AN OUTLINE OF THE PHYLOGENETIC SYSTEM OF CLASSIFICATION OF THE TRIBE CACTEAE (CACTOIDEAE-CACTACEAE).
III. System of classification of the subtribes Epithelanthinae, Astrophytinae - Echinocactinae
Doweld A. B.S U M M A R Y
Национальный институт карпологии
(Гертнеровский Институт), г. Москва
A new system of classification and phylogeny of three subtribes (of 12) of Cacteae, Epithelanthinae, Astrophytinae, and Echinocactinae, is presented. On the basis of new available data on seed morphology and anatomy of the tribe, published recently (Doweld, 1995), supplementing other available data on spine and areole morphology, flower and fruit structure, the generic circumscription of all three subtribes has been re-appraised. The subtribe Epithelanthinae is composed of only two genera having apapillate seed sculpturing type with no cuticular sculpturing. Judging by seed anatomy and morphology, the genera Epithelantha and Mammilloydia are closely related to the plexus of two relatively archaic subtribes, Sclerocactinae and Bravocactinae, representing, perhaps, a one more blind height in the irradiation of the genera with papillate/apapillate seed sculpturing without cuticular sculpturing.
The affinity of Epithelanthinae with foveolate subtribes (Escobariinae, Escobrittoniinae, and Cactinae) is fully lacking. The revision of the so-called 'basal' in Cacteae genus Echinocactus by exclusion aberrant species into distinct genera Meyerocactus and Emorycactus (Doweld, 1996) and restriction of the genus to species having only apapillate seeds with faceted cuticular sculpturing, fully debunks the concept of the polymorphic genus Ferocactus sensu Britton et Rose and validates the splitting of the polyphyletic genus into three genera, Parrycactus, Bisnaga, and Ferocactus s.str. The seed-coat of Ferocactus s.str. is formed in another (although similar) way, and the phylogenetic nearness of the genus to Echinocactus, Parrycactus, and Bisnaga is not so close as has been thought by various researchers.
The inclusion of Ferocactus into Echinocactinae is not final and definitive at present time; its probable phylogenetic relationships with Thelocactinae (Stenocactus) need a further study. The occurrence of the apapillate seed sculpturing and faceted cuticular sculpturing within Echinocactus s.str. confirms the naturalness of the splitting of the rest species of Ferocactus into two genera – Parrycactus with similar echinocactoid seeds and Bisnaga with foveolate seeds and faceted cuticular coating, which are derivative of the Echinocactus—Parrycactus seed type. The genus Astrophytum is considered in its own monotypic subtribe Astrophytinae, closely allied to Echinocactinae, but essentially distinct in specialized apapillate seed type (with finely faceted cuticular sculpturing) and inflated hilum. It is probable that Astrophytum diverged early from the rest of highly irradiating Echinocactinae.