Phanera larseniana Chantaranothai, Mattapha & Wangwasit, 2017

CHANTARANOTHAI, PRANOM, MATTAPHA, SAWAI & WANGWASIT, KHANIT, 2017, Phanera larseniana (Leguminosae: Cercidoideae), a new species from Thailand, Phytotaxa 303 (2), pp. 187-193 : 188-192

Phanera larseniana Chantaranothai, Mattapha & Wangwasit , sp. nov. ( Figs. 1−3 ).

Phanera larseniana is similar to P. rubro-villosa but differs in having a shorter hypanthium, smaller calyces and petals, longer fertile filaments, longer ovary and style. Fertile filaments and style are much exserted (vs. inserted in P. rubro-villosa ).

Type:— THAILAND, Sakon Nakhon, Phu Phan district, Ban Nakamglang , 25 March 2000, by the main road no. 213 between Kalasin and Sakon Nakhon provinces, ca. 20 km south of the headquarters of Phu Phan National Park , elevation of ca. 200 m, 16°57’48.77”N 103°54’20.14”E, P. Chantaranothai et al. 2000-01 (holotype AAU; isotype KKU) .

Large woody liana, bark fissured or furrowed; tendrils 7–18 cm long; young twigs densely ferruginous tomentose. Leaves simple, bifid, markedly broad, coriaceous; petioles (5–) 9.5–17.5 cm long, with dense ferruginous tomentose hairs; lamina ovate or oblong–ovate, (8.5–)19–35 × (7–) 13.5–26.5 cm long, bifid to 1/2 of lamina length with a narrow sinus, apex acute or obtuse with mucro 0.7–2 cm long, margin tomentose, base deeply cordate, 10–13-veined, densely tomentose along veins on both sides; upper surface sparsely tomentose; lower surface tomentose, especially along veins. Stipules falcate–oblong, 6–20 × 3–9 mm, apex obtuse or truncate, inner surface glabrous, outer surface densely hairy, persistent. Inflorescences corymbose, terminal, erect, up to 15.5 cm long, densely flowered, with (12–)20– 64 flowers, densely ferruginous tomentose on axis. Pedicels 2.5–5 cm long, densely ferruginous tomentose; bracts persistent, subulate, 7–14 × 1–2 mm, apex acuminate, inner surface glabrous, outer surface tomentose; bracteoles persistent, linear, 3–7 × 0.5 mm, apex acuminate, inner surface glabrous, outer surface tomentose, inserted on upper part of pedicel. Buds ellipsoid or ovoid, 9–13 mm long, tomentose, apiculate at apex. Hypanthium funnel-shaped, 5–7 mm long, ferruginous tomentose. Calyx 5-lobed, ovate, acute, 7.5–8.5 mm long, dividing into 2 segments during anthesis; upper segment united with 2 minute lobes at apex, and lower segment united with 3 minute lobes, inner surface glabrous, outer surface tomentose. Petals 5, white turning yellow when mature, subequal, oblanceolate or obovate, 13–19 × 7–14 mm, apex rounded or obtuse, margin undulate, crisped, inner surface glabrous, outer surface densely brownish tomentose to silky, glabrous near margin; claw 3–5 mm long. Fertile stamens 3, alternipetalous; filaments 26–35 mm long; anthers creamy white to greenish white, oblong–ovoid, 4–5 × 2 mm, dehiscing by longitudinal slits, versatile. Staminodes 2–6; longest staminodes 2, alternipetalous; filaments 4–6 mm long; anthers 0.5 mm long; short staminodes 0–4, alternipetalous or antipetalous; filaments 1.5–3 mm long, filiform, without anthers. Floral disc absent. Ovary stipitate, 7–8 mm long, densely ferruginous tomentose, 9–12-ovuled; stipe 1–2 mm long; style 21–30 mm long, sparsely hairy at base, glabrous at upper part; stigma light green to dark brown, peltate, 1–1.3 mm in diameter. Pods dehiscent, woody, oblong, flat, strap-shaped, (17–)20–45 × (4–) 5–9 cm, densely ferruginous tomentose, (4–)6–11(– 12)-seeded. Seeds flattened, ovate, broadly oblong, or rarely rounded (18–)20–32 × (12–) 14–24 mm, hilum crescentic, surface mostly slightly lustrous, glabrous, reddish brown to dark brown.

Etymology: —The species is named after Supee Saksuwan Larsen and the late Professor Kai Larsen, prominent botanists who contributed the account of the genus Bauhinia to the Flora of Thailand.

Distribution: —Only known from north–eastern Thailand ( Fig. 3 ).

Habitat and Ecology: —Dry evergreen forest, elevation of ca. 200 m.

Phenology: —Flowering March–April. Fruiting April–May.

Vernacular name: —Khruea saksuwan (เครอศกดสวรรณ).

Notes: — Phanera larseniana is characterized by the calyces and the corolla which are shorter than those of P. rubro-villosa . It differs obviously from the latter by acute calyx lobes which the length is 7.5–8.5 mm long. The petal shape of P. larseniana slightly resembles P. rubro-villosa but it shorter in length, 13–19 mm long (vs. 20–25 mm long in P. rubro-villosa ). The short staminodes vary significantly in number from absent to four, and can be positioned opposite or alternate to the petals. Although superficially similar to P. rubro-villosa , the style length of P. larseniana can be distinguished by much longer than the calyx, 21–30 mm in length (in P. rubro-villosa , as long as the calyx, 10–15 mm in length).

Conservation status:—There is only one known population of P. larseniana , which is situated in an abandoned paddy field in an abandoned paddy field surrounded by dry dipterocarp forest in between Phu Phan National Park and a village, and is observed to contain around eight mature individuals. This population is potentially at risk from deforestation and clearing for agriculture. It is expected that the species may be present in similar habitat in other parts of the national park, but a search of these areas has not yet been carried out due to their inaccessible nature. Therefore, according to the IUCN Red List Criteria ( IUCN 2012), the species is assessed here as Data Deficient (DD) as it is currently only known from a single population; a further assessment should be carried out when more data is available. An ex-situ individual of the new species exists in Khon Kaen Botanic Garden, produced by the third author of this paper who collected seed from the type locality and successfully germinated it in 2005.

Additional specimen examined (paratype):— THAILAND. Khon Kaen, Phon district, Khon Kaen Botanic Garden, cultivated in 2005, previously identified as Bauhinia sp. , collected on 18 March 2015, P. Chantaranothai, K. Wangwasit & B. Boonsuk 2015-1 (KKU).

Figures

FIGURE 1. Phanera larseniana: A. Leaf; B. Inflorescence; C. Floral bud; D. Flower; E. Calyx, E1. Lower segment with 3 minute lobes, E2. Upper segment with 2 minute lobes; F. Petal showing the dorsal view; G. Fertile stamen; H. Pistil; I. Pod, hairs not shown (drawn by Woranat Thammarong).

FIGURE 2. Phanera larseniana: A. Habit, B. Tendrils; C. Inflorescence; D. Flower (ventral view); E. Flower (dorsal view), arrows indicate the calyx segments; F. Pod (photos by Boonchuang Boonsuk).

FIGURE 3. Known distribution of Phanera larseniana Chantaranothai, Mattapha & Wangwasit in the north-east of Thailand. The map was created using QGIS version 2.14.1-Essen (QGIS 2016).