Danser of Borneo and N. macfarlanei Hemsl. of Peninsular Malaysia. These species belong to different sections of Nepenthes and the hairy lower surface of the lid character appears to have developed independently. In the case of the Bornean species the hairs are elaborated into robust bristles up to 1 mm diam quite different to those of N. macfarlanei and N. maryae which have fine hairs less than 0.1 mm diam. In N. lowii, N. rajah Hook.f. and N. macrophylla (Marabini) Jebb & Cheek, nutrients are obtained not only by trapping insects, but predominantly by attracting tree shrews, which lick the nectar secreted on the lids and then defecate into the pitcher mouth (Chin et al. 2010). These species have 10-15 cm broad, woody, robust pitchers with large, reflexed, concave lids. In contrast, the pitchers of N. macfarlanei and N. maryae are papery, 2 -4 cm broad, with lids flat, and held over the pitcher mouths and can be supposed to trap insects as in most species of the genus where observations on animal-protein capture have been made. Examination of the pitcher contents of both species confirms the presence of insect remains (two N. maryae upper pitchers examined contained Diptera, Coleoptera and Hymenoptera, but no ants: Argent et al. 205, K ; while two upper pitchers of N. macfarlanei contained Coleoptera and Hymenoptera, but no ants: Wray 3849, K ). It is here conjectured that the function of the fine hairs of the lids in both species is to impair secure footing of insects of these groups (but not ants) as they seek nectar from the glands of the lower leaf surface, analogous to the case of N. gracilis as revealed by Bauer et al. (2012). Bauer et al. (2012) showed that the lower surface of the lid in N. gracilis has a waxy coating of plates (unlike in most other species of the genus, where wax plates are absent from the lid) similar but differing in microstructure, to those of the detentive zone of the inner pitcher wall. Ants have no difficulty negotiating this surface in an inverted position to obtain nectar from the glands of the lower surface, except when it starts to rain. Raindrops striking the lid flick ants on its lower surface through the mouth, into the liquid at the bottom of the pitcher where they are readily wetted by the pitcher fluid and trapped (Bauer et al. 2012). The wax coating was proven to be crucial in the mechanism since once the coating was stabilised by experimental means, the percentage of ants dislodged by raindrops from the lid was greatly reduced (Bauer et al. 2012). Experimental evidence is needed to test the conjecture that the hairs on the lower surface of the lids of N. macfarlanei and N. maryae might have an analogous function.

The flick of the lid mechanism
An alternative secondary function of these hairs might be to reduce 'robbing' of nectar by animals which might be unlikely to be trapped, by acting as a barrier, much as hairs on a plant surface can act to reduce predation, however, this conjecture seems less likely than the first.