PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 122(2):146–149. 2009. A new genus, Khasianthus, from India, Myanmar, and China (Vernonieae: Asteraceae) Harold Robinson* and John J. Skvarla (HR) Department of Botany, MRC 166, National Museum of Natural History, P.O. Box 37012, Smithsonian Institution, Washington, D.C. 20013-7012, U.S.A., e-mail: [email protected]; (JJS) Department of Botany and Microbiology, and Oklahoma Biological Survey, University of Oklahoma, Norman, Oklohama 73019-6131, U.S.A., e-mail: [email protected] Abstract.—A new Asian genus of Vernonieae, Khasianthus, is named for Vernonia subsessilis DC. It is most closely related to the primarily African genus Baccharoides Moench. The recognition that the genus Verno- Materials and Methods nia Schreb. is mostly North American (Robinson 1999a) means that most spe- Pollen was removed from herbarium cies formerly placed in that genus have to sheets from the U.S. National Herbarium be reassigned. Species to be reassigned in Washington, D.C. and treated with include all the Old World members of the acetolysis solution (Erdtman 1960). Prep- tribe Vernonieae under the name Verno- aration for scanning electron microscopy nia. Reassignment of paleotropical Ver- (SEM) consisted of staining with osmium- nonieae was begun by Robinson (1999b), thiocarbohydrazide and pulse sputter but that treatment was incomplete and coating as described in detail in recent overly simplistic. More concise concepts studies of Asian Vernonieae (Robinson & have more recently been derived for Skvarla 2006, 2007; Robinson et al. 2008). members of the subtribe Gymnanthemi- Examination was with JEOL 880, LEICA nae in Asia with the restoration of the 440, and AMRAY 1810 scanning electron genera Monosis DC. (Robinson & microscopes; all equipped with lanthanum Skvarla 2006), Strobocalyx Blume ex hexaboride (LaB6) electron sources. These DC. (Robinson et al. 2008), and the microscopes were at the Samuel Roberts description of a new genus Decaneuropsis Microscopy Laboratory at the University based on Vernonia cumingiana Benth. of Oklahoma and the SEM laboratory of (Robinson & Skvarla 2007). Among the the United States National Museum of Erlangeine genera, the genus Acilepis D. Natural History in Washington. Don, resurrected by Robinson (1999b), has been considerably enlarged and more Discussion precisely delimited (Robinson & Skvarla 2009). An additional element of the Asian Vernonia subsessilis DC. is a species Vernonieae is treated here, a new genus from northern India, northern Myanmar, Khasianthus, which seems most closely and southwestern China, that bears a related to the African genus Baccharoides superficial resemblance to certain species Moench. now placed in the genus Acilepis (Robin- son & Skvarla 2009). Although described mostly as an undershrub, specimens on herbarium sheets can hardly be distin- * Corresponding author. guished from the more herbaceous Acile- VOLUME 122, NUMBER 2 147 Fig. 1. Scanning electron micrographs of pollen of Khasianthus subsessilis (DC.) H. Rob. & Skvarla, India Orient., Khasia, s.d., J. D. Hooker s.n. [US, sheet #2492470]. A, Polar view showing 3 colpi and a polar lacuna; B, Intercolpar view; C, Colpar view; D, Partially broken grain showing columellae. pis in habit. Furthermore, the involucral roots, it possesses a basically branching bracts in Vernonia subsessilis are narrowly perennial structure. The most important attenuate in many series, as in many of differences between the genera, however, the typical members of Acilepis.This become apparent when V. subsessilis is resemblance to Acilepis drew our atten- subjected to microscopic examination. tion to the species treated below. Differences are seen in the anthers, in Macroscopic features that distinguish the setulae of the achenes, and especially Vernonia subsessilis from Acilepis include in the pollen (Fig. 1A–D). leaf venation and habit. In V. subsessilis, The anthers of Vernonia subsessilis the cuneate basal parts of the leaves have consistently show a large broad basal many widely spreading secondary veins, appendage on the lower end of the spurred in contrast with the more ascending theca. Such appendages are totally lacking secondary veins of Acilepis. Vernonia in Acilepis. The setulae of the achene in V. subsessilis is also apparently shrubbier subsessilis have their two cells fused to than Acilepis. Although sometimes small their tips, in contrast to Acilepis in which and appearing unbranched from the the cells of the setulae are deeply separat- 148 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON ed, often to the base. The pollen of V. Subshrubs up to 1 m tall; stems erect subsessilis differs from that of Acilepis in from basal cluster of roots, sparingly four ways (Fig. 1A–D). First, it is tricol- branched, densely pubescent with strong- porate rather than triporate (Fig. 1B, C). ly antrorse, whitish hairs, hairs mostly of Second, the spinules are distinctly longer a long, I-shaped, rather straight terminal and more pointed (ca. 3–4 mm long versus cell. Leaves alternate, subsessile, charta- ca. 1 mmlonginAcilepis). Third, the ceous, oblanceolate to obovate, with cun- tectum along the crests of the muri has eate bases, margins remotely serrulate or distinct perforations (Fig. 1D). Fourth, crenulate to subentire, apices acuminate the muri are firmly attached to the foot to rounded, with many spreading lower layer by columellae with no intervening secondary veins, surfaces with prominu- rhizomate base that is easily stripped from lous veins and veinlets, with sparse, small the foot layer, in contrast to Acilepis glandular dots, with appressed hairs on (Robinson & Skvarla 2009). midvein and sometimes sparsely over The resemblance of Vernonia subsessilis abaxial surface. Inflorescence corymbi- to Acilepis is evidently superficial. The form or nearly racemiform, with linear pollen, in particular, shows that this bracts at lower nodes; peduncles elongate, species is most likely related to primarily with dense whitish hairs. Heads with African genera such as Baccharoides.For involucre broadly campanulate; involu- the present, well-developed tricolporate cral bracts gradate, persistent, sericeous lophate pollen is not known in the on outer surface, ca. 80 in 5–6 series, 3– subtribe Erlangeinae H. Rob. to which 7 mm long, lanceolate or acicular to Acilepis belongs. Among paleotropical linear-lanceolate, apices slender and her- Vernonieae with tricolporate lophate baceous in all but inner series, recurved in pollen, Baccharoides of the subtribe Lin- anthesis in lower series, inner bracts erect, ziinae Keeley & H. Rob. possesses almost with raised midvein, with short-acute tips; exactly the same kind of tricolporate, receptacle alveolate, with fine hairs. Flo- echinolophate, microperforate, pollen rets 40–50; corollas purple, becoming with a lacuna at each pole, features whitish, basal tube slender with small otherwise uncommon among African stipitate glands, lobes as long as throat, Vernonieae. However, the Asian species lobes erect, with glandular dots mostly does not key to Baccharoides in Robinson near tip; anther base spurred, with (2007) because its pappus bristles lack distinct broad tail; endothecial cells with flattened outer surfaces. The involucral vertical annulations; apical appendages bracts of V. subsessilis also lack the oblong-ovate, with narrowly rounded highly differentiated, often showy, mem- tips, glabrous, cells thin-walled; style shaft branous tips that are characteristic of thick, rounded at base to narrow inser- Baccharoides. tion, without basal node; style branches Etymology.—The new genus established with sharply acute sweeping hairs. here for Vernonia subsessilis is named after Achenes to 3.5 mm long, 10-ribbed, with Khasia, the region of Assam, India from many slender setulae that have pairs of which most of the material has been seen. cells fused to the tip, glands dense between ribs, raphids elongate, mostly in Khasianthus H. Rob. & Skvarla, gen. nov. ribs; pappus reddish, of many capillary Type species.—Vernonia subsessilis DC., bristles, not or scarcely broadened at tips, Prodr. 5:62 (1836). not flattened on outer surface, outer series A Baccharioides similis sed in bracteis of short bristles. Pollen grains ca. 60 mm involucri distaliter non elaboratis et in in diameter in fluid, tricolporate, echino- setis pappi abaxialiter non planis. lophate with sharp spinules, muri firmly VOLUME 122, NUMBER 2 149 attached to foot layer by columellae, Acknowledgments tectum restricted to crests of muri, with distinct perforations; one lacuna at each Marjorie Knowles, technician in the pole, intercolpar lacunae arranged in Department of Botany, National Muse- groups of six, one near each pole and um of Natural History, Smithsonian two rows of two equatorially (1:2:2:1) Institution, is thanked for help in prepa- (Fig. 1A–D). ration and correction of the manuscript. The genus appears to contain only a Jun Wen, of the Department of Botany, is single species with two varieties. thanked for suggestions regarding the Rock collection from China. Khasianthus subsessilis (DC.) H. Rob. & Skvarla, comb. nov. Literature Cited Conyza divergens Wall. Numer. List Candolle, A. P. de. 1836. Trib, 1. Vernoniaceae. [Wallich] n. 3000 comp. 110, nom. nud. Less.—Prodromus systematis naturalis regni vegetabilis 5:9–103. Vernonia subsessilis DC., Prodr. 5:62 Erdtman, G. 1960. The acetolysis method. A revised (1836). description.—Svensk Botanisk Tidskrift 54: Conyza bracteolata Wall. Numer. List 561–564. [Wallich]