Acer wenshanense (Sapindaceae), a critically endangered new species from Yunnan, China

Acer wenshanense (Sapindaceae), a new species, is described and illustrated based on specimens from Wenshan City, Yunnan Province, China. Acer wenshanense is similar to A. sino-oblongum but differs in having sepals ca. 2.5 mm long (vs. ca. 4 mm long), petals narrowly oblong, ca. 3.5 mm long (vs. oblanceolate, ca. 4 mm long), ovary densely whitish hairy (vs. glabrous), young fruit green (vs. purplish red), and wings incurved and intercrossed (vs. spreading at an angle of 70–120°). It is also resembles​ A. fabri but differs in leaves abaxially whitish glaucous or pale green (vs. green),inflorescence corymbose (vs. paniculate), sepals yellowish green (vs. purplish red), petals yellowish green, narrowly oblong (vs. white, obovate), stamens yellowish green (vs. red), ovary densely whitish hairy (vs. glabrous), young fruit green (vs. purplish red), and wings incurved and intercrossed (vs. spreading at an angle of 60–130°). Acer wenshanense is currently known only from its type locality, represented by a single large tree. No seedlings, saplings, or other juvenile individuals were observed. We therefore recommend that this species be classified as a Plant Species with Extremely Small Populations (PSESP).