 | Ceratozamia whitelockiana Chemnick & Gregory 1995Common NamesTaxonomic notes"The current state of taxonomy within the genus Ceratozamia is confused, ambiguous, and incomplete. Three of the most widespread taxa, both in the wild and in cultivation, C. mexicana Brongniart (Vovides et al. 1983, Stevenson et al. 1986), C. robusta Miquel (Vovides et al. 1983; Stevenson et al. 1986), and C. latifolia Miquel (Vovides et al. 1983; Stevenson et al. 1986) are based on vague and obscure descriptions and neotypifications. Locality information is either non-existent or too generalized. Important morphological data such as male and female cone descriptions are incomplete or omitted. When considered from a historical perspective, the neotypifications assign the above specific epithets to localities of Ceratozamia which do not necessarily correspond to the most likely localities where the original authors and collectors might have been in the mid 1800's, when access into Mexico was much more restricted than today. The many isolated populations, forms, ecotypes, and varieties of the large-leaved Ceratozamia have been treated within the above three taxa with apparently little regard for valid character differences that in some cases might suggest separation at the species level."Since cytological and genetic evidence currently does not yield any measurable character differences upon which to base species differentiation within the genus (Walters et al. 1991), classic taxonomic consideration of characters and weighting of those characters is our basis for conferring specific status to Ceratozamia whitelockiana and assigning it to the miqueliana group which also includes the various forms of C. miqueliana and C. euryphyllidia Vazquez Torres, Sabato, & Stevenson" (1). Description"Ceratozamia whitelockiana spec. nov., from Oaxaca, Mexico, differs from others in the genus in the upright habit of its few large, glaucous, pea-green leaves with comparatively long petioles and relatively small megastrobili and microstrobili. It is most closely related to Ceratozamia miqueliana Wendland (Vovides et al. 1983; Stevenson et al. 1986), having similar cones, caudex, and leaf color but differing in the habit, size, and shape of the leaves. [It] is distinguished from the other large-leaved Ceratozamia as follows:"C. mexicana has smooth, dark brown, globose stems to 1 m tall and 20 cm in diameter; numerous, glabrous, dark-green, arching leaves which are heavily armed with numerous spines; megastrobili which are on average 35 cm long and 12 cm in diameter, borne on a peduncle 10 cm long; microstrobili which are on average 38-43 cm long and 7-8 cm in diameter, borne on a peduncle 8-10 cm long and 2.5 cm in diameter. C. whitelockiana has rough, cylindrical, reddish stems that are much smaller than C. mexicana, and its few sparsely-armed, upright, glaucous, pea-green leaves with long petioles are strikingly different than the leaves of C. mexicana, as are the much smaller male and female cones of C. whitelockiana. "C. latifolia stems are globose, light brown, and frequently sucker, especially in cultivation; leaves are 90-150 cm, leaflets are coriaceous, unequally attenuate, slightly overlapping, 20-30 cm long and 33-43 mm wide. C. whitelockiana stems are solitary, even in cultivation; leaves are 2.0-2.5 m long; leaflets are papyraceous, 30-50 cm long, 30-38 mm wide, and not overlapping. "C. robusta has very large stems to 1.5 m, numerous, heavily-armed, glabrous, dark-green leaves to 2.25 m, megastrobili on average 38 cm long and 15.25 cm in diameter, borne on a peduncle 7.5 cm long and 28 mm in diameter, microstrobili 45 cm long and 8 cm in diameter. C. whitelockiana is a much different plant than C. robusta, based on many characteristics, but especially in the detail of the male and female cones which, as reproductive structures, are characters of the highest weight" (1). RangeMexico: Oaxaca. "[K]nown only from the Atlantic drainage of the Sierra Madre de Oaxaco in montane tropical forest within the range of 335-973 m, but occurs more commonly at lower elevations (335-600 m). Habitat consists of very steep slopes with small pockets of remnant primary forest now covered mostly by coffee and banana groves and secondary growth. The patchy canopy consists of emergent trees to 40 m covered with epiphytes. Ceratozamia whitelockiana occurs on heavily shaded east- and west-facing slopes in primary forest with Chamaedorea sp., Geonoma sp., Melastoma spp., Acanthus sp., Ficus sp., Begonia sp., and Selaginella sp. Soil is light-colored, crumbly, rocky clay with outcroppings of sedimentary rock. Ceratozamia whitelockiana growing in exposed, deforested areas have extremely bleached, yellow leaves. The entire locality in the drainage of the Valle Nacional is rapidly being cleared and burned, and thus this cycad must be considered endangered. In our most recent survey of the Valle Nacional locality in May, 1995, we found approximately 250 plants during three days of field work. The same areas were visited several times in 1979, 1980, and 1981, and the population of Ceratozamia whitelockiana was considerably larger then, perhaps by twice as many individuals. Since this cycad is seldom seen in collections, it appears that habitat destruction is the greatest threat to its existence. The more inaccessible reaches of the Rio Valle Nacional drainage are likely to contain many pocket populations of Ceratozamia whitelockiana, but the rapid rate of deforestation will soon reach areas that are currently inaccessible. In May 1995, the smoke from clearing fires was intense, and recently cleared fields, as evidenced by still fresh, charred remains, were spread throughout the drainage like a patchwork quilt. This cycad does not seem to persist in open situations or in second growth forest for very long. The only plants we found in cleared areas were artificially maintained by local farmers and appeared bleached and chlorotic. Another locality of C. whitelockiana was found in the drainage east of the Cd. Mirador some 50 km southeast of the type locality by the author during a field trip in March 1996, consisting of approximately 100 individuals."Stevenson et al. (1986), figure 7 indicates three populations of Ceratozamia robusta in north central Oaxaca. One of these populations appears to occur in the drainage of the Rio Valle Nacional. Similarly, in their paper on the distribution of Ceratozamia, Moretti et al. (1980), figure 1, identifies several populations in northern Oaxaca belonging to the C. mexicana complex. The localities are not described in the detailed text that precedes the illustration, but the placement of one of those populations would appear to be in the Rio Valle Nacional drainage. We have searched extensively for other Ceratozamia in the drainage of the Rio Valle Nacional, from the municipality of Valle Nacional up to 2,200 meters, but have only found C. whitelockiana" (1). Big TreeOldestDendrochronologyEthnobotanyObservationsRemarksNamed in honor of Loran Whitelock, American cycad biologist (1).Citations(1) Chemnick, Jeffrey and Timothy J. Gregory. 1995. A new species of Ceratozamia (Zamiaceae) from Oaxaca, Mexico with comments on distribution, habitat, and relationships. The Cycad Newsletter (online edition). Also published in Phytologia (below).See also: |
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