Biodiversity and Conservation 13: 1101–1121, 2004. # 2004 Kluwer Academic Publishers. Printed in the Netherlands. Endemic species of grasses in Mexico: a phytogeographic approach PATRICIA DÁVILA-ARANDA1,*, RAFAEL LIRA-SAADE1 and JESÚS VALDÉS-REYNA2 1 Unidad de Biologı́a, Tecnologı́a y Prototipos, Facultad de Estudios Superiores-Iztacala, Universidad Nacional Autónoma de México, Av. De los Barrios 1, Los Reyes Iztacala, Tlalnepantla Edo. De México, CP. 54090, Mexico; 2Universidad Autónoma Agraria Antonio Narro, Saltillo, Coahuila, Mexico; *Author for correspondence (e-mail: pdavilaa@servidor.unam.mx) Received 2 September 2002; accepted in revised form 4 April 2003 Key words: Biogeography, Conservation, Endemism, Mexico, Poaceae Abstract. The Poaceae family includes approximately 700 genera and 10 000 species, and Mexico is considered one of its most important centers of diversity and endemism. A total of 256 taxa (including 16 subspecific taxonomic units), belonging to 65 genera, are endemic to Mexico. Some of them are close relatives of important crops, while others are used in different ways all over the country. The aim of this paper is to discuss the distribution patterns at state level of the Mexican endemic species of Poaceae. Using cluster strategies, the states are classified according to their floristic similarities. Later, hotspots of endemism are identified, in order to discuss their role in conservation strategies. To evaluate the importance of each state in the conservation of the Mexican endemic Poaceae, two iterative complementarity methods were also used. Our results show that the largest concentration of endemic taxa occurs in a few states, such as Jalisco, Mexico, Michoacán, Durango, Oaxaca, Veracruz, San Luis Potosi, Chiapas, Chihuahua, Puebla, and Coahuila. The results also show that there are some patterns in the relationship to its endemism that seem to reflect important diversification trends in the family. Accordingly, 31% of the grass genera of Mexico have at least one endemic species, and 16.7% of the genera have only one endemic species. In contrast, six genera contribute 47.2% of the total number of grass endemics in Mexico. The Chloridoideae contributes 42.9% of the total grass endemic species of Mexico, whereas the Panicoideae includes 24.6%, and the Pooideae 19.8%. Thus, these three subfamilies contribute about 87% of the species endemism. On the basis of the habitat and distribution patterns of these subfamilies, two main areas of endemicity can be identified. The first area is located in warm habitats, whereas the second is related to temperate and high regions. The cluster analyses indicate the occurrence of four state groups whose phytogeographical explanation is discussed on the basis of a floristic regionalization of Mexico. The results also indicate the need to establish a relatively high number of sites and states for the conservation of 256 endemic taxa. The elevated number of sites required to conserve the Mexican endemic Poaceae is mainly due to the fact that many taxa have a restricted distribution pattern. On the basis of the patterns obtained, a few proposals are presented for undertaking the establishment of conservation priorities of these taxa. Introduction The widespread Poaceae family includes approximately 700 genera and 10 000 species (Clayton and Renvoize 1983), and Mexico is one of its most important centers of diversity. According to recent taxonomic and floristic studies, 1000 species (940 wild and 60 cultivated) thrive in the Mexican territory (Valdés and Dávila 1995). 1102 Over time many Poaceae species have had important biological, cultural, and economic roles. Several species are among the plants that were first domesticated by humans, and presently form part of the staple crops at world level. Some Mexican and Latin American wild species have been identified as close relatives of some of those crops, and others are employed in different ways by local people (Mejı́a-Saules and Dávila 1992). On the other hand, many grass species are catalogued among the most aggressive existent weeds. A recently published catalogue of Mexican weeds includes a total of 283 grass species (Villaseñor and Espinosa 1998). Traditionally, species richness and levels of endemism have been considered among the leading criteria for defining conservation strategies. Unfortunately, in the case of the Poaceae these criteria rarely have been applied. Thus, although 65 genera and more than 200 out of the 940 Mexican wild species are endemic to the country, and 60 of them are currently being used by rural people, they have not been included in the inventories of Mexican endangered and/or threatened species. Since determination of the geographical distribution patterns of organisms is an essential requirement to propose strategies for their conservation, the aim of this paper is to perform an analysis of the Mexican endemic Poaceae distribution at the state level. With this information, we identify those states showing the highest endemism rates, and discuss which states should have priority in implementing conservation actions. The adoption of the state level for the analysis is based on the fact that countries such as Mexico generally undertake conservation decisions considering political, rather than natural boundaries. Methods Floristic and taxonomic bibliographic information, as well as a preliminary phytogeographical study of Mexican grasses (Delgadillo et al. 2003) and the database of the first author are the main sources of information used in this work. The classification followed in this work is according to Judziewickz et al. (2000), Peterson et al. (2001) and the MO-w3 TROPICOS Database – New World Grasses (http://mobot.mobot.org/W3T/). In protected areas selection, hotspots are usually defined as areas of peak value in terms of criteria such as species richness, endemism or rarity (Turpie et al. 2000). Thus, we examined the patterns of endemism richness in the 32 Mexican states (Figure 1), in order to evaluate whether any state hotspot could be identified for the Mexican wild endemic genera and species in the Poaceae family. A sound design of protected areas should take into consideration biogeographic zonation (Turpie et al. 2000). Accordingly, a Mexican state zonation using cluster analysis was produced. The analysis was performed by using the full distribution data set of the Mexican endemic Poaceae. In order to identify hierarchical floristic similarities among the 32 states, the Jaccard index of similarity, and the UPGMA clustering method were used. The analysis was performed on a personal computer using the statistical package NTSYS-PC (version 2.0), developed by Rohlf (1997). 1103 Figure 1. The 32 Mexican states. AGS ¼ Aguascalientes, BC ¼ Baja California, BCS ¼ Baja California Sur, CAMP ¼ Campeche, CHIS ¼ Chiapas, CHIH ¼ Chihuahua, COA ¼ Coahuila, COL ¼ Colima, DF ¼ Distrito Federal, DUR ¼ Durango, GTO ¼ Guanajuato, GRO ¼ Guerrero, HGO ¼ Hidalgo, JAL ¼ Jalisco, MEX ¼ México, MICH ¼ Michoacán, MOR ¼ Morelos, NAY ¼ Nayarit, NL ¼ Nuevo León, OAX ¼ Oaxaca, PUE ¼ Puebla, QR ¼ Quinatana Roo, QRO ¼ Querétaro, SLP ¼ San Luis Potosı́, SIN ¼ Sinaloa, SON ¼ Sonora, TAB ¼ Tabasco, TAMP ¼ Tamaulipas, TLA ¼Tlaxcala, VER ¼Veracruz, YUC ¼ Yucatán, ZAC ¼ Zacatecas. In order to evaluate the importance of each state in the conservation of the Mexican endemic Poaceae, two iterative complementarity methods were used. Complementarity analysis is an iterative selection technique that identifies how a target set of species can be conserved at the minimum number of sites (Pressey et al. 1993). The first method used was that proposed by Vane-Wright et al. (1991) and the second by Rebelo (1994). Both methods were recently employed in a similar study for the Mexican Asteraceae (Villaseñor et al. 1998) and Cucurbitaceae (Lira et al. 2002). The first method (Vane-Wright et al. 1991) selects areas to be protected on the basis of the total taxa richness. In this case the following procedures were followed: (1) the state with the greatest number of taxa was selected, and the taxa scored in such a state were dropped from the analysis; (2) the procedure was repeated with the remaining taxa (complement) that had not yet been selected in the former procedure; (3) when in further iterations two or more states had the same complement, the state selected was that with the highest total number of taxa. If two or 1104 more states were still tied, the first state identified was selected; (4) the procedure finished when all taxa had been selected. The second method (Rebelo 1994) attempts to optimize a reserve system by selecting the areas according to an endemicity score (ES). The ES is the sum of the rarity values of all the attributes (in this study the Mexican endemic Poaceae taxa) present in each unit or state. The rarity value of a particular taxon was calculated by dividing, in each iteration, the total number of states by the number of states where a particular taxon occurs. The following procedures were performed in sequence: (1) the rarity value of each taxon and the ES of each state was determined; (2) the state with the highest ES was selected, and the taxa already scored in the selected state were dropped from the analysis; (3) the procedure was repeated with only those taxa that had not yet been selected (complement), occurring in the nondropped states; (4) the procedure was replicated until all taxa were included at least once in the selected states with higher ES. Following Villaseñor et al. (1998), when the procedure yielded a tie, the state selection preference was done on the basis of those states with the highest number of endemic taxa. When no endemic taxa were present, the state with the highest number of taxa was selected. Each state suggested by these methods as important for conservation, and the cumulative numbers of total and endemic taxa were provided. In addition, the protection frequency (occurrence frequencies) for each taxa was calculated, under the assumption that at least one population of a taxon would be protected as many times as it occurred in each selected state. Results and discussion Diversity and general distribution patterns A total of 256 taxa (including 16 subspecific taxonomic units), belonging to 65 genera, were recorded as endemics (Appendix 1). The species figure represents the 25.6% of all the family’s diversity in the country, which is lower than the national level of endemism (56%) (Rzedowski 1978, 1991) or that of several other families well represented in the country, such as Asteraceae (65.7%) (Villaseñor 1990; Villaseñor et al. 1998), Cucurbitaceae (49.6%) (Lira et al. 2002), Leguminosae (51.8%) (Sousa and Delgado 1993), Lamiaceae (77%) (Ramamoorthy and Elliott 1998), or Acanthaceae (50%) (Daniel 1998). However, considering the cosmopolitan character and reproduction behavior of the family, the endemism rate can be considered high. Most of the endemic species of Poaceae distribute over almost all of its territory (excluding the state of Tabasco, where no endemic species have been recorded). However, the largest concentration of them occurs in several states (Table 1), such as Jalisco (74 species), Mexico (61), Michoacán (49), Durango (46), Oaxaca (44), Veracruz (42), San Luis Potosi (39), Chiapas (37), Chihuahua (36), Puebla (36), and Coahuila (35). Besides their endemism richness, some of these states stand among the floristically richest in the country (Table 2). For example, the states of Veracruz 1105 Table 1. Endemism level of the Poaceae family in the 32 Mexican states. State Total/endemic species % Endemism Jalisco México Michoacán Durango Oaxaca Veracruz San Luis Potosı́ Chiapas Puebla Chihuahua Coahuila Guanajuato Nuevo León Nayarit Guerrero Hidalgo Tamaulipas Distrito Federal Morelos Zacatecas Sinaloa Sonora Colima Aguascalientes Querétaro Baja California Sur Tlaxcala Yucatán Baja California Campeche Quintana Roo Tabasco 417/74 305/61 338/49 336/46 445/44 457/42 240/39 444/37 378/36 337/36 308/35 157/30 203/30 241/28 208/25 221/25 208/23 177/22 218/19 273/19 170/19 217/18 152/18 178/17 156/15 128/11 96/7 97/6 197/4 149/4 92/1 153/0 17.7 20.0 14.5 13.7 9.8 9.1 16.3 8.3 9.5 10.7 11.4 19.1 14.8 11.6 12.0 11.3 11.0 12.4 8.7 6.9 11.1 8.3 11.8 9.5 9.6 8.6 7.3 6.2 2.0 2.7 1.0 0.0 Table 2. The floristically richest Mexican states, ranked by the total number of species and endemic taxa (between parentheses) of Poaceae and the other four most important families they contain (ASTER ¼ Asteraceae, FABAC ¼ Fabaceae s. l., ORCHI ¼ Orchidaceae, CUCUR ¼ Cucurbitaceae). State ASTER FABAC POACE ORCHI CUCUR Oaxaca Chiapas Jalisco Michoacán Veracruz Puebla 1(2) 5(9) 2(1) 3(3) 4(6) 8(5) 1(1) 2(6) 4(2) 5(3) 3(5) 9(7) 2(5) 1(8) 4(1) 6(5) 1(6) 5(9) 2(1) 1(2) 5(5) 6(6) 3(4) 7(7) 1(2) 2(11) 3(1) 4(3) 5(9) 8(5) 1106 Table 3. Species frequencies of Mexican Cucurbitaceae, grouped on arithmetic scale units (x2 scale or log2) according to state occurrences. Number of states Endemic species 1 2–4 5–9 10 102 93 49 12 and Oaxaca occupy the first and second place, respectively in relation to its endemism richness of Poaceae. In addition, they also rank within the first places for its floristic richness in Asteraceae, Cucurbitaceae, and Fabaceae (Villaseñor 1990; Rzedowski 1991; Lira et al. 2002; Villaseñor, personal communication). The geographic distribution of Mexican endemic Poaceae allowed us to recognize relatively well defined patterns. Table 3 shows the number of state occurrences for each endemic species of Poaceae, based on a log2 scale (Octave scale of Preston 1948). Thus, we considered four sets of species, on the basis of their distribution patterns: (1) scarcely distributed (those species found only in one state); (2) narrowly distributed (in 2–4 states); (3) normally distributed (in 5–9 states); (4) widely distributed (recorded for 10 or more states). Most of the members of the first group, such as Festuca hintoniana, are only known from one or a few localities, while others are only known from just the type collection, for example Schaffnerella gracilis. On the largest part of the scale are found species that might be considered the widespread taxa. Interestingly, most of the so-called widespread endemic species belong to the Chloridoideae and Panicoideae subfamilies occurring in the country. In the Chloridoideae, the most widespread endemic species are: Bouteloua scorpioides, Hilaria ciliata and Muhlenbergia puebescens, among others. Within the Panicoideae the most widespread species are: Pennisetum crinitum, Panicum decolorans and Urochloa meziana, among others. Several of these grasses correspond to weedy or ruderal species that can inhabit disturbed habitats or edges of modified plant communities, such as pine–oak forests or tropical deciduous forests. Urochloa meziana seems to be the endemic species most widely distributed (19 states), and in some regions it is considered a weed that can hardly be eradicated. Despite the cosmopolitan character of the Poaceae, our results show that grass endemism reflects important diversification trends in some genera of the family. Accordingly, the data of this work shows that 31% of the grass genera of Mexico have at least one endemic species. In addition, 16.7% of the genera have only one endemic species, whereas another six genera contribute 47.2% to the total Poaceae endemism in Mexico. These genera are: 1. Muhlenbergia (47); 2. Bouteloua (23); 3. Paspalum (16); 4. Festuca (15); 5. Sporobolus (10); 6. Aristida (10). At the subfamily level, some general endemism patterns can be observed. The Chloridoideae contributes 42.9% of the total grass endemic species of Mexico, 1107 Figure 2. Floristic similarities among 31 Mexican states based on Mexican Poaceae endemic species. Similarity coefficient used: Jaccard; clustering method: UPGMA. whereas the Panicoideae includes 24.6% and the Pooideae 19.8%. Accordingly, with these three subfamilies about 87% of the species endemism for the whole family is explained. On the basis of the habitat and distribution patterns of these subfamilies, it seems that two areas of endemism can be observed. The first one reflects an endemicity region located in warm habitats, which can be dry (in Chloridoideae) or humid (in Panicoideae). On the other hand, the second endemicity area is related to temperate and high regions such as the mountains of the country (Pooideae). State regionalization The results of the cluster analyses indicate the occurrence of several state groupings (Figures 2 and 3), which show some relationship with the hierarchical arrangement obtained when using the crude data (Table 1). Thus, the dendrogram in Figure 2 distinguishes four main groups, which are described in the following paragraphs. Group 1. This group includes most of the Mexican states (20). Three main subgroups can be distinguished. The first subgroup (1A) includes nine states from northern-central and central Mexico. Most of these states (Aguascalientes, San Luis Potosı́, Durango, Zacatecas, etc.) are part of the so-called Mexican High Plateau Province proposed by Rzedowski (1978), where arid and semi-arid zones are very 1108 Figure 3. Distribution of the groups derived from the cluster analysis. 1109 Figure 4. Floristic regionalization of Mexico, according to Rzedowski (1978). well represented. The second subgroup (1B) includes states from southern and southeastern Mexico (Oaxaca, Chiapas, Veracruz, and Puebla). Finally, the third subgroup (1C) is formed by states from central and western Mexico (Distrito Federal, México, Michoacán, Jalisco, Guerrero, and Morelos). The state of Colima is also joined to group 1, although at a relatively low similarity value. Some of the species represented in group 1 are Agrostis rosei, A. bourgaei, Andropogon pringlei, Blepharoneuron shepherdii, Chaboissaea ligulata, and Olmeca reflexa. Group 2. This group includes three states from northeastern Mexico that are geographically very close together (Coahuila, Nuevo León, and Tamaulipas). Some of the species that are exclusive to this group are Brachypodium pringlei, Bromus densus, Festuca pinetorum, F. valdesii, Piptochaetium angustifolium, and Achnatherum editorum. Group 3. This group includes five states from northwestern Mexico (Baja California, Baja California Sur, Sonora, Nayarit, and Sinaloa). Some representative species of this group are Bouteloua annua, B. reflexa, and Distichlis palmeri. Group 4. This group is placed in the lower part of the dendrogram, and it is joined at a relatively low similarity value to the remaining groups. It is formed by three states of the Yucatan Peninsula (Campeche, Yucatán, and Qintana Roo) in southeastern Mexico. The most representative species of this group are Gounia papillosa, Paspalum sparsum, P. mayanum, and Schizachyrium gaumeri. 1110 Table 4. Hierarchical arrangement of Mexican states according to the results obtained with the iterative methods of Vane-Wright et al. (1991) and Rebelo (1994). The numbers in parentheses correspond to the accumulated taxa in each iteration. State Vane-Wright et al.’s method State Rebelo’s method Jalisco México Coahuila Veracruz Durango Chiapas Oaxaca Chihuahua Baja California Sur Colima Nayarit Nuevo León San Luis Potosı́ Michoacán Baja California Guerrero Tamaulipas Yucatán Puebla Aguascalientes Sinaloa Sonora Zacatécas 74 34 30 19 15 12 10 8 8 6 6 6 6 4 3 3 3 3 2 1 1 1 1 Jalisco Coahuila México Veracruz Chihuahua Chiapas Oaxaca Durango Colima Nayarit Baja California Sur Nuevo León San Luis Potosı́ Michoacán Guerrero Tamaulipas Baja California Yucatán Aguascalientes Sinaloa Sonora Zacatecas Puebla 74 32 32 19 14 11 10 10 6 7 7 6 6 4 3 3 3 3 1 1 1 1 2 (74) (108) (138) (157) (172) (184) (194) (202) (210) (216) (222) (228) (234) (238) (241) (244) (247) (250) (252) (253) (254) (255) (256) (74) (106) (138) (157) (171) (182) (192) (202) (208) (215) (222) (228) (234) (238) (241) (244) (247) (250) (251) (252) (253) (254) (256) Floristic regionalization The groups obtained by the cluster analysis (Figure 2) can be broadly explained, from the biogeographical point of view, when the floristic regionalization proposed by Rzedowski (1978) is used (Figure 4). Group 1 includes different phytogeographical kingdoms, regions and provinces that are arranged in a complex topographic, climatic and floristic mosaic. Indeed, it represents the well known complexity of the country, in relation to its geological and biological history. Subgroup 1A basically belongs to the Mexican High Plateau Province of the Xerophytic Region, in the Neotropical Kingdom. With respect to subgroups 1B and 1C, they are located in two different floristic kingdoms (Holartic and Neotropical) and consequently, various regions and provinces are involved. Group 2 belongs to two different floristic provinces (Mexican High Plateau and Northeastern Coast Plateau) that are part of the Mexican Xerophytic Region of the Neotropical Kingdom. In contrast, Group 3 is located in both the Mexican Xerophytic and Caribbean Region of the Neotropical Kingdom. Finally, Group 4 belongs to the Yucatan Peninsula Floristic Province in the Caribbean Region of the Neotropical Kingdom. 1111 Accordingly, although the biogeographical explanation of the Mexican grass endemism is complex, it is possible to observe that, except for subgroup 1C, the remaining groups have a strong biogeographical affinity to the Mexican Xerophytic Region. In addition, there is also an important biogeographical affinity to the Caribbean Region (subgroups 1B and 1C, Groups 3 and 4). Finally, a lower affinity to the Mesoamerican Montane Region (only subgroups 1B and 1C) is also observed. Complementarity analyses The results obtained from the two complementarity analyses were strongly consistent (Table 4). Thus, in both cases the same 24 states were required to establish an adequate conservation strategy that can enable the protection of the Mexican endemic Poaceae. The only difference observed is the hierarchical arrangement of some states. These results are also strongly correlated with the general distribution patterns of endemism shown in Tables 1 and 2. They suggest that for this family, at least at the state level, there is an important correlation between total plant diversity and endemism rates. Similar results have been recorded in the country for other plant groups, such as genera of Asteraceae (Villaseñor et al. 1998) and wild Cucurbitaceae (Lira et al. 2002). Conclusions The results obtained from the three methods used are strongly consistent, although the most useful seem to be the iterative ones. Most of the results can be broadly explained by floristic arguments. However, the fact that the state assemblages are not biologically based, limits a clear understanding of their biogeographical affinities. The results also indicate the need to establish a relatively high number of sites and states (24) for the conservation of 256 taxa. However, if the raw data or the biogeographic regions were used directly, the number of taxa will be still higher. The elevated number of sites required to conserve the Mexican endemic species of Poaceae is mainly due to the fact that 102 taxa out of 256 have a restricted distribution pattern (Table 3). Accordingly, an optimal reserve system for this plant group can only be obtained by the establishment of conservation priorities for various taxa or plant groups. A first possibility, for undertaking a feasible conservation strategy for the endemic grasses of Mexico, will be by combining our results with those similarly obtained for other plant or animal groups. However, this kind of information is still scarce. With respect to plants, useful data can be obtained from Villaseñor et al. (1998) on the Asteraceae and Lira et al. (2002) on the Cucurbitaceae, but as far as we know, not many other useful data are available. A second possibility for undertaking a conservation strategy of these endemic species can be targeted by using the combination of those results obtained by iterative methods with those obtained from the cluster analysis. For instance, the cluster analysis results of this work highlight the importance of western and northwestern 1112 Mexico (states of Jalisco, Sinaloa, Sonora, and Baja California). Consequently, it seems feasible to propose a reserve system mostly focused to protect those species inhabiting the tropical deciduous forest, thorn forest or xerophytic shrublands of western and northwestern Mexico (Xerophytic Region). On the other hand, conservation strategies in the southern and eastern portion of the country (states of Chiapas, Oaxaca, Puebla, Querétaro, and Veracruz) mostly should focus on the protection of those species inhabiting the tropical forests, including both the rain (Caribbean Region) and cloud forests (Mesoamerican Montane Region). An additional difficulty for establishing conservation priorities in the Poaceae is the lack of biological and ecological information on most of the endemic species, including data on their population status and complete knowledge of their distribution patterns. On the other hand, a conservation proposal that might include several endemic species of Poaceae can be strongly criticized, due to the fact that several species are considered weeds, at least locally. However, it is important to know that at least 60 of them are currently used in the rural areas of Mexico and their abundance could probably be related to traditional management strategies. It is worthwhile to remember that many of these species have been recognized as close relatives of economically important cultivars, and undoubtedly represent potential genetic resources for their further genetic improvement. Finally, at least the geographically restricted endemic species and those shared with the southern region of the United States and northern Central America should be analyzed in a biological study by which relevant conservation data will surely be obtained. Acknowledgements We wish to thank the National commission for the knowledge and use of biodiversity from Mexico (CONABIO) for the financial support to undertake the research leading to this article (project CONABIO U031). In addition, we are also grateful to Dr. José Luis Villaseñor (Instituto de Biologı́a, UNAM) for sharing some grass diversity state data that helped us to perform part of the analysis used in this paper. Figure 4 was done by Adriana Espinosa and Miguel Pérez, from the Coordinación de Recursos de Apoyo a la Práctica Académica of FES-Iztacala, UNAM. Appendix List of the Mexican endemic taxa of Poaceae and their distribution in the Mexican states. See Figure 1 for the acronyms of the state names. Achnatherum acutum (Swallen) Valdés-Reyna & Barkworth: COA. A. altum (Swallen) Hoge & Barkworth: COA. A. bracteatum (Swallen) Valdés-Reyna & Barkworth: BC. A. constrictum (Hitchc.) Valdés-Reyna & Barkworth: HGO, MEX, NL, OAX, TAMP, VER. 1113 A. editorum (E. Fourn.) Valdés-Reyna & Barkworth: COA, NL, TAMP, VER. A. hirticulme (S.L. Hatch, Valdés-Reyna & Morden) Valdés-Reyna & Barkworth: COA, NL. A. multinode (Scribn. ex Beal) Valdés-Reyna & Barkworth: CHIH, COA, NL, PUE. Aegopogon solisii G.A. Levin: COL. Agrostis bourgeaei E. Fourn.: DF, GTO, HGO, MEX, MICH, TLA. A. calderoniae Acosta: MEX. A. ghiesbreghtii E. Fourn.: CHIS, GRO, HGO, MOR, OAX, PUE, VER. A. liebmannii (E. Fourn.) Hitchc.: DUR, MEX, OAX, PUE, QRO. A. novogaliciana McVaugh: JAL. A. rosei Scribn. & Merr.: DUR, ZAC. A. schaffneri E. Fourn.: CHIS, DF, MEX, MICH, MOR, OAX, PUE, QRO, TLA. Andropogon liebmannii Hack.: JAL, MEX, MICH, NAY, OAX, PUE, VER. A. pringlei Scribn. & Merr.: CHIS, DF, JAL, MEX, MICH, OAX, PUE, VER. A. spadiceus Swallen: COA. Anthaenantia villaregalis (McVaugh & R. Guzmán) Espejo & López-Ferrari: JAL. Aristida appressa Vasey: CAMP, CHIS, DF, DUR, GTO, JAL, MEX, MICH, MOR, OAX, PUE, YUC. A. curvifolia E. Fourn.: CHIS, COA, DUR, NL, PUE, SLP, ZAC. A. eludens Allred & Valdés-Reyna: CHIH, COA, DUR, GTO, NL, OAX, QRO, SLP. A. gypsophila Beetle: CHIH, COA, SLP. A. hitchcockiana Henrard: GTO, JAL, NAY, OAX, PUE, QRO, ZAC. A. jaliscana R. Guzmán & V. Jaram.: GTO, JAL. A. petersonii Allred & Valdés-Reyna: OAX. A. scribneriana Hitchc.: AGS, DUR, GTO, GRO, JAL, MICH. A. tenuifolia Hitchc.: COL. A. tuitensis Sánchez-Ken & Dávila : JAL. Aulonemia fulgor Soderstr.: OAX, VER. Axonopus arsenei Swallen: COL, DF, MEX, MICH. A. deludens Chase : JAL, NAY. A. multipes Swallen: VER. A. poiophyllus Chase: CHIS, VER. A. rosei (Scribn. & Merr.) Chase: NAY. Bealia mexicana Scribn. ex Beal: CHIH, DUR. Blepharoneuron shepherdii (Vasey) P.M. Peterson & Annable: CHIH, DUR, SON. 1114 Bothriochloa hirtifolia (J. Presl) Henrard: CHIS, DF, GTO, GRO, JAL, MEX, MICH, MOR, OAX, PUE, VER. B. saccharoides (Sw.) Rydb. ssp. reevesii (Gould) Allred & Gould: COA. Bouteloua annua Swallen: BCS, SON. B. barbata Lag. var. sonorae (Griffiths) Gould: BCS, SIN, SON. B. bracteata (McVaugh) Columbus: MICH. B. chasei Swallen: COA, NL, SLP, ZAC. B. chihuahuana (M.C. Johnst.) Columbus: CHIH. B. curtipendula (Michx.) Torr. var. tenuis Gould & Kapadia: JAL, ZAC. B. distans Swallen: OAX. B. elata Reeder & C. Reeder: CHIS, COL, GRO, JAL, NAY, OAX. B. eriostachya (Swallen) Reeder: COA. B. johnstonii Swallen: COA. B. karwinskii (E. Fourn.) Griffiths: COA, NL, SLP, TAMP, ZAC. B. multifidum (Griffiths) Columbus: GRO, MEX, OAX, TAMP. B. nervata Swallen: HGO, MEX. B. parryi (E. Fourn.) Griffiths var. gentryi (Gould) Gould: SIN. B. pedicellata Swallen: HGO, PUE, TLA. B. polymorpha (E. Fourn.) Columbus: AGS, COL, DUR, GTO, GRO, HGO, NAY, PUE, SLP, SON, TLA. B. purpurea Gould & Kapadia: DF, GTO, HGO, MEX, MICH, QRO, SLP. B. quiriegoensis Beetle: SON. B. reederorum Columbus: AGS, DUR, OAX, PUE, SLP, ZAC. B. reflexa Swallen: BCS, NAY, SIN, SON. B. scorpioides Lag.: AGS, CHIH, DF, DUR, GTO, HGO, JAL, MEX, MOR, OAX, PUE, QRO, SLP, TAMP, TLA, ZAC. B. uniflora Vasey var. coahuilensis Gould & Kapadia, AGS, COA, NL, SLP, TAMP, ZAC. B. varia (Swallen) Columbus: OAX, PUE. Brachypodium pringlei Scribn. ex Beal: COA, NL, TAMP. Bromus attenuatus Swallen: HGO, NL. B. densus Swallen: COA, NL, TAMP. B. meyeri Swallen: NL. Calamagrostis erectifolia Hitchc.: COL, JAL, PUE. C. orizabae Steud.: DF, MEX, MOR, OAX, PUE, VER. C. valida Sohns: JAL, MICH, SIN. Cenchrus palmeri Vasey: BC, BCS, SIN, SON. Ctenium planifolium (J. Presl) Kunth: CHIS, OAX. 1115 C. plumosum (Hitchc.) Swallen: JAL, NAY, SIN. Chaboissaea decumbens (Swallen) Reeder & C. Reeder: CHIH. C. ligulata E. Fourn: AGS, CHIS, DF, DUR, GTO, JAL, MEX, SLP. C. subbiflora (Hitchc.) Reeder & C. Reeder: DUR. Chusquea aperta L.G. Clark: OAX. C. bilimekii E. Fourn.: MEX. C. circinata Soderstr. & C.E. Calderón: MICH, OAX. C. galeottiana Rupr. ex Munro: OAX. C. glauca L.G. Clark: VER. C. mulleri Munro: VER. C. perotensis L.G. Clark, G. Cortés & Cházaro: OAX, VER. C. repens L.G. Clark & Londoño ssp. oaxacensis: L.G. Clark & Londoño: OAX. C. repens L.G. Clark & Londoño ssp. repens: CHIS. Danthonia filifolia F.T. Hubb.: CHIS, HGO, PUE. Deschampsia liebmanniana (E. Fourn.) Hitchc.: DF, JAL, MEX, MICH, PUE, VER. Dichanthelium dichotomum (L.) Gould var. dichotomum: HGO, MEX. D. macrospermum Gould: SLP. Digitaria breedlovei R.W. Pohl & Davidse: CHIS. D. distans (Chase ex Hitchc.) Fernald: JAL. Distichlis palmeri (Vasey) Fassett: BC, SON. D. spicata (L.) Greene var. mexicana Beetle: DUR. Echinochloa jaliscana McVaugh: GTO, JAL, MEX, MICH. Elymus pringlei Scribn. & Merr.: COA, GTO, HGO, MEX, NL, PUE, QRO, SLP, TAMP. Enteropogon brandegei (Vasey ex Brandegee) Clayton: BCS. E. chlorideus (J. Presl) Clayton: CHIS, MOR, VER. Eragrostis glandulosa L.H. Harv.: GRO. E. hirta E. Fourn. var. longiramea (Swallen) Whiterspoon: TAMP. E. plumbea Scribn. ex Beal: AGS, COL, GTO, MICH, PUE, SLP, VER. E. pringlei Mattei: CHIH, DUR, JAL, MICH, ZAC. Festuca bajacaliforniana M. González & S.D. Koch: BC. F. bidenticulata E.B. Alexeev: VER. 1116 F. coahuilana M. González & S.D. Koch: COA. F. diclina Darbysh.: CHIH. F. hintoniana E.B. Alexeev: COA, NL. F. jaliscana E.B. Alexeev: COL, JAL. F. livida (Kunth) Willd ex Sprengel: CHIS. MEX, PUE, VER. F. orizabensis E.B. Alexeev: CHIS, DF, DUR, JAL, MEX, MICH, MOR, VER. F. pinetorum Swallen: COA, NL, TAMP. F. pringlei St.-Yves: CHIH, DUR, JAL. F. roblensis M. González: ZAC. F. rosei Piper: AGS, CHIS, DF, DUR, GRO, JAL, MEX, MICH, MOR, PUE, QRO, SLP, TLA, VER. F. rzedowskiana E.B. Alexeev: MEX. F. tancitaröensis M. González & S.D. Koch: MICH. F. valdesii M. González & S.D. Koch: COA, NL, TAMP. Gouldochloa curvifolia Valdés-Reyna, Morden & Hatch: TAMP. Gouinia isabelensis J.J. Ortiz: NAY. G. mexicana (Scribn.) Vasey: SLP. G. papillosa Swallen: QR, YUC. G. virgata (J. Presl.) Scribn. var. robusta J.J. Ortı́z: GRO. Hilaria annua Reeder & C. Reeder: COL. H. ciliata (Scribn.) Nash: BCS, CHIH, COL, GTO, GRO, JAL, MICH, NAY, OAX, QRO, SLP, SON, TAMP, VER. H. hintonii Sohns: GRO, MEX, MICH, MOR, QRO. H. semplei Sohns: MICH. Ixophorus unisetus (J. Presl.) Schltdl.: COL, JAL. Leersia ligularis Trin. var. ligularis: VER. Leptochloa aquatica Scribn. & Merr.: GRO, JAL, MICH, MOR, NAY, SIN. Luziola fluitans (Michx.) Terrell & H. Rob. var. oconnorii (R. Guzmán) G.C. Tucker: JAL. Metcalfia mexicana (Scribn.) Conert: CHIS, COA, HGO, MEX, NL, OAX, PUE, QRO, SLP, TAMP. Muhlenbergia aguascalientensis Y. Herrera & De La Cerda-Lemus: AGS. M. alamosae Vasey: AGS, BCS, CHIH, DF, GTO, JAL, MEX, SIN, SON. M. annua (Vasey) Swallen: CHIH, DUR. M. argentea Vasey: CHIH. 1117 M. brandegei C. Reeder: BCS. M. brevifolia Scribn. ex Beal: DUR, GTO, JAL, NAY. M. breviseta Griseb. ex E. Fourn.: GRO, JAL, MEX, MICH, NAY, VER. M. brevivaginata Swallen: JAL, NAY, ZAC. M. capillipes (M.E. Jones) P.M. Peterson & Annable: CHIH. M. cualensis Y. Herrera & P.M. Peterson: JAL. M. durangensis Y. Herrera: DUR. M. elongata Scribn.: CHIH, SON. M. eriophylla Swallen: DUR, MEX, MICH. M. flavida Vasey: CHIH, DUR, JAL, NAY, SIN, SON. M. flaviseta Scribn: CHIH, DUR. M. gigantea (E. Fourn.) Hitchc.: CHIS, GRO, HGO, JAL, MEX, MICH, OAX, PUE, SLP, SIN, VER. M. grandis Vasey: JAL, NAY, SIN, SON. M. gypsophila C. Reeder & Reeder: COA, NL, SLP. M. hintonii Swallen: MEX, VER. M. iridifolia Soderstr.: JAL. M. jaime-hintonii P.M. Peterson & Valdés-Reyna: NL. M. jaliscana Swallen: JAL. M. laxa Hitchc.: VER. M. longiglumis Vasey: AGS, DUR, JAL, ZAC. M. lucida Swallen: CHIH. M. macroura (Kunth) Hitchc.: CHIS, MICH. M. majalcensis P.M. Peterson: CHIH. M. michisensis Y. Herrera & P.M. Peterson: DUR. M. mutica (Rupr. ex E. Fourn.) Hitchc.: CHIS, VER. M. pilosa P.M. Peterson, Wipff & S.D. Jones: GRO, MEX. M. pubescens (Kunth) Hitchc.: AGS, CHIH, COL, DF, DUR, GTO, HGO, JAL, MEX, OAX, PUE, SLP, ZAC. M. pubigluma Swallen: COA, NL. M. purpusii Mez: CHIH, COA, SLP, TAMP. M. reederorum Soderstr.: DUR. M. schimtzii Hack.: CHIH, HGO, MEX, MICH. M. scoparia Vasey: CHIH, JAL, MICH, NAY, SIN, SON. M. seatonii Scribn.: DF, PUE. M. speciosa Vasey: CHIH, DUR, JAL, NAY, SIN. M. spiciformis Trin.: CHIS, HGO, MICH, OAX, QRO, VER. M. stricta (J. Presl) Kunth: COL, GTO, JAL, MEX, MICH, MOR, NAY, VER, ZAC. M. strictior Beal: CHIH, DUR, MEX, SON. M. subaristata Swallen: DUR, JAL, MEX, OAX, VER. M. villiflora Hitchc. var. villiflora: TAMP. M. virescens (Kunth) Trin.: AGS, COA, DUR, GTO, JAL, SLP, ZAC. M. virletii (E. Fourn.) Soderstr.: DUR, MEX, MICH, MOR, PUE, SLP, TLA, ZAC. 1118 M. watsoniana Hitchc.: JAL, SLP. M. xanthodas Soderstr.: CHIS. Nassella mexicana (Hitchc.) R.W. Pohl: CHIS, DF, HGO, MEX, PUE. Olmeca recta Soderstr.: VER. O. reflexa Soderstr.: CHIS, OAX, VER. P. aztecanum Zuloaga & Morrone: DF, JAL, MEX, MICH, SIN. P. crateriferum Sohns: GRO, OAX. P. decolorans Kunth: CHIH, DUR, GTO, HGO, JAL, MEX, MICH, OAX, PUE, QRO, SLP, SIN. P. longum Hitchc. & Chase: VER. P. manantlense R. Guzmán: JAL. P. multiglandulosum Sánchez-Ken & Dávila: JAL. P. tamaulipense F.R. Waller & Morden: SLP, TAMP. P. vaseyanum Scribn. ex Beal: AGS, CHIS, CHIH, DF, GTO, GRO, JAL, MEX, MICH. Paspalum arsenei Chase: JAL, MICH, NAY, PUE. P. crinitum Chase ex Hitchc.: COA, DUR, JAL, NL, PUE, SLP. P. erectum Chase: COL. P. guayanerum Beetle: NAY, SIN. P. hintonii Chase: MEX, MICH, NAY. P. leptachne Chase: NAY. P. longicuspe Nash: CHIS, GRO, JAL, MICH, MOR, NAY, OAX, SIN, VER. P. longum Chase ex I.M. Johnst.: COL. P. luxurians R. Guzmán & L. Rico: COL, JAL, MEX. P. mayanum Chase ex Swallen: CAMP, YUC. P. mutabile Chase: HGO, OAX, TAMP, SLP. P. nelsonii Chase: CHIS. P. palmeri Chase: JAL, MOR, SON. P. sparsum Chase ex Swallen: CAMP, YUC. P. tolucencis R. Guzmán: MEX. P. virletii E. Fourn.: CHIS, GTO, SLP, SON. Pennisetum crinitum (Kunth) Spreng.: AGS, CHIS, DUR, GTO, JAL, MEX, MICH, MOR, NAY, PUE, VER, ZAC. P. durum Scribn. ex Beal: CHIH, OAX. P. prolificum Chase: GRO, OAX, VER. Peyritschia koeleroides (Peyr.) E. Fourn.: MEX, MICH, OAX, PUE, VER. Piptochaetium angustifolium (Hitchc.) Valencia & Costas: COA, NL, TAMP. P. brevicalyx (E. Fourn) Ricker: DF, DUR, GTO, HGO, MEX, NL, PUE, SLP. 1119 Poa mulleri Swallen: NL. P. sharpii Swallen: VER. Reederochloa eludens Soderstr. & H.F. Decker: DUR, SLP. Rhipidocladum martinezii Davidse & R.W. Pohl : CHIS. Schaffnerella gracilis (Benth.) Nash: SLP. Schizachyrium gaumeri Nash: CAMP, CHIS, MEX, YUC. Setaria latifolia (Scribn.) R.A.W. Herrm.: DUR, JAL. S. palmeri Henrard: BCS. Setariopsis latiglumis (Vasey) Scribn.: CHIS, CHIH, MICH, MOR, PUE. Soderstromia mexicana (Scribn.) C.V. Morton: GRO. Sohnsia filifolia (E. Fourn.) Airy Shaw: QRO, SLP. Sorghastrum pohlianum Dávila, L.I. Cabrera & Lira: COL. Sporobolus airoides (Torr.) Torr subsp. regis (I.M. Johnst.) Wipff & S.D. Jones: COA. S. atrovirens (Kunth) Kunth: BCS, DUR, TAMP, YUC. S. coahuilensis Valdés-Reyna: COA. S. hintonii T.G. Hartley: MEX. S. palmeri Scribn.: COA, DUR, SLP. S. potosiensis Wipff & S.D. Jones: SLP. S. spiciformis Swallen:, CHIH, COA, NL. S. splendens Swallen: CHIS, JAL, NAY, OAX. S. trichodes Hitchc.: CHIH, GTO, GRO, JAL, MEX, MICH, MOR, VER. S. viscidus Sohns: MEX. Steinchisma cuprea (Hitchc. & Chase) W.V. Br.: DUR, GTO, MEX, MICH, PUE. Triniochloa talpensis M. González & Gómez-Sánchez: JAL. Tripsacum manisuroides de Wet & J.R. Harlan: CHIS. Trisetum curvisetum Morden & Valdés-Reyna: NL. T. filifolium Scribn. ex Beal: CHIH, COA, DUR, HGO. T. mexicanum (Swallen) S.D. Koch: JAL, MEX. T. virletii E. Fourn.: CHIS, DF, GTO, GRO, HGO, JAL, MEX, MICH, VER. 1120 Tristachya angustifolia Hitchc.: NAY. T. contrerasii R. Guzmán: JAL. T. laxa Scribn. & Merr.: DUR, NAY, SIN. T. papilosa R. Guzmán: NAY. Tuctoria fragilis (Swallen) Reeder: BCS. Urochloa discifera (E. Fourn.) Morrone & Zuloaga: AGS, DUR, GTO, JAL, MICH, OAX, SLP. U. meziana (Hitchc.) Morrone & Zuloaga: AGS, CHIH, COA, COL, DF, DUR, GTO, HGO, JAL, MEX, MICH, NL, OAX, PUE, QRO, SLP, TAMP, VER, ZAC. U. ophryodes (Chase) Morrone & Zuloaga: NL, TAMP. U. venosa (Swallen) Morrone & Zuloaga: MICH. Zea diploperennis H.H. Iltis, Doebley & R. Guzmán: JAL. Z. mays L. ssp. mexicana (Schrad.) H.H. Iltis: CHIS. Z. perennis (Hitchc.) Reeves & Mangelsd.: JAL. Zeugites capillaris (Hitchc.) Swallen: GRO, JAL, MEX, MICH, OAX, VER. Z. hackelii Swallen: JAL, SIN. Z. hintonii T.G. Hartley: MEX. Z. latifolia (Rupr. ex E. Fourn.) Hemsl., CHIS, GRO, JAL, OAX. Z. sagittata T.G. Hartley: MEX. Z. smilacifolia Scribn.: GRO, HGO, JAL, MEX, MICH, MOR. References Clayton W.D. and Renvoize S.A. 1983. Genera graminum: grasses of the world. Kew Bulletin. Additional Series XIII. Her Majesty’s Stationery Office, Royal Botanical Gardens, Kew, UK, 387 pp. Daniel T.F. 1998. Mexican Acanthaceae: diversity and distribution. In: Ramamoorthy T.P., Bye R., Lot A. and Fa J.A. (eds) Biological Diversity of Mexico, Origins and Distribution. Oxford University Press, New York, pp. 541–558. Delgadillo C., Villaseñor J.L. and Dávila P. 2003. Endemism in the Mexican flora: a comparative study in three plant groups. Annals of the Missouri Botanical Garden 90: 25–34. Judziewickz E.J., Soreng R.J., Davidse G., Peterson P.M., Filgueiras T.S. and Zuloaga F.O. 2000. Catalogue of New World grasses (Poaceae): I. Subfamilies Anomochlooideae, Bambusoideae, Ehrhaartoideae, and Pharoideae. Contributions of the U.S. National Herbarium 39: 1–128. Lira R., Villaseñor J.L. and Ortı́z E. 2002. A proposal for the conservation of the family Cucurbitaceae in Mexico. Biodiversity and Conservation 11: 1699–1720. Mejı́a-Saulés M.T. and Dávila P. 1992. Gramı́neas útiles de México. Cuadernos del Instituto de Biologı́a. 16. Instituto de Biologı́a, Universidad Nacional Autónoma de México, México. Peterson P.M., Soreng R.J., Davidse G., Filgueiras T.S., Zuloaga F.O. and Judziewicz E.J. 2001. Catalogue of New World grasses (Poaceae): II. Subfamily Chloridoideae. Contributions of the U.S. National Herbarium 41: 1–255. Pressey R.L., Humphries C.J., Margules C.R., Vane-Wright R.L. and Williams P.H. 1993. Beyond opportunism: key principles for systematic reserve selection. Trends in Ecology and Evolution 8: 124–128. 1121 Preston F.W. 1948. The commonness and rarity of species. Ecology 29: 254–283. Ramamoorthy T.P. and Elliott M. 1998. Mexican Lamiaceae: diversity, distribution, endemism, and evolution. In: Ramamoorthy T.P., Bye R., Lot A. and Fa J.A. (eds) Biological Diversity of Mexico, Origins and Distribution. Oxford University Press, New York, pp. 513–539. Rebelo A.G. 1994. Iterative selection procedures: centres of endemism and optical placement of reserves. Strelitzia 1: 231–257. Rohlf F.J. 1997. NTSYS. Numerical Taxonomy and Multivariate Analysis System. Version 2.0. Applied Biostatistics Inc., New York. Rzedowski J. 1978. Vegetación de México. Limusa, México D.F. Rzedowski J. 1991. Diversidad y orı́genes de la flora fanerogámica de México. Acta Botánica Mexicana 14: 3–21. Sousa M. and Delgado A. 1993. Mexican Leguminosae: phytogeography, endemism, and origins. In: Ramamoorthy T.P., Bye R., Lot A. and Fa J.A. (eds) Biological Diversity of Mexico, Origins and Distribution. Oxford University Press, New York, pp. 459–511. Turpie J.K., Beckley L.E. and Katua S.M. 2000. Biogeography and the selection of priority areas for conservation of South African coastal fishes. Biological Conservation 92: 59–72. Valdés J. and Dávila P. 1995. Clasificación de los géneros de gramı́neas (Poaceae) mexicanas. Acta Botánica Mexicana 33: 37–51. Vane-Wright R.I., Humphries C.J. and Williams P.H. 1991. What to protect? Systematics and the agony of choice. Biological Conservation 55: 235–254. Villaseñor J.L. 1990. The genera of Asteraceae endemic to Mexico and adjacent regions. Aliso 12: 685–692. Villaseñor J.L. and Espinosa F.J. 1998. Catálogo de Malezas de México. UNAM – Fondo de Cultura Económica, México, D.F. Villaseñor J.L., Ibarra G. and Ocaña D. 1998. Strategies for the conservation of Asteraceae in Mexico. Conservation Biology 12: 1066–1075.