Introduction

Garcinia L. is a group of dioecious, sometimes polygamo-dioecious, evergreen trees, occasionally shrubs and the largest genus in the Clusiaceae Lindl. (Guttiferae Juss.). The genus consists of 403 accepted species, and is distributed throughout the tropics and subtropics (POWO 2022) with centres of diversity in Southeast Asia and Madagascar (Sweeney & Rogers 2008). In Asia, Garcinia is most diverse in the Malesian region but also spreads north into southern China, west to India and east to the Micronesian islands (Nazre et al. 2018). Previous studies on Garcinia revealed that the Malay Peninsula had c. 60 species (King 1890; Ridley 1922; Kochummen & Whitmore 1973; Whitmore 1973), India 40 species (Maheshwari 1964; Singh 1993; Srivastava 1994; Sabu et al. 2013; Sarma et al. 2016; Shameer et al. 2017, 2021), Indo-China 34 species (Gagnepain 1943), China 20 species (Li et al. 2007) and Java 8 species (Backer & Bakhuizen van den Brink 1963).

In Thailand, 20 species of the genus Garcinia were enumerated by Craib (1925), the northern region had 6 species (Gardner et al. 2000), and the peninsular region had 23 species (including 5 unidentified species) (Gardner et al. 2015). In 2016 and 2022, Ngernsaengsaruay & Suddee described two new species: G. nuntasaenii from north-eastern Thailand and G. santisukiana from eastern Thailand (Ngernsaengsaruay & Suddee 2016, 2022). In 2022 Ngernsaengsaruay et al. described G. dumosa King as a new record from Peninsular Thailand (Ngernsaengsaruay et al. 2022).

Garcinia is characterised by a dioecious habit, the plant sometimes apparently polygamo-dioecious; yellow, pale yellow, white, cream or clear latex secreted from cut boles, twigs, leaves and fruits; decussate leaves with scattered black or brown gland dots, or interrupted wavy lines of differing lengths; 4- or 5-merous flowers; many to numerous stamens, always united in a bundle at the centre of the flowers: 4 or 5 bundles, distinctly or weakly 4-lobed, 4-angled, a column or a ring; fruits berries, and seeds usually with thick or thin sarcotesta (Ngernsaengsaruay et al. 2022).

A taxonomic revision of the genus Garcinia has recently been undertaken by the first author as part of the Flora of Thailand. A. F. G. Kerr first found and collected specimens of a Garcinia with yellow fruits on 14 March 1928 from evergreen forest, Khlong Ton, Satun Province (originally labelled “Garcinia sp.”, C. Ngernsaengsaruay identified this as G. gracilis Pierre, 2 June 2011). Mr Sarmrong then found and collected specimens of a Garcinia species with young fruits in Jan. 1969 from evergreen forest, Khao Chong, Trang Province (originally labelled “G. cf. rostrata”). Dr Chawalit Niyomdham then collected specimens of this species with yellow fruits (originally labelled “G. cf. urophylla”) in May 2001 from Sirindhorn Waterfall, Narathiwat Province. Mr Pachok Puudjaa and Mr Chandee Hemrat collected specimens with mature and ripe fruits (originally labelled “G. urophylla Scort. ex King”) in Aug. 2009 from evergreen rain forest, Hala-Bala Wildlife Sanctuary, Waeng Distr., Narathiwat Province. Dr Voradol Chamchumroon et al. then collected specimens with ripe fruits (originally labelled “Garcinia sp.”, identified by H. Toyama as G. lanceifolia Roxb.) in Dec. 2011 from evergreen forest, near the 24-ha long-term ecological research plot, Khao Chong, Na Yong Distr., Trang Province. During field work with Mr Nattanon Meeprom and Assist. Prof. Dr Sutee Duangjai, in July 2016 we collected specimens with a few ripe fruits from tropical lowland evergreen rain forest, near the 24-ha long-term ecological research plot, Khao Chong, Chong Subdistr., Na Yong Distr., Trang Province, but specimens were lost (photos were taken by C. Ngernsaengsaruay). The first author and others then collected specimens with young fruits in March 2018 from the same place. The first author and colleagues then collected specimens with female flowers, young, mature and ripe fruits in Feb. 2022 and March 2022 from Khao Chong Botanical Garden, Chong Subdistr., Na Yong Distr., Trang Province (Mr Preecha Puttarak collected a living plant from the natural habitat of Khao Chong and cultivated it in the nursery of Khao Chong Botanical Garden). From these, we selected the complete and well-preserved specimen C. Ngernsaengsaruay, N. Meeprom, W. Boonthasak, J. Jarernrattawong & P. Puttarak G26-18022022 as the holotype and isotypes, as it is in the best condition. These specimens did not match any existing species in Thailand or the surrounding regions and are described here as new to science.

Materials and Methods

The collected specimens were examined by consulting taxonomic literature (e.g. King 1890; Ridley 1922; Kochummen & Whitmore 1973; Whitmore 1973; Gardner et al. 2015), and by comparing with herbarium specimens deposited in the following herbaria AAU, BK, BKF, BM, C, CMUB, K, P, PSU, QBG, SING, and those included in the digital herbarium databases of AAU (https://www.aubot.dk/search_form.php), BM (https://www.nhm.ac.uk/our-science/collections/botany-collections.html), E (https://data.rbge.org.uk/search/herbarium/), K (http://www.kew.org/herbcat), JSTOR (https://plants.jstor.org/), L (https://bioportal.naturalis.nl/) and P (https://science.mnhn.fr/institution/mnhn/collection/p/item/search) were also examined. All acronyms follow Thiers (2022, continuously updated). The morphological characters, distribution, habitat, phenology and uses were described from our observations during field work and from label information of the specimens examined. The assessment of conservation status was performed following the IUCN Red List Categories and Criteria (IUCN Standards and Petitions Committee 2022) for a preliminary assessment of the conservation category in combination with GeoCAT analysis (Bachman et al. 2011) and field information. The calculation of Extent of Occurrence (EOO) and Area of Occupancy (AOO) are based on GeoCAT (http://www.geocat.kew.org).

Taxonomic Treatment

Garcinia siripatanadilokii Ngerns., Meeprom, Boonth., Chamch. & Sinbumr., sp. nov. Type: Thailand, Trang Province, Khao Chong Botanical Garden, Chong Subdistr., Na Yong Distr., c. 60 m alt. (cultivated), small tree 2 m tall, with female flowers and young, mature and ripe fruits, 18 Feb. 2022, C. Ngernsaengsaruay, N. Meeprom, W. Boonthasak, J. Jarernrattawong & P. Puttarak G26-18022022 (holotype BKF!, dry and spirit collections; isotypes K!, QBG!).

http://www.ipni.org/urn:lsid:ipni.org:names:77304120-1

Shrub or small evergreen tree, 2 – 4 m tall, 7 – 15 cm girth; latex yellow, sticky; branches decussate, horizontal; branchlets 4-angular, dark brown. Bark scaly, dark brown; inner bark pale yellow. Terminal bud concealed between the bases of the uppermost pair of petioles. Leaves decussate; lamina elliptic or oblong-elliptic, 6 – 13.3 × 2.6 – 4.7 cm, apex caudate or acuminate, base slightly attenuate, margin undulate, subcoriaceous, slightly bullate, shiny dark green above, paler below, glabrous on both surfaces, with a few scattered black gland dots below, sometimes on both surfaces, midrib raised above and below, secondary veins 4 – 9 pairs, curving towards the margin connected in distinct loops and united into an intramarginal vein, flattened above, slightly raised below, with intersecondary veins, veinlets finely reticulate, distinctly on both surfaces; petiole 4 – 8 mm long, 1 – 1.7 mm in diam., grooved above, twisted, glabrous, with a small basal appendage clasping the branch; young leaves shiny red, greenish-red, turning pale green and petiole pale green or greenish-red; fresh leaves crispy when crushed; leaves turning yellow and falling off. Flowers unisexual, plants dioecious, 4-merous, sepals and petals decussate, concave, glabrous. Male flowers not seen. Female flowers terminal, solitary, 0.7 – 1 cm in diam., fully opened flowers with an apical opening; bracts 4, decussate, pale green, turning pale yellow, caducous, longer pair lanceolate, 3 – 5 × 0.8 – 1.3 mm, apex acute, shorter pair narrowly triangular or lanceolate, 1.5 – 3 × 0.8 – 1.2 mm, apex acute; pedicel pale green, turning pale yellow, 2.5 – 4 mm long, 1.5 – 2 mm in diam. glabrous; sepals 4, pale yellow, coriaceous, suborbicular, 4.5 – 7 × 4 – 6.5 mm, the outer pair slightly smaller than the inner pair, apex rounded; petals 4, pale yellow, coriaceous, suborbicular, 5.5 – 7.5 × 5 – 7 mm, subequal, apex rounded; staminodes 4 – 7; filaments 1 – 1.5 mm long, basally united in a number of bundles surrounding the base of ovary but distally free; anthers c. 0.5 × 0.5 – 0.8 mm; pistil mushroom-shaped (fungiform), 3 – 4 mm long; ovary pale green, depressed subglobose, 2.8 – 3.5 mm in diam., very shallowly lobed or indistinctly lobed, 8 – 11-locular; stigma creamy white, sessile, convex, 3 – 4.5 mm in diam., radiate, shallowly 8 – 11-lobed, papillate. Fruit a berry, subglobose or depressed globose, 2.7 – 3.8 × 2.8 – 4.5 cm, usually asymmetrical, not lobed (very shallowly lobed or indistinctly lobed in young fruits), apex usually concave, green, greenish-yellow, turning bright yellow when ripe, glabrous, glossy, pericarp 4 – 6.5 mm thick, cut fruits with sticky, yellow latex; persistent stigma dark brown, flattened, 5 – 6 mm in diam., radiate, shallowly 8 – 11-lobed, papillate; persistent sepals pale green, greenish-yellow, turning pale yellow, larger than in flowering material; fruiting stalk 2 – 3.5 mm long, 2 – 3.5 mm in diam., colour same as persistent sepals. Seeds 1 – 4 or often aborted, brown, compressed, reniform, 1.2 – 1.5 cm × 6 – 9 mm, 2.7 – 3.8 mm thick, obtuse at both ends, with white sarcotesta. Figs 1 – 3.

Fig. 1
figure 1

Garcinia siripatanadilokii. A branches, leaves and female flower buds; B upper surface of leaf (left) and lower surface of leaf (right); C female flower bud with bracts; D female flower; E female flower showing pistil and staminodes (sepals and petals removed); F fruiting branch; G fruit with persistent sepals; H fruit with persistent stigma; J transverse section of fruit. Materials from C. Ngernsaengsaruay et al. G26-18022022. drawn by wanwisa bhuchaisri.

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Fig. 2
figure 2

Garcinia siripatanadilokii. A habitat and habit; B outer bark and inner bark with yellow latex; C branches, young and mature leaves; D branches and mature leaves; E female flower bud with bracts; F female flower; G branches, leaves and young fruits with persistent sepals; H – K branches, leaves and ripe fruits. photos: chatchai ngernsaengsaruay.

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Fig. 3
figure 3

Garcinia siripatanadilokii. A outer pair of sepals (lower) and inner pair of sepals (upper); B outer pair of petals (lower) and inner pair of petals (upper); C female flower showing pistil and staminodes (sepals and petals removed); D transverse section of young fruits; E transverse section of ripe fruits; F seeds. photos: a – c, f weereesa boonthasak; d – e chatchai ngernsaengsaruay.

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recognition. Garcinia siripatanadilokii is similar to G. lanceifolia in its habit (shrub or small tree), 4-merous flowers, sepals and petals decussate and concave, stigma radiate, shallowly lobed, papillate, fresh leaves crispy when crushed, fruits and leaves have a sour taste. Differences between these two related species are shown in Table 1.

Table 1. Morphological differences between Garcinia siripatanadilokii and the related species, G. lanceifolia.
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distribution. Known only from Peninsular Thailand: Khao Chong, Trang Province, Khlong Ton, Satun Province and Hala-Bala Wildlife Sanctuary, Narathiwat Province, but to be expected in Peninsular Malaysia (Map 1). Garcinia lanceifolia is distributed from India (Assam), Bangladesh (Chittagong hills), Myanmar to Indochina. In Thailand, this species is known from north-eastern (Bueng Kan), south-western (Kanchanaburi), south-eastern (Chachoengsao, Rayong, Chanthaburi, Trat) and peninsular (Ranong, Surat Thani, Phangnga).

Map 1
figure 4

Distribution of Garcinia siripatanadilokii, known only from three localities and three provinces in Peninsular Thailand: Trang (Khao Chong), Satun (Khlong Ton) and Narathiwat (Hala-Bala Wildlife Sanctuary).

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additional specimens examined. thailand. peninsular. Trang [Khao Chong, in evergreen forest, shrub 3 m tall, fruits green, 30 Jan. 1969 [as Garcinia cf. rostrata], Sarmrong (S. P.) 35 (BKF!, C!); near 24-ha long-term ecological research plot, Khao Chong (information from Dr Voradol Chamchumroon) (originally “Ton Plio Waterfall, Na Yong Distr., in evergreen forest, 103 m alt.” on the label), tree c. 4 m high, fruits yellow, 5 Dec. 2011 (as Garcinia sp., H. Toyama then identified as G. lanceifolia, 12 May 2019), V. Chamchumroon, N. Suphuntee, S. Sirimongkol & J. S. Strijk 5217 (BKF!); near 24-ha long-term ecological research plot, Khao Chong, Chong Subdistr., Na Yong Distr., in tropical lowland evergreen rain forest, 125 m alt., small tree 2.5 m tall, young fruits green, 17 March 2018, C. Ngernsaengsaruay, N. Meeprom, P. Wessapak & W. Boonthasak G25-17032018 (BKF!, dry and spirit collections, QBG!); Khao Chong Botanical Garden, Chong Subdistr., Na Yong Distr., c. 60 m alt. (cultivated), small tree 2 m tall, with female flowers and young, mature and ripe fruits, 8 March 2022, C. Ngernsaengsaruay, W. Boonthasak, P. Sutthaporn, J. Jarernrattawong & P. Puttarak G30-08032022 (BKF!, dry and spirit collections, QBG!)]; Satun [Khlong Ton, in evergreen forest, c. 200 m alt., small tree, fruits yellow, 14 March 1928 (as Garcinia sp., C. Ngernsaengsaruay then identified as G. gracilis, 2 June 2011), A. F. G. Kerr 14580 (BM!, K!)]; Narathiwat [Sirindhorn Waterfall, 150 m alt., shrub 2 m high, fruits yellow, 8 May 2001 (as G. cf. urophylla), C. Niyomdham 6495 (BKF!); Hala-Bala Wildlife Sanctuary, Waeng Distr., shady evergreen rain forest, 60 m alt., shrub c. 3 m high, fruits green, yellow when ripe, 25 Aug. 2009 (as G. urophylla), P. Puudjaa & C. Hemrat 1530 (BKF!)].

habitat. In tropical lowland evergreen rain forest, 50 – 200 m alt.

conservation status. This species is known only from three localities and three provinces in Peninsular Thailand. A small number of mature individuals were found in each locality. It has a relatively small Extent of Occurrence (EOO of 4,918.60 km2) and a small Area of Occupancy (AOO of 12 km2). We therefore consider the conservation assessment as Endangered [EN B1B2ab(ii, iv, v)].

phenology. Flowering and fruiting more than once, flowering October to July; fruiting December to August.

etymology. The specific epithet and Thai name are in honour of Dr Somkid Siripatanadilok, the former Associate Professor of the Department of Forest Biology, Faculty of Forestry. He taught the forest biology component of courses in field forest biology (in Peninsular Thailand, Khao Chong Botanical Garden is one of several study areas of the course), anatomy of trees, plant tissue culture and research techniques in forest biology (plant microtechniques) when the first author was an undergraduate student and a graduate student at Kasetsart University. He encouraged and supported the first author to work in the laboratory for plant tissue culture as an undergraduate student (1994 – 1997). He was the former co-advisor of the first author in his master's degree (1997 – 2000). He was a superb and a brilliant teacher, actively involved in many aspects of forest science in Thailand.

vernacular name. Som Kaeo Somkid (ส้มแก้วสมคิด) (suggested here); Som Kaeo (ส้มแก้ว) (Satun) (from A. F. G. Kerr 14580).

uses. The ripe fruits are edible. The pericarp, sarcotesta, young shoots, leaves and flowers have a sour taste. It is suitable for cultivation as an ornamental.

notes. Garcinia siripatanadilokii belongs to Garcinia sect. Brindonia (Thouars) Choisy with Garcinia lanceifolia. The section is characterised by the following: stamens in one central mass or column or in a ring (G. atroviridis Griff. ex T.Anderson); anthers 4-thecous, ellipsoid or rectangular; pollen colporate, reticulate; stigma generally completely divided into the same number of rays as there are locules of the ovary, verrucose; sepals and petals 4; pistillode absent (except in G. atroviridis). One feature distinguishes Garcinia sect. Brindonia from all others, namely, the 4-thecous anthers (Jones 1980), but Ngernsaengsaruay (2022) recorded 2-thecous anthers (of 4 pollen sacs) of G. atroviridis, G. lanceifolia and G. pedunculata Roxb. ex Buch.-Ham. in agreement with Maheshwari (1964), Singh (1993) and Gogi & Das (2016). This section is one of the largest and best known of Garcinia because several species are cultivated for their edible fruits. The section is widespread in Southeast Asia, with its range extending from India and Sri Lanka through Indo-China as far as southern China and throughout Indonesia and the Philippines (Jones 1980).

We have never seen male flowers of the species, but the female plants can produce fruits with or without seeds (abortion). We therefore expect the species to be apomictic, forming seed asexually without fertilisation.