Addendum to the checklist of the helminth parasites of vertebrates in Costa Rica

In this work, we present an addendum to the "Checklist of the helminth parasites of vertebrates in Costa Rica" with a parasite-host list as well as a host-parasite list. This addendum updates the available information on this group of parasites in Costa Rica, since very recently a new input has been made to describe the helminth fauna of vertebrates, particularly at the Area de Conservación de Guanacaste. In this paper, we add 33 records, representing 23 species. This raises the number of helminth species described in vertebrates from Costa Rica to 325, represented by 89 species of digeneans, 23 of monogeneans. 63 of cestodes, 13 of acanthocephalans, and 137 of nematodes. In total, 133 species of vertebrates have been studied for helminths in Costa Rica (31 species of fishes. 7 amphibians, 18 reptiles, 40 birds, and 37 mammals). Currently, 67 species (20.6 %) have been recorded as new species from Costa Rica and most of them are endemic to particular regions. The Colecci6n de Helmintos de Costa Rica, housed at the Universidad de Costa Rica (UCR), San José, is the depositary of only 23% of the species recorded so far; however this situation is changing and people recognizes.     

A checklist of helminth parasites of Elasmobranchii in Mexico

A comprehensive and updated summary of the literature and unpublished records contained in scientific collections on the helminth parasites of the elasmobranchs from Mexico is herein presented for the first time. At present, the helminth fauna associated with Elasmobranchii recorded in Mexico is composed of 132 (110 named species and 22 not assigned to species), which belong to 70 genera included in 27 families (plus 4 incertae sedis families of cestodes). These data represent 7.2% of the worldwide species richness. Platyhelminthes is the most widely represented, with 128 taxa: 94 of cestodes, 22 of monogeneans and 12 of trematodes; Nematoda and Annelida: Hirudinea are represented by only 2 taxa each. These records come from 54 localities, pertaining to 15 states; Baja California Sur (17 sampled localities) and Baja California (10), are the states with the highest species richness: 72 and 54 species, respectively. Up to now, 48 elasmobranch species have been recorded as hosts of helminths in Mexico; so, approximately 82% of sharks and 67% of rays distributed in Mexican waters lack helminthological studies. The present list provides the host, distribution (with geographical coordinates), site of infection, accession number in scientific collections, and references for the parasites. A host-parasite list is also provided.     

Checklist of the helminth parasites of vertebrates in Costa Rica

Helminth parasites of vertebrates have been studied in Costa Rica for more than 50 years. Survey work on this group of parasites is far from complete. We assembled a database with all the records of helminth parasites of wild and domestic vertebrates in Costa Rica. Information was obtained from different sources such as literature search (all published accounts) and parasite collections. Here we present a checklist with a parasite-host list as well as a host-parasite list. Up to now, 303 species have been recorded, including 81 species of digeneans, 23 monogeneans, 63 cestodes, 12 acanthocephalans, and 124 nematodes. In total, 108 species of vertebrates have been studied for helminths in Costa Rica (31 species of fishes, 7 amphibians, 14 reptiles, 20 birds, and 36 mammals). This represents only 3.8% of the vertebrate fauna of Costa Rica since about 2,855 species of vertebrates occur in the country. Interestingly, 58 species (19.1 %) were recorded as new species from Costa Rica and most of them are endemic to particular regions. Considering the valuable information that parasites provide because it is synergistic with all the information about the natural history of the hosts, helminth parasites of vertebrates in Costa Rica should be considered within any initiatives to accomplish the national inventory of biological resources. Starting with this compilation work, the Colección de Helmintos de Costa Rica (CHCR), hosted at the Facultad de Microbiología, Universidad de Costa Rica, has re-emerged and it is our hope that it will have the standards of quality to assure that it will become the national depository of helminths in the country.     

Helminth infracommunity structure of the sympatric garter snakes Thamnophis eques and Thamnophis melanogaster from the Mesa Central of Mexico

Seventy-two Mexican garter snakes (Thamnophis eques) and 126 black-bellied garter snakes (T. melanogaster) were collected from 4 localities of the Mesa Central of Mexico between July 1996 and February 1998 and examined for helminths. Both species of garter snakes occurred sympatrically in every locality except in Lake Cuitzeo. Both species of snakes shared 9 helminth species, and in general, T. melanogaster hosted a larger number of species than T. eques. In each locality, a different helminth species showed the highest levels of prevalence and abundance (Spiroxys susanae in Ciénaga de Lerma, Telorchis corti in Lago de Pátzcuaro, Proteocephalus variabilis in Lago de Cuitzeo, and Contracaecum sp. in Lago de Chapala). Helminth communities in garter snakes of the Mesa Central are depauperate and dominated by a single parasite species. In those localities where the snakes occurred in sympatry, helminth communities were, in general, more diverse and species-rich in T. melanogaster. Differences in the ecology and physiology of these species of garter snakes may explain this pattern because black-bellied garter snakes (T. melanogaster) are more aquatic than Mexican garter snakes (T. eques) and primarily eat aquatic prey, potentially exposing themselves to a larger number of helminths transmitted by predator-prey infection. The helminth infracommunities of garter snakes in the Mesa Central of Mexico show a strong Nearctic influence because most of the species infecting these hosts have been recorded in other Nearctic colubrid snakes. However, the helminth infracommunities of these garter snakes are less species-rich and less diverse than those in colubrid snakes in more temperate latitudes. The widespread ecological perturbation of sampling sites in the Mesa Central because of human activity, and geographic differences in foraging ecology of the hosts and, thus, exposure to parasites transmitted by intermediate hosts may help to explain these patterns.     

中国两栖、爬行动物更新名录

本文在2015年发表的爬行动物名录及同年《中国两栖类信息系统》发布的两栖动物名录的基础上, 通过整理新发表的分类学研究及先前名录遗漏的部分早期文献, 更新了截至2019年底中国现生本土两栖、爬行动物物种名录。2015-2019年间, 中国两栖动物新记录1科, 新描述2属, 恢复1属有效性, 新记录1属, 新描述或恢复有效种74种, 新增国家纪录18种; 另6属、8种的有效性未得到近年研究证据支持(在此视为次定同物异名而未做收录, 后同)。同期, 中国爬行动物新恢复5科, 新描述1亚科, 新描述1属, 恢复3属有效性, 新记录3属, 新描述、恢复或提升有效种43个, 新增国家纪录10种; 另有5属、4种的有效性未得到近年研究证据支持, 并移除1属、4种在我国的分布纪录。此外, 通过整理2015年前文献, 爬行动物增补3属, 提升3亚种至种级地位, 增补国家新纪录3种, 另有3属、2种的有效性未得到近年研究证据支持, 同时移除1种在我国的分布纪录。综上, 截至2019年底, 我国共记录现生本土两栖动物3目13科62属515种(蚓螈目1科1属1种, 有尾目3科14属82种, 无尾目9科47属431种), 爬行动物3目35科135属511种(鳄形目1科1属1种, 龟鳖目6科18属34种, 有鳞目蛇亚目18科73属265种、蜥蜴亚目10科43属211种)。此外, 本文还对先前名录中部分爬行动物的中文名提出了修改建议, 建议恢复部分物种的惯用中文名。2015-2019年, 新物种及新纪录已知物种数量占现两栖、爬行动物物种总数的17.1%和10.2%。近年来, 我国发表的两栖、爬行动物新物种和已知物种的新纪录数量持续增加, 分类体系也在研究中不断完善, 建议今后及时地进行阶段性总结, 同时对存在的问题提出讨论, 以推动中国两栖、爬行动物分类学研究工作的进一步开展。     

湖北星斗山国家级自然保护区两栖爬行动物资源调查

2002年6～9月对湖北星斗山国家级自然保护区的两栖、爬行动物资源进行了调查,结合文献资料,该保护区现已知有两栖、爬行动物80种,其中两栖动物38种,隶属2目9科22属;爬行动物42种,隶属2目11科31属.国家Ⅱ级重点保护野生动物大鲵Andrias davidianus、虎纹蛙Hoplobatrachus rugulosus 2种;湖北省重点保护动物35种,占湖北省重点保护两栖爬行动物的75%.被列入<中国濒危动物红皮书>的两栖、爬行动物有21种(极危物种1种,濒危物种6种,易危物种11种,依赖保护物种1种,需予关注物种2种).对两栖爬行动物的种类组成和区系进行了分析,并提出了保护措施.     

What would it take to describe the global diversity of parasites?

How many parasites are there on Earth? Here, we use helminth parasites to highlight how little is known about parasite diversity, and how insufficient our current approach will be to describe the full scope of life on Earth. Using the largest database of host–parasite associations and one of the world’s largest parasite collections, we estimate a global total of roughly 100 000–350 000 species of helminth endoparasites of vertebrates, of which 85–95% are unknown to science. The parasites of amphibians and reptiles remain the most poorly described, but the majority of undescribed species are probably parasites of birds and bony fish. Missing species are disproportionately likely to be smaller parasites of smaller hosts in undersampled countries. At current rates, it would take centuries to comprehensively sample, collect and name vertebrate helminths. While some have suggested that macroecology can work around existing data limitations, we argue that patterns described from a small, biased sample of diversity aren’t necessarily reliable, especially as host–parasite networks are increasingly altered by global change. In the spirit of moonshots like the Human Genome Project and the Global Virome Project, we consider the idea of a Global Parasite Project: a global effort to transform parasitology and inventory parasite diversity at an unprecedented pace.     

贵州大沙河自然保护区两栖爬行动物多样性研究

对贵州道真县大沙河保护区的两栖爬行动物进行了3次调查研究。共采获两栖动物2目8科15属27种（亚种）,占贵州省两栖动物总种数62种（亚种）的43．5％;爬行动物3目10科（亚科）28属34种（亚种）,占贵州省爬行动物总种数104种的32．7％。从物种组成和区系分析,本保护区的两栖动物以无尾目的蛙科为主,共12种,占保护区内总种数27种的44．4％;主要区系成分为东洋界的华中区种,共11种,占保护区总种数的40．74％;其物种的组成与中国及贵州的两栖动物区系特点一致。爬行动物以游蛇科为其主要组成部分,共有17种,占该保护区爬行动物种数的50．0％;这一特征与我国以及贵州爬行动物的组成特征是基本一致的。但是大沙河地区爬行动物组成中,蝮亚科有2属5种,居第2位,与我国以及贵州的爬行动物组成特点不同,故蝮亚科为构成该区爬行动物区系的主要特征成分之一。本文还运用G-F指数对大沙河自然保护区的两栖爬行动物进行科属间的物种多样性分析。结果表明爬行动物的科内和科间的多样性较高,属内和属间的多样性较低,G-F指数为正值;两栖动物的科内和科间的多样性较低,属内和属间的多样性较高,G—F指数为负值。     

Diversity and biogeographical relationships of the Australian cestode fauna

The Australian cestode fauna remains poorly documented with a total of 342 species recorded to date. The best-studied host groups are the elasmobranchs and the marsupials, but even in these groups, only 32 and 25% of known host species, respectively, have been examined for parasites. Overall, cestodes have been reported from only 5% of the known vertebrate species. Representatives of virtually all cestode orders and most of the cyclophyllidean families have been recorded from Australia. In spite of these deficiencies, some biogeographical patterns are discernible. In the elasmobranchs, a significant proportion of the known cestodes is endemic while other associations exist with eastern Pacific and Indo-west Pacific faunas. Also identifiable is a group of cosmopolitan species. The nematotaeniids of amphibians suggest Gondwanan affiliations, while the known proteocephalideans, parasitic in reptiles and amphibians, may represent an Asian invasion. Associations of the avian cestodes represent an unexplored but potentially rewarding avenue of biogeographical study. The cestodes of mammals include families with a Gondwanan distribution (Linstowiidae, Hymenolepididae) as well as those (Anoplocephalidae) with an apparent origin in southeast Asia. In addition, a number of genera of cyclophyllidean cestodes (Anoplotaenia, Dasyurotaenia) occurring in marsupials represent biogeographical challenges, not being accommodated within any of the known cestode families. The Australian cestode fauna therefore provides potentially outstanding opportunities for studies of the biogeographical relationships of a number of cestode groups.     

Helminths of the Virginia opossum Didelphis virginiana (Mammalia: Didelphidae) in Mexico

The goal of this study was to provide further information about helminth parasites of Virginia opossum Didelphis virginiana Kerr, 1792 from Mexico. During routine faunal investigations between 1958 and 2001, 101 opossum were necropsied. Nineteen taxa of helminths were collected, representing 13 genera from hosts in 27 localities from Mexico. There are 58 new locality records, with 6 species recorded in Mexico for the first time: Brachylaima virginiana Dickerson, 1930; Cruzia americana Mapleston, 1930; Didelphonema longispiculata (Hill, 1939); Didelphostrongylus hayesi Prestwood, 1976; Viannaia didelphis Travassos, 1914; and Viannaia viannai Travassos, 1914. This increases the number of helminth taxa previously known for this host in Mexico to 28.     

A predictable suite of helminth parasites in the long-billed dowitcher, Limnodromus scolopaceus, from the Chihuahua desert in Texas and Mexico

Eighty-eight long-billed dowitchers, Limnodromus scolopaceus, were examined for helminth parasites, 62 from Texas and 26 from Mexico. In total, 3,558 helminth parasites were obtained from this host, 2,273 from Texas birds and 1,285 from birds from Mexico. The component communities consisted of 22 species of helminths in Texas, and 19 in Mexico. Of a total of 26 helminth species recorded from the 2 localities, 15 were common to both, 7 found only in Texas, and 4 only in Mexico. Fifty-nine of 62 Texas birds and 25 of 26 birds from Mexico were infected. The most prevalent helminth for Texas was the cestode Shipleya inermis. The cestode Aploparaksis retroversa was the most abundant, accounting for 37% of the total abundance, and was second highest in prevalence. Five species of cestodes, A. retroversa, Aploparaksis diagonalis, Aploparaksis occidentalis, Aploparaksis rissae, and Shipleya inermis accounted for 79% of total abundance. In the sample from Mexico, S. inermis was also highest in prevalence, followed by the nematode Hystrichis tricolor. The cestode A. retroversa was highest in abundance at 50% of the total, and was third highest in prevalence. Mean species richness, diversity, and evenness were similar among the component communities of Texas and Mexico. A predictable suite of aploparaksid cestodes, together with the cestode S. inermis, constituted 79%, and 61%, of total abundance for the component communities of Texas and Mexico, respectively, and were present in all component communities for locality, season, and year. The cestodes, A. retroversa and S. inermis, were the dominant species in all component communities. Differences among component communities and low similarities for all other comparisons were largely caused by less predictable suites of helminth species. A checklist of helminth parasites reported for long-billed dowitchers is included.     

Morphological and molecular identification of helminths of the greater bulldog bat Noctilio leporinus (Quiroptera: Noctilionidae) from Campeche,Mexico

Surveys on parasites of bats from the Americas have been conducted, but information on helminths is still scarce, especially in the Neotropical region. In Mexico, there are species of bats that lack of a record for helminth species, such as members of the family Noctilionidae. The present study describes for the first time the helminths of Noctilio leporinus in Campeche, Mexico. In 2017, six specimens of N. leporinus were studied for helminths. The species identification of helminths was based on morphological studies and molecular analysis of fragments of the 28S rDNA. All bat specimens were infected for at least one helminth species. Three helminth taxa were identified: the trematode Pygidiopsis macrostomum, and the nematodes Tricholeiperia cf. proencai, and Heligmonellidae gen. sp. The morphological identification of P. macrostomum was confirmed by sequence analysis of 28S rDNA gene. The phylogeny of P. macrostomum grouped our sequence with other sequences of the same species collected in Brazil. The phylogenetic tree of Heligmonellidae gen. sp. indicated that the helminth belongs to clade formed by the species Odilia bainae, Nippostrongylus magnus and Nippostrongylus brasiliensis of the family Heligmonellidae. The phylogenetic analysis of the 28S sequences of T. cf. proencai did not show any similarity or close affinity with nematodes from which that gene has been sequenced to date. The findings of the present study increase the number of helminth species parasitizing bats in Mexico.     

Checklist of helminth parasites of the cane toad Bufo marinus (Anura: Bufonidae) from Mexico

Thirty-four adult cane toads Bufo marinus L. (12 males and 22 females) collected from 2 localities in Mexico (Cerro de Oro and Temascal Dams, Oaxaca) in September 2003 were examined for helminth parasites. In total, 14,749 helminths belonging to 14 taxa were collected. Included were 2 adult digeneans (Choledocystus hepaticus, Mesocoelium monas); 1 larval cestode (an unidentified pseudophyllidean); and 11 nematodes, including 3 species of larvae (Contracaecum sp., Physaloptera sp., Physocephalus sexalatus) and 8 species of adults (Aplectana itzocanensis, Cosmocerca sp., Cruzia morleyi, Ochoterenella digiticauda, Oswaldocruzia sp., Raillietnema sp., Rhabdias americanus, and Rhabdiasfuelleborni). Higher species richness was recorded in B. marinus from Cerro de Oro (12 taxa versus 9 in those from Temascal); hosts from both localities shared 7 taxa. There were 25 new locality records, and 2 taxa were registered in Mexico for the first time. To date, 112 helminth species have been recorded parasitizing B. marinus along its native and introduced range of distribution, with 40.5% of them reported from Mexico.     

Current knowledge on B chromosomes in natural populations of helminth parasites: a review

Helminths, traditionally classified into three phyla Platyhelminthes, Nemathelminthes and Acanthocephala, are a phylogenetically broadly diversified group of invertebrates, characterised by a parasitic life style. Current estimates of the helminth species diversity are at least 23-40,000 platyhelminthes, 10-26,000 nematodes and 1,200 acanthocephalans. Recent information on helminth karyotypes is fragmentary, and basic karyological data are known from approximately 1.1% of known species. Supernumerary chromosomes have been reported in selected populations of only 11 digenean flukes (Platyhelminthes), 1 thorny-headed worm (Acanthocephala) and 4 roundworms (Nematoda), which represent 3.6, 7.7 and 1.3% of the total number of species cytogenetically analysed to date within respective helminth groups. B chromosome presence was not generally associated with heteromorphic sex chromosomes as they occurred both in hermaphroditic flukes and dioecious helminths, and in species having male or female heterogametic sex chromosomes (ZW of schistosomes, XO of acanthocephalans and XY of nematodes). Numbers of B chromosomes varied from 1 to 10. Most often, Bs represented one or two of the smallest elements of the complement but they could be much bigger in some digenean flukes. B chromosomes showed a diverse morphology, including telocentric to metacentric structure. There is no detailed banding or ultrastructural study of Bs in the majority of helminth carriers. Assumptions on the possible relation between the occurrence of Bs in endoparasitic helminths and extreme environments are discussed.     

Biogeography of helminth parasites of freshwater fishes in Mexico: the search for patterns and processes

Aim To uncover and describe patterns of biogeography of helminth parasites in freshwater fishes of Mexico, and to understand processes that determine them. Three predictions about host‐specificity, faunal exchange in transitional areas, and the biogeographical ‘core’ fauna, are evaluated, all of which follow from a fundamental hypothesis: that parasites show characteristic associations with particular host clades. The parasite fauna of the southern Mexican cichlids and of the fishes of the Mesa Central are examined as case studies that reflect Neotropical and Nearctic historical influences. Location The region covered in this study includes most of Mexico, with emphasis on six biogeographical areas: the Yucatán Peninsula (area 1), the Grijalva‐Usumacinta drainage (area 2), the Papaloapan and Pánuco drainages (area 3), the Balsas drainage (area 4), the Lerma‐Santiago drainage (area 5), and the Bravo drainage (area 6). Methods A parasite data base containing all the records of helminth parasites of freshwater fishes of Mexico was filtered to extract records of adult helminth parasites in freshwater fishes from the six biogeographical areas designated in this study. Jaccard's similarity coefficients and cluster analyses (using upgma ) were used to analyse the extent of faunal similarity between the designated biogeographical areas and between host (fish) families. Taxonomic composition of parasite assemblages in different host groups was also qualitatively compared from summary data. These data were used to test the three main predictions. Results To date, 184 species of helminths (120 as adults) have been recorded from 127 freshwater fishes in Mexico (almost 33% of the total fish diversity of Mexico). Of these parasite species, 69 are digenetic flukes, 51 are nematodes, 33 are monogeneans, 25 are tapeworms, and only six are acanthocephalans. The data and analyses from the six biogeographical areas corroborate the predictions that: (1) the adult parasite fauna is largely circumscribed by higher levels of monophyletic host taxa (families, orders, etc.), and that this pattern is independent of areas; (2) areas within a certain biogeographical region, and consequently with similar fish composition (e.g. areas 1, 2 and 3) have more similar parasite faunas compared to areas with less similar fish faunal composition; and (3) ‘core’ parasite faunas persist to some extent in transitional areas with limited host‐sharing. Main conclusions Helminth biodiversity in Mexican freshwater fishes is determined by the historical and contemporary biogeography of their hosts. Host lineage specificity, mainly at the level of the host family, appears to be an important factor in the distribution of the parasites. Most fish families (Characidae, Cichlidae, Pimelodidae, Ictaluridae, Catsotomidae, Goodeidae, Atherinidae) possess their own characteristic ‘core’ helminth fauna, with limited host‐sharing in transitional areas (e.g. areas 3 and 4). A re‐evaluation of the helminth fauna of Mexican cichlids questions the hypothesis that cichlids lost parasites during the colonization of Mexico from South America. The evidence supports the idea that they acquired new parasites by host switching, possibly from marine or brackish‐water percomorphs. In contrast, the parasite fauna of the Mesa Central remains enigmatic and reflects the region's history of endemicity with historical marine and Nearctic connections.     

The helminth fauna of wild and domestic ruminants in Mongolia—a review

The helminth fauna of eight species of wild ruminants and five species of domestic ruminants sharing common grassland in Mongolia was reviewed. A total of 108 species of helminths, belonging to 40 genera, 23 families, 11 superfamilies, 6 orders and 3 classes were reported in wild and domestic ruminants in Mongolia. Several new host–helminth associations have been recorded. Twenty seven helminth species have been found in certain host species for the first time in Mongolia. These included 2 species of trematodes, 2 species of cestodes and 23 species of nematodes. Helminths that are specific for some of the examined ruminant species were determined. However, wild animals may serve as a reservoir of helminth infections for domestic animals when sharing grassland in Mongolia. The helminth fauna of the ruminants with respect to occurrence, distribution, prevalence and intensity of infection was considered for six geographic regions of Mongolia.     

Helminth parasites of the tropical gar, Atractosteus tropicus Gill, from Tabasco, Mexico

A total of 8 helminth species were recorded in an examination of 43 tropical gar, Atractosteus tropicus Gill, collected at the Pantanos de Centla Biosphere Reserve, Tabasco, Mexico. The parasite species included 1 adult trematode, 3 metacercariae, 1 cestode, 1 adult nematode, and 2 nematode larvae. Six of these 8 species were rare, with low prevalence (< 17%) and abundance (< 1.0 helminths per examined fish). The larvae of Contracaecum sp. were the most abundant in the sample, constituting 60% of the total helminths (64% prevalence, 3.8 +/- 5.2 abundance), followed by the cestode Proteocephalus singularis, constituting 18% of the worms (30.5% prevalence, 1.1 +/- 3.0 abundance). Species richness, individual parasite abundance, and diversity were low in the infracommunities. The recording of 3 specialist species in the tropical gar confirms that the helminth fauna of gar has an appreciable degree of specificity. This study indicates the importance of ecological determinants of richness in helminth communities of the tropical gar.     

Biological diversity in the Tehuacán-Cuicatlán Valley, Mexico

A general overview of the biological knowledge of the floristic province of the Tehuacán-Cuicatlán Valley in central-southern Mexico is presented. Floristic and faunistic richness and endemism, as well as uses of the flora are analyzed and discussed for this area, recently declared a biosphere reserve. The analysis shows that, in approximately 10 000 km² the Tehuacán-Cuicatlán Valley contains between 10 and 11.4% of the Mexican flora. In addition, the valley possesses 365 endemic species that represent 13.9% of its flora. With respect to the fauna diversity, the available information is less comprehensive than for plants. Nevertheless, the study shows that the 11 species of amphibians, 48 species of reptiles, and 91 species of birds recorded for the valley surpasses the diversity found in other dry-lands of the world. In relationship to the mammals of the region, the available data are poor for most of the groups except for bats, for which 24 species have been reported. Regarding the use of the flora, the analysis revealed that 815 species are utilized by the people in the valley. A discussion related to future research activities is also included.     

Helminths of amphibians of the Fergana valley of Uzbekistan

Species diversity and some ecological peculiarities of helminthes parasitizing amphibians in the Fergana Valley of Uzbekistan have been investigated. In 652 examined specimens of amphibians (Bufo viridis--237, Rana ridibunda--415 specimens), have been found 32 helminth species belonging to 26 genera of 12 families.     

Endemic species of grasses in Mexico: a phytogeographic approach

The Poaceae family includes approximately 700 genera and 10000 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.