The Chihuahuan Desert Region has been

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1 DAVID BRAILOVSKY SIGNORET & HÉCTOR M. HERNÁNDEZ Mazapil, Zacatecas: diversity and conservation of cacti in a poorly known arid region in northern Mexico The Chihuahuan Desert Region has been the focus of numerous investigations regarding the diversity, degree of endemism, and conservation status of its rich assemblage of cactus species. However, most of these studies have been carried out in particular portions of this desert region, predominantly in the areas of highest diversity and endemism. An area that has remained poorly known to botanists, explorers, and amateurs is the Mazapil region in the northern portion of the Mexican state of Zacatecas, located between the Central Plateau and the Sierra Madre Oriental, in the central-west sector of the vast region of the Chihuahuan Desert. The heterogeneous topography that characterizes Mazapil results in a rich mosaic of climatic, edaphic, and vegetation features. The outstanding variety of ecological conditions in this region makes it an excellent candidate to observe marvelous examples of cactus diversity in North America. ABOVE Area elevation and sampling sites, Map by D Brailovsky BELOW Mazapil Church, Historical and environmental setting Traveling through this amazing region is, in a certain BELOW Study Area (Map by D Brailovsky) 2010 VOLUME 82 NUMBER 4 197

2 ABOVE ABOVE BELOW Mineral de Aranzazú, Camino Real panorama, Photo: A Ibarra way, is similar to coming back through a window into historical Mexico. Examples of places of historical relevance include the handsome and mysterious remains of the Mineral de Aranzazú, a ghost town reminiscent of the ancient Mexican haciendas and forgotten mining facilities. Another, relevant historical feature is the Camino Real that goes from Concepción del Oro to Mazapil; this is just a small branch of the great Camino Real de Tierra Adentro, also known as Silver Road or Road to Santa Fé, built in the XVI century by the Spanish conquerors along 2900 km to develop commerce, facilitate transportation of the wealth extracted from the mines, as well as to support militarization, colonization, and evangelization in northern New Spain. This wonderful track, made up of local materials and surrounded by juniper-pinion forests and arborescent cactus scrub, has some of the best views of the ranges and valleys below, and brings a wide panorama of the magnificent desert environments. Although there is a dominance of arid and semiarid vegetation assemblages in the area, more temperate and partially sub-humid climates occur on the ranges and elevated areas up to 3100 m altitude, which allow development of open pinion-juniper woodlands. 198 Camino Real view, Photo: A Ibarra People from the Mazapil region still keep traditional uses of several desert plants. Two interesting examples are the sotol (Dasylirion spp., Nolinaceae), used for the rustic preparation of an alcoholic beverage similar to the famous tequila, as well as the extraction of ixtle fibers from Agave lechuguilla. Another fascinating case of a useful succulent plant is the candelilla (Euphorbia antisyphilitica), which is employed to obtain a wax-like oleic substance with numerous industrial applications. We should not forget the case of the guayule rubber (Partenium incanum), another plant species with a remarkable history. During the difficult years of WWII, many tons of biomass of this species were removed from the ranges of Mazapil and elsewhere in northern Mexico and Texas Big Bend to produce a hypoallergenic rubber. Massive amounts of this rubber were exported to the United States of America in order to supplant the shortage of this indispensable material due to the suspension of rubber exports from Asia during war time. Remains of an old guayule rubber extraction factory can be seen in Hacienda de Cedros, near Mazapil. BELOW Rattlesnake in the scrub, The study In order to assess the cactus diversity of the Mazapil region, a quarter degree geographical square (30 latitude x 30 longitude) was established between and N, and between and W, this being located in the northern region of the State of Zacatecas CACTUS AND SUCCULENT JOURNAL

3 ABOVE LEFT On expedition Photos: D Brailovsky ABOVE RIGHT Chihuahuan Desert panorama, northeast of San Jeronimo, and a south eastern portion of Coahuila. The overall cactus diversity of the area was evaluated with the idea of increasing the current biogeographic knowledge of the cactus family within the region and to visualize the general spatial pattern displayed by the species. The geographical grid square was further divided into 25 (6 x 6 ) subsquares in each of which we sampled the cactus diversity along two separate, 3-km-long transects. Specimens or fragments of specimens, as well as seeds, flowers, and fruits were collected whenever it was possible. Cactus diversity and endemism A total of 45 species were registered in the area (see list below), including one hybrid (Opuntia carstenii) described by Puente and Hamann (2005). Of these, 23 species were reported as new records for the study area (51.11% of the overall species richness); in addition, seven were new records for Zacatecas (15.55%), and two for Coahuila (11.11%). Interestingly, a high level of endemicity was recorded as 64% of all of the species were found to be restricted to the Chihuahuan Desert region. In the slopes and ranges it is usual to find globose species such as Lophophora williamsii, Mammillaria formosa, M. heyderi, M. pottsii, Ferocactus pilosus, Echinocactus platyacanthus, E. horizonthalonius, and Opuntia stenopetala. In addition, there are species such as Opuntia rufida, O. microdasys, O. rastrera, and O. macrocentra, as well as the very frequent and somewhat weedy Cylindropuntia imbricata, C. tunicata, C. leptocaulis, and C. kleiniae that are more abundant in the lowland arid and semiarid valleys. On the other hand, there are species like Escobaria lloydii and Turbinicarpus beguinii that grow among the vegetation of juniper-pine forests in semiarid to temperate climates of the higher ranges. The Mazapil area is home of some interesting species found nowhere else in Mexico. For instance the hybrid Opuntia carstenii is a microendemic of Zacatecas and Coahuila, while Escobaria lloydii and Echinocereus palmeri subsp. mazapil, are restricted to Zacatecas. An interesting species, probably considered among the rarest and probably most endangered cactus species, is Opuntia chaffeyi. This microendemic, restricted to silty, dry lake beds, has only been found in three localities, being extremely rare 2010 VOLUME 82 NUMBER 4 BELOW Chihuahuan Desert at dusk at the northeastern plains of Zacatecas, Mazapil, Photo: H Hernández in nature as only a few individuals have been recorded. Diversity and endemism of cacti on the region are thus noticeable although somewhat lower than in areas such as El Huizache in San Luis Potosí, where a richness of 75 species is reached. In light of the present evidence, El Huizache is an extremely important area in terms BELOW Flood exposed basin at the northeastern plains of Zacatecas, 199

4 ABOVE Euphorbia antisyphilitica Zucc., Photo: H Hernández ABOVE Agave lechuguilla, Photo: H Hernández of cactus diversity and conservation as it contains the highest concentration of cactus species in the world. The distribution pattern in Mazapil was more homogeneous than what was expected regarding the large environmental heterogeneity found in this region. Threats and conservation priorities The greatest treat for the conservation of the cacti in the region is related to excessive pasturing and exploitation of the desert resources; fortunately, illegal and unscrupulous collectors appear not to be a major problem in the area. However, there are some contemporary mine developments, such as the Mina Peñasquito ore development, that might pose some threats to the diversity of life in particular areas through land use change, soil movements, and environmental pollution. In order to prioritize the different areas within the Mazapil region in terms of their conservation importance, we used a method known as complementarity analysis. This approach, which uses two variables: species richness and taxonomic composition, allowed us to rank the (6 x 6 ) sub squares according to their complementarity value. The analysis showed that all of the 45 species registered in the study can be contained in a minimum BELOW Ariocarpus kotschoubeyanus (Lem.) K Schum., 200 of 8 subsquares scattered in the studied region, which represent 32% of the total area. Richness in the priority subsquares varies from 15 to 26 species and the main subsquare (northeastern) is relatively low in altitude with several slopes and a small range called Sierra de Enfrente, toward the northwestern section. We hope that this interesting region, with its fascinating biodiversity and handsome landscapes, may be included among the future conservation efforts of our country. Acknowledgements: This work was supported by a grant from the Research Committee of the Cactus and Succulent Society of America, by the Universidad Nacional Autónoma de México and CONACYT. We are grateful to the people of Zacatecas, as well as to Norma Sánchez Santillan, Rolando Bárcenas, Carlos Gómez Hinostrosa, BELOW Echinocactus platyacanthus Link & Otto, Photo: C Gómez CACTUS AND SUCCULENT JOURNAL

5 ABOVE Ariocarpus retusus Scheidw., Bárbara Goettsch, and all the people that contributed during the field and laboratory work. BELOW Ferocactus pilosus (Galeotti ex Salm-Dyck) Werderm. at Sierra del Mascaron, in the Mier y Noriega region, Mexico. Biodiversity and Conservation 9: Goettsch B, Hernández HM Beta diversity and similarity among cactus assemblages in the Chihuahuan Desert. Journal of Arid Environments 65(4): Hernández HM, Gómez-Hinostrosa C, Bárcenas RT Diversity, spatial arrangement, and endemism of Cactaceae in the Huizache area, a hot-spot in the Chihuahuan Desert. Biodiversity and Conservation 10: Hernández HM, Gómez-Hinostrosa C, Goettsch B Checklist of Chihuahuan Desert Cactaceae. Harvard Papers in Botany 9 (1) : Hernández HM, Goettsch B, Gómez-Honostrosa C, Arita HT Cactus species turnover and diversity along a latitudinal transect in the Chihuahuan Desert region. Biodiversity and Conservation 17(4): Parfitt BD Flowering of Opuntia chaffeyi Britton & Rose. Cactus and Succulent Journal 57: Puente R, Hamann C A new Hybrid Prickly Pear from Coahuila, Mexico. Opuntia carstenii sp. nov. (Cactaceae). Cactus and Succulent Journal 77(5): David Brailovsky Signoret & Héctor M Hernández Departamento de Botánica, Instituto de Biología, National Autonomous University of Mexico, Apartado Postal , C.P , Mexico City, Mexico BELOW Opuntia xcarstenii Puente & Hamann, Photo: D Brailovsky References 1 Goettsch B, Hernández HM Beta diversity and similarity among cactus assemblages in the Chihuahuan Desert. Journal of Arid Environments 65: Gómez-Hinostrosa C, Hernández HM Diversity, geographical distribution, and conservation of Cactaceae 2010 VOLUME 82 NUMBER 4 201

6 ABOVE Coryphantha delicata L Bremer, ABOVE Lophophora williamsii (Lem. Ex Salm-Dyck) JM Coult., CACTUS SPECIES IN THE MAZAPIL REGION Ariocarpus kotschoubeyanus (Lem.) K Schum. A. retusus Scheidw. Coryphantha compacta (Engelm.) Britton & Rose C. delicata L Bremer C. macromeris (Engelm.) Lem. C. poselgeriana (A Dietr.) Britton & Rose Cylindropuntia imbricata (Haw.) FM Knuth C. kleiniae (D.C.) FM Knuth C. leptocaulis (D.C.) FM Knuth C. tunicata (Lehm.) FM Knuth Cylindropuntia sp. (possible hybrid) Echinocactus horizonthalonius Lem. E. platyacanthus Link & Otto Echinocereus enneacanthus Engelm. E. palmeri Britton & Rose subsp. mazapil HM Hern. & C Gómez-Hinost. Echinocereus parkeri NP Taylor subsp. mazapilensis Blum & Lange E. pectinatus (Scheidw.) Engelm. E. stramineus (Engelm.) F Seitz Echinomastus unguispinus (Engelmann) Britton & Rose Escobaria lloydii Britton & Rose Ferocactus hamatacanthus (Muehlenpf.) Britton & Rose F. pilosus (Galeotti ex Salm-Dyck) Werderm. Grusonia moelleri (A Berger) EF Anderson Leuchtenbergia principis Hook. Lophophora williamsii (Lem. ex Salm-Dyck) JM Coult. Mammillaria formosa Galeotti ex Scheidw. M. heyderi Muehlenpf. M. lasiacantha Engelm. M. pottsii Scheer ex Salm-Dyck Neolloydia conoidea (DC.) Britton & Rose Opuntia engelmannii Salm-Dyck O. leucotricha DC. O. macrocentra Engelm. O. microdasys (Lehm.) Pfeiffer O. phaeacantha Engelm. O. rastrera FAC Weber O. rufida Engelm. O. stenopetala Engelm. O. carstenii Puente & Hamann Peniocereus greggii (Engelm.) Britton & Rose Sclerocactus uncinatus (Galeotti) NP Taylor Stenocactus multicostatus (Hildm. ex K Schum.) A Berger ex AW Hills Thelocactus bicolor (Galeotti ex Pfeiff.) Britton & Rose T. hexaedrophorus (Lem.) Britton & Rose Turbinicarpus beguinii (NP Taylor) Mosco & Zanovello 202 ABOVE Mammillaria formosa Galeotti ex Scheidw., ABOVE Neolloydia conoidea (DC.) Britton & Rose BELOW Stenocactus multicostatus (Hildm. Ex Pfeiff.) Britton & Rose, Photos: A Ibarra ABOVE Thelocactus hexaedrophorus (Lem.) Br. & R. BELOW Turbinicarpus beguinii (NP Taylor) Mosco & Zanovello, Photos: D Brailovsky CACTUS AND SUCCULENT JOURNAL