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

Martinez-Dominguez, Lili, Nicolalde-Morejon, Fernando, Lorea-Hernandez, Francisco G., Vergara-Silva, Francisco & Stevenson, Dennis Wm., 2020, A novelty in Ceratozamia (Zamiaceae, Cycadales) from the Sierra Madre del Sur, Mexico: biogeographic and morphological patterns, DNA barcoding and phenology, PhytoKeys 156, pp. 1-25 : 1

Ceratozamia leptoceras Mart.- Dominguez, Nic-Mor., D.W. Stev. & Lorea-Hern. sp. nov. Figures 6 , 7 , 8

Type.

Mexico. Guerrero: Tlacoachistlahuaca, 3 Km NW of San Pedro Cuitlapan, 1,400 m, 26 Jun. 2019, L. Martínez-Domínguez & F. Nicolalde-Morejón 1867 ♀ (holotype CIB; isotypes MEXU, NY).

Ceratozamia leptoceras is most similar to C. robusta , but can be distinguished by its linear membranaceous leaflets and petioles with thin prickles. In addition, C. leptoceras is easily distinguished from its congeners by having obconic microsporophylls with a long, linear infertile portion (0.83-0.96 cm), and two thin horns; ovulate strobilus with abundant pubescence at base of megasporophylls, 8-9 orthostichies, and 7-9 sporophylls per orthostichy.

Additional specimens examined

(paratypes). Mexico. Guerrero: Cochoapa El Grande, 4 km to W-NW of San Pedro by a logging road, 1,170 m, 4 Feb 1984, F. Lorea-Hernández 2928 (FCME); Tlacoachistlahuaca, San Pedro Cuitlapan, riverbank “Chipili”, 1,200 m, 29 May 2019, L. Martínez-Domínguez et al. 1756 (CIB), 1757 (CIB, MEXU), 1758 (XAL), 1759 (CIB, MEXU); F. Nicolalde-Morejón et al. 3173 (XAL), 3174 (FCME), 3175 (CIB); 3 km NW of San Pedro Cuitlapan, 1,400 m, 26 June 2019, L. Martínez-Domínguez & F. Nicolalde-Morejón 1860, 1861 (MEXU), 1862-1866 (CIB).

Description.

Stem epigeous, erect to decumbent, 30-150 cm in length, 11-35 cm in diameter, covered with leaf bases. Cataphylls persistent, reddish-brown, densely brownish tomentose abaxially at emergence, pubescent at maturity, triangular, apex acuminate, 9-11 × 2.5-3 cm at base. Leaves 7-50, descending, 93.5-281 cm, green at emergence with sparse reddish-brown pubescence, glabrous at maturity. Petiole terete, linear, 45-85 cm, armed with long (0.48-0.68 cm) and thin prickles, copperish-green in mature leaves. Rachis terete, linear, 75-196 cm, armed with long and thin prickles, green in mature leaves. Leaflets 22-61 pairs, linear, abaxially curved, not basally falcate, membranaceous, flat, opposite to subopposite, plane, green, adaxial and abaxial surfaces glabrous, acuminate and symmetric apex, attenuate at base, with conspicuous and green veins; median leaflets 28-43.5 × 1.9-2.8 cm, 1.8-2.8 cm between leaflets; articulations generally copperish-green. Pollen strobilus generally solitary (rarely 2), cylindrical, erect, 40-45 cm in length, 6.0-7.8 cm in diameter, brownish-yellow at emergence, yellowish-green with brownish trichomes at maturity; peduncle tomentose, reddish-brown to brown, 13-19 cm in length, 1.5-2.0 cm in diameter; microsporophylls 2.1-2.45 × 1.09-1.30 cm, obconic, non-recurved distal face, fertile portion deeply lobate, infertile portion 0.83-0.96 cm, linear, horns 0.1-0.23 cm, straight, thin, 0.44-0.56 cm between horns, 180-230 sporangia on abaxial side. Ovulate strobilus solitary, cylindrical, erect, 23.5-28 cm in length, 9.5-11 cm in diameter, brownish-green with greyish-black trichomes at emergence, copperish-green with greyish-black pubescence at maturity, acute apex; peduncle tomentose, brown, 11-16 cm in length, 1.5-2.0 cm in diameter; megasporophylls 56-81, 8-9 orthostichies (column), 7-9 sporophylls per column, 4.9-5.6 × 2.2-2.6 cm, prominent distal face, horns 0.63-0.81 cm, straight, 0.95-1.35 cm between horns, straight angle between horns. Seeds ovoid, 2.43-2.71 cm in length, 1.4-1.8 cm in diameter, sarcotesta whitish-pink when immature, light brown at maturity.

Etymology.

The specific epithet alludes to microsporophylls horns shape, which are short and thin. This name comes from the Greek “lepto”, which means thin or fine, and “ceras” in reference to horns.

Distribution and habitat.

Only known from Guerrero, Mexico, on the karstic rocks within the elevation range of 1,170-1,400 m of the Sierra Madre del Sur subprovince of the Guerreran district ( Morrone 2017) (Fig. 1 ). This species occurs in cloud forest. The climate type is (A) C (w2)-semi-warm temperate subhumid with summer rains, and the annual precipitation is from 2, 000 to 2, 500 mm ( García 2004).

Phenology.

The leaves are produced in groups of 9 to 15 and mature almost simultaneously. Ovulate strobili mature from June to July; seeds mature from August to September. Pollen strobili mature from January to May.

Common names.

The common local name for this species by the “Mixteco” ethnic group is Shalukaá.

Figures

Figure 1. Distribution map of the genus Ceratozamia (black solid circles). Distributions for species morphologically similar to Ceratozamia leptoceras are represented with an asterisk and a double circle. Guerrero state and Putla subregion of cloud forest are shown with outline and shaded area, respectively. Inset: points corresponding to the Guerrero mountain range where Ceratozamia was collected.

Figure 6. Ceratozamia leptoceras A adult plant in habit B ovulate strobilus C detail of leaflets D seedling E ptyxis F prickles on petiole.

Figure 7. Illustration of Ceratozamia leptoceras A cataphyll B microsporophyll C ovulate strobilus D leaves and detail of leaflets E stem F seed G leaflet. This illustration is based on L. Martinez-Dominguez & F. Nicolalde-Morejon 1867, with exception microsporophyll, which is based on L. Martinez-Dominguez et al. 1757.

Figure 8. Ceratozamia leptoceras A detail of ovulate strobilus and megasporophylls B seeds C abaxial view of microsporophylls D cataphylls A, B, D are based on L. Martinez-Dominguez & F. Nicolalde-Morejon 1867; C is based on L. Martinez-Dominguez et al. 1757.