New Combinations in the Tribe Poraneae (Convolvulaceae) for the Flora of China

Abstract

New combinations are made for 10 taxa formerly included in the genus Porana s.l. in the account of the Convolvulaceae for the Flora Reipublicae Popularis Sinicae, which are now considered to belong in the genera Dinetus, Poranopsis, and Tridynamia, as follows: Dinetus decorus, D. dinetoides, D. duclouxii, D. grandiflorus, D. truncatus, Poranopsis discifera, P. sinensis, Tridynamia megalantha, T. sinensis var. sinensis, and T. sinensis var. delavayi. A key to the genera is provided, and 11 additional taxa formerly accepted in Porana are reduced to synonymy. The genus Porana N. L. Burman comprises 57 nominate taxa, the majority distributed in mainland tropical Asia. Twenty-eight (14 species, 14 varieties) were recognized in the account of the Convolvulaceae for the Flora Reipublicae Popularis Sinicae (Fang & Huang, 1979). My revisionary study of the genus Porana and other taxa of the tribe Poraneae H. Hallier (Staples, 1987) indicates that there has been considerable overdescription in the genus Porana, and the number of species is actually much lower than the number of named species. Although a comprehensive taxonomic revision of Porana s.l. has been submitted to Systematic Botany Monographs (Staples, submitted manuscript), several new combinations, and reduction of additional names to synonymy, are needed for the account of the Convolvulaceae for the Flora of China, which is scheduled for publication before the revision will appear. This paper makes 10 new combinations needed for use in the Flora, and reduces to synonymy 11 other taxa of Porana recognized by Fang & Huang (1979). To summarize the major conclusions of the revision, Porana s.l. proved to be a polyphyletic assemblage comprising four distinct groups of species; a preliminary analysis indicated that these four species groups are not a monophyletic lineage inter se (Staples, 1987). I recognize them at generic rank, emending the generic concept of Porana to accommodate one group comprising three species, and take up the previously established generic names Tridynamia Gagnepain (1950), Poranopsis Roberty NOVON 3: 198-201. 1993. (1952), and Dinetus Sweet (1825) for the other three groups of species. Furthermore, the genus Cordisepalum Verdcourt is maintained as a genus distinct from and closely related to Poranopsis. These five genera may be distinguished by the following key. Full descriptions of all taxa, distribution data, ecological and phenological summaries, and detailed nomenclatural discussion are presented in the revision (Staples, submitted manuscript) so they are omitted here. KEY TO GENERA OF ASIATIC PORANEAE la. Leaf venation pinnate, or with a single basal pair of secondary veins; calyx about half as long as the corolla, sepals all + equal in length .. P orana s.s. lb. Leaf venation palmate; calyx minute, usually < 1/o as long as the corolla, if larger then sepals markedly unequal. 2a. Plants entirely herbaceous; flower buds with a minute apical tuft of hairs, otherwise glabrous externally Dinetus 2b. Plants woody (often with herbaceous stem tips); flower buds hairy externally. 3a. Sepals unequal in flower; fruiting sepals with 3-9 parallel longitudinal veins Tridynam ia 3b. Sepals (sub)equal in flower; fruiting sepals with 1 evident midvein. 4a. Corolla funnelform, white; fruit sessile on torus ........ Poranopsis 4b. Corolla rotate, yellowish; fruit borne on a slender stalk ...... Cordisepalum As construed here, Porana s.s. and Cordisepalum do not occur within the geographic range of the Flora of China. Some species of Poranopsis, Dinetus, and Tridynamia occur within the political boundaries of the People's Republic of China, and the following new combinations are proposed for them.