Journal of Systematics and Evolution 52 (1): 1–15 (2014) doi: 10.1111/jse.12064 Research Article Reassessing the taxonomic status of two enigmatic Desmos species (Annonaceae): Morphological and molecular phylogenetic support for a new genus, Wangia 1Xing GUO 1Jing WANG 1Bine XUE 1Daniel C. THOMAS† 1Yvonne C. F. SU‡ 2Yun‐Hong TAN 1Richard M. K. SAUNDERS* 1(School of Biological Sciences, The University of Hong Kong, Hong Kong, China) 2(Key Laboratory of Tropical Forest Ecology, Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, Yunnan, China) Abstract The systematic position of two enigmatic Annonaceae species from China, Desmos saccopetaloides (W. T. Wang) P. T. Li and Desmos yunnanensis (Hu) P. T. Li, has been controversial, with both species having been transferred between several different genera within subfamilies Annonoideae and Malmeoideae. Phylogenetic analyses of eight chloroplast regions (matK, ndhF, ndhF‐rpl32, psbA‐trnH, rbcL, rpl32‐trnL, trnL‐F, and ycf1; ca. 9.2 kb, 66 taxa) unambiguously placed D. saccopetaloides in a subclade of tribe Miliuseae, nested among the genera Monoon, Neo‐uvaria, Phaeanthus, Sageraea, and Stelechocarpus. This relationship was also supported by endosperm rumination patterns in the seed; other morphological characters furthermore indicated that D. saccopetaloides has closer affinities with Monoon, Neo‐uvaria, and Phaeanthus rather than either Sageraea or Stelechocarpus. Desmos saccopetaloides is distinguished from these genera by its leaf‐opposed inflorescences, sepaloid outer petals, saccate inner petals with basal glandular tissue, moniliform monocarps with uniseriate seeds, and rectangular disulculate pollen with two “cryptoapertures.” On the basis of the combined molecular phylogenetic and morphological data, we propose a new genus, Wangia, to accommodate D. saccopetaloides. The molecular phylogenetic analyses furthermore indicated that D. yunnanensis belongs to the genus Dasymaschalon: examination of the type collections revealed that it is conspecific with Dasymaschalon obtusipetalum, although the combination Dasymaschalon yunnanense has nomenclatural priority. Key words Dasymaschalon, molecular phylogeny, morphology, Phaeanthus, taxonomy. Early studies of higher‐level taxonomic relation- several taxa remain obscure, including those of two ships within the pantropical flowering plant family enigmatic species from China, currently recognized as Annonaceae were based by necessity on morphological Desmos saccopetaloides (W. T. Wang) P. T. Li and characters, including pollen (e.g., Walker, 1971), Desmos yunnanensis (Hu) P.T. Li (Li et al., 2011). The flowers (e.g., Van Heusden, 1992), and fruits and seeds former species has been variously placed in Desmos (e.g., Van Setten & Koek‐Noorman, 1992). Reliance on Lour. (subfam. Annonoideae) and Phaeanthus Hook. f. these characters ultimately proved unsatisfactory due to & Thomson (subfam. Malmeoideae), and the latter in extensive morphological convergence (Saunders, Dasymaschalon (Hook. f. & Thomson) Dalla Torre 2010), and most recent higher‐level classifications of & Harms (subfam. Annonoideae), Desmos and the family have been based on DNA sequence data, Phaeanthus. particularly that of the chloroplast genome (e.g., The outer petals of D. saccopetaloides (ca. 4 mm Chatrou et al., 2012). Despite significant advances long) and D. yunnanensis (ca. 3 mm long) are much over the past decade, the phylogenetic affinities of shorter than the inner petals (27–35 mm and ca. 28 mm, respectively). This feature is characteristic of Phaean- thus, leading Hu (1940) and Wang (in Wu & Wang, Received: 18 July 2013 Accepted: 17 October 2013 † 1957) to describe these species as Phaeanthus Current address: Naturalis Biodiversity Centre, Section NHN, Leiden University, 2300 RA Leiden, The Netherlands. yunnanensis Hu and Phaeanthus saccopetaloides ‡ Current address: Duke‐NUS Graduate Medical School Singapore, W. T. Wang. Wang furthermore suggested an affinity Singapore 169857, Singapore. Ã Author for correspondence. E‐mail: [email protected]. Tel.: 852‐ between the two species by comparing them in the 2299‐0608. Fax: 852‐2517‐6082. diagnosis of the latter species, in which he contrasted © 2013 Institute of Botany, Chinese Academy of Sciences 2 Journal of Systematics and Evolution Vol. 52 No. 1 2014 the oblong to lanceolate inner petals and flat monocarps terized by flowers with greatly reduced sepaloid outer of P. saccopetaloides with the ovate inner petals and petals, and globose to ellipsoid monocarps, with one cylindrical monocarps of P. yunnanensis (Wu & Wang, (rarely two) seeds (Mols & Keßler, 2000). Li et al. 1957). (2011) recognized the doubtful affinities of the two Bân (1975) examined one of the type specimens of species, stating that their taxonomic placement “re- P. yunnanensis with fruits (C. W. Wang 79167, A) and quires further research.” The aims of the present study noted that the monocarps are moniliform (elongated, are therefore to: (i) clarify the phylogenetic relation- with constrictions between seeds), a fruit shape that had ships of the two species based on chloroplast DNA never previously been reported in Phaeanthus;he sequence data; (ii) assess the morphological support for accordingly transferred the species to Dasymaschalon, these relationships and to identify synapomorphies; and which is characterized by such fruits. Although Bân did (iii) validate consequential nomenclatural changes as not examine flowering material, he doubted whether necessary. there were truly six petals in the type specimen: he argued that Hu (1940) had erroneously interpreted an apical expansion of the pedicel as sepals (1 mm long in 1 Material and methods Hu’s description) and the sepals (3 mm long) as outer petals, and hence believed that the flowers only had 1.1 Taxon and DNA region sampling three petals (also characteristic of Dasymaschalon). The 66‐accession dataset included a paratype (T. T. Tsiang & Li (1979) subsequently dissected flowers Yu 16484, PE) and isotype (T. T. Yu 17336,A)of from another type specimen of P. yunnanensis (C. W. Phaeanthus (Desmos) saccopetaloides, the isotype Wang 79167, PE) and agreed with Hu’s (1940) (C. W. Wang 79167,A)ofPhaeanthus (Desmos) observation of six petals in two whorls. This evidence, yunnanensis, 46 accessions representing 27 genera together with the moniliform shape of the monocarps, led from subfam. Malmeoideae, and 13 accessions repre- them to recognize both P. yunnanensis and P. saccope- senting 11 genera from subfam. Annonoideae. The taloides in Desmos (Tsiang & Li, 1979; Li, 1993), a genus outgroups consisted of three species from subfam. that has moniliform fruits that resemble those of Ambavioideae and one species of Anaxagorea A. Dasymaschalon, but which, unlike Dasymaschalon,has St.‐Hil. (subfam. Anaxagoreoideae). Preliminary phy- flowers with six petals in two whorls. logenetic analyses indicated that D. saccopetaloides Desmos yunnanensis in Thailand was described was nested within tribe Miliuseae (subfam. Malmeoi- and illustrated by Chalermglin (2001: 118–119) as deae), and we accordingly focused taxon sampling on “Dasymaschalon yunnanense (Hu) Bân.” Wang et al. this tribe, including one to four species for each genus. (2009) examined Thai specimens and found that this Sequences of five chloroplast DNA regions (matK, species only has three petals; on the basis of previous ndhF, rbcL, psbA‐trnH, and trnL‐F) which are descriptions by Hu (1940) and Tsiang & Li (1979) of six frequently used in Annonaceae phylogenetic studies petals per flower, Wang et al. (2009) believed that the were newly generated or downloaded from GenBank Thai specimens differed from “true” Desmos yunna- (http://www.ncbi.nlm.nih.gov). In order to better nensis in China. They therefore described a new resolve the tribe Miliuseae, which is notoriously species, Dasymaschalon obtusipetalum Jing Wang, recalcitrant (Mols et al., 2004b; Couvreur et al., Chalermglin & R. M. K. Saunders. The two enigmatic 2011; Xue et al., 2011, 2012; Chaowasku et al., species, currently recognized in the Flora of China (Li 2012; Chatrou et al., 2012; Thomas et al., 2012), we et al., 2011) as Desmos saccopetaloides and Desmos incorporated three additional regions (ndhF‐rpl32, yunnanensis, have therefore been variously associated rpl32‐trnL, and ycf1) that have been shown to be with several morphologically and phylogenetically highly variable and phylogenetically useful in the tribe distinct genera. Desmos and Dasymaschalon (both in Miliuseae (Thomas et al., 2012). In total, 59 sequences subfam. Annonoideae) share the unusual characteristic were newly generated for this study (voucher informa- of moniliform monocarps, but differ markedly in floral tion and GenBank accession numbers listed in structure: Desmos flowers have six petals in two whorls, Appendix I). Percentages of missing data are 33.8% with both whorls basally constricted around the in the total dataset and 28.1% in subfamily reproductive organs; whereas Dasymaschalon flowers Malmeoideae. have only three petals (regarded as homologous with the outer petals of other Annonaceae: Wang et al., 2012) 1.2 DNA extraction, amplification, and sequencing that are apically connivent over the reproductive Total DNA was isolated from herbarium material organs. Phaeanthus (subfam. Malmeoideae) is charac- using the innuPrep Plant DNA Kit (Analytik Jena, Jena, © 2013 Institute of Botany, Chinese Academy of Sciences GUO et al.: Wangia, gen. nov. (Annonaceae) 3 Germany)