Revisions and key to the Vernonieae (Compositae) of Thailand

Abstract Seventeen genera and 48 species, in five subtribes, are recognized in Thailand. These include 15 endemic taxa, half of which are in the largest genus, Acilepis, with others in the genera Camchaya, Koyamasia, and Okia. A new monotypic genus, Pulicarioidea, is established with P. annamica, the new name for the species formerly known as Vernonia pulicarioides. New combinations are also made for Acilepis kerrii, Cyanthillium montanum, Koyamasia curtisii and Okia pseudobirmanica. Forty-six characters including habit, leaf, flower, achene and pollen morphology were analyzed using UPGMA. Five clusters of taxa were identified. Keys to genera, species and varieties, descriptions, vernacular names, ecological data and illustrations are provided.

Vernonieae taxa of many south and southeast Asian, Indo-Chinese and Malaysian Vernonieae lack any kind of treatment beyond the earliest naming and description and hence have not been included in this study. Additionally, there are > 200 species in this region which fact has also made understanding of the relationships among these taxa extremely challenging. Th e present study provides a revision of the genera and species, with keys and complete descriptions for all Vernonieae found within Th ailand.

Specimens and morphological measurements
Herbarium specimens were obtained from AAU, B, BCU, BK, BKF, BM, C, E, G, K, KKU, L, P, PSU, QBG and US. Field collections were also made throughout Th ailand by the fi rst author and have been deposited at KKU, QBG and US. Information recorded from specimens included distribution, and when available ecological data and vernacular name(s). Only mature vegetative and reproductive parts were measured or scored. Macromorphological measurements, presence/absence and specifi cs of surfaces and vestitures were obtained by light microscope. Achenes, leaf surfaces and unacetolyzed pollen were observed with scanning electron microscopy (SEM) using a LEO, 1450VP. A complete listing of taxa and voucher information are given in Table 1.

Phenetic analysis
Twenty-six binary and 20 multistate characters were obtained for 42 species (Table 1, 2), morphological characters are shown in Figs 1, 2, and representative pollen types in Fig. 3. At least 15 specimens per taxon were measured and scored. Data for some taxa were already available (Bunwong and Chantaranothai 2008) and were used as recorded in that study as the methodology was the same as that used here. All data were prepared using MacClade 4.03 (Maddison and Maddison 2001) and imported into PAUP* 4.0b10 (Swoff ord 2002) for Unweighted Pair Group Mathematical Average (UPGMA) cluster analysis. UPGMA tree were constructed using distance mesure of mean character diff erence. Th e number of 1000 replicates is used for all bootstrap tests.

Results and discussion
Five clusters of taxa are recognized in the UPGMA analysis as shown in Fig. 4. Th ese groups largely correspond to three Old World subtribes recognized by Robinson (1999b), the Centrapalinae, Erlangeinae, Gymnantheminae, and two adventive New World subtribes, Elephantopinae, and Vernoniinae. In addition, seven taxa, Cyanthillium montanum , Kurziella gymnoclada , Okia birmanica , O. pseudobirmanica , Koyamasia curtisii , K. curtisii Table 1. Taxa and voucher information for species included in UPGMA analysis.

Species
Locality (Province) Voucher information

No. Characters and character states
Camchaya is a well-supported genus within the subtribe Centrapalinae (Fig. 4). It is characterized by an annual habit, erect, leafy stems, achenes without a carpopodium, a deciduous pappus, and echinolophate hexaporate pollen. Bunwong et al. (2009) distinguished the genus Iodocephalopsis from Camchaya based on the absence of a spine at the margin of the involucral bracts, diff erences in bract shape, and the former taxon's tricolporate pollen. Although both genera are clearly closely related, their placement within the subtribe Centrapalinae may be subject to change. Robinson (pers. comm.) expressed doubt about the existence of true Centrapalinae in Th ailand because the taxa are morphologically distinct from those in this same subtribe in Africa, the taxa for which the subtribe was originally described. As a result, the position of Th ai taxa now ascribed to this subtribe will need to be evaluated within a larger analysis that also includes African Centrapalinae taxa before a fi nal decision can be made.
Structural features including pollen place the Asian Gymnanthemum and Decaneuropsis clearly in the subtribe Gymnantheminae, but DNA sequencing is still need-    Table 2, Figs 1, 2, 3). Number above the lines indicate bootstrap support (1000 replications). Zero length branches indicated by arrows. ed for confi rmation. Th e place of Monosis is less certain. For example, genera such as Decaneuropsis (and possibly Strobocalyx and Tarlmounia ) have been assigned to the Gymnantheminae (i.e. Robinson 2007, Robinson and Skvarla 2007, Robinson et al. 2008, 2010 while others have been removed and placed in their own subtribe, i.e., Distephanus , now in subtribe Distephaninae (Keeley and Robinson 2009). Typical African Gymnantheminae diff er in habit from their Th ai counterparts as well. African species are typically low-growing scandent shrubs while southeast Asian taxa are large shrubs and treelets. Taxa also diff er in corolla morphology and in infl orescence type, characteristically thrysiform in African taxa rather than corymbiform as in the Th ai species (Robinson and Skvarla 2007). On the other hand, both African and southeast Asian taxa now placed in this subtribe share deciduous involucral bracts, blunt sweeping hairs on the style, an indurate appendage on the anthers, refl exed and deeply divided corolla lobes, and tricolporate, non-lophate pollen (Robinson 2007, Ro binson et al. 2008, Robinson and Skvarla 2009. Whether the Th ai genera should be placed in a new subtribe separate from the African Gymnantheminae will require a more detailed study that includes putative members of the subtribe from across its geographical range. A similar situation also appears to exist in the subtribe Erlangeinae which, like the Gymnantheminae and Centrapalinae, is primarily African (Keeley and Robinson 2009). Th e six Th ai endemic Acilepis species, as well as Kurziella gymnoclada , now assigned to the Erlangeinae, diff er from their African relatives in both reproductive and morphological characters. Also, as is the case for the other subtribes in this study, no African taxa were included in the analyses and, as a result, relationships to other members of this subtribe, including the type genus Erlangea , are unknown. Additionally, other taxonomic changes may also be necessary to create monophyletic genera. Further, the subgroup composed of Iodocephalopsis , Struchium and Koyamasia curtisii also needs a more thorough evaluation. Robinson (1999a,b) placed Struchium in the primarily New World subtribe Lepidaploinae, and its putative alliance with Old World taxa, as seen here (Fig. 4), may be due to morphological convergence rather than to a close genetic relationship. Until such a time when a wider range of Erlangeinae taxa can be included in an analysis with Th ai species, the subtribal status and the relationships among this threesome will remain unclear.
Unlike the Centrapalinae, Erlangeinae, and Gymnantheminae described above, however, the membership of taxa in the Elephantopinae is clear (Fig. 4). Additionally, this subtribe has been previously shown to be monophyletic using DNA sequence data (Keeley et al. 2007). Species in this subtribe are annual to biennial herbs or subshrubs with liguliform zygomorphic corollas, capitula clustered within foliose bracts, fi liform hairs on the leaf surfaces and echinolophate triporate pollen, a distinctive combination of characters that clearly sets this subtribe off from the rest of the Vernonieae. Keeley et al. (2007) also found that the Elephantopinae are New World in origin, and Elephantopus mollis , E. scaber and Pseudelephantopus spicatus now found in disturbed locations throughout the tropics has achieved this distribution by following in the wake of people and their domestic animals. Th ey are excellent camp followers.

Conclusions
Th ere is now a taxonomic framework that will allow for future development of and testing of hypotheses of Vernonieae relationships over a wide region of the Old World including Africa and south and southeast Asia. Of particular interest are the relationships of taxa now putatively in the same subtribe but whose characteristics diff er (i.e., between Asia and Africa). Th ailand may also be key to understanding subtribal radiations across the Old World as it is located at the crossroads of biotic migrations westward from Malaysia and eastward from India and Africa. Understanding the subtribal histories will allow us to follow the historical pathways of dispersal, and identify habitat types that promote endemism and local adaptive radiations. Th e Vernonieae has been referred to as the "evil tribe" (Keeley et al. 2007) because of its taxonomically refractory nature. It has always been diffi cult to make clear distinctions at every level from the most inclusive subtribe and genus (i.e., Vernonia ) to the individual species. However, the Vernonieae is also one of the few plant groups blessed with the right combination of geographical distribution, and diversity of genera and species to make it possible to gain a good picture of plant evolution across a region of rich biotic diversity, such as is found in Th ailand and southeast Asia.
Diagnostic characters. Cyanthillium patulum diff ers from C. cinereum by having only single series of pappus, a 5-ribbed achenes without hair and a globose capitula.
Diagnostic characters. Th is species is characterized by discinctly sweet smell, the habit of shrubs or subshrubs, and obtuse phyllaries.