Thelocactus

Abstract: This study aimed to test the phylogenetic relationships of the tribe Cacteae, the generic circumscription within the tribe, in particular, the monophyly of the genus Ferocactus, and to provide a biogeographical hypothesis about the origin of Cacteae. The analysis included 135 species from all of the 27 accepted genera and four outgroup species. Five chloroplast regions were sequenced, aligned, and coded postulating gaps, simple sequence repeats (SSRs), and inversions as potential synapomorphies, and their contributions to phylogenetic reconstruction were evaluated. The phylogenetic analyses recovered 63% of the genera as monophyletic. The contribution of rpl16, trnL-F and psbA to the phylogenetic signal was higher than in the two more slowly evolving genes (rbcL, matK), but the gaps and SSRs supported some of the genera. This result differs from those of previous phylogenetic studies in which less than 35% of the genera were recovered as monophyletic. In this work, Astrophytum and Echinocactus were re-circumscribed with five and four species, respectively. Turbinicarpus was found to be polyphyletic; 11 species correspond to Turbinicarpus s.str., whereas a highly supported clade corresponded to Rapicactus, and three species need further study. Contrary to its current circumscription, Ferocactus was not supported as monophyletic because it is polyphyletic concerning Glandulicactus, Leuchtenbergia, Stenocactus and Thelocactus. We recognize this group of genera as the Ferocactus clade in which the species share the presence of scales in the pericarpel and ribbed stems, whether tuberculated or not. The Cacteae seem to have originated in the Sierra Madre Oriental and then dispersed to the Mexican Plateau, where radiation and diversification occurred at the boundaries of the Miocene–Pliocene Epoch. The development of the Mexican Plateau and the Trans-Mexican Volcanic Belt may have favoured the isolation of the Cacteae. A taxonomic diagnosis is presented for the tribe Cacteae and 18 genera that we now recognize.

Abstract: The family Cactaceae is the diversified group of angiosperm plants whose pollen statistics has been used for taxonomic identification. In this article, we present the pollen morphology of eight species belong to seven taxonomically complex genera of Cactaceae including Astrophytum, Cylindropuntia, Echinocereus, Echinopsis, Mammillaria, Opuntia, and Thelocactus using light and scanning electron microscopy. The pollen grains were acetolyzed, measured, described, and electron photomicrographs were taken. Cactaceae can be characterized by presenting different palynomorphological features including pollen type, sculpturing, polar and equatorial diameter, aperture orientation, exine thickness, P/E ratio, and echini features. Four types of pollen shapes, that is, prolate spheroidal (three species), subprolate (two species), prolate (two species), and oblate spheroidal in Echinocereus reichenbachii were observed. The polar and equatorial diameter observed maximum in O. ficus indica 116.95 and 112.27 μm while minimum in M. compressa 38.42 and 21.05 μm. Pollen of two types, tricolpate in members of subfamily Cactioideae and pantoporate in the Opuntioideae were examined. The fertility percentage has been observed maximum in Opuntia macrocentra (83.84%) and minimum in Opuntia ficus-indica (57.89%). Exine sculpturing showing great variations such as granulate, reticulate, granulate perforate and micro-echinate foveolate ornamentation was examined only in Echinopsis eyriesii. A key to species, based on pollen micromorphological attributes, has been constructed for correct identification of complex cactus species.

Abstract: A B S T R A C T Structural and developmental data indicate that Lophophora (Cactaceae) should be retained as a genus, which appears to be most closely related to Thelocactus (sensu lato) Within Lophophora morphological differences suggest that two species should be recognized In the extensive northern population (Texas along the Rio Grande to San Luis Potosi in Mexico) the tubercles are usually arranged as distinct ribs or elevated podaria, whereas in the restricted southern population (limited to the Mexican State of Queretaro) podaria and ribs are poorly developed or lacking and there are also differences in pollen structure We believe that these two populations should be recognized as distinct species, L williamsii and L diffusa, respectively We

Abstract: Thelocactus bicolor and T. hexaedrophorus are compared to Ferocactus hamatacanthus and Hamatocactus setispinus in 19 characters. H. setispinus has a greater similarity to T. bicolor than to the other 2 species and is placed in Thelocactus as T. setispinus (comb. nov.). The following characteristics of Thelocactus are discussed: ribs and tubercles, areoles, spines and extrafloral nectaries, epidermis, outer cell layers, druses and crystals, flowers, pollen, fruits, and seeds. Ecological characteristics, such as distribution, soils, habitat characteristics, sympatry, and associated plants, are described. The relationships and general features of each species are considered. In the section on formal taxonomy Thelocactus is redefined to include T. setispinus, T. bicolor, T. leucacanthus, T. macdowellii, T. tulensis, T. hastifer, T. conothelos, T. heterochromus, T. hexaedrophorus, T. lausseri, and T. rinconensis.