Monograph of Ceratozamia (Zamiaceae, Cycadales): an endangered genus Author Martinez-Dominguez, Lili https://orcid.org/0000-0003-1158-1501 Posgrado en Ciencias Biologicas, Instituto de Biologia, Universidad Nacional Autonoma de Mexico, 3 er. Circuito Exterior, Ciudad Universitaria, 04510, Coyoacan, CDMX, Mexico lilimartinezd@gmail.com Author Nicolalde-Morejon, Fernando https://orcid.org/0000-0003-1423-7474 Laboratorio de Teoria Evolutiva e Historia de la Ciencia, Instituto de Biologia, Universidad Nacional Autonoma de Mexico, 3 er. Circuito Exterior, Ciudad Universitaria, 04510, Coyoacan, CDMX. Mexico Author Vergara-Silva, Francisco https://orcid.org/0000-0001-5024-268X Posgrado en Ciencias Biologicas, Instituto de Biologia, Universidad Nacional Autonoma de Mexico, 3 er. Circuito Exterior, Ciudad Universitaria, 04510, Coyoacan, CDMX, Mexico Author Stevenson, Dennis Wm. https://orcid.org/0000-0002-2986-7076 Laboratorio de Taxonomia Integrativa, Instituto de Investigaciones Biologicas, Universidad Veracruzana, Xalapa, 91190, Veracruz. Mexico dws@nybg.org text PhytoKeys 2022 2022-09-21 208 1 102 http://dx.doi.org/10.3897/phytokeys.208.80382 journal article http://dx.doi.org/10.3897/phytokeys.208.80382 1314-2003-208-1 F47A23EA345757E29C2800F6D51CEE05 24. Ceratozamia oliversacksii D.W.Stev., Mart.- Dominguez & Nic.-Mor., Kew Bull. 77: 212. 2022 Fig. 27B Type . Mexico . Oaxaca : Mun. Candelaria Loxicha, Cerro Perico , 1,616 m , 10 Jun 2021 , L. Marti ́nez-Domínguez et al. 2261 ♀ ( holotype : CIB! [acc. # 23411UV]; isotypes: K!, MEXU!, NY!) . Description. Stem 30-80 cm long, 10-40 cm in diameter, epigeous, decumbent. Cataphylls 6.5-7.5 x 1.6-2.0 cm wide at the base, persistent, triangular, reddish brown, brown tomentose at emergence, glabrous at maturity, apex acuminate. Leaves 7-36 (50), 124-258 cm long, descending, green at emergence with brown trichomes, glabrous at maturity. Petiole 45-110 cm long, terete, linear, green at emergence, dark green in mature leaves; with 40-65 thin prickles, 0.50-0.70 cm long. Rachis 85-182 cm long, terete, linear, dark green in mature leaves with prickles. Leaflets 24-47 pairs, opposite to subopposite, insertion in one plane, linear, longitudinally curved abaxially to planar, not basally falcate, papyraceous, flat, green with adaxial and abaxial sides glabrous, distal end with entire margins, acuminate and symmetrical (rarely asymmetrical) at the apex, attenuate at base, with conspicuous and light-green veins; median leaflets 25-40 x 2.3-3.6 cm, 2.0-3.3 cm between leaflets; articulations 0.5-1.1 cm wide, green. Pollen strobili 20-35 cm long, 3.0-5.7 cm in diameter, solitary, cylindrical, erect, greenish with reddish trichomes at emergence, greenish yellow with reddish brown trichomes at maturity; peduncle 10-15 cm long, 1.2-1.8 cm in diameter, pubescent, reddish brown; microsporophylls 2.5-2.75 x 0.99-1.28 cm, obconic with a non-recurved distal face and a lobate fertile portion, infertile portion 0.60-0.80 cm long and a rounded with straight horns 0.08-0.18 cm long, 0.50-0.70 cm and an acute angle between the horns. Ovulate strobili 33-36 cm long, 11.5-14 cm in diameter, solitary, cylindrical, erect, greenish yellow with few reddish trichomes at emergence, green with brown to reddish brown trichomes or glabrous at maturity, acute apex; peduncle 8.0-10.0 cm long, 1.4-1.6 cm in diameter, erect, pubescent, light brown; megasporophylls 80-210, 9-10 orthostichies with 11-13 sporophylls per orthostichy, 2.3-2.9 x 3.9-5.0 cm, with a truncate distal face, horns straight and 0.31-0.53 cm long, 1.33-1.40 cm between horns with a right angle between the horns. Seeds 2.45-2.65 cm long, 1.4-1.6 cm in diameter, ovate, sarcotesta whitish yellow to yellow when immature, light brown at maturity. Distribution and habitat. Ceratozamia oliversacksii occurs along the Eastern Sierra Madre del Sur in the Oaxacan Highlands, Mexico (Fig. 21D ), it is found on karstic rocks with abundant organic matter in cloud forest and the transition zone between it and pine forest between 1,040 to 1,850 m. Etymology. The specific epithet honors Oliver Sacks, who loved cycads and was a distinguished American neurologist and historian of science. Sacks published Island of the Color Blind and Cycad Island ( Sacks 1997 ) and Oaxaca Journal ( Sacks 2002 ) ( Martinez-Dominguez et al. 2022b ). Common names. None recorded. Uses. None recorded. Preliminary conservation status. Ceratozamia oliversacksii should be listed as "Vulnerable (V)". We visited four populations in Oaxaca in which each population size was between 50 to 300 adult plants. We observed different age classes from seedling to reproductive individuals. Discussion. Ceratozamia oliversacksii is similar to C. robusta and C. leptoceras but is characterized by green leaves at emergence and the combination of linear and papyraceous leaflets. The ovulate strobili have 11 to 13 sporophylls per orthostichies and an acute apex, acute horns of megasporophylls up to 0.53 cm long, and microsporophylls with a rounded distal face and straight horns. Specimens examined. Mexico . Oaxaca : Mun. Candelaria Loxicha , 1,380 m , 3 May 2005 , A. Luna-Jose & B. Rendon-Aguilar 1472, 1473 (XAL); 1,630 m , 23 Jun 2019 , F. Nicolalde-Morejon & L. Martinez-Dominguez 3231-3243 (CIB); 1,630 m , 23 Jun 2019 , L. Martinez-Dominguez & F. Nicolalde-Morejon 1832-1839 (CIB), 1840 (CIB, MEXU); 1,418 m , 20 April 2021 , L. Martinez-Dominguez et al. 2160, 2161 (CIB); 1,616 m , 10 Jun 2021 , M. Rios-Mendez et al. 105 (CIB). Mun. San Agustin Loxicha , 1,760 m , 12 Oct 2003 , A. Luna-Jose & B. Rendon-Aguilar 5 18 (XAL); 1,400 m , 23 Jun 2019 , F. Nicolalde-Morejon & L. Martinez-Dominguez 3229, 3230 (CIB); 1,400 m , 23 Jun 2019 , L. Martinez-Dominguez & F. Nicolalde-Morejon 1829-1831 (CIB). Mun. Santa Catarina Juquila , 1,850 m , 13 Apr 1965 , J. Rzedowski 1 9557 (ENCB); 1,450 -1,700 m, 11 Feb 1965 , R. McVaugh 22346 (ENCB; MICH). Mun. San Miguel del Puerto , 1,060 m , 25 Jun 2019 , F. Nicolalde-Morejon & L. Martinez-Dominguez 3244-3249 (CIB); 1,430 m , 17 Apr 2000 , J. Rivera H. et al. 2378 (FCME, SERO); 1,060 m , 25 Jun 2019 , L. Martinez-Dominguez & F. Nicolalde-Morejon 1847-1849, 1851, 1852 (CIB), 1850 (CIB, MEXU); 1,040 m , 1 Apr 2003 , L. Schibli et al. 152 (SERO).