Begonia pentandra W.N.Takeuchi, 2015

Hughes, Mark & Takeuchi, Wayne, 2015, A new section (Begonia sect. Oligandrae sect. nov.) and a new species (Begonia pentandra sp. nov.) in Begoniaceae from New Guinea, Phytotaxa 197 (1), pp. 37-44 : 39-42

Begonia pentandra W.N.Takeuchi sp. nov. ( Figs. 1–3 )

wo other species in Begonia sect. Oligandrae with entire leaves: B. sandsiana and B. brassii . Begonia pentandra differs from B. brassii in having unbranched, capitate styles, and differs from B. sandsiana in being a much smaller plant with hairy stems and leaves. The ciliate bracts of B. pentandra distinguishes it from all other species in sect. Oligandrae.

Type: — PAPUA NEW GUINEA. Western Province: Strickland drainage, Juha South , mossy montane forest on limestone, 05°53.951’S, 142°26.037’E, 975 m, 18 February 2008, Takeuchi, Gambia & Jisaka 23126 (holotype A!; isotypes E!, K!, L!, LAE!) .

Perennial herbs, 5–17 cm tall, monoecious. Basal stems 0.4–2.5 × 0.1–0.25(–0.4) cm, creeping, stoloniferous, rooting at the nodes, angulate (or cylindrical), pilose, glabrescent; surfaces furrowed, pustulate or not, fuliginous to brunnescent, often chalky. Ascending stems 0.2–1.05 × 0.05–0.2 cm, compressed (or terete), monoaxial (or furcately once branched), adventitiously rooting, straight, obscurely articulated by transverse ridges, not or only weakly nodose, indument and surfaces as for basal axes; internodes (4–)10–35(–49) mm long. Leaves 1–6, cauline or with 1–3 on short branches, rarely with single leaves from stolons, alternate, distichous, lax, obliquely ascending, often encrusted with calciferous granules; stipules lanceolate, 6–12 × 1.7–4 mm, glabrous, scarious, hyaline, crispate, persisting, 4–5- costate; petioles (15–)25–62(–80) × 0.5–1.2 mm, mostly cylindrical, shortly pilose to glabrate, weak, brunnescent or white-chalky, not articulated, not expanded at either end; leaf-blades lanceolate, ovate (or orbicular), 43–85(–93) × (24–)30–60(–68) mm, asymmetric, chartaceous; base obliquely cordate (or subtruncate), sinus open; margin ciliate, variously subentire, repand, or toothed (senescing leaves erose); apex acute-acuminate, acumen to ca. 1.5 × 0.5 cm; lamina surfaces dull, adaxially olivaceous or fuliginous, abaxially mostly orange brown to yellow green, bifacially appressed-hairy, indument denser on upper side, older blades glabrescent; venation 5–8-palmatinerval, furcately branching towards the margin, weakly raised on both sides; reticulum adaxially invisible, abaxially irregular, coarsely areolate. Inflorescence terminal, cymose, 4–11.5(–14) × 1–4.5(–7.3) cm, dichotomously branched through 1–3 orders, solitary (or 2 together), ascending, few-flowered, glabrous or glabrescent (excepting bracts); peduncle 22–86 × 0.5–1.2 mm, usually compressed, channelled, with or without reduced stipuliform leaves; axes to 33–37 × 0.2–0.6 mm, angulate or flat, nodose, jointed; bracts ovate-obovate, 9–13 × 7–13 mm, obtuse, paired, distichous, crowded, hiding axes and flowers, papery, persisting, ciliate (hairs glandular-capitate). Male flowers (measurements from spirit-preserved material) pedicels 9–15 × 0.7–1.5 mm, distally flared, not articulated, flaccid, nodding; tepals 4 in 2 unequal pairs, free; outer (major) tepals flabellate, 6.5–7 × 8.5–10 mm, distinctly more broad than long, obscurely venose, 7–9-costate; inner (minor) tepals cymbiform, 6.5–7 × 2.2–3 mm, subacute, inserted at right angles to the outer pair; stamens 5, 4 antetepalous and 1 in the center, free, subequal, ascending; filaments 0.9–1 × 0.1–0.2 mm, incurved or not; anthers suborbicular, 1.1–1.3 × 1.1–1.2 mm, 2-celled, basifixed, longitudinally dehiscent, latrorse, connective not prolonged. Female flowers (measurements from spirit-preserved material) pedicels as for the male but shorter, 7.5–9 × 0.8–1.5 mm; tepals 4 in 2 unequal pairs, free; outer (major) tepals flabellate, 8–9 × 9–11 mm, obscurely venose, 8–10-costate; inner (minor) tepals cymbiform, 8–9 × 2.8–3.5 mm, subacute, inserted at right angles to the outer pair; staminode(s) absent; ovary 3-locular, unequally 3-alate, laxly furnished with papilliform capitate hairs; placentae 2 per locule, ovules numerous; major wing horn-like, 5–7 × 2.9–4 × 1–1.3 mm, opposite an outer (large) tepal, antrorsely curved, planate, obtuse; minor wings (2) deltoid, 3.8–4.5 × 5.5–8.5 × 2–2.2 mm; styles 3, columnar, free, 0.7–1 × 0.5–0.7 mm; stigmas capitate, 0.9–1 × 1.3–1.8 mm, proximally truncate, notched at the top, papillate. Infructescence to 15.2 cm long, ebracteate, glabrous or nearly so. Fruits (measurements from spirit-preserved material) loculicidal, 3-lobed, solitary; pedicels to ca. 29 × 1 mm; major lobe 12–13 × 6–6.5 × 4–5 mm; minor lobes 6–6.5 × 7.5–8.5 × 3–4 mm.

Field characters: —Hairy on nearly all parts; stems fleshy (or slightly juicy); basal stems 1.4–2.7 × 0.2–0.5 cm in vivo, adhesively rooting to limestone walls, creeping; aerial stems suberect; stipules 10–14 × 4.5–5.5 mm in vivo, red; leaf-blades thick-fleshy, adaxially dark green, red, or purple gray, abaxially reddish-purple, yellow green, or pale green; inflorescence ascending, axes reddish-pink; bracts conspicuous, white (or pink); perianth (both sexes) white (or pink); anthers red; stigma initially green, later bright yellow; fruits pendulous, fleshy, red turning green, brown after dehiscence.

Distribution: —Endemic to the Strickland drainage of Western Province, Papua New Guinea ( Fig. 4 ).

Habitat and ecology: —Mossy montane forest on limestone karst, 975 m.

Phenology: —Flowering and fruiting in February.

Additional specimen examined (paratype): — PAPUA NEW GUINEA. Western Province: Strickland drainage, Juha South, mossy montane forest on limestone, 05°53.951’S, 142°26.037’E, 975 m, 18 February 2008, Takeuchi, Gambia & Jisaka 23127-B (A!, E!, LAE!).

23126, E–F without collection, Juha South, February 2008.

Figures

FIGURE 1. Begonia pentandra. Vegetative structures and habit. A, colony on limestone wall; B, stem indument and stipules. A–B without collection, Juha South, February 2008.

FIGURE 2. Begonia pentandra. Male inflorescence. A, aspect; B, oblique view of flowers with 5 stamens. A–B from Takeuchi, Gambia & Jisaka 23126.

FIGURE 3. Begonia pentandra. Female inflorescence. A, aspect; B, oblique view of 2 flowers at different stages of maturation; C, flower viewed from above; D, flower from side; E, fruits in oblique view; F, same as preceding, side view. A–D from Takeuchi, Gambia & Jisaka

FIGURE 4. Island of New Guinea. Collection localities for the 5 species in Begonia sect. Oligandrae.