Polyosma affinis Schulze-Menz ex B.J.Conn & O.K.Paul, 2024

Paul, O. K., Conn, B. J. & Henwood, M. J., 2024, Taxonomic review of Polyosma (Escalloniaceae) in Papuasia, Blumea 69, pp. 54-88 : 65

1. Polyosma affinis Schulze-Menz ex B.J.Conn & O.K.Paul , sp. nov. — Fig. 4

Etymology. The specific epithet of this new species ( affinis = ‘akin’) refers to it being morphologically most like P. macrobotrys , but also with similarities to P.integrifolia and, to a lesser extent,to P. amygdaloidea and P.glaberrima .

Polyosma affinis is morphologically most similar to P. macrobotrys . Both species have glabrous, elliptic leaves with base of lamina acute and margin entire; however, P. affinis usually has smaller leaves (usually 4–9 cm long, and mostly 2–4 mm wide), compared to P. macrobotrys that has leaves 12–22 cm long and 4–7.5 cm wide. It also differs by having a brownish maroon corolla and smaller brownish green fruits (4–5 mm long, 3–4 mm diam),compared to a white corolla and larger dark blue fruits (7–10 mm long, 6–8 mm diam) in P. macrobotrys . — Type: T.G. Hartley 11816 (holo CANB [CANB151125]; iso K, L, LAE [ LAE 66976]), Papua New Guinea, Morobe, Summit of Mt Kaindi, c. 6 miles SW of Wau, 8 May 1963.

Subcanopy tree,c. 12 m tall,bole c. 5 m tall,c. 12 cm diam. Branchlets glabrous, brown, lenticels vertical, white. Leaves glabrous; petiole 0.5–1.5 cm long, brown; lamina elliptic, 4–9 by 2–4 cm, coriaceous, drying brown on both surfaces; base acute, margin entire, apex shortly acuminate; secondary veins 10–25 on each side and at an angle greater than 45° from midrib, regularly looping near margin onto the next secondary vein; tertiary veins weakly percurrent, not prominent on abaxial surface. Inflorescence racemose, terminal, <20-flowered, erect; rachis 1.5–4 cm long, sparsely hairy; flowers loosely arranged and evenly spaced; pedicels 3–5 mm long; bracteoles 1–3 mm long, sparsely hairy. Calyx lobes 1–3 mm long. Corolla buds tubular, 8–12 mm long, green, brownish green, sometimes becoming brownish maroon; corolla moderately hairy, fully split into 4 lobes at anthesis. Fruits ovoid, 4–5 by 3–4 mm, sparsely hairy, brownish green.

Distribution — Papua New Guinea (West Sepik, Morobe).

Habitat & Ecology — Occurring in lowland to montane forests at elevations up to 2 550 m.

Conservation status — Probably not of concern.

Additional specimens examined (Paratypes). PAPUA NEW GUINEA, West Sepik, Mori, Vanimo , J. S. Womersley NGF 13930 ( K, L); ibid., D. Sayer NGF 19517 ( K, NSW); ibid., D. Sayer NGF 19517 A ( L, LAE ) ; Morobe, Garaina , T. G. Hartley 12772 ( K, LAE ) .

Notes — 1. This species has a widespread altitudinal range, occurring from lowland to montane forest.

2. Polyosma affinis is morphologically also like other species with entire leaves, such as P. integrifolia and, to a lesser extent, to P. amygdaloidea and P. glaberrima . It can be distinguished from P. integrifolia by the inflorescence rachis being 1.5–4 cm long (vs P. integrifolia 9–22 cm long); corolla green (vs P. integrifolia white); fruits sparsely hairy, brownish green (vs P. integrifolia glabrous and bluish black when mature). It has shorter leaves (4–9 cm long, vs (7–) 10–16 cm long in P. amygdaloidea ), shorter rachis (1.5–4 cm long, vs (3–) 5–10 cm long in P. amygdaloidea ), and green corolla (vs yellowish white in P. amygdaloidea ). Polyosma affinis has brown branchlets with vertical lenticels (vs black branchlets with scattered lenticels in P. glaberrima ) and leaves elliptic (vs obovate leaves in P. glaberrima ).

3. Collections of P. affinis and P. alipensis were often included in a broadly circumscribed P. forbesii . These two new species are readily distinguished by several morphological characteristics, namely, P. alipensis is usually a larger tree (12–24 m high), with larger leaves (petioles 2.5–4 cm long; lamina 13–17 by 4–8 cm) compared with P. affinis which is a smaller tree about 12 m high, with petioles 0.5–1.5 cm long, and lamina 4–9 by 2–4 cm. Furthermore, the leaf margin of P. alipensis is serrate (like P. forbesii ) compared to P. affinis that is entire. Polyosma forbesii has leaves with the apex attenuate whereas P. alipensis has subacute to acute leaves.

Figures

Fig. 4 Holotype collection of Polyosma affinis Schulze-Menz ex B.J.Conn & O.K.Paul, sp. nov., showing branchlets with leaves,flowers,and fruits (T.G. Hartley 11816 [CANB151125.1]).