Goniothalamus roseipetalus resembles G. scortechinii and G. uvarioides but is distinguished by its leaves with generally fewer secondary veins (15–22 pairs), wider sepals (24–35 mm), and wider inner petals (8–11 mm). It is also distinguished from G. scortechinii by its wider outer petals (14–25 mm), and is distinguished from G. uvarioides by its smaller, single-seeded monocarps (8–15 by 7–9 mm), borne on shorter stipes (3–5 mm).

Figure 1. 

Goniothalamus roseipetalus sp. nov. A flowering branch B flower C calyx of fused sepals (abaxial) D calyx of fused sepals (adaxial) E outer petal (abaxial) F outer petals (adaxial) G inner petal (abaxial). H inner petal (adaxial) I stamen (abaxial) J stamen (adaxial) K carpel (abaxial) L carpel (adaxial) M fruit, composed of separate monocarps. N–P seeds (different orientations). Drawn by A. Somphrom A–L from C. Leeratiwong 21–1708 (PSU) M–P from C. Leeratiwong 21–1707 (PSU).

Thailand: Narathiwat: Cha Nae, Du Son Yo subdistrict, 400 m alt., 15 April 2021, C. Leeratiwong 21–1706 (holotype PSU; isotypes BKF, KKU).

Figure 2. 

Goniothalamus roseipetalus sp. nov. A branch with leaves (adaxial) B fruiting branch with leaves (abaxial) C, D flowers. Photos by P. Chalermglin.

Shrubs to small trees, to 4 m. Young branches glabrous. Leaf laminas 15–40 by 3–13 cm, length/width ratio 2.8–5, elliptic to oblanceolate, apex generally acuminate (rarely acute to obtuse), acumen 3–10 mm long, base broadly cuneate, chartaceous, glabrous ab- and adaxially (sometimes sparsely pubescent over midrib); midrib strongly prominent abaxially, sunken adaxially; secondary veins 15–22 pairs, plane adaxially; tertiary veins percurrent, slightly distinct, lacking a ‘granular’ appearance abaxially; petioles 12–22 mm by 1.5–2.5 mm, glabrous to sparsely pubescent. Flowers solitary, often on main trunk (cauliflorous), rarely on older branches (ramiflorous), pendent; flowering pedicels 10–17 mm long, sparsely hairy; pedicel bracts ovate to broadly lanceolate, 2–4 by 2–3 mm. Sepals (violet-)pink, broadly ovate, 20–30 by 24–35 mm, basally connate (10–17 mm from base), apex rounded, glabrous ab- and adaxially, with sparsely hairy margins, venation distinct, 5–7-veined. Outer petals greenish-pink when young, (violet-)pink (green at claw) when mature, 25–45 by 14–25 mm with 4–10 mm-long claw, length/width ratio 1.7–2.2, fleshy, (lanceolate-)ovate, apex obtuse to mucronate, reflexed, sparsely hairy abaxially (more densely along margins basally), sparsely hairy (more densely apically) adaxially with velutinous basal region facing apertures between inner petals, midrib and venation indistinct ab- and adaxially. Inner petals 12–20 by 8–11 mm with 2–5 mm-long claw, length/width ratio 1.5–1.8, oblanceolate, densely hairy ab- and adaxially, greenish-pink when young, pale pink when mature, apex acute, lacking a glabrous lasteral flange on the inner petal claws. Stamens numerous, narrowly oblong, 3–4 mm long; connectives apiculate, papillate. Carpels 20–35 per flower, ovary oblong, 2–2.5 mm long, with white hairs; stigma and pseudostyle 2–3 mm long, stigma subulate, glabrous. Fruits with persistent calyx, immature fruits greenish-pink, mature fruits (pinkish-)red; fruiting pedicels 10–20 by 2–2.5 mm, sparsely hairy to glabrous. Monocarps 5–20 per fruit, 1–2-seeded, 8–17 by 7–10 mm, length/width ratio 1.1–1.7, ellipsoid to ovoid, apex apiculate, apicule 0.5–1.5 mm long, smooth, sparsely hairy, glossy, pericarp 1–2 mm thick, stipes 3–6 by 1.5–2 mm, moderately hairy. Seeds with mucilage, 9–11 by 8–9 mm, length/width ratio 1.1–1.6, ovoid, testa sparsely pubescent, rugose.

Figure 3. 

Goniothalamus roseipetalus sp. nov. A, B flowers C, D fruits showing persistent calyx. Photos by P. Chalermglin.

Flowering in March and April; fruiting in August (based on limited data).

Endemic to Peninsular Thailand, where it occurs in Narathiwat and Yala Provinces (Fig. 4). Growing in shady and moist areas of tropical rainforests and forest margins between para-rubber plantations and remnant rainforests; 100–400 m alt.

Figure 4. 

Distributions of Goniothalamus roseipetalus and G. sukhirinensis.

In reference to the red pigmentation of the petals.

Panan klip muang (ปาหนันกลีบม่วง) (general).

Thailand: Yala Province, Bannang Sata, 350 m alt., 1 August 2020, C. Leeratiwong 20–1684 (PSU); Narathiwat Province: Cha Nae District, Du Son Yo subdistrict, 100 m alt., 6 March 2021, C. Leeratiwong 21–1705 (PSU).

Although G. roseipetalus is yet to be included in a molecular phylogenetic analysis, it shares several morphological similarities with species in a clade (nested within clade ‘A1a’ sensu Tang et al. 2015a, b) that comprises G. loerzingii R.M.K.Saunders, G. macrophyllus, G. scortechinii, G. uvarioides and G. wrayi King. These species were previously classified by Bân (1974) within Goniothalamus subgen. Goniothalamus sect. Goniothalamus, and are characterised by their essentially glabrous vegetative shoots and petioles, percurrent tertiary leaf venation, generally fused sepals with distinct venation, short inner petals, apiculate staminal connectives, relatively few carpels per flower, thick-cylindrical pseudostyles with a broad, hairy stigma, and seeds with a hairy testa. Although G. roseipetalus shares most of these diagnostic characters, its stigmas are glabrous.

Goniothalamus roseipetalus is morphologically most similar to G. scortechinii and G. uvarioides. It differs from these species, however, as it generally has fewer secondary veins in its leaves (15–22 pairs, vs [18–]21–26[–32] in G. scortechinii and 24–35 in G. uvarioides), larger sepals (20–30 by 24–35 mm, vs 8–24 by 8–23 mm in G. scortechinii and 12–16 by 5–13 mm in G. uvarioides), and wider inner petals (8–11 mm, vs 5–8 mm in G. scortechinii and 7–8.5 mm in G. uvarioides). It also has wider outer petals (14–25 mm) than G. scortechinii (8–14 mm), and can be distinguished from G. uvarioides by reference to its smaller monocarps (8–15 by 7–9 mm, vs 31–44 by 15–18 mm) with a single seed (vs four or five seeds per monocarp) and shorter stipes (3–5 mm, vs 12.5–17.5 mm). Goniothalamus roseipetalus also resembles the widespread species G. macrophyllus, although the latter species has creamy-white petals.

Goniothalamus roseipetalus also resembles G. calycinus J. Sinclair, a species that is endemic to Terengganu in Peninsular Malaysia (Saunders 2003). Goniothalamus roseipetalus differs, however, in its flower position (with flowers borne on young or older branches in G. calycinus), larger sepals (only 4.5–17 by 4–17 mm in G. calycinus), wider outer petals (only 7–14 mm wide in G. calycinus), larger inner petals (only 8–14 by 5–7.5 mm in G. calycinus), and by the absence of a persistent calyx in fruits of G. calycinus.

Goniothalamus sukhirinensis resembles G. macrophyllus and G. scortechinii, but is distinguished by its densely hairy shoots, numerous secondary veins (32–40 pairs per leaf), generally longer pedicels (flowering: 12–18 mm; fruiting: 20–25 mm), larger outer petals (34–37 by 18–22 mm), larger monocarps (20–27 by 9–13 mm) that are densely hairy, and longer seeds (13–17 mm).

Figure 5. 

Goniothalamus sukhirinensis sp. nov. A vegetative branch B petiole, showing base of leaf lamina C flowers D sepal (abaxial) E sepal (adaxial) F outer petal (abaxial) G outer petals (adaxial) H inner petal (abaxial) I inner petal (adaxial) J stamen (abaxial) K stamen (adaxial) L carpel (abaxial) M carpel (adaxial) N fruit, composed of separate monocarps O seed with hairy surface. Drawn by A. Somphrom from C. Leeratiwong 21–1708 (PSU).

Thailand: Narathiwat: Sukhirin, Ban Yade village, Ma Mong subdistrict, 167 m alt., 6 March 2021, C. Leeratiwong 21–1708 (holotype PSU; isotypes BKF, KKU).

Figure 6. 

Goniothalamus sukhirinensis sp. nov. A leaf (abaxial) B, C flowers D fruit. Photos by P. Chalermglin.

Shrubs to small trees, to 4 m. Young branches densely appressed-pubescent. Leaf laminas 28–50 by 7–16 cm, length/width ratio 3.1–4, (lanceolate-)oblong, apex generally acuminate to caudate (rarely acute to obtuse), acumen 7–20 mm long, base broadly cuneate, subcoriaceous, glabrous abaxially (sparsely hairy over midrib), sparsely pubescent adaxially (densely hairy over veins); midrib strongly prominent abaxially, sunken adaxially; secondary veins 32–40 pairs, plane adaxially; tertiary veins percurrent, distinct, lacking a ‘granular’ appearance abaxially; petioles 20–30 mm by 4–6 mm, densely pubescent. Flowers solitary or paired, often on main trunk (cauliflorous), rarely on older branches (ramiflorous), pendent; flowering pedicels 12–18 mm long, densely hairy; pedicel bracts ovate-triangular, 2.5–3 by 1–1.5 mm. Sepals greenish-pink, broadly ovate, 7–9.5 by 7.5–10 mm, basally connate (2.5–3 mm from base), apex acute, moderately hairy abaxially, sparsely hairy adaxially, venation indistinct. Outer petals greenish-yellow when young, whitish-yellow (green at claw) when mature, 34–37 by 18–22 mm with 3–5 mm-long claw, length/width ratio 1.6–1.9, fleshy, (lanceolate-)ovate, apex acuminate, densely hairy abaxially, moderately hairy adaxially with velutinous basal region facing apertures between inner petals, midrib raised adaxially, venation indistinct ab- and adaxially. Inner petals 13–15 by 7–8 mm with 2–3 mm long claw, length/width ratio 1.8–1.9, ovate-lanceolate, densely hairy abaxially, sparsely hairy distally adaxially, yellowish-green when young, pinkish-orange to reddish-brown when mature, apex acuminate, lacking a glabrous lasteral flange on the inner petal claws. Stamens numerous, oblong, 2.5–3.7 mm long; connectives apiculate, papillate. Carpels 11–20 per flower, ovary oblong, 2–3 mm long, with white hairs; stigma and pseudostyle 2–2.5 mm long, stigma funnel-shaped, hairy. Fruits sometimes with persistent calyx, immature fruits brownish-green, mature fruits not seen; fruiting pedicels 20–25 by 2–3.5 mm, sparsely hairy. Monocarps 5–14 per fruit, single-seeded, 20–27 by 9–13 mm, length/width ratio 2–2.7, (obovoid-)ellipsoid, apex apiculate, apicule 5–8 mm long, smooth, densely hairy, glossy, pericarp 1–2 mm thick, stipes 7–15 by 2–3 mm, densely hairy. Seeds 13–17 by 8–10 mm, length/width ratio 1.6–1.7, ellipsoid, testa densely villose, slightly rugose.

Flowering and fruiting in February and March (based on limited data).

Endemic to Narathiwat Province, Peninsular Thailand (Fig. 4). Growing in shady and moist areas of tropical rainforests; 167–200 m alt.

From the name Sukhirin, Narathiwat Province.

Ratchakhru khao (ราชครูขาว) (Narathiwat).

Thailand: Narathiwat Province: Sukhirin District, Ban Yade village, Ma Mong subdistrict, 200 m alt., 28 February 2021, C. Leeratiwong 21–1707 (PSU).

As with the previous species, G. sukhirinensis is yet to be included in a molecular phylogenetic analysis but has strong morphological affiliations with a clade that comprises G. loerzingii R.M.K.Saunders, G. macrophyllus, G. scortechinii, G. uvarioides and G. wrayi King (nested within clade ‘A1a’ sensu Tang et al. 2015a, b). The morphological characteristics of this clade are detailed under G. roseipetalus, above.

Goniothalamus sukhirinensis resembles G. macrophyllus and G. scortechinii, but differs in several key characters: densely hairy shoots (vs glabrous to medium-hairy); numerous secondary veins (32–40 pairs per leaf, vs 12–23 in G. macrophyllus and [18–]21–26[–32] in G. scortechinii); generally longer flowering pedicels (12–18 mm, vs 5–11.5 mm in G. macrophyllus and 8–13 mm in G. scortechinii); larger outer petals (34–37 by 18–22 mm, vs 10–28 by 4.5–11.5 mm in G. macrophyllus and 20–33 by 8–14 mm in G. scortechinii); longer fruiting pedicels (20–25 mm, vs 7–19 in G. macrophyllus and 8–20 mm in G. scortechinii); larger monocarps (20–27 by 9–13 mm, vs 8–15 by 7.5–10 mm in G. macrophyllus and 9–18 by 6–10 mm in G. scortechinii) that are densely hairy (vs subglabrous to medium-hairy); and longer seeds (13–17 mm, vs 8.5–12 mm in G. macrophyllus and 8–11 mm in G. scortechinii). Goniothalamus sukhirinensis also differs from G. macrophyllus as its leaves lack the fine ‘granular’ appearance of the latter species (due to the immersion of tertiary and higher-order veins: Saunders, 2002), and has longer monocarp stipes (7–15 mm, vs up to 1.8 mm in G. macrophyllus).