Ceratozamia leptoceras Mart.- Dominguez , Nic.-Mor., D.W.Stev. & Lorea-Hern., PhytoKeys 156: 13. 2020

Martinez-Dominguez, Lili, Nicolalde-Morejon, Fernando, Vergara-Silva, Francisco & Stevenson, Dennis Wm., 2022, Monograph of Ceratozamia (Zamiaceae, Cycadales): an endangered genus, PhytoKeys 208, pp. 1-102 : 1

16. Ceratozamia leptoceras Mart.- Dominguez, Nic.-Mor., D.W.Stev. & Lorea-Hern., PhytoKeys 156: 13. 2020

Fig. 7C

Type.

Mexico. Guerrero: Mun. Tlacoachistlahuaca, 3 km NW de San Pedro Cuitlapan , 1,400 m, 26 Jun 2019, L. Martínez-Domínguez & F. Nicolalde-Morejón 1867 ♀ (holotype: CIB! [acc. # 22405UV]; isotypes: MEXU!, NY!) .

Description.

Stem 30-150 cm long, 11-35 cm in diameter, epigeous, erect to decumbent. Cataphylls 9-11 × 2.5-3 cm wide at the base, persistent, triangular, reddish brown, densely brown tomentose abaxially at emergence, pubescent at maturity, apex acuminate. Leaves 7-37 (55), 93.5-281 cm long, descending, green at emergence with sparse reddish brown pubescent, glabrous at maturity. Petiole 45-85 cm long, terete, linear, copperish green in mature leaves; with 50-75 thin prickles, 0.48-0.68 cm long. Rachis 75-196 cm long, terete, linear, green in mature leaves, with prickles. Leaflets 22-61 pairs, opposite to subopposite, insertion in one plane, linear, abaxially curved, not basally falcate, membranaceous, flat, green with adaxial and abaxial sides glabrous, distal end with entire margins, acuminate and symmetrical at the apex, attenuate at base, with conspicuous and greenish veins; median leaflets 28-43.5 × 1.9-2.8 cm, 1.8-2.8 cm between leaflets; articulations 0.70-1.15 cm, generally copperish green. Pollen strobili 40-45 cm long 6.0-7.8 cm in diameter, generally solitary (rarely 2), cylindrical, erect, brownish yellow at emergence, yellowish green with brownish trichomes at maturity; peduncle 13-19 cm long, 1.5-2.0 cm in diameter tomentose, reddish brown to brown; microsporophylls 2.1-2.45 × 1.09-1.30 cm, obconic with a non-recurved distal face and a deeply lobate fertile portion, infertile portion 0.83-0.96 cm long and linear with straight and thin horns and 0.1-0.23 cm long, 0.44-0.56 cm and an acute angle between the horns. Ovulate strobili 23.5-28 cm long, 9.5-11 cm in diameter, solitary, cylindrical, erect, brownish green with greyish black trichomes at emergence, copperish green with greyish black pubescent at maturity with an acute apex; peduncle 11-16 cm long, 1.5-2.0 cm in diameter, erect, tomentose, brown; megasporophylls 56-81, 8-9 orthostichies with 7-9 sporophylls per orthostichy, 4.9-5.6 × 2.2-2.6 cm, with a prominent distal face, horns straight and robust and 0.63-0.81 cm long, 0.95-1.35 cm between horns and angle straight between the horns. Seeds 2.43-2.71 cm in long, 1.4-1.8 cm in diameter, ovoid, sarcotesta whitish pink when immature, light brown at maturity.

Distribution and habitat.

Ceratozamia leptoceras is endemic to the Sierra Madre del Sur in Guerrero State, Mexico (Fig. 19D ), where it occurs on karstic rocks in cloud forest at 1,170-1,400 m.

Etymology.

The specific epithet is derived from the Greek words that describe the shape of the horns on the sporophylls: “lepto” for thin or fine and “ceras” in reference to the horns.

Common names.

Mexico. Guerrero: Shalukaá is the name used by the “Mixteco” ethnic group ( Martínez-Domínguez et al. 2020).

Uses.

None recorded.

Preliminary conservation status.

Only three populations of Ceratozamia leptoceras are known. In particular, one of these populations has few adult plants (approximately 30 individuals). The cloud forests in this area are less affected by anthropogenic pressures; however, this vegetation type is one of the most threatened in Mexico ( Williams-Linera 2002). Based upon this information, C. leptoceras should be considered "Endangered (EN)" in accordance with IUCN criteria.

Discussion.

Ceratozamia leptoceras is distinguished from C. oliversacksii by its linear and membranaceous leaflets. The main differences are in reproductive structures, C. leptoceras has and linear infertile portion of microsporophylls and ovulate strobilus with abundant pubescence at the base of the megasporophylls.

Specimens examined.

Mexico. Guerrero: Mun. Cochoapa El Grande , 1,170 m, 4 Feb 1984, F. Lorea-Herna ́ndez 2928 (FCME). Mun. Tlacoachistlahuaca , 1,200 m, 29 May 219, F. Nicolalde-Morejón et al. 3173 (XAL), 3174 (FCME), 3175 (CIB); 1,200 m, 29 May 2019, L. Martínez-Domínguez et al. 1756 (CIB), 1757 (CIB, MEXU), 1758 (XAL), 1759 (CIB, MEXU); 1,400 m, 26 Jun 2019, F. Nicolalde-Morejo ́n & L. Marti ́nez-Domínguez 3255-3261 (CIB) ; 1,400 m, 26 Jun 2019, L. Martínez-Domínguez & F. Nicolalde-Morejón 1860, 1861 (MEXU), 1862-1866 (CIB).

Figures

Figure 7. Plants of Ceratozamia in habitat A C. kuesteriana B C. latifolia C C. leptoceras D C. matudae E C. mexicana F C. miqueliana G C. mirandae H C. mixeorum I C. morettii J Epiphytic C. morettii.

Figure 19. Distribution of Ceratozamia species A C. huastecorum B C. kuesteriana C C. latifolia D C. leptoceras.