Callerya tenasserimensis Mattapha & Sirich.

Sirichamorn, Yotsawate, Balslev, Henrik & Mattapha, Sawai, 2016, Two new species of Callerya Endl. (Leguminosae: Papilionoideae) from Thailand, Phytotaxa 263 (1), pp. 42-50 : 47-49

2. Callerya tenasserimensis Mattapha & Sirich.

Diagnosis:— Callerya tenasserimensis is easily distinguishable from its sympatric species, C. chlorantha by the hairiness of young leaves (glabrous or sparsely pubescent, less than 5 trichomes per a square centimeter vs moderately pubescent, 10–25 trichomes per a square centimeter), colour of flowers (purple vs pale green), floral bracts length (1–1.5 mm vs 3–5 mm), basal callosities (absent vs present), and lateral pockets on wing petals (present vs absent).

Type:— THAILAND. Ratchaburi: Suan Phueng district, Khoa Chon (Khao Chan) waterfall, climbing on Elaeocarpus trees near stream of the waterfall, dry bamboo-deciduous forest, with granite rock, 150–350 m elevation, GPS coordinate 13°31’31.8”N 99°14’19.8”E, 12 September 2015, Sirichamorn 2015-13 (holotype BKF!; isotypes BK!, K!, KKU!, L!) .

Woody climber. Basal stem diameter 10–15 cm, twigs 6–10 mm diam., lower part lenticellate, glabrescent, upper part (thinly) pubescent. Stipules minute, acicular, 1–2.5 mm long, caducous. Petiole 2.5–7 cm long, grooved above, thinly pubescent or glabrescent; rachis 3–5.5 cm long, grooved above, thinly pubescent or glabrescent; pulvinus 5–10 mm long, thinly pubescent or glabrescent, stipellae filiform, 1–2 mm long. Leaflets 5, when young light green, sparsely pubescent to glabrous, chartaceous, the terminal leaflet elliptic, ovate or obovate, 8–15 cm long, 4.5–11 cm wide, length/width ratio 1.3–1.7, base acute to obtuse, apex with acumen up to 15 mm long, acute, rounded or slightly retuse, glabrous adaxially and abaxially, midrib and secondary veins raised in a furrow adaxially, distinctly raised abaxially, 7–9 per side, 9–25 mm apart, not reaching the margin but curving towards the apex, sometimes anastomosing near the margin, venation reticulate; lateral leaflets similar to the terminal one, elliptic to ovate, 5–12.5 cm long, 4–7.5 cm wide, length/width ratio 1.3–1.7; pulvinus 2–3 mm long, thinly pubescent. Inflorescences in axillary or terminal leafy panicles, to 30+ cm long, peduncle 2–5 cm long, (thinly) pubescent; primary or secondary lateral branches to 15 cm long. Bracts subtending lateral branches minute, filiform, caducous or becoming leaf-like, persistent; floral bracts minute, caducous, distinctly shorter than buds, narrowly elliptic or narrowly ovate, 1–1.5 mm long, 0.5 mm wide, abaxial side sericeous, adaxial side glabrous. Pedicels 2–4 mm long, sericeous. Bracteoles absent. Calyx purple with golden-brown pubescent hairs, cup-shaped, 5–6 mm long, tube ca. 5 mm long, with 4–5 lobes; upper lip inconspicuously lobed to 2-lobed, lobes semicircular, 0.7–1 mm long, 1.5–2 mm wide, sometimes indistinct, lateral lobes triangular, 1–1.5 mm long, 1–2 mm wide; lower lobe triangular, ca. 1–2 mm long, 1–2 mm wide; abaxially sericeous, adaxially glabrous.

Corolla dark purple or maroon, standard with greenish central patch. Standard petal: claw 1–2 mm long; blade broadly ovate or orbicular, 8–10 by 8–9 mm, apex slightly emarginate, abaxially sericeous, adaxially glabrous, basal callosities absent. Wing petals: claw 1–1.5 mm long; blade narrowly oblong or obovate, 7–8 mm long, ca. 3 mm wide, apex rounded, abaxially with few hairs at the lower-middle part, adaxially glabrous; lateral pocket ca. 0.8 mm; upper auricle 0.8–1 mm long, lower auricle indistinct. Keel petals: claw 2–2.5 mm long; navicular-obovate, 6–7 by 3–3.5 mm, apex rounded, inside with few hairs at the lower-middle part, outside glabrous; lateral pocket 1–2 mm; upper auricle 1–1.5 mm long, Stamens diadelphous, 9–10 mm long, free part 1.5–2 mm long, glabrous or with few hairs on filaments; anthers 0.6–0.8 mm long, 0.4–0.5 mm wide, glabrous. Disc tubular, ca. 1 mm high, glabrous. Ovary 5–7 mm long, sericeous; ovules 4–6; style 2–3 mm long, sparsely sericeous. Pods usually strap-like, 7–13 cm long, 1–1.5 cm wide, glabrescent, slightly contracted between the seeds, seed chamber absent, mature pods sometimes with undeveloped seeds. Seeds 2–6 per pod, lenticular, 10–12 by 10–11 by ca. 3–4 mm; hilum slightly eccentric, ca. 2 mm long.

Phenology:—Flowering August to October, fruiting November to January.

Ecology:—Dry deciduous or bamboo forest semi or fully-exposed to sunlight with granitic bedrock.

Distribution:—Southwestern Thailand (Ratchaburi and Kanchanaburi province), Central Thailand but adjacent to South western Thailand (Suphan Buri province). Possibly along Tenasserim range and also in Myanmar but still no evidences for that.

Elevation:—Up to 400 m.

Proposed IUCN conservation assessment:— Callerya tenasserimensis would be Vulnerable (VU B2 ab(iii,v), D1, D2) according to the red list criteria ( IUCN 2012) because it is only known from three small populations from three localities (extent of occurrence less than 2000 km 2 in total) which are disturbed by tourism and agricultural activities. The entire population is estimated to contain fewer than 1000 individuals, and fewer than 50 mature plants were observed for each locality. Although several hundreds of seedlings can be found on the forest ground, they are easily killed by seasonal forest fire, grazing or trampling which are common in the dry deciduous-bamboo forest. Forest clearing happens at all known collection sites. For the time being we consider Callerya tenasserimensis to be Vulnerable (VU), but more field surveys are needed to make a final conservation assessment.

Etymology:— Specific epithet, “tenasserimensis ” refers to the Tenasserim range where this species has been found.

Additional specimens examined (paratypes):— THAILAND. Suphan Buri, Dan Chang district, near Phu Toei National Park, growing naturally in dry deciduous and bamboo forest, GPS coordinate 14°56’26.2”N 99°24’45.6”E, 22 September 2015, W. Tanming 816 (QBG!).