Three cryptic new species of Aristea (Iridaceae) from southern Africa

Abstract

Field work in southern Africa over the past several years has resulted in the discovery of three new species of the sub- Saharan African and Madagascan genus Aristea Aiton, which now comprises some 53 species. Aristea has a pronounced centre in southern Africa and a centre of diversity in the winter rainfall zone of the subcontinent, where all three new species occur, one extending eastward into the adjacent southern edge of the summer rainfall zone. All three novelties have been collected in the past but were confused with related species. A elliptica (subgenus Eucapsulares), confused in the past with A. pusilla (Thunb.) Ker Gawl., has a more robust habit, usually with 4 or 5 flower clusters per flowering stem, pale blue flowers, smooth ellipsoid seeds with flattened surface cells, and pollen shed as monads, whereas A. pusilla usually has 1-3 flower clusters per flowering stem, dark blue flowers, pollen shed as tetrads, and globose seeds with faint foveate sculpturing and colliculate surface cells. A. nana (also subgenus  Eucapsulares), known from few collections, and also confused with A. pusilla or A. anceps Eckl. ex Klatt. has the unbranched and leafless flowering stem of the latter but has large green floral spathes, flowers borne on long pedicels, and lacks a leaf subtending the single terminal flower cluster in contrast to nearly sessile flowers in A. pusilla and A. anceps, and in the latter, dry, rusty spathes. A. cistiflora (subgenus Pseudaristea) closely resembles A. teretifoha Goldblatt & J.C.Manning but has linear to narrowly sword-shaped leaves and ± secund flowers with the outer tepals only slightly smaller than the inner and with small, dark brown markings at the bases of all the tepals. In contrast, A. teretifolia has narrower, sometimes terete leaves and flowers held upright with the outer tepals notice-ably smaller than the inner and bearing dark markings covering the lower half, whereas the inner tepals are unmarked.