Garcinia hopii H.Toyama & V.S.Dang, 2017

Toyama, Hironori, Dang, Van-Son, Tagane, Shuichiro, Nguyen, Ngoc Van, Naiki, Akiyo, Nagamasu, Hidetoshi & Yahara, Tetsukazu, 2017, Garcinia hopii (Clusiaceae), a new species from Bidoup Nui Ba National Park, southern Vietnam, PhytoKeys 77, pp. 63-70 : 64-66

Garcinia hopii H.Toyama & V.S.Dang sp. nov. Figures 1 , 2

Diagnosis.

This species is similar to Garcinia hendersoniana Whitmore (endemic to Peninsular Malaysia) in elliptic-orbicular coriaceous leaves but differs from that species in relatively larger leaves (10-23.5 × 6.5-15.5 cm vs. 8-14 × 5.5-8.5 cm), clustered pistillate flowers (2-4 vs. solitary), a greater number of sterile anthers of pistillate flowers (40-64 vs. ca. 25) and a larger stigma of young fruits (4-6 mm vs. 3-4 mm in diam.).

Type.

VIETNAM. Lam Dong Province, Bidoup Nui Ba National Park , montane evergreen forest, alt. 1781 m, 12°11.41'N, 108°42.81'E (DDM), 27 February 2016, H. Toyama, H. Nagamasu, S. Tagane, VS. Dang, VN. Nguyen & J. Wai V4475 [female fl. & young fr.] (holotype KYO!; isotypes DLU!, FU!, NTUF!, VNM!)

Description.

Dioecious evergreen trees up to 10 m tall, all parts glabrous; trunk pale grey-brown to brown, with pale yellow-orange latex; twigs reddish green or green and slightly tetragonous when young, turning to greenish brown or dark-brown and terete when aging, with pale yellow latex. Leaves opposite; petioles 1.0-2.0 cm long; blade elliptic to orbicular, (4-)10-23.5 × (3.2-)6.5-15.5 cm, length/width ratio 1.2-1.9, thickly coriaceous, obtuse to rounded at base, acute to rounded at apex, margin entire, slightly recurved when dried; mid-ribs slightly prominent above and prominent below; lateral veins 10-18 pairs, prominent and distinct on both surfaces when dried, joining into a weak intra-marginal vein that is ca. 2 mm apart from the margin; tertiary venation slightly visible on both surfaces when dried. Inflorescence of staminate flowers axillary, fascicles of (1-)2-9 flowers. Staminate flowers tetramerous; pedicels ca. 2 mm long; sepals 4, ovate-orbicular, outer sepals 6.5-9 × 7-9.5 mm, inner ones 7-9 × 8-10 mm wide, apex rounded, dark red when young, turning yellowish green when aging; petals 4, ovate-orbicular, outer petals 7-9.5 × 9-13 mm, inner ones 7-9 × 8-12 mm, thicker than sepals, apex rounded, bright yellow to yellow-orange; stamens 46-55, pharangiate, surrounding pistillode; free part of stamens 0.7-1.5 × 0.5-1 mm; free part of filaments ca. 0.5 mm long; anthers with one theca, peltate, dehiscing by a circumscissile slit; pistillode present, ca. 3.5 mm long, ca. 1 mm in diam. Inflorescence of pistillate flowers axillary, fascicles of (1-)2-4 flowers. Pistillate flowers tetramerous; pedicels ca. 2 mm long; sepals ovate-orbicular, outer sepals 6-9 × 8-10 mm, inner ones 7-8 × 9-10 mm, apex rounded, dark red when young, turning yellowish green when aging; petals ovate-orbicular, outer petals 8-9.5 × 8.5-11.5 mm, inner ones 6-8.5 × 8-10 mm, thicker than sepals, apex rounded, bright yellow or pale dark red; staminodes present, 40-64, united in a ring surrounding pistil, 5-6 × 18-22 mm when open, connate into a receptacle; free part of filaments almost sessile; pistil 5.5-10 mm long, 5-7 mm in diam.; ovary ovoid, 3-6 mm long, 4.8-7 mm in diam., 4-locular; style ca. 1-2 mm long, 3-4.5 mm in diam.; stigma convex, 2-2.5 mm long, 4-5.5 mm in diam., papillose. Young fruits (Toyama et al. V4475, Tran & Dang dv127) solitary, ellipsoid or flask-shaped, 1.1-2.0 cm long, 1.3-1.4 cm in diam., yellow green with red gradient, sepals and staminodes persistent at base, stigma persistent at apex, ca. 1 mm long, 4-6 mm in diam., slightly convex when young, turning to flat when aging; pedicels ca. 3 mm long. Mature fruits unknown. Seeds unknown.

Other specimen examined.

VIETNAM. Lam Dong Province, Bidoup Nui Ba National Park, 12°11'N, 108°43'E, 23 April 1997, L. Averyanov, NQ. Binh & NT. Hiep VH4229 [female fl.] (HN!); ibid., alt. 1644 m, 12°11.21'N, 108°42.87'E (DDM), 19 November 2014, H. Toyama, S. Tagane, VS. Dang, H. Nagamasu, A. Naiki, H. Tran, CJ. Yang, NQ. Cuong, HNP. Hieu & XN. Loi V1891 [male fl. buds] (FU!, VNM!); ibid., alt. 1644 m, 12°11.21'N, 108°42.87'E (DDM), 24 April 2015, H. Tran & VS. Dang dv127 [male fl. & young fr.] (KYO!, VNM!); ibid., alt. 1807 m, 12°11.47'N, 108°42.78'E (DDM), 23 February 2016, S. Tagane, H. Nagamasu, A. Naiki, VS. Dang, VN. Nguyen & J. Wai V4174 [male fl.] (DLU!, FU!, NTUF!, VNM!); ibid., alt. 1807 m, 12°11.47'N, 108°42.78'E (DDM), 27 February 2016, H. Toyama, H. Nagamasu, S. Tagane, VS. Dang, VN. Nguyen & J. Wai V4476 [male fl.] (DLU!, FU!, NTUF!, VNM!)

Distribution and habitat.

Garcinia hopii is only known from Bidoup Nui Ba National Park, southern Vietnam. It is common in moist evergreen forests dominated by Quercus poilanei Hickel & A.Camus, Neolitsea umbrosa (Nees) Gamble, Podocarpus neriifolius D.Don, Polyosma nhatrangensis Gagnep. and Symplocos sulcata Kurz at alt. 1640-1810 m.

Phenology.

Flower buds were observed in November. Flowers were observed in February and April. Immature fruits were observed in April.

Etymology.

Garcinia hopii is named after Prof. Hop Tran, University of Science Ho Chi Minh City, who collected the flowering and fruiting specimens [Tran & Dang dv127 (FU, VNM)].

Preliminary conservation status.

Garcinia hopii is commonly found at Hon Giao Ridge area in Bidoup Nui Ba National Park. There are many reproductive trees and the forest is well protected. Therefore, this species is assessed as Least Concern (LC) according to IUCN Red List Categories ( IUCN 2012).

Note.

In Indochina, Garcinia hopii is similar to Garcinia poilanei , but differs from that species in having larger leaves (10-23.5 × 6.5-15.5 cm vs. 8-11 × 5-5.5 cm), clustered staminate flowers (2-9 vs. solitary), pistillode present (vs. absent), short pedicellate flowers (pedicels ca. 2 mm long vs. sessile) and a greater number of anthers of staminate flowers (46-55 vs. 15-18).

GenBank Accession No.

Toyama et al. V1891, LC198063 (rbcL), LC198064 (matK).

Figures

Figure 1. Garcinia hopii H. Toyama & V. S. Dang, sp. nov. A branch with pistillate flower B longitudinal section of staminate flower C lateral view of staminate flower, tepals removed D free part of stamens E lateral view (upper) and longitudinal section (lower) of pistillode F longitudinal section of pistillate flower G pistillate flower, tepals removed (left) and tepals and staminodes removed (right) H staminodes cut in half longitudinally I immature fruit (left) with sepals (sp) and staminodes (st) and its longitudinal (middle) and transverse (right) section. A, F-H from Toyama et al. V 4475 (KYO) B-E from Toyama et al. V 4476 (FU) I from Tran & Dang dv 127 (FU). Drawn by H. Toyama.

Figure 2. Garcinia hopii H. Toyama & V. S. Dang sp. nov. A branch with leaves B abaxial surface of leaf C trunk D latex E staminate flower buds F staminate flower G pistillate flower and buds H pistillate flower I pistillate flower, some tepals removed J immature fruits. A - C photographed on 22 January 2015 E photographed on 19 November 2014 D, F - I photographed on 27 February 2016, J photographed on 24 April 2015.