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Citation: Strijk JS, Sirimongkol S, Rueangruea S, Ritphet N, ChamchumroonV (2013) Lithocarpus orbicarpus (Fagaceae), a new species of Stone Oak from Phang Nga province, Thailand. PhytoKeys 34: 33–45. doi: 10.3897/phytokeys.34.6429
A new species is described, Lithocarpus orbicarpus Strijk, collected from Ton Pariwat Wildlife Sanctuary, Mueang district, Phang Nga Province in the Peninsular Floristic Region of Thailand. We provide the first technical illustrations and colour photographs of the new species, as well as a description of its conservation status and the collecting locality. The species can be easily distinguished by its unique orbicular acorns, each covered with a dense pattern of irregularly placed scales, which completely conceal the nut, except for a tiny apical pore, and which are arranged in a dense cluster on an erect woody spike. We also provide an amendment to the existing diagnostic key to Lithocarpus, and discuss important differences with morphologically similar species found in Thailand and the surrounding region.
Lithocarpus orbicarpus, new species, Stone Oaks, Fagaceae, Thailand, Ton Pariwat Wildlife Sanctuary
Lithocarpus Blume is the second largest genus within Fagaceae, with over 300 species described (
Previous studies and the most recent treatment for Thailand have recovered 57 species of Lithocarpus (
urn:lsid:ipni.org:names:77135982-1
http://species-id.net/wiki/Lithocarpus_orbicarpus
Fig. 1, 2THAILAND, Ton Pariwat Wildlife Sanctuary, Mueang district, Phang Nga Province, 8°37'25"N; 98°33'14"E; alt. 455 m, 16 July 2013, Chamchumroon et al. 5823 (Holotype: BKF; Isotypes: E, K, L, SING).
Lithocarpus orbicarpus is a small-medium sized tree. It differs from similar species by its unique orbicular acorns, each covered with a dense pattern of irregularly placed scales, which completely conceal the nut, except for a tiny apical pore, and which are arranged in a dense cluster on an erect woody spike. Unique for Thai species of Lithocarpus, almost the entire surface of the round nut is covered with scar area (receptacle tissue), leaving only the topmost part of the nut covered with a thin vestigial exocarp layer. Pending discovery of additional individuals, the species appears to be locally restricted to low-mid-elevation forests in the peninsular region of Thailand.
Small-medium sized tree, up to 15 m tall. Bark smooth to slightly rough grey-green, with superficial horizontal lines. Sapwood white to yellow, with inner bark ridges forming light brown longitudinal slits in sapwood surface. Branches dark brown to grey brown, mostly glabrous, densely lenticellate; young twigs, leaf buds and old fruits with short, soft (occasionally long) gray indumentum. Leaf buds tiny and terminal buds solitary. Leaves simple; lamina elliptic to oblanceolate with (strongly) acuminate tip, 11.0–22.3 × 4.4–7.1 cm. Margin entire. Leaves often with slightly asymmetric lamina. Leaf apex acuminate to strongly acuminate, leaf base cuneate to slightly attenuate. Both surfaces generally glabrous except emerging leaf buds, terminal shoots and young leaves, which have soft grey indumentum. Young leaves light green, but turning dark green above and glaucous below when older. Venation. Pinnately veined; secondary venation discretely anastomosing near the leaf margin. Pairs of secondary veins 9–13, slightly raised and clearly visible on underside of leaf. Peduncles carrying fruits 5–11 cm long, up to 1 cm thick at the base, glabrescent, grey-brown and densely lenticellate. Male and female inflorescences not seen. Infructescence a woody spike, terminal, up to 15–21 cm long. Fruits sessile on thick woody peduncle, closely pressed against each other, but walls of individual units not fused. Number of fruits per infructescence very variable, ranging from 9–20 units. Acorn. Orbicular, globose, 2.7–3.4 by 2.9–3.5 cm (including cupule) and covered with glabrous, semi-concentric interlocking ridges when young, which transform over time into ridges with irregularly placed scales. Cupule nearly completely enclosing the nut, indehiscent, but showing small cracks when mature; fruit wall up to 4–6 mm thick, apical pore very small, 1–4 mm wide, exposing the persistent punctiform styles (3) and a tiny fraction of vestigial exocarp. Young cupule walls light green, ridges light to dark brown. Old cupule walls turning light brown to yellow-brown and pubescent with short (occasionally long), greyish-yellow indumentum. Nut 1 in each cupule, ball shaped, globose, 2.4–2.9 by 2.6–3.0 cm. Up to 95% of surface area of the nut made up of scar area (receptacle tissue), upper 5% of surface area of the nut slightly raised and made up of vestigial exocarp layer. Nut scar pale yellow-whitish, tiny exocarp layer light brown. Scar area covered with deep groves and red-brown to purplish vein-like lines, stretching down to the base of the nut. Up to 5/6 of the scar area of the young nut (from the base upward) covered with dotted pattern of small depressions. Cotyledons black when dried.
Lithocarpus orbicarpus Strijk, sp. nov. Chamchumroon et al. 5823 (BKF). Technical illustration. A Habit B Detail of glabrous young fruit with ridges and apical pore C Detail of interior of young fruit, showing nearly complete fruit scar, covered umbo and 'pitted pattern'; on the nut surface D Infructescence with ripe fruits showing highly irregular scaly patterns on the fruit exterior E Details of seed, from left to right: bottom view, side view, top view. Note venation and crevice pattern on surface of fruit, and cover of the umbo section. All drawings by J.S. Strijk.
Lithocarpus orbicarpusStrijk, sp. nov. Chamchumroon et al. 5823 (BKF). Pictures from field collection. A Branch with leaves B Young infructescences C Bark and sapwood D Fresh fruit – top view E Fresh fruit – side view F Fresh fruit – bottom view G Dried fruit – top view H Dried fruit – side view J Dried fruit – bottom view (G–J: blue lines demarcate vestigial exocarp; red lines demarcate scar area (receptacle tissue)) K Dried infructescence L Young acorn, opened up to show dotted pattern of small depressions and surface structure of the umbo M Cross-section of fried nut, showing seed coat and black cotyledons N Terminal leaf, twig and very small terminal bud, showing grey indumentum O Young emerging leaf with soft grey indumentum. All pictures by S. Sirimongkol and J. S. Strijk.
Flowering unknown, but thought to be around November-January. Infructescences on the ground in July, fruiting commencing possibly as early as April-May.
This species is only known from Thailand, and has not been recorded outside Ton Pariwat Wildlife Sanctuary, Mueang district, Phang Nga Province. During our field survey, we found only one individual tree, located on a gentle sloping section of closed dense forest. Additional survey work will have to be undertaken to determine the actual population size of this species within the wildlife sanctuary.
This species grows in dense hillside forest at an elevation of around 450 m.
Unknown.
Lithocarpus orbicarpus is named after its unique orbicular acorns, arranged densely clustered on an erect spike, of which the cup almost completely encloses the nut (except for a tiny apical pore). The exterior of the cup is covered with a dense pattern of ridges, transforming with age into horizontal and vertical lines with irregularly placed scales. Apart for a tiny portion of the umbo which is covered with vestigial exocarp, the exterior surface of the nut is completely covered by scar. Although the cupule nearly completely covers the nut, the latter is free and not fused to the wall of the cupule – a condition which occurs throughout the genus (
Thailand has a total of 121 species, 2 subspecies and 2 varieties of Fagaceae in four genera indigenous to the country. Of these, nine species (Castanopsis: 4; Quercus: 1; Lithocarpus: 4) and 1 subspecies (Quercus: 1) are national endemics (
Lithocarpus in Thailand can be further characterized based on their acorn (cupule+nut) properties. The open- or semi-open type, in which the cupule shape ranges from saucer shaped-flat to covering up to 4/5th of the nut is present in 37 species (64%), while the remaining 18 species have cupules that entirely cover the nut, in most cases leaving a tiny portion of the umbo uncovered. With one exception (Lithocarpus truncates (King ex Hook.f.) Rehder), all closed-type species occur in the Peninsula, and eight are restricted to it (two shared with the Southeast). Lithocarpus orbicarpus resembles species in this group, with its indehiscent and near-closed cupules, restricted geographical distribution and presence in lower elevation habitat, but is clearly distinct from them based on the structure and shape of the fruit, the infructescence and the properties of the nut.
During our field survey, we encountered and collected additional Fagaceae species, e.g. Lithocarpus reinwardtii (Korth.) A.Camus (Burma, Cambodia, Malaysia, Indonesia), Lithocarpus sundaicus (Blume) Rehder (Malaysia, Indonesia, Brunei), Lithocarpus cantleyanus (King ex Hook.f.) Rehder (Burma, Malaysia, Singapore) and several, as of yet, unidentified collections. Additional species encountered in previous surveys in the wildlife sanctuary are: Castanopsis javanica (Blume) A.DC. (Vietnam, Malaysia, Singapore, Indonesia); Castanopsis nephelioides King ex Hook. f. (Malaysia, Singapore); Castanopsis purpurea Barnett (Thailand (endemic)); Castanopsis wallichii King ex Hook. f. (Malaysia, Singapore, Indonesia); Castanopsis inermis (Lindl.) Benth. & Hook. f. (Burma, Malaysia, Singapore, Indonesia, Philippines); Lithocarpus bennettii (Miq.) Rehder (Malaysia, Singapore, Indonesia); Lithocarpus clementianus (King) A.Camus (Malaysia, Indonesia); Lithocarpus eucalyptifolia (Hickel et A.Camus) A.Camus (Burma, Vietnam, Cambodia); Lithocarpus falconeri (Kurz) Rehder (Burma, Malaysia); Lithocarpus garrettianus (Craib) A.Camus (China, Burma, Laos, Vietnam); Lithocarpus lucidus (Roxb.) Rehder (India, Malaysia, Singapore, Indonesia, Brunei); Lithocarpus macphailii (Henders.) Barnett (Malaysia, Indonesia); Lithocarpus wrayi (King) A.Camus (Vietnam, Malaysia, Indonesia) and Quercus oidocarpa Korth. (Burma, Vietnam, Malaysia, Indonesia). Out of these 17 species, at least 14 have a geographic distribution that is primarily or completely located in the Sundaland biogeographic region. Conversely, only three species have a distribution that is mostly or entirely contained within the Indochinese biogeographic region. Despite the paucity of detailed biological records on this remote area, the distributional data shows us that the Fagaceae flora in Ton Pariwat Wildlife Sanctuary is distinctly Sundaic in composition, and differs substantially from forests in the more northern Indochinese region. This is in fact not surprising, as the Ton Pariwat Wildlife Sanctuary is located near the southern edge of one of the world’s major phytogeographic and zoogeographic transition zones: the ~500km stretch between the biogeographically distinct and well-known Isthmus of Kra – the narrowest part of the connection between mainland Southeast Asia and the Malay Peninsula (10°30'N) – and the line between Kangar (Malaysia) - 6.°51’N, and Pattani (Thailand) 6°87'N. Within this relatively short distance, an abrupt and major shift takes place from northern Indochinese flora and fauna, to those distinct for the southern Sundaland region (
When looking at the Fagaceae flora in the wider region, some properties of Lithocarpus orbicarpus resemble species in Peninsular Malaysia, such as Castanopsis nephelioides King ex Hook.f., but can easily be distinguished from species within Castanopsis (D.Don) Spach, based on the presence of bark ridges that penetrate the sapwood, the nut which is not fused to the cup and the orbicular shape of the fruit. Congeneric species from the Indo-Chinese zone that share some characters with Lithocarpus orbicarpus are Lithocarpus rouletii (Hickel & A.Camus) A.Camus (but fruit with basal scar, flattened, dehiscent; South Vietnam); Lithocarpus pachycarpus (Hickel & A.Camus) A.Camus (but leaves with yellow indumentum, cupules pear-shaped, acorns not orbicular; Vietnam-Laos); Lithocarpus kontumensis A.Camus (but cupules truncate, higher than acorn, cupules sometimes fused; Vietnam-Laos); Lithocarpus lepidocarpus (Hayata) Hayata (but cupules truncate, sometimes fused, fruit not orbicular; central and south Taiwan); and Lithocarpus laoticus (Hickel & A.Camus) A.Camus (but cupule ovoid, high elevation habitat (Tibet, south and central China, Vietnam) (
This species is endemic to Thailand and is currently only known from one location in Ton Pariwat Wildlife Sanctuary. The sanctuary covers a region of low-lying forested mountains with a total area of approximately 100, 000 ha at the southern end of the Phuket mountain range. As such it is an integrated part of the Southern Forest Complex of Thailand. The sanctuary is popular for its rich bird- and wildlife (e.g. Blue-banded Kingfisher (Alcedo euryzona Temminck, Alcedinidae) and Whitehanded Gibbons (Hylobates lar L., Hylobatidae) as well as rare flora, such as Rafflesia kerrii Meijer (Rafflesiaceae). Its unique species composition, high diversity and relatively intact forest structure underscore the importance of strengthening ongoing and future conservation measures at Ton Pariwat Wildlife Sanctuary, as a key element of wider conservation efforts in southern Thailand.
Morphological differences between Lithocarpus orbicarpusand other Thai species of Fagaceae.
Characters | Lithocarpus orbicarpus Strijk | Lithocarpus encleisocarpus A.Camus | Lithocarpus wrayi (King) A.Camus | Castanopsis nephelioides King ex Hook.f. |
---|---|---|---|---|
1. Nut wall | Free from the cup | Free from the cup | Free from the cup | Fused to the cup |
2. Cupule enclosure | Almost complete, but small apical pore showing flat umbo remains (≤5%). Indehiscent. | Almost complete, but raised umbo free (±5-10%). Easily dehiscent in irregular parts. | Almost complete, but raised umbo free (±5-15%). Indehiscent. | Enclosure complete. Indehiscent. |
3. Nut shape | Orbicular. | Ovoid to globose. | Broadly conical. | Ovoid, usually depressed to one longitudinal side. |
4. Cup surface | Spines absent. Small, flattened scales present. Irregularly intersecting lines present.<br/> Old acorns pubescent with short (occasionally long), greyish-yellow indumentum. | Spines and scales absent. Wall smooth, densely greenish-brown hairy. | Alternate pseudo-spines and free scales present; pseudo-spines incurved or erect. | Sparsely covered with short, woody spines, 2-3 branched reclining and decurved. |
5. Acorn shape | Orbicular, symmetric; young fruits occasionally slightly skewered in young and dense infructescences | Ovoid or turbinate. | Broadly ovoid. | Obovoid, always asymmetric, usually flattened adaxially. |
6. Leaf margin | Entire throughout. | Entire throughout. | Entire throughout. | Entire or serrate in the upper half. |
7. Scar position, shape and size | Orbicular, covering ≥95% of the fruit, from the base upward. | Basal, slightly concave, ca. 1 cm in diameter. | Basal, concave, ca. 1.5 cm in diameter. | - (nut fused to wall). |
8. Nut indumentum | Glabrous. | Greyish pubescent. | Sparsely sericeous then dull brown. | - (nut fused to wall). |
Following the treatment of Fagaceae for the Flora of Thailand (
(based on vegetative characters and acorns)
1 | Outer surface of cupules with annular or lamellate markings or markings lacking | |
2 | Cupules without lamellae, chartaceous or subcoriaceous, enclosing nearly all of the nut, more or less dehiscent when mature | |
3 | Cupules weakly dehiscent from the apex, cupule surface distinctly undulate with vertical and horizontal lines | |
4 | Cupule urn-shaped | |
5 | Cupule base broadly conical, much broader than apex, skin distinct with many vertical filiform lines or without. Nut conical | 5. Lithocarpus blumeanus |
5 | Cupule base obconic, much narrow than apex, surface distinct with 3-4 horizontal filiform lines. Nut obconical | 33. Lithocarpus maingayi |
4 | Cupule top or globe shaped | |
6 | Cupule top-shaped, enclosing 4/5 of nut, surface with 2–6 distinct horizontal, filiform lines | 30. Lithocarpus macphailii |
6 | Cupule globe-shaped, enclosing nut completely, except for a tiny section at the apex, surface with distinct irregularly placed scales along 5–9 horizontal and vertical lines | 36. Lithocarpus orbicarpus |
3 | Cupules readily dehiscent into irregular parts from the top, surface with 2–5 filiform, undulate, horizontal lines | |
7 | Cupules with 2 or 3 such lines | 18. Lithocarpus encleisocarpus |
7 | Cupules with 4 or 5 such lines | 37. Lithocarpus pattaniensis |
2 | Cupules with distinct lamellae, coriaceous, enclosing a variable amount of the nut, indehiscent | |
8 | Cupule enclosing not less than 1/2 of the nut | |
9 | Cupule enclosing about 1/2 of the nut | |
10 | Nuts ovoid to conical at apex, scar shallowly concave or flattened | 24. Lithocarpus gracilis |
10 | Nuts subhemispheric or depressed at apex, scar deeply concave | 8. Lithocarpus clementianus |
9 | Cupule enclosing not less than 3/4 of the nut | |
11 | Cupules obconic, enclosing nut almost completely except around the umbonate apex | |
12 | Nut longer than broad, ca. 1 by 0.7 cm | 26. Lithocarpus hendersonianus |
12 | Nut shorter than broad, 1–2.7 by 2–3 cm | 32. Lithocarpus magnificus |
11 | Cupules saucer-shaped, enclosing ca. 3/4 of the nut | 1. Lithocarpus aggregatus |
8 | Cupule enclosing not more than 1/4 of the nut | |
13 | Nuts hemispheric or depressed on both sides | |
14 | Cupule enclosing 1/5 to 1/4 of the nut | 39. Lithocarpus platycarpus |
14 | Cupule enclosed only the base of the nut | |
15 | Acorns sessile. Scar deeply concave | 15. Lithocarpus eichleri |
15 | Acorns with stalk up to 0.5 cm long. Scar slightly concave | 6. Lithocarpus cantleyanus |
13 | Nuts conical to broadly ovoid, or with a dome-shaped apex | |
16 | Cupule enclosing only the base of the nut | |
17 | Acorns sessile. Leaves oblanceolate | 29. Lithocarpus lucidus |
17 | Acorns with fruit-stalk up to 0.5 cm long. Leaves oblong | 43. Lithocarpus reinwardtii |
16 | Cupule enclosing ca. 1/4 of the nut | |
18 | Nut with one horizontal ring around equator. Leaves ensiform to linearlanceolate | 28. Lithocarpus loratefolius |
18 | Nut without horizontal ring. Leaves ovate, ovate-oblong or narrowly elliptical | |
19 | Nut ovoid or conical. Cupules cup or saucer-shaped. Leaves ovate or ovate-oblong, apex caudate | 3. Lithocarpus bancanus |
19 | Nut broadly ovoid. Cupules slightly obconical to saucer-shaped. Leaves narrowly elliptical | 41. Lithocarpus rassa |
1 | Outer surface of cupules with alternate lamellae (resembling fish scales) or pseudospines | |
20 | Mature cupules of one infructescence more or less fused together | |
21 | Acorns broader than long, depressed both on top and at base. Cupules saucer- or cupshaped or obconic, some hardly distinct from each other through fusion | |
22 | Infructescences with densely arranged cupules | |
23 | Cupules barely distinct, resembling a large gall | 13. Lithocarpus echinophorus |
23 | Cupules distinct, saucer-shaped | |
24 | Nut flattened or apiculate at apex, to 2.2 cm diam. Leaves cuneate at base | 16. Lithocarpus elegans |
24 | Nut retuse at apex, not less than 3 cm diam. Leaves auriculate at base | 2. Lithocarpus auriculatus |
22 | Infructescences with spaces between cupules | |
25 | Rachis of infructescence always with sub-branches. Acorns stalked | 34. Lithocarpus mekongensis |
25 | Rachis of infructescence without sub-branches | |
26 | Acorns sessile | 24. Lithocarpus finetii |
26 | Acorns stalked | 50. Lithocarpus tenuinervis* |
21 | Acorns longer than broad, conical, ovoid or turbinate. Cupules cup-shaped or cylindric | |
27 | Rachis of infructescence always with sub-branches. Acorns stalked, nuts shining | |
28 | Acorn up to 1 cm high. Rachis up to 4 mm in diam. | 7. Lithocarpus ceriferus |
28 | Acorn not less than 1 cm high (to 2.5 cm). Rachis not less than 4 mm in diam | 40. Lithocarpus polystachyus |
27 | Rachis of infructescence without sub-branches. Acorns sessile, nuts more or less shining | |
29 | Twigs glabrous or sparsely pubescent then glabrous | |
30 | Cupules cup-shaped, enclosing up to 1/2 of the nut | 12. Lithocarpus dealbatus |
30 | Cupules turbinate, enclosing the whole nut, open only around umbo | 53. Lithocarpus truncatus |
29 | Twigs ferruginous or tomentose | |
31 | Leaves glabrous except along midrib. Cupules enclosing up to 1/3 of the nut | 25. Lithocarpus harmandianus |
31 | Leaves densely tomentose especially on lower surface. Cupules enclosing 1/2 of the nut | 27. Lithocarpus lindleyanus |
20 | Mature cupules of one infructescence, free, not fused | |
32 | Acorn longer than broad, conical, ovoid or obconical. Cupules cup- or saucer-shaped or obconic | |
33 | Cupules enclosing nut completely or 2/3 of the nut | |
34 | Cupules enclosing ca. 2/3 of the nut | |
35 | Cupules slightly obconical-shaped, nuts hairy at style apex (if persistent) | 45. Lithocarpus rufescens |
35 | Cupules cup or saucer-shaped | 16. Lithocarpus elegans |
34 | Cupules enclosing nut completely, or up to the apex of the nut | |
36 | Cupules dehiscent, obconic or ovoid | |
37 | Cupules obovoid, sessile, surface with dense, long and narrow recurved pseudospines | 42. Lithocarpus recurvatus |
37 | Cupules ovoid, fruit stalk 2–3 mm long, surface finely ornamented with thin, triangular lamellae throughout | 35. Lithocarpus neo-robinsonii |
36 | Cupules indehiscent, ovoid, surface clothed with dense, triangular lamellae | |
38 | Infructescences up to 18 cm long. Leaves up to 16 cm long | 9. Lithocarpus craibianus |
38 | Infructescences not less than 20 cm long. Leaves not less than 20 cm long | 19. Lithocarpus erythrocarpus |
33 | Cupules enclosing up to 1/2 of the nut | |
39 | Acorns stalked | |
40 | Cupules slightly obconic. Leaves ovate, ovate-oblong or obovate | 48. Lithocarpus sootepensis |
40 | Cupules cup-shaped or saucer-shaped | |
41 | Cupules cup-shaped. Leaves lanceolate to lanceolate oblong | 47. Lithocarpus siamensis |
41 | Cupules saucer-shaped to flattened. Leaves oblong to oblong-lanceolate | 10. Lithocarpus curtissii |
39 | Acorns sessile | |
42 | Acorns (mature) not less than 3.5 by 2.2 cm | |
43 | Cupule lamellae bearing pseudo-spined reflexed towards the base. Leaves acute to obtuse at apex | 46. Lithocarpus scortechinii |
43 | Lamellae curved towards the cupule apex. Leaves acuminate at apex | 20. Lithocarpus eucalyptifolius |
42 | Acorns (mature) up to 3 by 2.2 cm | |
44 | Infructescence with acorns in clusters, but not fused | |
45 | Nuts ovoid. Leaves usually curved to one side | 54. Lithocarpus wallichianus |
45 | Nuts strongly apically depressed, occasionally conic. Leaves not curved | 51. Lithocarpus thomsonii |
44 | Infructescence with acorns solitary, with spaces between them | |
46 | Cupules saucer or cup-shaped, limb recurved. Leaves not less than 12 cm long | 21. Lithocarpus falconeri |
46 | Cupules obconical, limb not recurved. Leaves up to 11 cm long | 4. Lithocarpus bennettii |
32 | Acorns broader than long, hemisphaeric-depressed | |
47 | Cupules enclosing the nut completely or up to the apex of the nut | |
48 | Cupules more or less up to the apex of the nut, lamellae with erect or reflexed pseudospines which are not fused | |
49 | Pseudo-spines erect or spreading. Leaves oblanceolate. Scar nearly 1/2 of the nut | 14. Lithocarpus echinops |
49 | Pseudo-spines reflexed. Leaves oblong or oblanceolate | |
50 | Infructescence with acorns packed close together, but not fused. Leaves slightly cuneate at base | 23. Lithocarpus garrettianus |
50 | Infructescence with acorns solitary, with spaces between them. Leaves obtuse at base | 54. Lithocarpus tubulosus |
48 | Cupules enclosing the nut completely, except the umbo | |
51 | Lamellae pointed, with narrowly pseudospines. Infructescence with acorns packed close together, but not fused | 57. Lithocarpus wrayi |
51 | Lamellae flattened and imbricate. Infructescence with acorns solitary, with spaces between them | |
52 | Lamellae fused on lower half, the upper half free and adaxially curved | 22. Lithocarpus fenestratus |
52 | Lamentas fused almost to apex, only a short free lobe adaxially curved | 52. Lithocarpus trachycarpus |
47 | Cupules enclosing up to 1/2 of the nut | |
53 | Acorns stalked, cupules enclosing only base of the nut | |
54 | Stalk up to 1 cm long. Leaves glaucous on lower surface, petiole up to 1 cm long | 49. Lithocarpus sundaicus |
54 | Stalk not less than 1 cm long. Leaves pale on lower surface, not glaucous, petiole not less than 1 cm long | 31. Lithocarpus magneinii |
53 | Acorns sessile, cupules enclosing up to 1/2 of the nut | |
55 | Acorns not less than 2 by 2.5 cm | |
56 | Cupules slightly obconical. Leaves oblong, acute to caudate at apex, margin not revolute, petiole not less than 1 cm | 11. Lithocarpus cyclophorus |
56 | Cupules saucer-shaped. Leaves obovate, obtuse at apex, margin revolute, petiole up to 0.6 cm long | 44. Lithocarpus revolutus |
55 | Acorns up to 1.5 by 2 cm | |
57 | Nuts convex at the apex | |
58 | Cupules saucer-shaped to flattened and discoid. Leaves not whorled | |
59 | Lamellae usually fused throughout. Leaves up to 15 cm long | 38. Lithocarpus pierrei |
59 | Lamellae fused at base only, apices free. Leaves not less than 18 cm long | 17. Lithocarpus elephantum |
58 | Cupules cup-shaped. Leaves usually whorled at the twig tips | 58. Lithocarpus xylocarpus |
57 | Nuts flattened at the apex. Cupule cup-shaped, enclosing 1/5 to 1/2 of the nut. Leaves with unequal sides, usually curved to one side | |
60 | Leaves oblong, elliptic oblong, not less than 10 by 3.5 cm, with 14–20 pairs of lateral nerves | 55. Lithocarpus vestitus |
We are grateful to staff of the Ton Pariwat Wildlife Sanctuary for assistance in the field. We thank R. Pooma and staff of the Forest Herbarium (BKF) for access to collections. Finally, we would like to acknowledge S. Suddee and A. Sinbumroong for advice in identification and the preparation of this manuscript. The first author was supported by a Postdoctoral Research Fellowship of the Chinese Academy of Sciences (2011–2014).