A new species of Camchaya (Asteraceae, Vernonieae) from Thailand

Abstract Camchaya thailandica Bunwong, Chantar. & S.C.Keeley, sp. nov. from Phu Phrabat Historical Park, Udon Thani, Thailandis described as a new species. Plant of this new species are similar to Camchaya gracilis (Gagnep.) Bunwong & H.Rob. but differ in having ovate phyllaries without margin spines, 10-ribbed achenes, and broadly ovate leaves. This species is a rare endemic known only from the type collection and probably confined to open areas of sandstone hills in Udon Thani province.


Introduction
described six species of Camchaya in Th ailand, recognizing the genus based on the presence of 5-10 ribbed achenes and a bristle-like pappus on some fl orets, thus broadening earlier concepts of the genus by Kerr (1935) and Kitamura (1968). Bunwong et al. (2009) Bunwong (2010) found seven species of Camchaya including a new taxon, C. thailandica, described here. Camchaya thailandica is one of the fi ve endemic Th ai species: including C. pentagona, C. spinulifera, C. tenuifl ora, and C. gracilis. Th e two remaining species, C. kampotensis and C. loloana extend beyond Th ailand into Laos, Cambodia and adjacent Yunnan, China.

Methodology
Camchaya specimens examined were obtained from the following herbaria: AAU, BK, BKF, BM, CMU, E, K, KKU, L, P, QBG, and US. All measurements given herein were taken from fi eld notes, dried herbarium specimens, and spirit collections. Pollen and achenes were obtained from fi eld collections around Th ailand by the fi rst author. Pollen samples for the SEM work were acetolyzed (Erdtman 1960). Acetolyzed pollen was freeze-dried using the critical point drying method. Acetolyzed pollen, unacetolyzed achenes and leaf surfaces were then placed on specimen stubs with double sided silver tape and sputter coated with gold. Photomicrographs were taken with SEM (LEO, 1450VP; Applied Taxonomic Research Center, Department of Biology, Faculty of Science, Khon Kaen University). Annual. Infl orescences axillary or terminal, pedunculate. Phyllaries imbricate in 5-6 series, arachnoid-glandular, apices purple. Diff ers from C. gracilis (Gagnep.) Bunwong & H.Rob. in having ovate acuminate rather than broadly ovate acute phyllaries without margin spines, 10-ribbed rather than 4-5-ribbed achenes, and broadly ovate leaves.
Distribution. Endemic to Th ailand. Only found in Phu Phrabat Historical Park, Udon Th ani province.
Ecology. Rocky areas of sandstone hills, scattering in dipterocarp forest, fl owering from November and December.
Discussion. Camchaya thailandica is similar to C. gracilis in having ovate phyllaries without spines on the margin, but diff ers in having 10-ribbed achenes and a broadly ovate leaf shape. Its 6-porate echinolophate pollen is unique to Camchaya (Bunwong and Chantaranothai 2008) and places it fi rmly in this genus. Additionally, this species has an inconspicuous carpopodium which is common in Camchaya.