Similar to Goniothalamus amuyon (Blanco) Merr. except with shorter inner petals (11–16 mm), hairy ovaries, and filiform pseudostyles with funnel-shaped stigmas.

Palawan: Puerto Princesa, Corrigutor, 31 May 2012, C.C. Tang TCC10 (holotype: L; isotypes: PNH).

Small trees, to 5 m tall, to 3 cm d.b.h. Young shoots (densely) hairy. Leaf laminas 18–31 cm long, 5.8–11 cm wide, length/width ratio 2.3–3.5, broadly elliptic or oblong elliptic, apex (long) acuminate, base acute, papyraceous to coriaceous, 50–100 μm thick, glabrous both ab- and adaxially; midrib slightly pubescent and very prominent abaxially; secondary veins 8 to 10 pairs per leaf, prominent adaxially; tertiary veins reticulate (sometimes slightly percurrent towards base of leaf), distinct; petioles 8.5–15.5 mm long, 1.5–2.8 mm in diameter, hairy. Flowers axillary, solitary, on young branches, pendent; pedicels 8–13(–16.5) mm long, 0.8–1.2(–1.7) mm in diameter, (sparsely) hairy; bracts 2 to 5. Sepals 3–4(–5) mm long, 3.5–4.5(–6.5) mm wide, length/width ratio 0.6–0.9, generally not reflexed at anthesis, not connate, triangular, 170–250 μm thick, (sparsely) hairy abaxially, glabrous to very sparsely hairy adaxially, green, venation indistinct. Outer petals 20.5–34 mm long, 5.5–13.5 mm wide, length/width ratio 2.4–4.9, broadly to elongated lanceolate, 450–1100 μm thick, (densely) hairy both ab- and adaxially, with glabrous region at base of adaxial surface, greenish yellow, venation indistinct. Inner petals 11–16.5 mm long, 5–9.5 mm wide, length/width ratio 1.6–2.5, with 2.3–3.4 mm wide basal claw, 330–800 μm thick, densely hairy abaxially, sparsely hairy adaxially, greenish yellow; apertures between inner petals 3.5–4.5 mm long, 3.5–5 mm wide. Stamens ca. 100 per flower, 1.9–2.2 mm long, 0.3–0.5 mm wide; connectives rounded, 0.2–0.5 mm long, papillate-hairy. Carpels 10 to 15 per flower; ovary 0.8–1.8 mm long, 0.4–0.7 mm wide, densely hairy with long golden-brown hairs; stigmas and pseudostyles 2.4–4 mm long; pseudostyles 0.1–0.3 mm wide, glabrous; stigma funnel-shaped, glabrous. Fruits unknown.

Flowering specimens collected in May and June; fruiting specimens unknown.

Endemic to Palawan (Fig. 3), in mixed dipterocarp and limestone forests; 50–120 m.

The specific epithet reflects the geographical distribution of the species in Palawan.

Philippines. Palawan: Bloomfield, St. Pauls Bay, Mt. Bloomfield, lowlands to the SSE, 4 May 1984, A. C. Podzorski SMHI2012 (K, L); Iraan Mountains, Aborlan, 29 May 1950, M. D. Sulit 14792 (L); Puerto Princesa, Corrigutor, 31 May 2012, C.C. Tang TCC06 (HKU), C.C. Tang TCC09 (HKU), C.C. Tang TCC11 (HKU), C.C. Tang TCC14 (HKU), C.C. Tang TCC17 (HKU).

Phylogenetic analysis of chloroplast DNA sequence data (C.C. Tang et al., unpubl.) indicates that this new species, Goniothalamus palawanensis, is sister to Goniothalamus amuyon (Blanco) Merr. with moderate to strong support (posterior clade probability = 0.97 and bootstrap support = 74%), and more distantly related to Goniothalamus costulatus Miq., Goniothalamus rufus Miq., Goniothalamus sawtehii C.E.C.Fischer, Goniothalamus tomentosus R.M.K.Saunders, Goniothalamus undulatus Ridl. and Goniothalamus velutinus Airy-Shaw. These species are all characterised by a distinct indument of rusty-red hairs on the young shoots and petals. Amongst these species, Goniothalamus amuyon and Goniothalamus palawanensis are distinct in possessing fewer secondary veins per leaf (8 to 11, compared with 11 to 25 in the other species, with the exception of Goniothalamus rufus), and in having indistinct sepal venation (although similar venation is observed in Goniothalamus velutinus). Goniothalamus palawanensis is furthermore geographically close to Goniothalamus amuyon, which occurs in Luzon, Visayas and Mindanao (Guzman et al. 1986). Morphological differences between Goniothalamus palawanensis and Goniothalamus amuyon include: inner petal length (11–16.5 mm vs 15–29 mm, respectively: Ying 1991; Liao 1996); ovary indument (hairy in Goniothalamus palawanensis [Fig. 1G] vs glabrous in Goniothalamus amuyon); and pseudostyle/stigma shape (filiform pseudostyle with small, funnel-shaped stigma in Goniothalamus palawanensis [Fig. 1G], vs relatively enlarged, fleshy pseudostyle with entire stigma in Goniothalamus amuyon).

The flora of Palawan shows close biogeographical affinities with Borneo, reflecting the extensive connectivity that existed between the two regions (Hall 2009). Two of the species listed above as close relatives of Goniothalamus palawanensis occur in Borneo, viz. Goniothalamus rufus and Goniothalamus velutinus. In addition to the differences in leaf and sepal venation alluded to above, these species differ from Goniothalamus palawanensis in possessing greatly enlarged and warty pseudostyles/stigmas (Mat-Salleh 1993).

There is only one Goniothalamus species, Goniothalamus obtusifolius Merr., that is sympatric with Goniothalamus palawanensis in Palawan. These two species are clearly distinct, however, as Goniothalamus obtusifolius has much smaller (15–18 × 6–8 cm) coriaceous leaves, and large (ca. 5 × 3.5 cm) membranous outer petals (Merrill 1906).

EN B1ab(iii) (IUCN, 2001). Goniothalamus palawanensis is endemic to Palawan, with an extent of occurrence of ca. 1, 800 km². The species is only known from three periods of collection (1950, 1984 and 2012), and from fewer than five localities. The region is subject to continuing habitat decline due to logging of low altitude forests (DENR/UNEP 1997), hence the endangered red list category recommendation.

Polyalthia angustifolia A.C.Sm., Bull. Torrey Bot. Club 70: 538. 1943. Type: FIJI: Viti Levu, J.W. Gillespie 2198 (holotype: A!; isotypes: BISH, GH!).

The historical delimitation of the genus Polyalthia has been shown to be highly polyphyletic, and large-scale taxonomic realignment and recognition of new genera has been undertaken to ensure strict monophyly of genera (Mols et al. 2008; Saunders et al. 2011; Xue et al. 2011, 2012, in press; Chaowasku et al. 2012). As part of this series of taxonomic revisions, chloroplast DNA regions were sequenced from eight species from the Melanesian island of Fiji (Xue, 2013) that had previously been assigned to Polyalthia. Phylogenetic analysis of this data revealed that most of these species align with either Hubera (Chaowasku et al. 2012; Xue 2013) or Meiogyne (Xue 2013; Xue et al. in press), although one species, Polyalthia angustifolia A.C.Sm., which was sequenced from the type material, is nested within the Goniothalamus clade (Xue 2013). Polyalthia angustifolia was originally described from fruiting material (Smith 1943), and it is likely that its incorrect generic affiliation was due to the absence of flowers, which are very different in Polyalthia and Goniothalamus. Subsequent phylogenetic analyses with a larger taxon sampling (C.C. Tang et al., unpubl.) have revealed Polyalthia angustifolia as sister to the Fijian species Goniothalamus monospermus (Baill.) R.M.K.Saunders with strong support (posterior clade probability = 1; bootstrap support = 96%); these two species are morphologically distinct, as Polyalthia angustifolia seeds lack the broad lateral testa wings that are diagnostic of Goniothalamus monospermus (Van Setten and Koek-Noorman 1992: pl. 39i). The transfer of the name Polyalthia angustifolia to Goniothalamus is accordingly validated here.