Dioon sonorense (De Luca, Sabato & Vázquez Torres) Chemnick, Gregory & Salas-Morales (1997:3)

Hernández-Tapia, Jessica E., Jiménez-Ramírez, Jaime & Vovides, Andrew P., 2020, Taxonomic revision of the genus Dioon (Zamiaceae), Phytotaxa 442 (4), pp. 267-290 : 283-285

Dioon sonorense (De Luca, Sabato & Vázquez Torres) Chemnick, Gregory & Salas-Morales (1997:3) . Type:—

MEXICO. Sonora: Álamos, 950 m, without date, Vázquez Torres et al. V –2308 (holotype: XALU!).

Basonym: Dioon tomasellii var. sonorense De Luca, Sabato & Vázquez Torres (1984: 226) . Dioon edule var. sonorense (De Luca, Sabato, Vázquez Torres) Mc Vaugh & Pérez de la Rosa (1992: 112) .

Short plants 0.3–0.6 m tall. Stems 22–25 cm diameter. Cataphylls triangular-aristate, lanate, 8–16 cm long, 3 cm wide at the base. Leaves 8–20 per crown, 80–120× 20–25 cm, tomentose, sometimes glabrescent, trichomes light brown. Leaflets 70–90 pairs, falcate, acuminate, reclined to descending, not imbricate, subopposite, margin entire, but sometimes with 1–3 prickles, veins 8–14, the apical leaflets 2–6.8 cm long, the intermediate 7.6–14.6 cm long, the basal ones 1–5.5 cm long, all of them 0.35– 0.35 cm wide, distance between articulations 0.2–0.9 cm, without pinnacanths, tomentose; rachis straight to twisted at the apex, semiterete, tomentose; petioles semiterete to terete, 8– 16.5 cm long, 0.3–0.9 cm wide, lanate at the base. Male strobili cylindrical, 25–26.5 cm long, 7–8 cm wide, peduncles short, appearing sessile. Female strobili cylindrical, 21 cm long, 15 cm wide, peduncles short, appearing sessile; megasporophylls oblong-trulate, flat, 3.6–8.5 cm long, 2.4–4 cm wide, lanate at the outer surface, the inner surface glabrate, sometimes both surfaces lanate. Seeds globose, 2–2.1 cm long, 2–2.1 cm wide, sarcotesta yellow to yellow-orange.

Distribution and habitat.—It is distributed in xeric shrublands, oak forests and tropical deciduous forests, including the ecotone of these types of vegetation in the states of Sinaloa and Sonora. It can be found within 1000– 1800 m, in semiarid climates. The collected individuals in Chihuahua are cultivated specimens.

Uses and common names.—It is used as an ornamental plant; the stem is used to produce alcohol and as treatment for insect and snake bites as well as articulations. The production of alcohol (Sotol and Bacanora) is an activity that has severely reduced the populations of the species, driving them to the verge of extinction. In the region, the specie is known as palma de la virgen, peine and peyote ( Bonta & Osborne 2007).

Taxonomic notes.—It is akin to D. vovidesii for presenting reclined to descending leaflets; however, it is distinguished for presenting longer and thinner falcate leaflets, the cataphylls are aristate and the megasporophylls are oblong-trulate. The synonym Dioon edule var. gentryi is considered as an invalid name, as there is no publication.

Specimens examined:— MEXICO. Chihuahua: Cuahutémoc , 2063 m, 10/September/1994, Bye R. 19387 ( MEXU) . Sinaloa: Choix , 842 m, 7/May/2004, Walters et al. TW 2004-08 A ( MEXU) . Sonora: Álamos , 20/ September/1965, Foster R. s.n. ( MEXU) ; Álamos , 22/October/1936, Gentry H. S. 2955 ( MEXU) ; Álamos , 1800 m, 19/July/2000, Vovides A. P. et al. 1392 ( MEXU) ; Álamos , 299 m, 30/April/2004, Vovides A. P. et al. 1480 ( MEXU) ; Álamos , 1020 m, 19/July/2000, Vovides A. P. et al. 1389 ( MEXU) ; Álamos , 1122 m, 6/May/2004, Walters T. et al. TW. 2004-06 A ( MEXU, SERO, XAL) .

Dioon spinulosum Dyer ex Eichler (1883: 411) . Type:— MEXICO. Yucatán: Progreso, not info, Hoge C. J. s.n. (holotype: K!).

Homonym: Dioon spinulosum Dyer (1884:191) .

Plants (3)5–16(18) m tall. Stems 18–25 cm diameter. Cataphylls triangular-acuminate, densely lanate, 13–18 cm long. Leaves 8–40 per crown, 100–250× 20–40 cm, glabrescent, trichomes whitish brown. Leaflets 60–130 pairs, falcate, acuminate, convex, not imbricate, sometimes slightly imbricate, covering less than a third of the width of leaflet, subopposite, the margin spinose with 8–12 prickles, rarely 6–15, veins 12–30, the apical leaflets 3.5–9 cm long, the intermediate 7.4–19 cm long. the basal ones 0.1–7 cm long, all of them (0.8) 1.3–1.8 cm wide, distance between articulations 0.2–2 cm, with pinnacanths, glabrate; rachis straight to semicurved at the apex, terete, glabrate; petioles semiterete, slightly petiolate in adult plants, in young plants elongate petiolate, lanate at the base. Male strobili cylindrical to ovoid, 21–50 cm long, 1–1.5 cm wide, peduncles short, appearing sessile; microsporophylls cuneate, tomentose, mucronate distally, 1.4–2.5 cm long, sori with 3–6 sporangia. Female strobili cylindrical to ovoid, 35–50 cm long, 20–27 cm, elongated peduncle; megasporophylls deltoid, flat, 6.5–8 cm long, 3.2–5 cm wide, lanate on the outer surface, the inner surface glabrate. Seed ovoid to ellipsoid, 3.4–4.8 cm long, 2.4–3.1 cm wide, sarcotesta yellow.

Distribution and habitat.—Along with D. rzedowskii , it’s distributed only in tropical rainforests, in very humid regions in the states of Oaxaca and Veracruz, within the 50– 600 m.

Uses and common names.—It is used as an ornamental plant. Seed husks are used to make bullroarers (zumbadores). In the region, it is known as coyolito de cerro, palma de chicle, palma de chicalite, palma de Dolores, chicalito and coyolillo (Bonta & Osborn 2007).

Taxonomic notes.—It is akin to D. rzedowskii but it is distinguished for presenting (6)8–12(15) prickles at the margin of the leaflets and the seeds are usually ellipsoid. Within the genus, it is the largest species, reaching 18 m tall in the oldest specimens. The name Dioon spinulosum var. spinulosum is in fact an invalid name because it lacks publication and type specimen.

Specimens examined:— MEXICO. CDMX: Jardín Botánico, Ciudad Universitaria, 4/July/2006, Abrego E. & González H. 1 ( UAMIZ). Oaxaca: Acatlán de Pérez Figueroa , 220 m, 8/October/2001, Guízar E. & Echeverría J. C. 5724 ( MEXU, UAMIZ) ; Acatlán de Pérez Figueroa , 110 m, 25/January/2008, Salas-Morales 6348 ( SERO) ; San José Chiltepec, 150 m, 8/January/1988, López A. R. et al. 456 ( UAMIZ) ; San Juan Bautista Tuxtepec, July /1963, Alcocer J. M. & Morales C. s.n. ( ENCB, MEXU) ; San Juan Bautista Tuxtepec, February /1962, s.n. ( FCME) ; San Juan Bautista Tuxtepec, 300 m, 10/April/1963, Madrigal X. 1458 ( ENCB, MEXU) ; San Juan Bautista Tuxtepec, 200 m, 6/February/1967, Martínez M. A. 11 ( ENCB) ; San Juan Bautista Tuxtepec, 18/September/1947, Miranda F. 4227 ( MEXU) ; San Juan Bautista Tuxtepec, 25/May/1961, Sousa M. s.n. ( FCME) ; San Juan Bautista Tuxtepec, 20/ May/1961, Sousa M. s.n. ( FCME) ; San Juan Bautista Tuxtepec, 100 m, 7/July/1980, Vovides A. P. 547 ( MEXU) ; San Juan Bautista Tuxtepec, 100 m, 19/January/1982, Vovides A. P. & Pattison G. 718 ( ENCB) ; San Juan Bautista Tuxtepec, 100 m, 7/July/1980, Vovides A. P. & Pattison G. 547 ( ENCB) ; San Juan Bautista Valle Nacional, 250 m, 25/April/1993, Ibarra G. 3881 ( MEXU) ; San Soyaltepec, 60 m, 21/May/1986, Cortes L. 379 ( MEXU) ; San Soyaltepec, 150 m, 8/ December/1985, Cortes L. 118 ( MEXU) ; San Soyaltepec, 154 m, 12/November/2004, Juárez G. 858 ( MEXU) ; San Soyaltepec , 116 m, 6/January/2014, Salas-Morales 7526 ( SERO) ; San Soyaltepec, 20/October/1962, Sousa M. 1783 ( MEXU) ; San Soyaltepec, 19/February/1961, Sousa M. 268 ( MEXU) ; Santa María Jacatepec, 165 m, 23/April/1993, Carrillo C. 176 ( MEXU) ; Santa María Jacatepec, 550- 270 m, 19/January/1988, Torres R. 11066 ( MEXU) ; Santa María Jacatepec, 140 m, 5/September/1984, Torres R. 6107 ( MEXU) ; Santiago Jocotepec, 90 m, 29/ Nocember /2003, Castillo-Campos G. et al. 20791 ( MEXU). Veracruz: Tezonapa , 600 m, 9/December/1974, Rees J. 1648 ( MEXU) .

Dioon stevensonii Nicolalde-Morejón. & Vovides (2009:74) . Type:— MEXICO. Guerrero: Coyuca de Catalán, 1181 m, 13/March/2007, Nicolalde-Morejón F. et al. 1551 (holotype: XAL!, isotypes: MEXU!). ( Fig. 3 ).

Plants 1.2 m tall. Stems 26 cm diameter. Cataphylls triangular-acuminate, lanate, 6–7 cm long, 1.5–3 cm wide. Leaves 2–25 per crown, 69–111× 21–23 cm, tomentose on the underside, trichomes golden brown. Leaflets 50–100 pairs, linear-lanceolate, sometimes subfalcate, acuminate, flat-convex, not imbricate, but sometimes slightly imbricate, covering less than a third of the distal region of the leaf, opposite to subopposite, margin entire, sometimes with 1–4 prickles at the leaflet apex, veins 11–20, the apical leaflets 1.1–4.5 cm long, the intermediate 4.3–14.5 cm long, the basal ones 1.3–5.8 cm long, all of them 0.5–1 cm wide, distance between articulations 0.2–0.5 cm, without pinnacanths, tomentose; rachis straight to twisted at the apex, semiterete, tomentose at the insertion of leaflet; petioles semiterete, 8– 19.5 cm long, 0.4–1 cm wide, lanate at the base. Male strobili cylindrical, 16–25 cm long, 7.2–75 cm wide, peduncles short, appearing sessile; microsporophylls cuneate, tomentose, mucronate distally, 1.6–2.2 cm long, sori with 4–5 sporangia. Female strobili ovoid, 30–35 cm long, 10–15 cm wide, peduncles short, appearing sessile; megasporophylls deltoid, flat to curved at the apex, 7.5–9.5 cm long, 3.5–4.5 cm wide, lanate on the outer surface, the apex occasionally glabrate, the inner surface glabrate. Seed globose to ovoid, 2.2–3.5 cm long, 2–3 cm wide, sarcotesta yellow.

Distribution and habitat.—It is found in oak forest, tropical deciduous forest and the ecotone between these two types of vegetation. It is endemic to the states of Guerrero and border Michoacán with Guerrero. It is listed as a Critically Endangered species (CR) in the IUCN Red List due to the poaching of plants for sale as ornamentals as well as the loss of habitat. It thrives in temperate to warm humid regions, within the 400–1550 m.

Uses and common names.—It is only used as an ornamental plant. In these regions, it is known as palma and palmita ( Bonta et al. 2019).

Taxonomic notes.—The main difference between D. stevensonii and D. tomasellii is that the former species presents megasporophylls with flat apices, but the rest of the sporophyll is curved, the leaflets tend to be linear-lanceolate and very rarely subfalcate. D. tomasellii presents a completely flat megasporophyll and falcate leaflets.

Specimens examined:— MEXICO. Guerrero: Arcelia , 1550 m, 6/December/1983, Sabato et al. 2335 ( MEXU) ; Arcelia, 400 m, without date, Vázquez M. V-2305, V-2325 ( XALU) ; Arcelia , 1397 m, 18/May/2004, Walters T. et al. TW 2004-18 B ( SERO) ; Coyuca de Catalán , 1215 m, 3/May/2001, Vovides A. P. et al. 1414 ( MEXU) ; Zirándaro , 1210 m, 6/November/1998, Calónico J. 12162 ( FCME, MEXU) ; Zirándaro , 1120 m, 22/June/1999, Calónico J. 15242 ( FCME, MEXU) ; Zirándaro , 1120 m, 22/July/1999, Calónico J. 15421 ( FCME, MEXU) ; Zirándaro , 1200 m, 9/March/1988, Contreras J. L. 2359 ( FCME) ; Zirándaro , 1100 m, 15/June/1988, Contreras J. L. 2399 ( FCME) ; Zirándaro , 1100 m, 16/June/1988, Contreras J. L. 2397, 2400 ( FCME) ; Zirándaro , 1150 m, 14/July/1982, Martínez 1993 ( MEXU) ; Zirándaro , 1397 m, 18/May/2004, Walters T. et al. TW 2004-18 A ( MEXU) ; Zirándaro , 940 m, 2/May/2001, Vovides A. P. et al. 1398, 1399, 1400, 1401 ( XAL) ; Zirándaro , 1100 m, 2/May/2001, Vovides A. P. et al. 1404, 1405, 1406, 1407 ( XAL) . Michoacán: Arteaga , 840 m, 16/May/2004, Walters et al. TW 2004-15 A ( MEXU) .

Figures

FIGURE 3. Dioon stevensonii. A) Stem apex with Leaf. B) Female strobili. C) Megasporophyll and seed. D) Male strobili. E) Microsporophyll. Illustrated by Ramiro Cruz, based in Contreras 2311.