A new species of ceratozamia (Zamiaceae) from Chiapas,Mexico

Ceratozamia norstogii sp. nov. from Chiapas, Mexico is described. This species is distinct from all others in the genus in that it has a straight rachis with very narrow leaflets (3–10 mm wide) which are strongly curved and almost round in cross section when dried. It is known only from Chiapas, Mexico and in cultivation.     

A new species of ceratozamia (Zamiaceae) from Veracruz,Mexico with comments on species relationships,habitats, and vegetative morphology in ceratozamia

Ceratozamia euryphyllidia from Veracruz is described and illustrated. This species differs from all others in the genus in its very large, broad leaflets (9–16 cm wide) which have undulate margins, prominent veins, and a membranous to translucent texture at maturity. It is apparently related to a group of species which all have relatively small strobili and leaflets that are attenuate basally, oblanceolate to obovate, inequilateral, abruptly acuminate apically, and generally papyraceous to membranaceous. The allopatric species of this group inhabit moist to very wet areas. The wetter the habitat, the larger and thinner the leaflets. Thus, for example,C. latifolia which has the smallest leaflets grows in the driest habitat whereasC. euryphyllidia which grows in the wettest habitat has the largest leaflets in the genus.     

A new species of Ceratozamia (Zamiaceae) from Chiapas, Mexico

Ceratozamia zoquorum sp. nov. from the northern mountains of Chiapas, Mexico, is described and illustrated. It has affinities with C. miqueliana Wendl. from Veracruz, but differs in leaf, male female cone and trunk morphology.     

Another new species of Ceratozamia (Zamiaceae) from Chiapas, Mexico

Ceratozamia mirandai sp. nov. from the Sepultura Biosphere reserve of Chiapas, Mexico, is described and illustrated. Its closest affinities are with C. kuesteriana Regel from Tamaulipas of north-east Mexico, but differs in male and female cone and trunk morphology.     

A new species of Ceratozamia (Zamiaceae) from Tabasco and Chiapas, Mexico

Ceratozamia becerrae sp. nov. is described and illustrated. This species from Tabasco and Chiapas has affinity with C. miqueliana H. Wendl. from Veracruz and Chiapas, but differs in morphology and habit of leaves, leaflets, male and female strobili and trunk. Ceratozamia becerrae is considered part of the C. miqueliana species complex that includes C. miqueliana, C. euryphyllidia Vázq.Torres, Sabato & Stevenson and C. zoquorum Pérez-Farrera, Vovides & Iglesias. The geographical range of this species complex is southern Veracruz, Tabasco and northern Chiapas in tropical rain forests.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 123–128.     

A new species of Ceratozamia (Zamiaceae, Cycadales) from Veracruz, Mexico

Ceratozamia huastecorum sp. nov. is from an isolated meseta or tepui-like mountain in the Huasteca region of northern Veracruz State, Mexico. It has affinity to C. morettii Vázq.Torres & Vovides from the Mexican transvolcanic mountain range, which lies over 200 km to the south. The most notable differences are in female cone colour, leaf and leaflet morphology and length. The specific epithet is chosen in honour of the Huasteca ethnic region of great cultural importance to northern Veracruz.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 141 , 395–398.     

Dioon merolae (Zamiaceae), a new species from Mexico

A new species ofDioon found in northwestern Chiapas is characterized by linear-lanceolate leaflets arising at an acute angle from the rachis, obliquely inserted on it and imbricate.     

Dioon holmgrenii (Zamiaceae), a new species from Mexico

A new species ofDioon (Dioon holmgrenii), found on the Pacific slope of southern Oa xaca, is characterized by leaflets which are spinulose especially on the upper margin, elongate and narrow. Distribution and ecology of OaxacanDioon species are reported.     

Dioon califanoi (Zamiaceae), a new species from Mexico

A new Mexican species ofDioon has been found in Oaxaca,Dioon califanoi, characterized by keeled fronds and leaflets inserted obliquely above the rachis. A key to the known species ofDioon is given.     

Dioon rzedowskii (Zamiaceae), a new species from Mexico

A new species ofDioon has been found in Oaxaca. It is characterized by leaflets which are entire, lanceolate but unequally tapering toward the apex and over 10 mm wide at the middle portion of the frond.     

Dioon caputoi (Zamiaceae), a new species from Mexico

A new species ofDioon (D. caputoi), found in Puebla, Mexico, is characterized by narrow leaflets, arising at an acute angle from the rachis and regularly and widely spaced along it. This species has hitherto been confused withD. purpusii.     

A new species in the genus Dioon (Zamiaceae) from north-central Oaxaca, Mexico

Dioon argenteum sp. nov. (Zamiaceae) is described from northern Oaxaca, México. Flat leaves, and persistently tomentose, slightly imbricate leaflets with marginal prickles characterize this species. The specific epithet argenteum was chosen to describe the silver appearance of the persistent tomentum covering the new leaves. D. argenteum appears to have affinities with D. purpusii and D. califanoi.   © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 141 , 471–476.     

Karyotype polymorphism in the cycad Zamia loddigesii (Zamiaceae) of the Yucatan Peninsula, Mexico

The cycad %amia loddigesii Miq. forms a morphologically variable complex on the Yucatan peninsula, Mexico. Several diploid chromosome numbers have been found in the species: In = 17, 24, 25, 26 and 27. Differing karyotypes and chromosome numbers were found in individuals of the same population and die karyotypes differ widely in numbers of metacentric and telocentric chromosomes present. Centrometric fission as well as pericentric inversions and unequal translocations are suggested to be the probable mechanisms for this karyotype variation. There appears to be a correlation between high chromosome number and increasing dryness of the habitats. Coupled with the strongly asymmetrical karyotypes, this suggests that karyotype evolution in Z- loddigesii is recent.     

The rediscovery of Tapura haitiensis (Dichapetalaceae)

Tapura haitiensis was described in 1926 from sterile material from the Massif de la Hotte, Haiti. It was recollected in 1983 from the same area and its flowers and young fruit are described here for the first time together with habitat details. It is compared with three related species,T. orbicularis, T. panamensis, andT. cubensis.     

Demography of the cycad Ceratozamia mirandae (Zamiaceae) under disturbed and undisturbed conditions in a biosphere reserve of Mexico

The cycad Ceratozamia mirandae is endemic to Chiapas, Mexico. Demographic studies were made in two of its populations in the Sepultura Biosphere Reserve under different conservation conditions; in the nucleus zone “Tres Picos” (conserved) and buffer zone “La Sombra” (disturbed and under management). Spatial distribution of C. mirandae was aggregated, showed a clumped local distribution on shallow soils on steep slopes and male and female cones appear to be synchronous in both populations. The population structure was of type I (Bongers) for both sites. Individuals between the sites showed differences in growth pattern. The oldest plants (80–90 cm tall) were estimated to be about 490 years at “La Sombra”. The finite growth rate () in the buffer zone population showed a tendency for decrease whilst in the nucleus zone this estimate remained stable. The highest elasticity values lied in the transition of the first three classes of the “La Sombra” population, in “Tres Picos” this corresponded to adult plants between 20 and 30 cm tall. Given the above, it is proposed that in the nucleus zone, reproductive adults should be of highest conservation priority, whereas in the buffer zone seedling reintroduction should be carried out regularly until the population increases. We recommend an IUCN Red List category of Vulnerable (VU C, 2a), largely due to difficult-to-control destructive annual forest fires that occur in this Reserve.