PHYLOGENY OF TRICALYSIA (RUBIACEAE) AND ITS RELATIONSHIPS WITH ALLIED GENERA BASED ON PLASTID DNA DATA: RESURRECTION OF THE GENUS EMPOGONA

Recent studies on the circumscription of the tribe Coffeeae (Rubiaceae) revealed a weakly supported clade containing Tricalysia A. Rich. and the allied genera Argocoffeopsis Lebrun, Calycosiphonia Pierre ex Robbr., Belonophora Hook. f., Diplospora DC., Discospermum Dalzell, Nostolachma T. Durand, and Xantonnea Pierre ex Pit. The phylogenetic relationships of Tricalysia and these allied taxa are investigated further using sequence data from four plastid regions (trnL-F intron and intergenic spacer, rpL16 intron, accD-psal intergenic spacer, and PetD). Our results demonstrate that Tricalysia sensu Robbrecht is not monophyletic. The genus name Tricalysia should be restricted to taxa from subgenus Tricalysia; subgenus Empogona (Hook. f.) Robbr. is sister to the genus Diplospora and is recognized at the genetic level. The 34 necessary new combinations for Empogona Hook. f. are provided: h. acidophylla (Robbr.) J. Tosh & Robbr., E. aequatoria (Robbr.) J.Tosh & Robbr., E. africana (Sim) J. Tosh & Robbr., E. aulacosperma (Robbr.) J. Tosh & Robbr., E. bequaertii (De Wild.) J. Tosh & Robbr., E. bracteata (Hiern) J. Tosh & Robbr., E. breteleri (Robbr.) J. Tosh & Robbr., E. buxifolia (Hiern) J. Tosh & Robbr. subsp. buxifolia, E. buxifolia subsp. australis (Robbr.) J. Tosh & Robbr., E. cacondensis (Hiern) J, Tosh & Robbr., E. concolor (N. Halle) J. Tosh & Robbr., E. coriacea (Sond.) J. Tosh & Robbr., E. crepiniana (De Wild. & T. Durand) J. Tosh & Robbr., E. deightonii (Brenan) J. Tosh & Robbr., E. discolor (Brenan) J. Tosh & Robbr., E. filiformistipulata (De Wild.) Bremek. subsp. filiformistipulata, E. filiformistipulata subsp. epipsila (Robbr.) J. Tosh & Robbr., & glabra (K. Schum.) J. Tosh & Robbr., E. gossweileri (S. Moore) J. Tosh & Robbr., E. kirkii Hook. f. subsp. junodii (Schinz) J.Tosh & Robbr., L. lanceolata (Sond.) J. Tosh & Robbr., E. macrophylla (K. Schum.) J. Tosh & Robbr., E. maputenis (Bridson & A. E. van Wyk) J. Tosh & Robbr., h. ngalaensis (Robbr.) J. Tosh & Robbr., E. nogueirae (Robbr.) J. Tosh & Robbr., E. ovalifolia (Hiern) J. Tosh & Robbr. var. ovalifolia, E. ovalifolia var. glabrata (Oliv.) J. Tosh & Robbr., E. ovalifolia var. taylorii (S. Moore) J. Tosh & Robbr., E. reflexa (Hutch.) J. Tosh & Robbr. var. reflexa, E. reflexa var. ivorensis (Robbr.) J. Tosh & Robbr., h. ruandensis (Bremek.) J. Tosh & Robbr., E. somaliensis (Robbr.) J. Tosh & Robbr., E. talbotii (Wernham) J. Tosh & Robbr., and E. welwitschii (K. Schum.) J. Tosh & Robbr.