Medium-sized plant, TRUNK cylindrical, semihypogeal becoming arborescent with age, sparsely branching (up to two branches), erect, 20-100 cm long, 17.8-33.1 cm in diameter, armed with light-brown persistent leaf bases in the upper part of the trunk. CATAPHYLLS triangular, stipulate, silvery sericeous in the middle and apical part, 4.5-7.5 cm long, 2.6-4 cm wide. LEAVES 7-22, ascending remaining erect to slightly descending near apical portion, pinnate, forming an open crown 34-244 cm long, 45-122 cm wide, reddish brown, white tomentose when emergent, dark green glabrous when mature, vernation erect, seedling eophylls 4. PETIOLE erect, light orange to straw coloured, terete, 38-80 cm long, 0.9-1.6 cm diameter, armed with stout slightly arched prickles being more numerous towards the base. RACHIS erect, semiterete, 48-150 cm long, armed with few prickles. LEAFLETS linear-lanceolate, flat in section, variable from nonfalcate to falcate to subfalcate, 29-68 pares, opposite at proximal and median part of leaf, subopposite towards distal portion of leaf; margins entire, subrevolute, brilliant dark green on adaxial surface, light green on abaxial surface, 27-46 cm long, 1.3-2 cm wide, venation visible on abaxial surface, 12-16 veins, distance between veins 0.97-1.70 mm; articulations green rarely slightly light yellow to copper, 0.55-0.87 cm wide. MICROSTROBILI conical, erect, light to olive green at emergence, creamy to light yellow when mature, 28-33 cm long, 3.1-5 cm diameter; peduncle tomentose, light brown at emergence turning brown at maturity, 6.8-7 cm long, 1.7-3 cm diameter. MICROSPOROPHYLLS indeterminate, cuneiform, bicornate at distal end, inserted spirally on cone axis forming apparent vertical rows, red tomentulose, fertile portion covering one-half to two-thirds of the abaxial surface excluding the horns, 1.2-1.9 cm long, 0.64-0.98 cm wide; MICROSPORANGIA indefinite in sori of 3-4, dehiscent by a longitudinal slit. MEGASTROBILI cylindrical or barrel shaped, erect when emergent, descending when mature, blue-green at emergence, dark brown when mature, 35-40 cm long, 7.3-10.6 cm diameter at median portion; peduncle slightly tomentose, 7-11 cm long, 1.92-1.94 cm diameter; MEGASPOROPHYLLS indefinite, spirally inserted on cone axis forming apparent vertical rows, distal face hexagonal, bicornate, with metallic-blue epidermal colouring on the margins of the lobes partly covered with greyish tomentulum extending to about one-third of the distance towards the horns 5.2-6.1 cm long, 1.9-2.5 cm wide. SEED ovate, sarcotesta white when immature, light yellow to light cream - beige upon maturity, sclerotesta smooth with 7-10 visible rays radiating from the micropyle, 2.5-2.9 cm long, 1.5-1.7 cm in diameter. Chromosome number 2n = 16.
A newly described species from the extreme western portion of the Sierra Madre de Chiapas massif, commonly known as the 'Sierra Atravesada', Oaxaca, Mexico. Ceratozamia chimalapensis is critically endangered, and is local to Oak a Pine forest at elevation.
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