The Neolloydia conoidea complex (N. conoidea, N. grandiflora, N. ceratites, N. texensis, and N. matehualensis) is shown to consist of a single species, N. conoidea. Neolloydia conoidea is compared with Echinomastus spp. and with N. warnockii; the latter is more closely related to Echinomastus and should be included in that genus. Several members of the Cactinae are compared on the basis of 26 characters. These data show that Gymnocactus, Turbinicarpus, Rapicactus, and Normanbokea should be included in Neolloydia to create a larger, newly-defined genus containing the following 15 species: N. conoidea, N. subterranea, N. mandragora (comb. nov.), N. valdeziana (comb. nov.), N. pseudopectinata (comb. nov.), N. gielsdorfiana, N. viereckii, N. horripila, N. smithii (=G. beguinii), N. saueri, N. knuthiana, N. schmiedickeana (comb. nov.), N. lophophoroides (comb, nov.), N. pseudomacrochele (comb. nov.), and N. laui (comb. nov.). Thelocactus is a closely related but separate genus.

New records for the rare species Rhytidocaulon paradoxum and Brachystelma discoideum are discussed. Caralluma tuberculata is shown to have an Indo-Arabian distribution with a new synonym, C. plicatiloba. The discovery of an alcohol specimen of the type collection of Stultitia miscella established that Caralluma bredae must be regarded as a synonym of it.

This is the fourth instalment of an annotated list of Mammillaria names, continued from Bradleya 3:53–66 (1985).

Recognizing the need for an internationally acceptable classification of the Cactaceae, and finding themselves broadly in agreement on the desirable ‘level’ of genus in this family, members of an IOS Working Party have agreed on a provisional list of genera recommended for adoption in forthcoming works of reference and other applications such as the arrangement of herbaria and the taxonomy of cacti of economic or conservation interest. The list of genera is presented with full synonymy and index.

The seed-morphology of the genus Notocactus (Schumann) Fric (sensu lato) was examined, and the genus divided into the following groups on the basis of seed-characters: IA. N. OTTONIS Group; IB. N. LINKII Group; II. N. CONCINNUS-N. SCOPA Group; IIIA. N. MAMMULOSUS Group; IIIB. N. UEBELMANNIANUS Group; IV. BRASILI-CACTUS Group; V. WIGGINSIA (Malacocarpus) Group; VI. ERIOCACTUS Group; VII. BRASILIPARODIA Group. A comparison with the seeds of the genus Parodia Speg. shows the close relationship of the two genera.