AUSTIN & STAPLES, CONVOLVULACEAE ADDITIONS AND CHANGES IN THE NEOTROPICAL CONVOLVULACEAE-NOTES ON MERREMIA. OPERCULINA, AND TURBINA D. F. AUSTIN AND G. W. STAPLES SINCE 1978 we have been preparing the first portion of the family Convol-vulaceae for Flora Neotropica. To date, we have examined 17 genera and about120 species. During this study various nomenclatural changes and additionshave been necessary (Austin & Staples, 1980, 1981; Staples & Austin, 1981):further work has revealed the need for additional changes, and several newtaxa require comment. Merremia Dennst. is represented in the New World by almost 30 species,and there are several others in the Old World. Division of this genus from bothIpomoea L. and Operculina Silva Manso has been debated for generations, butour own studies (Austin, 1979: Austin & Staples, 1980, 1981; Staples, 1979;Staples & Austin, 1981) have convinced us that they are best treated separately. THE MERREMIA DIGITATA COMPLEX On the basis of scant material (about ten sheets) available to him, O'Donell(1941) recognized three species of IMerremia, M. digitata (Sprengel) H. Hallier,M. contorquens (Choisy) H. Hallier, and M. ericoides (Meisner) H. Hallier.Growth habit and the degree and nature of the pubescence were the criteriaused to separate these taxa. During our investigations we have had the op-portunity to examine a sample (106 sheets total) larger than O'Donell's, in-cluding several type specimens unavailable to him. We found that O'Donell'scharacters do not provide consistent differentiation between these three nom-inate species; pubescence, in particular, intergrades completely among them.These taxa all have linear-lanceolate bracts 1-5 mm long, and calyxes withunequal sepals having noticeably scarious margins-characteristics that distin-guish this complex from other, similar Brazilian campo cerrado merremias(M. cissoides (Lam.) H. Hallier and M. flagellaris (Choisy) O'Donell). We preferto recognize these somewhat arbitrary units as varieties of AM. digitata. Thesecan be distinguished with the aid of the key presented below, which is followedby the synonymy and the necessary new combinations. KEY TO TAXA OF THE MERREMIA DIGITATA COMPLEX 1. Plants erect; sepals and stems glandular.......... .Mlerremia digitata var. ericoides. 1. Plants decumbent or trailing; sepals and stems stellate to glabrous. 2. Leaves entire to lobed, if lobed the lobes over 1 cm wide .................... ..... . Merremia digitata var. elongata.c President and Fellows of Harvard College, 1983.Journal of the Arnold Arhoretum 64: 483-489. July, 1983.483
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