Comp.Newsl.23.1993 PSEUDOCADISCUS LISOWSKI SUNKIN STENOPS NORD. (COMPOSITAE-SENECIONEAE) B. BertilNordenstam DepartmentofPhanerogamic Botany SwedishMuseum ofNaturalHistory S-10405Stockholm, Sweden In 1987 Lisowski described a new monotypic genus from Zaire. He named it Pseudocadiscus, because of its partial resemblance to the South African aquatic genus Cadiscus ofthe Senecioneae. However,Lisowskireferredhisnew genusto the tribe Anthemideae and considered it related to Chrysanthemum, obviously misledby thewhiteray-florets. However, Pseudocadiscus zairensis is clearly closely related to Stenops helodes B. Nord. from Tanzania and Zambia (Nordenstam 1978: 73 ff.). Characters in common include the uniseriate connate involucre, the conical naked receptacle, the white rays and yellow disc, the conspicuous basal swelling of the filament collar, the ecaudate anthers with radial endothecium, the shortly bilobed disc sty- les with truncate tips, the epappose 5-veinedcypselas, and the homomorphic rec- tangular ovary wall crystals. Besides, both are glabrous annual herbs of wet habitats, andwith stems rootingatnodes (cf. Fig. 1). Quite clearly,Pseudocadiscus iscongeneric with Stenopsandhastobe sunk. The two species involved seem to be rather closely allied, but sufficiently different to be upheld. The necessary new combination isgivenbelow. Stenopszairensis (Lisowski) B.Nord.,comb.nov. Basionym: Pseudocadiscus zairensis Lisowski, Bull. Jard. Bot. Nation. Belg. 57 (3/4): 468 (1987). -Type: Lisowski84604 (POZGholo., BRiso.!). Differences from S. helodes B. Nord. are the floating aquatic habit, the parallel- veined leaves, and the winged cypselas. In S. zairensis the number ofray-florets isusually c. 13, in S. helodesaround 8. References Lisowski, S. 1987. Pseudocadiscus Lisowski (Asteraceae), genre monotypique nouveauduZaire.Bull.Jard.Bot.Nation.Belg. 57 (3/4):467-^69. Nordenstam, B. 1978. Taxonomic StudiesintheTribeSenecioneae(Compositae). (9pera5(?r. 44, 83pp. Comp.Newsl.23. 1993 — Fig—. 1. Stenops helodes B. Nord. (A E) and S. zairensis (Lisowski) B. Nord. (F J). A, F: Habit, x 0.4. B: Involucre and receptacle, x 5. C, G: Ray-floret, X 5. D, H: Disc-floret, x 5. E, I: Corolla oBf—disc-floret, laid out, x 5. J: Winged cypsela, x 5. (A: Richards 16354 in K; E: Sanane 241 in K; F: dc Witte G— 6350 in BR; J: Lisowski 84604 in BR, isotypus). - Del auct.