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Ceratozamia zaragozae has been considered to be the most threatened cycad species in its genus since only 50 individuals were reported for the only known population in the state of San Luis Potosi, Mexico. In this report we present information on newly discovered populations, as well as data on their population structure and spatial distribution. Six different populations were found, one of which is located in a Natural Protected Area. Population density was low (0.05 ± 0.038 ind/m2) and populations exhibited an unconventional ecological affinity for the genus, occurring on igneous soils in oak and pine-oak forests at elevations over 2000 m. Populations showed heterogeneous growth rates (λ = 0.89 ± 0.49). Spatial clustering patterns in all populations indicated adequate recruitment, low survival of juveniles, and spatial dependence between seedlings/juveniles and reproductive adults. We recommend the ex-situ cultivation of the species and the establishment of corridors between areas of habitat, in order to secure the preservation of the species.

The taxonomic status of the Mexican cycad Ceratozamia brevifrons is reassessed based on information from habitat, herbaria and living collections in the Botanic Garden ‘Jardin Botanico Francisco Javier Clavijero.’ Comparison of gross morphology of C. brevifrons with that of C. mexicana as well as analysis of leaflet anatomy, including that of C. robusta, has provided sufficient evidence for the removal of C. brevifrons from synonymy with C. mexicana. A neotype is designated for C. brevifrons and a description is presented.

Zamia tolimensis , a large arborescent species from the Central Cordillera of Tolima, Colombia, is described and illustrated. It is compared to Z. lindenii and Z. poeppigiana, the two most similar species. From these it is distinguished by leaflets with fewer teeth, sparse prickles on its petioles, beige-yellow ovulate strobili with shorter peduncles, and more microsporangia aggregated into a single group on the abaxial surface of the microsporophyll. Brief descriptions of Z. lindenii and Z. poeppigiana are also provided, as well as a key to separate the three species.

Zamiapyrophylla, a new species from Choco, Colombia, is described and illustrated. It is compared to Z. amazonum, Z. cunaria, and Z. ipetiensis. It is distinguished by its bright orange and red emerging leaves with leaflets that progressively turn green from the apex to the base as they mature, petioles with branched prickles and with ferruginous pubescence when immature, villous strobilar axes, and adaxial microsporangia.

A new cycad species, Cycas annaikalensis, has been discovered from the Malabar Coast of the southern Western Ghats of India. Although geographically distributed in a small population within the range of C. circinalis, it can be distinguished from the other described Indian Cycas species by its distinct habitat, habit, morphology of vegetative and reproductive parts, and anatomy of leaflets.

Somatic chromosomes of Stangeria eriopus (Stangeriaceae, Cycadales) were investigated by fluorescent in situ hybridization (FISH) using an 18S ribosomal DNA (rDNA) probe. Stangeria eriopus showed a chromosome number of 2n = 16 with a karyotype of 12 median-, 2 subterminal-, and 2 terminal-centromeric chromosomes. FISH study of S. eriopus revealed 16 signals made up of rDNA sites located on the terminal regions of the long arms of the 7 median- and 2 subterminal-centromeric chromosomes, on terminal region of the short arm of the 1 median-centromeric chromosome, on the terminal regions of the long and the short arms of 1 median- and 2 terminal-centromeric chromosomes. This result suggests that, not only karyomorphologically but also molecular-cytologically, the genus Stangeria may be more closely related to the genus Ceratozamia than the genus Bowenia or the genus Microcycas previously hypothesized.

Artabe et al. (2005) described a new fossil cycad genus, Chamberlainia, from the Allen Formation (Late Cretaceous) of Baja de Santa Rosa, Rio Negro Province, Argentina. Unfortunately, this name is preoccupied by a moss genus in the Brachytheciaceae, described by Grout (1928). Thus, Chamberlainia Artabe, Zamuner & D. W. Stev. is a later homonym (Art. 53.1, ICBN Vienna) and a new name is required.

A new species of cycad allied to theC. circinalis group,Cycas pranburiensis, is described from the southeast karst area of Thailand near Pranburi, Prachuap Khiri Khan province. It is distinguished by its short leaves with broad, coriaceous leaflets and mostly unarmed petioles, and the extended, gently curved sterile apices of the microsporophylls. The cone beetle fauna of the new species, believed to be involved in pollination, is distinct from that of other southeast Asian species ofCycas.

Comparisons of midribs of three cycad genera,Chigua, Cycas, andStangeria, the only three genera characterized by midribs in the pinnae, show that those ofChigua andStangeria are very similar to each other and quite unlike those ofCycas. Midribs ofCycas include a single, median vein, and the pinnae of these species lack lateral veins. Pinnae midribs ofChigua andStangeria include several (2–5 and 2–8, respectively) longitudinal parallel veins, and dichotomizing lateral veins arising from the midrib. Pinnae of other cycads, includingZamia, with whichChigua appears to be most closely allied, exhibit evenly spaced, longitudinally parallel, dichotomizing veins, a character considered to be primitive. All veins in cycad leaves have a single mesarch protoxylem pole. The midrib condition inChigua andStangeria represents an advanced state in comparison to that in the leaf of the Marattiales, for example, where there is a single veined midrib but with numerous mesarch protoxylem poles. It would appear that the midrib has been derived independently at least three times within the cycads, once in each major group.

A phylogenetic analysis of American cycad genera, all belonging to the family Zamiaceae, was attempted using chloroplast DNA restriction fragment polymorphisms.Ceratozamia mexicana Brongn.,Chigua restrepoi D. Stevenson,Dioon edule Lindley,Microcycas calocoma (Miq.) A. DC.,Zamia fischeri Miq., andZamia skinneri Warsz. ex A. Dietrich were used as representatives of the genera.Cycas revoluta Thunb., belonging to the family Cycadaceae, was used as an outgroup, following previous morphological works. One hundred and forty-one shared restriction fragments were scored for presence/absence and both Wagner and Dollo parsimony analyses were performed. The single, fully resolved, most parsimonious trees obtained from the analyses were topologically identical and perfectly matched previous morphology-based phylogenetic hypotheses. Statistical evaluation of the data showed a good reliability for the obtained phylogeny.Dioon edule, belonging to a different subfamily and more primitive on morphological grounds, proved to be the most primitive among American cycads as inferred from the molecular data;Chigua restrepoi, never analyzed before on cladistic grounds, was found to be the sister group of the genusZamia.