Phyllanthus chayamaritiae Chantar. & Kantachot, 2013

Phyllanthus chayamaritiae Chantar. & Kantachot View in CoL , sp. nov. ― Fig. 1 View Fig , 2 View Fig , 3c, d View Fig

A P. amario L. et P. urinario L. affinis , ovario et capsula dense spiniformibus differt. ― Typus: P. Chantaranothai & C. Kantachot 2010-1 (holo KKU; iso BKF), Thailand, Sakon Nakhon, Phu Phan National Park, 10 July 2010.

Etymology. The name of the species honours Dr Kongkanda Chayamarit, the head of the Euphorbiaceae project for the Flora of Thailand.

Annual herb up to 70 cm high; branchlets angled, glabrous. Stipules lanceolate or ovate-lanceolate, 0.3 –1 mm long. Leaves: petiole 0.2 –0.8 mm long; blade oblong, elliptic-oblong or obovate, 2.6–11 by 1.3– 5 cm, chartaceous or subcoriaceous, finely puberulous on both sides, base slightly unequal, obtuse or rounded, margin entire and finely puberulous, apex obtuse or rounded and apiculate; lateral veins in 3 –4 pairs; reticulation inconspicuous on both sides. Flowers axillary, mostly bisexual fascicles; first 1 or 2 axils with staminate flowers, succeeding axil each with 1 pistillate flower and 1 staminate flower and the last 1 or 2 axils of the distal axils with 1 pistillate flower. Staminate flowers: pedicels 0.5 –1 mm long; sepals 6, ovate or elliptic, 0.2 –0.7 by 0.1– 0.4 mm, light yellowish; disc glands 6, star-shaped or orbicular; stamens 3, staminal column 0.1–0.3 mm long, anthers 0.1–0.3 mm long. Pistillate flowers: pedicels

© 2013 Nationaal Herbarium Nederland

mm

0.7–1.2 mm long; sepals 6, obovate-oblong or lanceolate, 0.3– 0.8 by 0.2 – 0.5 mm, glabrous, apex acute with broad whitish scarious margin; disc glands 6; ovary covered with soft spine-like hairs; styles 0.1–0.2 mm long; stigma c. 0.1 mm long. Fruits: pedicel 1.5 –2 mm long, 0.8– 2 mm diam, capsular, depressed globose, covered with soft spine-like hairs, light green or light yellowish green. Seeds trigonous, 0.5 –1.2 by c. 1 mm wide, with 2 hollows on the sides.

Distribution ― Thailand: North­Eastern: Sakon Nakhon, Khon Kaen; Eastern: Ubon Ratchathani.

Habitat & Ecology ― Phyllanthus chayamaritiae occurs in open places of deciduous forests with stone bedrock habitat, at 300 –600 m a.s.l. The populations cover restricted areas of only 15– 40 m 2 and are growing together with Amalocalyx microlobus Pierre ex Spire ( Apocynaceae ), Crotalaria sp. ( Fabaceae ), Droogmansia godefroyana Schindl. ex Gagnep. ( Fabaceae ), Eriocaulon echinulatum Mart. ( Eriocaulaceae ), Fimbristylis dichotoma (L.) Vahl ( Cyperaceae ), Justicia diffusa Willd. ( Acanthaceae ), Lindernia kerrii T.Yamaz. ( Schrophulariaceae), Tephrosia vestita Vogel ( Fabaceae ) and Xyris sp. ( Xyridaceae ).

Phenology ― Flowering occurs from June to September and fruiting from July to November.

Voucher specimens. THAILAND, Ubon Ratchathani, Phu Jong Nayoi National Park , 3 Oct. 2010, C . Kantachot 495 ( KKU) ; Sakon Nakhon, Phu Phan National Park , 28 Sept. 2004, Daroon 05 ( KKU) ; Sakon Nakhon, Phu Phan National Park , 25 Oct. 2010, C . Kantachot 500 ( KKU) ; Khon Kaen, Nam Phong National Park , 15 July 2011, P . Chantaranothai 2011-1 ( KKU) .

Note ― The morphological, anatomical and SEM investiga- tions ( Table 1) show the characters of P. chayamaritiae as compared with P. amarus and P. urinaria . However, P. chayamaritiae differs from other species in having long spine hairs on the capsule, and ovary and absence of druses in pith. It is found in Sakon Nakhon, Khon Kaen and Ubon Ratchathani provinces in north-eastern and eastern Thailand whereas P. amarus and P. urinaria are widespread through the country.