Taxonomic revision of the genus Dioon (Zamiaceae) Author Hernández-Tapia, Jessica E. 0000-0002-4616-3126 Universidad Nacional Autónoma de México, Departamento de Biología Comparada, Herbario de la Facultad de Ciencias (FCME), Ciudad de México. jessica.hernandez@ciencias.unam.mx Author Jiménez-Ramírez, Jaime 0000-0002-2979-8891 Universidad Nacional Autónoma de México, Departamento de Biología Comparada, Herbario de la Facultad de Ciencias (FCME), Ciudad de México. jessica.hernandez@ciencias.unam.mx Author Vovides, Andrew P. 0000-0002-3779-1374 Instituto de Ecología, A. C., apartado postal 63, Xalapa Veracruz, México. andrew.vovides@inecol.mx text Phytotaxa 2020 2020-05-13 442 4 267 290 http://dx.doi.org/10.11646/phytotaxa.442.4.2 journal article 10.11646/phytotaxa.442.4.2 1179-3163 13878274 Dioon tomasellii De Luca, Sabato & Vázquez Torres (1984: 225) . Type:— MEXICO . Nayarit : Miravalles, 950 m , no date, Vázquez Torres et al. V–2307 ( holotype : NAP, isotypes : ENCB!, MEXU!). = Dioon tomasellii var. tomasellii De Luca, Sabato & Vázquez Torres (1984: 226) . Type :— MEXICO . Nayarit , not info, Rose 2014 (F, NY, US ). Plants 1 m tall, rarely 2 m tall. Stems 25 cm diameter. Cataphylls triangular-acuminate, lanate, 4–10 cm long, 4–5.5 cm wide. Leaves 10–15 per crown, 100–150 cm long, glabrescent, except for the rachis and petiole, trichomes golden brown. Leaflets 83–110 pairs, falcate, acuminate, reclined to descending, not imbricate, sometimes slightly imbricate, covering less than a third of the leaflet width, subopposite, margin entire, sometimes with 1–5 prickles, veins 11–18, the apical leaflets, 2.2–7 cm long, the intermediate ones 7.5–17 cm long, the basal ones 1.2–6.5 cm long, all of them (0.4) 0.6–1.1 cm wide, distance between articulations 0.15–0.95 cm , without pinnacanths, glabrate, rachis straight to twisted at the apex, semiterete, tomentose; petioles semiterete, 12.5–20 cm long, 0.8–1.8 cm wide, tomentose, lanate towards the base. Male strobili cylindrical, 35–50 cm long, 8–10 cm wide, peduncles short, appearing sessile; microsporophylls cuneate, lanate, recurved mucronate distally, 2.2–4 cm long, 0.7 cm wide. Female strobili ovoid, 20–30 cm long, 15–20 cm wide, slightly stalked, apparently sessile; megasporophylls deltoid, elongated, flat, 3–10.7 cm long, 2.7–4.5 cm wide, outer surface lanate to slightly lanate, the inner surface glabrate. Seed ovoid to globose, 2.4–3 cm long, 2.1–2.5 cm wide, sarcotesta yellow. Distribution and habitat .—It is distributed along the Pacific coast, in tropical deciduous forest, pine-oak forest, pine forest, tropical rain forest and oak forest, in the states of Durango , Jalisco , Nayarit and Sinaloa . It can be found within 600–1900 m , in warm-humid and temperate climates. The specimens of Veracruz come from cultivated individuals. Uses and common names .—It is used only as an ornamental plant. In the regions where it is found is known as palma, palma de la virgen, palma del diablo, palmita and peinetillo (Bonta & Osborn 2007). Taxonomic notes .—It can be distinguished from D. stevensonii for presenting reclined to descending, falcate leaflets and the flat apex of the megasporophylls. It can be distinguished from D. sonorense and D. vovidesii by the enlogated deltoid megasporophylls, while these two species present oblong-trulate and deltoid megasporophylls, respectively. 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. Specimens examined: — MEXICO . Durango : Tamazula , 1500 m , 19/March/1990 , Koch S . D. & Chávez J . 680 ( UAMIZ ) ; Tamazula , 1900 m , 24/November/1983 , Sabato S . et al. 2315 ( MEXU ) ; Tamazula , 400 m , without date, Vázquez M . V-2315 ( XALU ) .; Tamazula , 615 m , 9/May/2004 , Walters et al. TW 2004-9 A ( MEXU , XAL , SERO ) . Jalisco : Cabo Corrientes , 1020 m , 19/April/2001 , Avendaño S . et al. 5266 ( MEXU ) ; Cabo Corrientes , 815 m , 23/ February/1993 , Castillo G .et al.10207 ( XAL ) ; Cabo Corrientes , 750 m , 5/July/1993 , Castillo G .et al.11578 ( XAL ) ; Cabo Corrientes , 630 m , 5/March/2007 , Nicolalde-Morejón et al. 1526 ( XAL ) ; Cabo Corrientes , 960 m , 18/November/1985 , Pérez J . A . 1020 ( XAL ) ; Cabo Corrientes , 1031 m , 8/May/2004 , Vovides A . P . et al. 1500 ( XAL ) ; García Barragán , 780 m , 20/April/2001 , Avendaño S . et al. 5245 ( MEXU ) ; Guadalajara , 1550 m , 24/July/2006 , Nicolalde-Morejón et al. 1430 ( XAL ) ; Puerto Vallarta , 600 m , 22/February/1998 , Ramíres-Delgadillo R . 5207 ( MEXU ) ; Puerto Vallarta , 900 m , 15/December/1983 , Sabato S . et al. V-2306 ( MEXU ) ; Puerto Vallarta , 900 m , 28/May/1979 , Vázquez M . V-2306 ( XALU ) ; San Sebastián del Oeste , 810 m , 5/April/2007 , Carrillo-Reyes P . & Cabrera-Toledo 5203 ( XAL ) ; San Sebastián del Oeste , 820 m , 19/April/1986 , Pérez J . A . 1088 D ( XAL ) ; Talpa de Allende , 909 m , 27/February/2004 , García V . et al. s.n. ( UAMIZ ) ; Telocotlán , 1850 m , 4/October/1980 , Vázquez M . V-2334 ( XALU ) ; Zapopan , 1422 m , 12/May/2004 , Walters T . et al. TW 2004-11 A ( SERO , MEXU ) . Nayarit : Compostela , 750 m , 11/August/1989 , Díaz C . L . 20810 ( XAL ) ; Compostela , 850 m , 4/March/2007 , Nicolalde-Morejón et al. 1519, 1520 ( XAL ) ; Compostela , 829 m , 7/May/2004 , Vovides A . P . et al. 1494, 1496, 1498 ( XAL ) . Sinaloa : Concordia , 1137 m , 3/May/2004 , Vovides A . P . et al. 1481 ( XAL , MEXU ) ; Concordia , 900 m , 4/May/2004 , Vovides A . P . et al 1482 ( XAL ) . Veracruz : Xalapa , 1270 m , 29/August/2007 , Luna V . E . 1595, 1596, 1597 ( XAL ) . Dioon vovidesii Gutiérrez-Ortega & Pérez Farrera (2018: 109) . Type:— MEXICO . Sonora : Mazatlán, 17/August/2016 , Pérez-Farrera M. A. 3453 ( holotype : HEM, isotypes : XAL, MEXU!). Plants 0.6–1.5 m tall. Stems 19.7–36.09 cm diameter. Cataphylls triangular-acuminate, lanate. Leaves 13–39 per crown, 61–133× 11–30 cm , tomentose to glabrescent, trichomes brown. Leaflets 59–100 pairs, linear-lanceolate, acuminate, reclined to descending, not imbricate, opposite to subopposite, margin entire, sometimes with 1–2 marginal prickles, veins 7–11, the apical leaflets 2.2–6.4 cm long, the intermediate 7.9–14.7 cm long, the basal ones 2.4–5.3 cm long, all of them 0.3–0.66 cm wide, distance between articulations 0.3–0.7 cm , without pinnacanths, tomentose on the underside to glabrate; rachis straight to twisted at the apex, terete to semiterete, tomentose; petiole semiterete, 2.5–11 cm long, lanate at the base. Male strobili globose to subglobose, 14.9–15 cm long, 8–9 cm wide, pedunculate, 4.8–5 cm long, lanate. Female strobili ovoid, 27–30 cm long, 17–21 cm wide, stalked; megasporophylls deltoid, flat to curved, 8.5–9 cm long, 5.2–6 cm wide, lanate on the outer surface, the inner surface glabrate, sometimes the apex glabrate. Seed ovoid, sarcotesta brown-orange. Distribution and habitat .—It is an endemic species of Sonora and it can be found in xeric shrublands, tropical deciduous forest and the ecotone between these two types of vegetation. It is the species with northernmost distribution for the genus. It grows within 850–1800 m . Taxonomic notes .— Dioon vovidesii is akin to D. sonorense , as they were considered as the same species. Dioon vovidesii is distributed in northern Sonora and D. sonorense is in southern Sonora and north of Sinaloa . Dioon sonorense is smaller, reaching up to 60 cm in height, it presents longer and thinner leaflets, its megasporophylls are oblong-trulate and the seeds are spherical. In contrast, D. vovidesii is distinguished for being a larger plant, reaching up to 1.5 m tall, presenting shorter and wider leaflets, deltoid megasporophylls and ovoid seeds. It is found in the most arid regions of the distribution and is the northernmost species of the genus. Specimens examined:— MEXICO . Sonora : Bacanora , 850 m , 4/May/2004 , Walters T . et al. TW 2004-03 A ( MEXU , SERO , XAL ) ; Mazatán , 900 m , 15/February/1984 , Sabato S . et al. V-2309 ( MEXU ) ; Mazatán , 900 m , 17/ April/1979 , Vázquez M . V-2309 ( XALU ) ; Mazatán , 900 m , 4/September/1980 , Vázquez M . V-2314 ( XALU ) ; Mazatán , 899 m , 2/May/2004 , Walters T . et al. TW 2004-01 A & B & C & D ( MEXU , SERO ) ; Rosario , 12/December/1959 , Felger R . S . 3056 ( MEXU ) ; Rosario , 14/October/1960 , Felger R . S . 4090 ( MEXU ) ; Rosario , 8/January/1978 , Warren P . & Gibson T . C . s.n. ( MEXU ) ; Soyopa , 1800 m , 31/May/2000 , Vovides A . P . 1382 ( MEXU ) .