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Map of the Baja California peninsula showing sites where species lists have been made and the locations of herbarium specimens with geospatial data.
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In 1978, Howard Scott Gentry published his second monograph on the genus Agave focusing on the plants of the peninsula of Baja California, México, and the related species in the group Deserticolae in the US and Sonora. We revisit Gentry's work with an emphasis on revising the genus and its taxonomic arrangement and including several recently descri...
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... States. The genus under- went rapid speciation between 8 and 6 million years ago and then again between 3 and 2.5 million years ago (Good-Avila et al. 2006). These speciation events bracket the widely accepted age of 5 million years ago for the opening of the Gulf of California ( Lucchitta 2003), which separated the Baja California peninsula ( Fig. 1) from mainland México. About ten percent of the known species of Agave occur on this peninsula, and most of them are endemics, which presumably evolved in the isolation of this long, nar- row strip of land over the ...
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... of perennial vegetation in the Sonoran Desert ( Turner et al. 1995) that recently has been focused on the desert areas of the Baja California peninsula ( Webb et al. 2014). The data- base of localities documented in Baja California con- tains 1,630 localities at which all perennial vegeta- tion within a hypothetical 100-m radius is recorded (Fig. 1); the geometry of specific sites varies greatly, from alluvial plains with unrestricted access to steep canyons with limited access, but the search area re- mained about the same for all plots. Agave species were observed and recorded at 720 of these ...
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... found many leaf variations of A. sobria in this area ( Fig. 32), as well as A. aurea ssp. aurea. Agave gigan- tensis is only known with certainty from its type lo- cality in the Sierra de las Palmillas (Sierra de las Pal- mas) and northwards on Cerro el Potrero, which are rugged mesas in the northern Sierra de la Giganta (Webb & Starr 2014a). (Fig. ...
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... in the field. Their habitats have little overlap: A. moranii occurs in the desert valleys on the east side of the Sierra San Pedro Martir, whereas A. pringlei grows at higher elevations in the mountains to the north. Agave moranii occurs with A. cerulata var. nel- sonii near its type locality on the southeastern end of the Sierra San Pedro Martir (Fig. 13), and we found no evidence that the two species hybridize. This recently described species is solitary with a rosette 0.4-1.2 m tall and 0.8-1.9 m wide. The leaves are gray-green to blue-glaucous green, lan- ceolate, with 10-40 per rosette; they are 40-90 cm long by 6-13 cm wide, have prominent leaf-margin impressions on both surfaces, ...
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... turneri is narrowly endemic to the hyper-ar- id Sierra Cucapá and Cerro Mayor south of Mexicali Fig. 13). Only 8 locali- ties of Agave turneri are known in these mountain rang- es, and all of them are on the eastern side in monzogran- ite, an unusual type of granitic rock high in potassium and white in color. With its semi-compact inflorescence and gray leaves, A. turneri superficially resembles both A. azurea and A. vizcainoensis of the ...
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... species occurs on both sides of the peninsula as well as on the peninsular divide over a wide area of central Baja California and Isla Ángel de la Guar- da (Fig. 17). Agave cerulata ssp. cerulata seldom is found as a solitary individual, and Gentry (1978) be- lieved that A. cerulata was one of the most numerous agaves in North America, after A. lechuguilla of the Chihuahuan Desert. As previously discussed, A. ceru- lata could be confused with A. deserti, but geograph- ic separation and the brown ...
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... et al. 2008, Felger andWilder 2012). Although three species of Agave occur in the is- land chain off the Sonoran coast ( Wilder et al. 2008), which in- cludes Isla Tiburón, the largest island in the gulf, A. cerulata ssp. dentiens is the only species on Isla San Esteban. Some re- ports have this subspecies grow- ing on Isla Ángel de la Guarda (Fig. 17) or on the mainland of Baja California in the vicinity of Bahía de los Angeles. Gentry (1978) reported a specimen (Gentry & Fox 11953) collected between Punta Prieta and Bahía de Los Angeles, and other unusual plants with affin- ity to A. cerulata were found in the mountains south- east of Bahía San Luis Gonzaga (M. Salazar-Ceseña, ...
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... Navarro- Quezada et al. (2003) found that genetic variation of A. cerulata ssp. dentiens was not signifi- cantly different from A. cerulata on the peninsula. However, given its relatively wide inflorescence, A. cerulata ssp. dentiens appears to be a viable subspecies and could represent a bridge between sections Deser- ticolae and Conicae. (Fig. 17). This prolifically offsetting variety of Agave ceru- lata has short-stemmed, compact rosettes that are 50-75 cm in diameter at maturity. The leaves are gray-green and mostly 20-35 cm by 6-8 cm, lan- ceolate to triangular-lanceolate, with a thick gray to bluish glaucous coating. The grayish brown mar- ginal spines are 3-9 mm long with a ...
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... change these plants from subspecies to variety because we found substantial overlap in distribution with Agave cerulata ssp. cerulata at the southern end of the distribution for A. cerulata var. nelsonii. (Fig. 17). For example, we found both taxa east of El Ro- sario, at Laguna Chapala, and at Agua de Higuera. Gentry (1978) discussed variability in the forms of A. cerulata found at the type locality of Calmallí, and one or more of those could be fit into variety nelso- nii. This variety is the dominant taxa in the north- ernmost distribution of ...
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... we found both taxa east of El Ro- sario, at Laguna Chapala, and at Agua de Higuera. Gentry (1978) discussed variability in the forms of A. cerulata found at the type locality of Calmallí, and one or more of those could be fit into variety nelso- nii. This variety is the dominant taxa in the north- ernmost distribution of the A. cerulata complex (Fig. 17), being found on both sides of the southern Sierra de San Pedro Mártir. Between El Rosario and the southwestern flank of the Sierra de San Pedro Mártir, the distribution overlaps with A. shawii ssp. goldma- niana and, because of its large clusters of dense ro- settes with broadly linear-triangular or broadly ovate leaves and frequently ...
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... cerulata ssp. subcerulata occurs mostly in Baja California Sur, but has a distribution that ex- tends into the state of Baja California just south of the type locality for A. cerulata at Calmallí (Fig. 17). The relatively broad, short leaves with prominent teats are distinctive in this subspecies in habitat, and it is relatively easy to differentiate from other species in Baja California. Subspecies subcerulata resembles A. subsimplex, another member of the Deserticolae from Sonora, and because it is the most southerly in- fraspecific ...
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... Subspecies subcerulata resembles A. subsimplex, another member of the Deserticolae from Sonora, and because it is the most southerly in- fraspecific taxon of A. cerulata, it may form a genetic connection to some strains of A. sobria. To empha- size this, we found one locality on the western side of the Sierra de la Giganta south of San Ignacio (Fig. 17). Johnston (1924, 1982 re- ported what they called "depauperate forms" growing in gypsum soils on Isla San Marcos, in the Gulf of California near Santa Rosalía (Fig. 1), and the size of rosettes depends upon slope aspect. Polymorphism in this subspecies likely is dependent upon substrate and aspect on the mainland as well, with ...
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... it may form a genetic connection to some strains of A. sobria. To empha- size this, we found one locality on the western side of the Sierra de la Giganta south of San Ignacio (Fig. 17). Johnston (1924, 1982 re- ported what they called "depauperate forms" growing in gypsum soils on Isla San Marcos, in the Gulf of California near Santa Rosalía (Fig. 1), and the size of rosettes depends upon slope aspect. Polymorphism in this subspecies likely is dependent upon substrate and aspect on the mainland as well, with populations near the type locality of San Ignacio (Fig. 20 Agave deserti has prolifically offsetting rosettes that are 30-50 cm tall and 40-60 cm wide. The leaves are variable ...
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... (1911) under A. deserti, includ- . pringlei, A. nelsonii, A. consociata, and A. dentiens. Gentry (1978) accepted some of this synonymy, but created A. deserti ssp. deserti and ssp. pringlei (with ssp. simplex in Arizona), and he proposed that populations in Paseo San Matias, which separates the Sierra San Pedro Mártir from the Sierra Juarez (Fig. 1), were a hybrid swarm and justified the reduction of A. pringlei to subspecies. Genetically, NavarroQuezada et al. (2003) found more dissimilarity among A. deserti populations than those of A. ceru- lata or A. subsimplex from Sonora and suggested that this finding could indicate an increased tendency to- wards hybridization in A. ...
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... species is only known from the two islands that form the barrier to create Bahía Magdalena on the west coast of Baja California Sur (Figs. 1, 24). Although several forms are thought to occur, the variability of this species is high, not unlike other species on the Baja California peninsula. ...
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... other species, in part because of its location on two islands with no other agaves nearby. Although glaucous blue-green forms are known (and may have been the inspiration for A. connochaetodon), we only observed the yellow- green rosettes on Isla Magdalena. (1978) reports that Orcutt probably collected a specimen from the Sierra Juarez in 1882 (Fig. ...
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... types occur on the other side of the peninsula along Bahía Concepción south of Mulegé (Fig. 29). In the southern part of the Sierra de la Giganta and on ad- jacent islands, many strongly divergent forms occur; the plants once described as Agave carminis (Fig. 30) are considerably different from those found along México Highway 1 south of Loreto (Fig. 31). Webb and Starr (2014a) believe one form of Agave sobria northeast of Misión San Javier has been mistaken for A. gigantensis (Fig. 32); another large form with relatively wide and numerous leaves occurs on Mesa Siquito west of Bahía Agua Verde (Fig. 33). Consid- erable additional field work, in addition to molecular data, would be ...
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... blue-green leaves, plants of this species have been confused with A. sebastiana, which only occurs on islands northwest of the Vizcaíno Peninsula (Webb & Starr 2014b) and has far more leaves that are more ovate; moreover, Agave azurea vegetatively re- sembles A. turneri, a species narrowly endemic to a mountain range near the US -Mexico border (Fig. 13) with a different type of inflorescence (see section Conicae). Gentry's collections of this species (Gentry 7693, 7713) from the Picachos de Santa Clara are listed under both A. gigantensis and A. vizcainoensis (Appendix 1). Agave gigantensis grows at higher eleva- tions in the northern Sierra de la Giganta, has green leaves and a ...
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Polianthes geminiflora (Lex) Rose (Agavaceae) is neotypified and its detailed description is presented. This species was described by Juan Jose Martinez de Lexarza as Bravoa geminiflora and published in Novorum vegetabilium descriptiones in 1824. According to Lexarza, the plant was collected in the mountains of Valladolid, nowadays Morelia, Michoac...
Citations
... Recently (~7 Mya and ~2.5 Mya), agaves experienced two bursts of evolutionary diversification that resulted in many endemic and microendemic species, with countless forms of leaves, rosettes, and inflorescences (Eguiarte et al., 2021;Gentry, 1978Gentry, , 1982Good-Avila et al., 2006;Jiménez-Barrón et al., 2020). On the Baja California Peninsula (BCP hereafter), for example, a total of 23 Agave taxa are found, with 22 of them being endemic (Trelease, 1911;Webb & Starr, 2015). Surprisingly, the rich diversity of agaves in the BCP has been little studied (Gentry, 1978;Webb & Starr, 2015). ...
... On the Baja California Peninsula (BCP hereafter), for example, a total of 23 Agave taxa are found, with 22 of them being endemic (Trelease, 1911;Webb & Starr, 2015). Surprisingly, the rich diversity of agaves in the BCP has been little studied (Gentry, 1978;Webb & Starr, 2015). For example, almost all Agave taxa in BCP represent species/subspecies complexes with unclear geographical boundaries or genetic relationships between and within them (Navarro-Quezada et al., 2003;Webb & Starr, 2015). ...
... Surprisingly, the rich diversity of agaves in the BCP has been little studied (Gentry, 1978;Webb & Starr, 2015). For example, almost all Agave taxa in BCP represent species/subspecies complexes with unclear geographical boundaries or genetic relationships between and within them (Navarro-Quezada et al., 2003;Webb & Starr, 2015). ...
Agaves are an outstanding arid‐adapted group of species that provide a unique chance to study the influence of multiple potential factors (i.e., geological and ecological) on plant population structure and diversification in the heterogeneous environment of the Baja California Peninsula. However, relatively little is known about the phylogeography of the endemic agave species of this region. Herein, we used over 10,000 single‐nucleotide polymorphisms (SNPs) and spatial data from the Agave aurea species complex (i.e., A. aurea ssp. aurea, A. aurea ssp. promontorii, and A. aurea var. capensis) to resolve genetic relationships within this complex and uncover fine‐scale population structure, diversity patterns, and their potential underlying drivers. Analyses resolved low genetic structure within this complex, suggesting that A. aurea is more likely to represent several closely related populations than separate species or varieties/subspecies. We found that geographical and historical ecological characteristics—including precipitation, latitude, and past climatic fluctuations—have played an important role in the spatial distribution of diversity and structure in A. aurea. Finally, species distribution modeling results suggested that climate change will become critical in the extinction risk of A. aurea, with the northernmost population being particularly vulnerable. The low population genetic structure found in A. aurea is consistent with agave's life history, and it is probably related to continuity of distribution, relatively low habitat fragmentation, and dispersion by pollinators. Together, these findings have important implications for management and conservation programs in agave, such as creating and evaluating protected areas and translocating and augmentation of particular populations.
... In the Desert Region, latitude, orientation, and access to groundwater impose varying constraints on plant growth. Such constraints include the latitudinal change in the proportion of winter and summer rains; the influence of coastal fog (Webb and Starr 2015); and the occurrence of shallow aquifers, gullies and dry arroyos embedded within a dryland matrix (Leó n de la Luz and others 2015). Such high contrasts in ecosystem functions between the regional landscape matrix and its embedded ecosystems (that is, less water-limited EFTs within a matrix of dryland EFTs) enhance ecological processes of the lateral transfer of matter and energy (Turner and Gardner 2015). ...
Conservation biology must set geographic conservation priorities not only based on the compositional or structural but also on the functional dimensions of biodiversity. However, assessing functional diversity is challenging at the regional scale. We propose the use of satellite-derived Ecosystem Functional Types (EFTs), defined here as patches of land surface that share similar primary production dynamics, to incorporate such aspects of ecosystem functional diversity into the selection of protected areas. We applied the EFT approach to the Baja California Peninsula, Mexico, to characterize the regional heterogeneity of primary production dynamics in terms of EFTs; to set conservation priorities based on EFT richness and rarity; and to explore whether such EFT-based conservation priorities were consistent with and/or complementary to previous assessments focused on biodiversity composition and structure. EFTs were identified based on three ecosystem functional attributes derived from seasonal dynamics of the Enhanced Vegetation Index: the annual mean (proxy of primary production), the seasonal coefficient of variation (descriptor of seasonality), and the date of maximum (indicator of phenology). EFT-based priorities identified 26% of the peninsula as being of extreme or high priority and reinforced the value of the ecosystem functional diversity of areas already prioritized by traditional conservation assessments. In addition, our study revealed that biodiversity composition- and structure-based assessments had not identified the full range of important areas for EFT diversity and tended to better capture areas of high EFT rarity than those of high EFT richness. Our EFT-based assessment demonstrates how remotely sensed regional heterogeneity in ecosystem functions could reinforce and complement traditional conservation priority setting.
... pecten-aboriginum, Cactaceae) that blooms November-February. Agave species occurred in all ecoregions where bat roosts were located but at lower densities and with less predictable flowering phenologies (Rebman and Roberts 2012; Webb and Starr 2015). ...
... The presence of winter-blooming agaves in the southern peninsula has been suggested as a food resource for lesser longnosed bats that overwinter in the Cape region of Baja (Fleming et al. 1993). While there are 22 species of agave that occur on the Baja peninsula, only 3 species are found in the southern peninsular Cape region (Webb and Starr 2015). Two of these species typically bloom in the spring months from roughly February to April and the other has a typical autumn bloom period from September to December (Rebman and Roberts 2012). ...
Migratory species that cross geopolitical boundaries pose challenges for conservation planning because threats may vary across a species' range and multi-country collaboration is required to implement conservation action plans. The lesser long-nosed bat (Leptonycteris yerbabuenae) is a migratory pollinator bat that was removed from the Endangered Species List in the United States in 2018 and from threatened status in Mexico in 2013. The seasonal ecology and conservation status of the species is well understood in the core part of its range on mainland Mexico and in the southwestern United States, but relatively little is known about the species on the Baja California peninsula in northwestern Mexico, a part of its range range separated by the Gulf of California. We studied the seasonal ecology of lesser long-nosed bats on the Baja peninsula at 8 focal roosts along a 450-km north-to-south transect to test hypotheses about migratory or residential status of the species on the Baja peninsula. We provide evidence of an extensive population of lesser long-nosed bats on the Baja peninsula that is primarily seasonally migratory and includes 2 mating roosts with males on the southern part of the peninsula. Seasonal ecology of lesser long-nosed bats was closely associated with the flowering and fruiting season of the cardón (Pachycereus pringlei), the dominant columnar cactus on the peninsula. However, we discovered that some female lesser long-nosed bats arrive and give birth at southern roosts in mid-February, about 2 months earlier than other migratory populations in more northern Sonoran Desert habitats. We documented the loss of nearly a third of the known maternity roosts during the study, demonstrating that action to protect key roosts remains a high priority. Migratory pollinators are particularly vulnerable to climate and land-use changes and we recommend continued monitoring and research to guide effective range-wide conservation of the species. Las especies migratorias o con rangos de distribución amplios que incluyen fronteras geopolíticas, representan desafíos particulares para la planificación de estrategias de conservación, ya que las amenazas así como las tendencias poblacionales pueden variar a lo largo de su rango geográfico y se requiere la colaboración de múltiples países para implementar planes de acción que permitan su conservación. El murciélago magueyero menor (Leptonycteris yerbabuenae) es un murciélago polinizador migratorio que recientemente fue sacado de la lista de especies en peligro en los Estados Unidos en 2018 y en México en 2013. La ecología estacional y el estatus de conservación de esta especie, ha sido bien estudiado en el centro de su rango de distribución en México continental, pero se sabe muy poco acerca de la especie en la Península de Baja California en el noreste de México, región que está separada del resto del rango por el golfo de California. Nosotros estudiamos la ecología estacional del murciélago magueyero menor, en ocho cuevas a lo largo de un transecto de 450 km norte-sur, en la Península de Baja California y pusimos a prueba la hipótesis del status migratorio o residente de sus poblaciones en esta región. Proporcionamos la primera evidencia de una extensa población de esta especie en la península, a cual es principalmente migratoria estacional e incluye dos cuevas de reproducción ubicadas al sur de esta región. La ecología estacional del murciélago magueyero menor estuvo fuertemente asociada con la estación de floración y fructificación del cardón (Pachycereus pringlei), el cactus columnar dominante en la península. Nosotros también descubrimos que algunas hembras llegan y dan a luz en las cuevas más sureñas, a mediados de febrero, cerca de dos meses antes que otras poblaciones migratorias, en el desierto de Sonora del norte. Durante el tiempo de este estudio, documentamos la destrucción de una de las cuevas de maternidad, lo que demuestra la necesidad de acciones de conservación para proteger estos refugios. Los polinizadores migratorios son particularmente vulnerables a cambios en el uso del suelo y al cambio climático y recomendamos continuar con el monitoreo y la investigación, con el fin de guiar su conservación a lo largo de todo el rango de distribución de la especie.
... I n our recent revision of the Baja Californian species of Agave L., Webb & Starr (2015) transferred to sectional rank four of the informal species groups in Agave Subg. Agave applied by Gentry (1982) and published earlier by Baker (1877) and Trelease (1912) as unranked infrageneric groups. ...
Plant macrofossils from packrat (Neotoma spp.) middens provide direct evidence of past vegetation changes in arid regions of North America. Here we describe the newest version (version 5.0) of the U.S. Geological Survey (USGS) North American Packrat Midden Database. The database contains published and contributed data from 3,331 midden samples collected in southwest Canada, the western United States, and northern Mexico, with samples ranging in age from 48 ka to the present. The database includes original midden-sample macrofossil counts and relative-abundance data along with a standardized relative-abundance scheme that makes it easier to compare macrofossil data across midden-sample sites. In addition to the midden-sample data, this version of the midden database includes calibrated radiocarbon (¹⁴C) ages for the midden samples and plant functional type (PFT) assignments for the midden taxa. We also provide World Wildlife Fund ecoregion assignments and climate and bioclimate data for each midden-sample site location. The data are provided in tabular (.xlsx), comma-separated values (.csv), and relational database (.mdb) files.
A diagnostic description of the genus is given with special emphasis on the occurrence of succulence amongst its species. The geographical distribution is outlined, together with a selection of important literature, and an explanation of the etymology of the name. This is followed by a short summary of its position in the phylogeny of the family and of the past and present classification in a phylogenetic context. The succulent features present amongst the species of the genus are shortly explained as to morphology and anatomy.
This is followed by a synoptical treatment of the species (all succulent) of the genus, complete with typification details, full synonymy, geographical and ecological data, a diagnostic description, and, where applicable, notes on phylogenetic placement and relationships, as well as economic and/or horticultural importance.
A diagnostic description of the genus is given with special emphasis on the occurrence of succulence amongst its species. The geographical distribution is outlined, together with a selection of important literature, and an explanation of the etymology of the name. This is followed by a short summary of its position in the phylogeny of the family and of the past and present classification in a phylogenetic context. The succulent features present amongst the species of the genus are shortly explained as to morphology and anatomy.
This is followed by a synoptical treatment of the species (all succulent) of the genus, complete with typification details, full synonymy, geographical and ecological data, a diagnostic description, and, where applicable, notes on phylogenetic placement and relationships, as well as economic and/or horticultural importance.
An updated infrageneric classification is provided for the genus Agave L. s.l., therefore including A. subg. Manfreda, i.e., the genera Manfreda Salisb., Polianthes L., and Prochnyanthes S.Watson (Asparagaceae: Agavoideae / Agavaceae), with emphasis on the rank of section. Nomenclatural assessments are provided for (1) all unranked infrageneric ‘group’ names introduced by Trelease (1913) for the Caribbean region, by (2) Gentry (1982) for continental North America, and (3) for all infrageneric taxa at sectional rank hitherto published in Agave by Salm-Dyck, Engelmann, Berger, Ullrich, Webb & Starr, Starr & Webb, and Hochstätter. We also show that Jacobi did not publish names at the rank of section. In addition, a revised infrageneric classification of Agave s.l. is provided, including new combinations and new names mainly at the rank of section, especially for those unranked group names used by Trelease (1913) and Gentry (1982) for which no corresponding formal name at sectional rank is available. Three new combinations are made in Agave for species recently described in Manfreda and Polianthes.
