American Journal of Botany 85(9): 1143±1158. 1998. MORPHOLOGY AND MOLECULAR DATA IN PHYLOGENETIC FRATERNITY: THE TRIBE WRIGHTIEAE (APOCYNACEAE) REVISITED1 BENGT SENNBLAD,2,4 MARY E. ENDRESS,3 AND BIRGITTA BREMER2 2 Department of Systematic Botany, Uppsala University, Villav. 6, S-752 36 Uppsala, Sweden; and 3 Institute of Systematic Botany, University of ZuÈrich, Zollikerstrasse 107, CH-8008 ZuÈrich, Switzerland The monophyly and classi®cation of the tribe Wrightieae of the subfamily Apocynoideae (Apocynaceae) are cladistically investigated. Nine taxa from the Wrightieae sensu Leeuwenberg, nine from other Apocynoideae sensu lato (s.l., including two from the traditional Asclepiadaceae), and two outgroup taxa from the Plumerioideae (Apocynaceae) were scored for rbcL sequence data and morphological data, mainly ¯oral characters, and analyzed using successive weighting parsimony analysis. The Wrightieae sensu Leeuwenberg are shown to be largely paraphyletic, the constituent taxa being dispersed among four monophyletic clades. Previously not suggested relationships indicated by the study are the association of Pachypodium with Funtumia, Holarrhena, and Mascarenhasia and the position of Beaumontia close to Trachelospermum. A reclassi®cation of the Wrightieae is discussed, in which three of the identi®ed clades are recognized as tribes, the Wrightieae sensu stricto (s.s.), the Nerieae, and the Malouetieae. The support for the Wrightieae s.s. is very strong, as evaluated with Bremer support and bootstrap analysis. The Malouetieae are also strongly supported, but the Nerieae less so. Using potential morphological synapomorphies identi®ed in the study, circumscription of the tribes is discussed. A potential pseudogene of rbcL is reported for Beaumontia. Key words: Apocynaceae; chloroplast DNA; classi®cation; ¯oral morphology; Malouetieae; Nerieae; phylogeny; rbcL; Wrightieae. Morphology has, without parallel, been the tradition- data (Olmstead et al., 1993; Sennblad and Bremer, 1996) ally most important source of information in plant tax- show that the Asclepiadaceae are nested within the sub- onomy. A majority of taxonomic groups recognized to- family Apocynoideae of the Apocynaceae, and thus sup- day are de®ned by cardinal characters mainly from ¯oral port the wider circumscription of Apocynaceae s.l. of Jus- morphology. The relatively recent addition of molecular sieu. The group comprising the Apocynoideae and the data together with a phylogenetic concept in systematics traditional Asclepiadaceae is, henceforth, referred to as challenges many of these groups, showing them to be the Apocynoideae s.l.; the Apocynoideae as traditionally paraphyletic assemblages. However, morphology should circumscribed (e.g., Schumann, 1895a; Pichon, 1950a; not simply be dismissed in favor of molecular data. In- Leeuwenberg, 1994, non sensu Woodson, 1930) are re- stead, combined analyses of morphological and molecu- ferred to as the Apocynoideae s.s. lar data sets provide a strong basis for phylogenetic hy- The subdivision of the subfamily Apocynoideae s.s. potheses and thus also for classi®cation. Morphological has always been considered problematic (e.g., Leeuwen- synapomorphies identi®ed in such an analysis may also berg, 1994); the number of tribes recognized has varied allow rapid prediction of the placement of further taxa. from two to four (e.g., Schumann, 1895a; Pichon, 1950a; Here, this is exempli®ed in a phylogenetic study of the Leeuwenberg, 1994; see Table 1). However, the tribe tribe Wrightieae from the subfamily Apocynoideae of the Wrightieae (also as Nerieae) has been recognized as dis- Apocynaceae s.l. tinct (Leeuwenberg, 1988, 1994), and its constituent gen- The Apocynaceae s.l. (de Jussieu, 1789) have tradi- era have by some authors been interpreted as ``basal'' tionally been divided into the Apocynaceae s.s. and the compared to the rest of the subfamily (MacFarlane, 1933; Asclepiadaceae (e.g., Brown, 1810; Schumann, 1895a, Pichon, 1950a). This interpretation has been based on the b). Recent phylogenetic studies based on rbcL sequence lower degree of specialization in the tribe, which thus shows a wide array of presumed plesiomorphic characters 1 Manuscript received 20 May 1997; revision accepted 2 December (see Appendix in Pichon, 1950a). 1997. Plesiomorphic characters, however, may not identify a The authors thank K. Andreasen, A. Backlund, K. Bremer, M. Chase, monophyletic group, and in the analysis by Sennblad and R. Olmstead, and an anonymous reviewer for comments on the manu- Bremer (1996) the tribe Wrightieae was also indicated to script, P. Berry, L. Dorr, V. Ferreira, P. Forster, P. Garnock-Jones, A. Leeuwenberg, S. Liede for sharing their material, K. Kullander and F. be paraphyletic, with the included representatives Ste- HallboÈoÈk for suggestions on ampli®cation problems, A. Igersheim and phanostema and Strophanthus being successive sister U.-B. SahlstroÈm for photography work, and N. Heidari, J. RoÈnnholm, taxa to a clade comprising the rest of the Apocynoideae and R. Siegrist for assistance with the laboratory work. The Uppsala s.l. Botanical Garden, the Uppsala Botanical Museum, the Department of Plant Taxonomy at Wageningen Agricultural University, the National HistoryÐThe tribe Wrightieae was ®rst described by Botanical Garden of Belgium, the Aarhus Botanical Garden, and the Fairchild Tropical Garden kindly provided plant material. This study Don (1838). It was based on presence of a chalazal hair was supported by the Swedish Natural Science Research Council, NFR. tuft (coma) on the seed and included the two genera 4 Author for correspondence. Wrightia and Kibatalia (Table 1). This treatment was fol- 1143 1144 AMERICAN JOURNAL OF BOTANY [Vol. 85 TABLE 1. Tribal and subtribal (if recognized) classi®cation, and genera included in the cladistic analysis. For the Plumerioideae taxa only subfamily is given. (ASC) indicates that the taxon was placed in the Asclepiadaceae. All other taxa are classi®ed in the Apocynoideae. A dash indicates that the taxon was not treated by the author heading the column. Schumann Pichon (1948a, b; Leeuwenberg Taxa Don (1838) (1895a, b) 1950a, b) (1994) Acokanthera Ð Plumerioideaea Plumerioideae Plumerioideae Picralima Ð Plumerioideae Plumerioideae Plumerioideae Thevetia Ð Plumerioideae Cerberoideae Plumerioideae Adenium Echiteae Echiteaeb Wrightieaec: Wrightieae: Adeniinae Neriinae Nerium Echiteae Echiteae Wrightieae: Wrightieae: Neriinaed Neriinae Beaumontia Echiteae Echiteae Wrightieae: Wrightieae: Beaumontiinae Wrightiinae Stephanostema Ð Ð Wrightieae: Wrightieae: Wrightiinae Wrightiinae Strophanthus Echiteae Echiteae Wrightieae: Wrightieae: Strophanthinae Wrightiinae Wrightia Wrightieae Parsonsieae Wrightieae: Wrightieae: Wrightiinae Wrightiinae Funtumia Ð Echiteae Wrightieae: Wrightieae: Kibataliinae Malouetiinae Mascarenhasia Ð Echiteae Wrightieae: Wrightieae: Mascarenhasiinae Malouetiinae Holarrhena Echiteae Plumerioideae Plumerioideae Wrightieae: Ala®inae not sampled Wrightieae: Ala®inae Apocynum Echiteae Echiteae Ecdysanthereae: Apocyneae: Apocyninae Apocyninae Baissea Ð Echiteae Ichnocarpeae: Apocyninae: Baisseinae Ichnocarpinae Mandevilla Ð Echiteae Ichnocarpeae: Echiteae: Mandevillinae Echitinae Pachypodium Echiteae Echiteae Parsonsieae: Echiteae: Pachypodiinae Pachypodiinae Parsonsia Echiteae Parsonsieae Parsonsieae: Echiteae: Parsonsiinae Parsonsiinae Prestonia Echiteae Parsonsieae Parsonsieae: Echiteae: Prestoniinae Echitinae Trachelospermum Ð Echiteae Parsonsieae: Echiteae: Chonemorphinae Echitinae Periploca Periploceae Periploceae Ð Ð (ASC) (ASC) Secamone Secamoneae Secamoneae Ð Ð (ASC) (ASC) a as Plumieroideae. b as Echitideae. c as Nerieae. d as Amphineuriinae. lowed by contemporary authors (e.g., Endlicher, 1841; de ceae s.s. by Leeuwenberg (1994), a wider subtribal de- Candolle, 1844) and recently also by Ly (1986). In the limitation was applied, and only four subtribes were rec- classi®cation of Schumann (1895a) only two tribes of the ognized (Table 1). Apocynoideae s.s. were recognized: the Parsonsieae and the Echiteae (Table 1). The former Wrightieae taxa were Aim of the studyÐIn the present study, we combine dispersed between these two tribes. data from the chloroplast gene rbcL and ¯oral morphol- A much wider circumscription of the Wrightieae was ogy to investigate the monophyly of the Wrightieae and presented by Pichon (1950a; see Table 1). His circum- its position in the Apocynaceae and to identify morpho- scription has been accepted by most subsequent authors logical synapomorphies useful in classi®cation of the (e.g., Wagenitz, 1964; Leeuwenberg, 1988, 1994), with group. minor additions and exclusions of genera. One such change is the inclusion of Holarrhena, Carruthersia, and MATERIALS AND METHODS Spirolobium, proposed by Endress et al. (1990). Pichon subdivided the Wrightieae into nine rather nar- Nine taxa were sampled so as to include representatives for all the rowly delimited subtribes (Table 1), some of which were, described subtribes of Wrightieae according to the classi®cation of or have now due to fusion of genera become, monoge- Leeuwenberg (1994) and as many subtribes as possible from other clas- neric. In the most recent classi®cation of the Apocyna- si®cations (Table 1). This corresponds to approximately half of the gen- August 1998] SENNBLAD ET AL.ÐPHYLOGENETIC FRATERNITY: THE WRIGHTIEAE 1145 TABLE 2. Sources and EMBL accession numbers for rbcL sequences used in the analysis. For the taxa sequenced in this study, the vouchers for the material