Begonia chambersiae Takeuchi, 2012

Takeuchi, Wayne, 2012, Additions to the flora of the southern mountains of Papua New Guinea: Begonia chambersiae sp. nov. (Begoniaceae), Kibara renneriae sp. nov. (Monimiaceae), and distributional records of four rarely seen taxa, Phytotaxa 52 (1), pp. 43-53 : 44-46

Begonia chambersiae Takeuchi , sp. nov. ( Figs. 1–2 )

Haec species Begoniae oligandrae similis sed a qua foliis cum pilis squamiformibus, staminibus 4 nec connatis, floribus femineis tepalis 3 ovaris alis majoribus usque ad 5–6 × 1.9–2.0 mm differt.

Type: — PAPUA NEW GUINEA. Western Province: Muller Range, Sawetau , Nothofagus -emergent montane forest on doline karst, 5°39.610'S, 142°18.018'E, 1450 m, 17 September 2009, Takeuchi, Ama & Gamui 24713 (holotype LAE!; isotypes A!, K!, L!) .

Herbs to 20 cm tall, monoecious. Basal stems compressed, 0.5–2(–2.5) mm wide, glabrous, rooting at the nodes, longitudinally striate, dark brown. Ascending stems monoaxial (or with 1–2 branches), 0.3–1(–1.5) mm across, glabrescent, often adventitiously rooting, shallowly rugose, reddish-brown to black; internodes 3–20 mm long. Leaves alternate, cauline and/or 1–3 on short branches, obliquely spreading; stipules ovate to narrowly triangular, 1–2(–4) × 0.4–0.7(–1.2) mm, apex acute or filiform-attenuate, subpersisting, hyaline, crispate; petioles 3–18 × 0.1–0.5(–1.2) mm, nigrescent, glabrescent, flat, thin, flaccid; leaf-blades membranous, pinnatiform; primary lobes 1–4, pinnatifid to bipinnatisect, to 12 × 3 mm (exceptionally to 22 × 6 mm), margins entire or coarsely 1–3(–5)-toothed, serrations apically filiform; surfaces nigrescent, lepidote, abaxially somewhat furfuraceous, the scale-hairs ca. 1 × 0.1–0.2 mm, adpressed, antrorsely directed, often curled, adaxially without the scale-hair indument; venation pinnate, midvein weakly raised or planate, lateral nerves 1 per serration, diverging from the midvein at ca. 45°, reticulum absent. Inflorescences terminal, racemose, 1–4-flowered, (10–) 22–32 mm long, erect; axes glabrous, striolate, nodulose; bracts elliptic-ovate, 2.6–5 × 0.6–1.8 mm, falling at anthesis. Male flowers (measurements from spirit-preserved material): pedicels 11–12 × 0.9–1.2 mm; tepals 4 in 2 unequal pairs, free, outer (larger) tepals ovate, 10.5–11 × 7.5–8 mm, adaxially papillate-hairy, abaxially glabrous, inner (smaller) tepals elliptic, 6–6.5 × 1.8–2.2 mm, bifacially papillate, induplicate or not; stamens 4, free, antetepalous, equal, glabrous, erect; filaments incurved, 2–2.5 × 0.2–0.3 mm; anthers ellipsoid-ovoid, 0.8–1 × 0.4–0.6 mm, 2-celled, basifixed, longitudinally dehiscent, introrse. Female flowers (measurements from spirit-preserved material): pedicels 1.2–4.5 × 0.7–1 mm; ovary inferior, 3-locular, 3-alate; major wing horn-like, 5–6 × 1.9–2.0 × 1.5–2 mm (length taken at right angle to flower axis), diverging, distally falcate, obtuse, minor wings (2) semicircular, 2.6–3.5 × 2.5–3.2 × 1–1.5 mm; tepals 3, adaxially papillate, free, outer (major) tepals 2, ovate, 11.5–14 × 7.5–9.5 mm, equal, innermost tepal smallest, narrowly elliptic, 6.5–8.5 × 2–2.2 mm; staminode(s) absent; styles 3, free, fleshy, globuliformconical, 1.5–1.8 × 1–1.5 mm; stigmatic arms 2, terete, 4.5–5 × 0.4–0.6 mm. Fruits capsular, loculicidal, 3- lobed, solitary, glabrous; pedicels 4.5–7 × 0.3–0.8 mm; major lobe cylindrical (or subulate), 7.5–10 × 0.5–1.2 mm, minor lobes 2, deltoid-oblongoid, 3–5.5 × 3.5–4.5 mm; placentation axillary.

Etymology: — Begonia chambersiae is named after Ann Cox Chambers, a sponsor of the Conservation International Rapid Assessment Program, former US ambassador to Belgium, director of various organizations including Atlanta Newspapers, and a plant enthusiast.

Field characters: —Understory herbs, delicate, probably annuals, stoloniferous; stems cylindrical or terete, juicy (watery sap), translucent pink turning dark red with age; leaves herbaceous, light green above, conspicuously glaucous underneath; flowers (both sexes) white or pale pink; male tepals distinctly marked with a red eye, adaxially canescent; stamens erect, entirely white; fruits red.

Distribution: —Known only from the type locality in the Muller Range of Papua New Guinea ( Fig. 3 : A).

Habitat and ecology: —Montane forest on doline karst, sinkhole limestone at 1450 m elevation.

Phenology: —Flowering and fruiting in September.

Additional specimen examined (paratype): — PAPUA NEW GUINEA. Western Province: Muller Range, Sawetau , Nothofagus -emergent montane forest on doline karst, 5°39.610'S, 142°18.018'E, 1450 m, 13 September 2009, Takeuchi, Ama & Gamui 24622 ( A!, BO!, LAE!) .

Of the 79 Begonia Linnaeus (1753: 1056) species from New Guinea, only 7 have male flowers with 4 tepals (section Diploclinium ; Sands 2009). The new Begonia differs from other Diploclinium taxa primarily by the 4-staminate flowers and the peculiarly shaped fruits. It is closest in appearance to Begonia oligandra Merrill & Perry (1943: 44) of Irian Jaya, a species whose sectional placement is unverified but probably referable to Diploclinium (see Doorenbos 1978; Doorenbos et al. 1998; Merrill & Perry 1943; Sands 2009).

The principal differences between B. chambersiae and B. oligandra are listed in Table 1.

Begonia chambersiae Begonia oligandra a

known only from the type locality in the Muller Range (PNG) at known from two localities in Papua Province ( Indonesia) at

1450 m 1600–2200 m

epilithic on limestone in doline sinkholes reported only from stream banks, not on limestone (as far as can be determined)

leaves pinnatiform; primary lobes 1–4, pinnatifid to leaves palmatiform; primary lobes 4–6, pinnatifid to

bipinnatisect, to 12(–22) × 3(–6) mm; abaxially furfuraceous bipinnatifid, to 27 × 3 mm; bifacially glabrous (or very sparsely setulose on abaxial side)

stamens 4, free, antetepalous stamens 6–8, basally connate, insertion various

female tepals 3, the minor tepal much smaller than the others female tepals 4, in 2 unequal pairs

ovary: major wing diverging, hornlike, 5–6 × 1.9–2.0 × 1.5–2 ovary: major wing oblique (asymmetric), flat, upper margin 4

mm; minor wings (2) semicircular, 2.6–3.5 × 2.5–3.2 × 1–1.5 mm long; minor wings (2) narrowly rotundate, 0.5 mm wide

mmb

a. entries taken from Merrill & Perry (1943), or modified by examination of the LAE isotype.

b. length taken at right angle to flower axis (length × width × thickness).

Figures

FIGURE 1. Begonia chambersiae. A, male flowers are 4-adelphous, the throat marked by a red eye; B, aspect. A–B from Takeuchi, Ama & Gamui 24713.

FIGURE 2. Begonia chambersiae. A, fruit, apical perspective; B, pinnatiform leaves with abaxially white surfaces. A–B from Takeuchi, Ama & Gamui 24713.

FIGURE 3. Island of New Guinea. Collection localities. A, Muller Range, type locality for Begonia chambersiae; B, Lakekamu, type locality for Kibara renneriae; C, Wabo; D, Tualapa; E, Juha North; F, Lordberg; G, Mt. Bosavi; H, Dieni; I, Kiunga; J, Mt. Amdutakin. Overlay (shaded area) shows distribution of the southern karst formations. A–E from the author's recent collections; F–J from historical localities of earlier collectors.