Abstract
A new species of Rubiaceae, Spiradiclisdetianensis is described from a limestone karst area of southwestern China. This new species is morphologically similar to S.cordata and S.spathulata. All of them have rosetted habit and long peduncles, but it differs from the former by the cuneate leaf bases (vs. basally cordate) and much longer corolla tubes (1.8-2.2 cm long vs. ca. 5 mm long), and from the latter mainly by its tubular-funnel shaped corolla (vs. slenderly salver shaped), 4.5-6.8 (vs. 1.5-2) mm in diam, inside throat and corolla densely puberulent (vs. glabrous except a ring of long hairs at the middle). It also resembles to S.tubiflora, but differs clearly by its subrosulate habit (vs. procumbent to creeping), longer leaf blades (7.0-10.5 cm vs. 0.5-2.5 cm) and longer corolla tubes (18-22 mm vs. 14-16 mm). At same time, color photos, illustrations, detailed descriptions and conservation status of the new species are provided.