On Decalobanthus, a new genus of Convolvulaceae from Sumatra

Being occupied with studies on the Convolvulaceae of Netherlands India I met with a remarkable specimen in the Buitenzorg Herbarium, collected by Dr. O. POSTHUMUS during the expedition in Djambi (Sumatra) in the year 1925. At first sight this plant seemed to be a Merremia. A closer examination, however, soon showed some important differences with that genus, especially in respect to the corolla, which has a long, narrow and rather fleshy tube and a limb with 5 short, reflexed (or patent?) lobes. Each lobe is deeply bifid, so that the limb appears 10-lobed. The middle part of the lobes is fleshy just as the tube; it corresponds with a midpetaline field of the corolla of most genera of Convolvulaceae, the lateral parts of the lobes (lobules) are much thinner, membranaceous and nerved. They represent the interpetaline fields of the Convolvulaceous corolla. In general there is a resemblance with the essential corolla construction of many species of Erycibe, where the lobes are also bifid and possess a thick middle part and two membranaceous lobules. The lobules in the new genus are not fully equal in size, those on the right of each lobe, as seen from the inside of the corolla being always slightly larger. The corolla is fully glabrous or bears some papillae at the base of the filaments. The pistil has a two-celled ovary, each cell with 2 ovules and bears a long, filiform style with two globular, papillose stigmas, exactly as in Merremia. I suppose this plant to be closely related to that genus, but as the corolla with its fleshy tube and remarkable lobes is so different from all other species, it is impossible to incorporate it in Merremia without important alteration of the generic limits. I, therefore, propose to establish a new genus, under the name of Decalobanthus (derived from dexa, ten, λoβoς, lobe and άνζος, flower).