Floristic analysis of the southwestern United States

A study was made of the distributions of native, terrestrial, vascular plants occurring in 50 local floras from throughout the Basin and Range and Colorado Plateau physiographic provinces of the southwestern United States. The objectives of the study were to objectively define and describe the floristic elements-assemblages of species with roughly coincident geographic distribution-occurring in the southwestern United States and to determine what such assemblages reveal about the floristic history of the region. The total flora (native, terrestrial species only) of the Southwest is estimated at 5,458 species, 77% of which were recorded in 1 or more of the local floras. Nearly 22% of these species are endemic to the study region. A majority of the species were found to be relatively rare. The average range of a species included only 4 floras, and 90% of the species were recorded from 11 or fewer floras; only 81 species (1.5%) were recorded from 50% or more of the floras. Trees constitute 2% of the regional flora and have the widest average distribution; perennial herbs constitute 59% of the flora and have the most restricted distributions.  Factor analysis was used to identify seven floristic elements for the region: a Great Basin element, a Mojavean element, a Colorado Plateau element, a Chihuahuan element, an Apachian element, and a Mogollon element. This factor analysis solution was shown to satisfy criteria of interpretability and consistency. The Mojavean, Colorado Plateau, and Apachian elements are believed to be autochthonous. The other four elements show high overlap in species composition with one or more adjacent regions. Each floristic element is mapped to show its geographic form and distribution. Analysis of these maps shows how the existence of objectively defined floristic elements is not contradictory to either the individualistic view of the distribution of a species or local continuity of vegetation and flora. The rarity of the majority of species and the clear association of floristic elements with rather narrowly circumscribed Holocene environments suggests that many Southwestern species have migrated little and are of rather recent, probably postglacial origin. Geographic “principles” derived from the distribution patterns of relatively few, widespread, dominant, usually woody species may not be applicable to entire, regional floras.       

Leptophlebiidae of the southwestern United States and northwestern Mexico (Insecta: Ephemeroptera)

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Effects of salinity on establishment of Populus fremontii (cottonwood) and Tamarix ramosissima (saltcedar) in southwestern United States

The exotic shrub Tamarix ramosissima (saltcedar) has replaced the native Populus fremontii (cottonwood) along many streams in southwestern United States. We used a controlled outdoor experiment to examine the influence of river salinity on germination and first year survival of P. fremontii var. wislizenii (Rio Grande cottonwood) and T. ramosissima on freshly deposited alluvial bars. We grew both species from seed in planters of sand subjected to a declining water table and solutions containing 0, 1, 3, and 5 times the concentrations of major ions in the Rio Grande at San Marcia, NM (1.2, 10.0, 25.7 and 37.4 meq 1 -1 ; 0.11, 0.97, 2.37, and 3.45 dS m -1 ). Germination of P. fremontii declined by 35% with increasing salinity ( P = .008). Germination of T. ramosissima was not affected. There were no significant effects of salinity on morality or above- and belowground growth of either species. In laboratory tests the same salinities had no effect on P. fremontii germination. P. fremontii germination is more sensitive to salinity outdoors than in covered petri dishes, probably because water scarcity resulting from eavaportion intensifies the low soil water potential associated with high salinity. River salinity appears to play only a minor role in determining relative numbers of P. fremontii and T. ramosissima seedlings on freshly deposited sandbars. However, over many years salt becomes concentrated on floodplains as a result of evaporation and salt extrusion from saltcedar leaves. T. ramosissima is known to be more tolerant of the resulting extreme salinities than P. fremontii . Therefore, increases in river salinities could indirectly contribute to decline of P. fremontii forests by exacerbating salt accumulation on floodplains.     

New genus, Aplanusiella , and two new species of leafhoppers from southwestern United States (Homoptera: Cicadellidae: Deltocephalinae)

A new genus, Aplanusiella (type-species, Aplanusiella utahensis , n. sp.) and two new species, A. utahensis and A. californiensis , are described and illustrated. The two species are allopatric and coexist on the same host genus ( Atriplex ) with members of a closely allied leafhopper genus, Aplanus . Notes on distribution of hosts and leafhoppers as well as leafhopper intergenetic relationships are also given.     

Climates of fescue grasslands of mountains in the western United States

Climates of fescue grasslands were described by summarizing USDC Weather Bureau records of representative sites. Mean temperatures of the warmest month declined from 18 to 14 C, average annual precipitation increased from 40–50 to 170 cm, and the number of arid months in an arbitrarily defined dry year declined from 3 to 1–2 as one moves from Festuca arizonica (14 stations) to F. scabrella (15) to F. idahoensis (17) to F. thurberi (6) to F. viridula (9). Climates of the grasslands are sufficiently like those of the Pseudotsuga menziesii and Abies lasiocarpa zones of the northern Rocky Mountains to make one ask what factors—wind, snow duration, soil characteristics, or fire—allow the fescue grasslands to persist in a conifer climatic zone.     

Improving national-scale invasion maps: tamarisk in the western United States

New invasions, better field data, and novel spatial-modeling techniques often drive the need to revisit previous maps and models of invasive species. Such is the case with the at least 10 species of Tamarix, which are invading riparian systems in the western United States and expanding their range throughout North America. In 2006, we developed a National Tamarisk Map by using a compilation of presence and absence locations with remotely sensed data and statistical modeling techniques. Since the publication of that work, our database of Tamarix distributions has grown significantly. Using the updated database of species occurrence, new predictor variables, and the maximum entropy (Maxent) model, we have revised our potential Tamarix distribution map for the western United States. Distance-to-water was the strongest predictor in the model (58.1%), while mean temperature of the warmest quarter was the second best predictor (18.4%). Model validation, averaged from 25 model iterations, indicated that our analysis had strong predictive performance (AUC = 0.93) and that the extent of Tamarix distributions is much greater than previously thought. The southwestern United States had the greatest suitable habitat, and this result differed from the 2006 model. Our work highlights the utility of iterative modeling for invasive species habitat modeling as new information becomes available. A menudo las nuevas invasiones, mejores datos de campo y técnicas novedosas de modelado espacial impulsan la actualización de los mapas y de los modelos existentes de especies invasoras. Este es el caso de al menos 10 especies de Tamarix, las cuales están invadiendo los sistemas ribereños en el oeste de los EE.UU. y extendiendo su distribución por toda Norteamérica. En 2006, desarrollamos un mapa nacional del tamarisco (National Tamarisk Map) utilizando una compilación de sitios de presencia y ausencia con datos de sensores remotos y técnicas de modelación estadística. Desde la publicación de este trabajo, nuestra base de datos sobre la distribución de Tamarix ha crecido considerablemente. Utilizando la base de datos actualizada de presencia de especies, nuevas variables predictoras y el modelo de máxima entropía (Maxent), hemos modificado nuestro mapa de la distribución potencial de Tamarix para el oeste de los EE.UU. El predictor más fuerte en el modelo fue la distancia al agua (58.1%), y la temperatura promedio del trimestre más cálido fue el segundo (18.4%). La validación de modelo, calculada como el promedio de 25 iteraciones del modelo, indicó que nuestro análisis tuvo una alta capacidad predictiva (ABC = 0.93), y que la distribución de Tamarix es mucho más extensa de lo que se pensaba. El suroeste de los EE.UU. tuvo la mayor cantidad de hábitat adecuado para la especie, y este resultado difirió del modelo de 2006. Nuestro trabajo enfatiza la utilidad del modelado iterativo para modelar el hábitat de las especies invasoras a medida que se disponga de nueva información.     

New grass distribution records for New Mexico and the United States

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Lichens of soil crust communities in the Intermountain Area of the western United States

Lichens are common components of microbiotic soil crusts. A total of 34 species from 17 genera are reported from soil crust communities throughout the Intermountain Area. Distribution of terricolous lichens is determined by various physical and biological factors: physical and chemical characteristics of the soil, moisture regimes, temperature, insolation, and development and composition of the vascular plant community. Some species demonstrate a broad ecological amplitude while others have a more restricted distribution. All growth forms are represented; however, the vast majority of soil crust lichens are squamulose (minutely foliose). Fruticose species are least abundant. In exposed, middle-elevation sites vagrant (detached) species are common. This paper describes and discusses terricolous lichen communities of desert habitats of the intermountain western United States. Effects of various human-related activities including grazing, wildfire, air pollution, and recreation vehicles on soil crust lichens are discussed. Gypsoplaca macrophylla (Zahlbr.) Timdal, a rare squamulose lichen which occurs on gypsifersous soils, was recently collected in Emery County, Utah, and is reported as new to the state.     

Spider fauna of selected wild sunflower species sites in the southwest United States

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A new species of Cryptantha (Boraginaceae) from Nevada

Described as new is Cryptantha welshii Thorne & Higgins from the White River Valley of Nye County, Nevada.     

Bryozoa collected by the United States Antarctic Research Program: new taxa and new records

Thirty-two species of cheilostomate Bryozoa are described and illustrated from 26 stations sampled by the United States Antarctic Research Program, including 29 new species and two new genera. A further new genus is introduced for two species formerly attributed to Osthimosia Jullien, 1888. One station was located in the Ross Sea and three in the cold temperate South Pacific; 14 stations were sampled in the region of the Scotia Arc, south of the Antarctic Convergence, and eight from the subantarctic southwest Atlantic, mostly in the vicinity of Tierra del Fuego. Nine new species were present in the Antarctic samples, whereas those from the southwest Atlantic yielded 18 new species and the two new genera. Three of the new subantarctic species are attributed to genera formerly considered to be Antarctic endemics, while the two newly assigned species of Osthimosia are presently known only from Antarctic localities.     

Nesting and predatory behavior of some Tachysphex from the western United States (Hymenoptera: Sphecidae)

The first published observations on the nesting and predatory behavior of Tachysphex antennatus Fox, T. occidentalis Pulawski, T. williamsi Bohart, T. yolo Pulawski, T. alpestris Rohwer, T. clarconis Viereck, T. apricus Pulawski, and T. cockerellae Rohwer are presented herein. Also included are host and behavioral data on T. tarsatus (Say), T. apicalis fusus Fox, T. similis Rohwer, T. ashmeadii Fox, and T. mundus exsectus Fox.         

Factors controlling structural and floristic variation of riparian zones in a mountainous landscape of the western United States

We examined landscape patterns in the physical conditions and vegetative composition of montane riparian zones to identify their most important sources of variation. Information on plant species cover and on physical characteristics that occur at coarse, medium, and fine scales was collected for 144 riparian plots located throughout the Lake Tahoe Basin, which straddles the California-Nevada border in the western United States. Constrained and unconstrained ordination analyses were used to identify the most important correlates of physical form and plant species composition. Through multivariate analysis of environmental variables (principal components analysis), vegetation data (detrended correspondence analysis), and the combined relationship between the environmental and vegetation data (canonical correspondence analysis), we consistently found that the greatest variation occurred along a gradient of decreasing valley width, decreasing stream sinuosity, and increasing stream slope. Although surface characteristics reflected a 2nd important source of variation in physical conditions, plant species distribution was not strongly correlated with riparian surface conditions. Strong correlations among physical variables that occur at different scales, such as between valley form and geofluvial surface and between geofluvial surface and surface conditions, support the use of a physically based hierarchical framework for organizing riparian zones within the landscape. Such a hierarchical framework would be useful for interpreting patterns in riparian structure and process at different scales and could be applied to riparian zones in other mountain landscapes of the western United States and elsewhere. Moreover, our finding that riparian plant species composition is most strongly correlated with environmental variables that occur at coarse to moderate scales, most of which can be derived from existing data, supports the idea that modeling montane riparian community distribution using topographic and remotely sensed data could be useful; however, a large degree of species variation, unexplained by the variables we collected, indicates that other variables, perhaps disturbance regime, should be included in such a venture. Nomenclature: Hickman (1993).     

A species of Cryptantha (Boraginaceae) dedicated to the memory of F. Creutzfeldt

Described as new is Cryptantha creutzfeldtii Welsh, named to honor the memory of F. Creutzfeldt, botanist with the Gunnison Expedition of 1853–54, who was killed along with Gunnison and other members of the party in an Indian ambush.     

Microvelia rasilis Drake in Arizona: a species new to the United States (Heteroptera: Veliidae)

Microvelia rasilis Drake was taken in Montezuma Well, Yavapai Co., Arizona, along with Microvelia hinei Drake and Hydrometra aemula Drake (Heteroptera: Hydrometridae). These are all new to this locality; however, the latter two species are previously known from Arizona.     

Colour and size reveal hidden diversity of Necturus (Caudata: Proteidae) from the Gulf Coastal Plain of the United States

ABSTRACT

Recent data from the mitochondrial genome reveal six lineages of Gulf Coast Waterdogs traditionally classified as Necturus beyeri. Here, we use patterns of colour and body size, along with previously published data, to reveal a large, heavily spotted phenotype with an unstriped larva possessing numerous white spots; we re-describe N. beyeri to correspond to this phenotype. We also reveal a small, weakly spotted phenotype possessing an unstriped larva lacking numerous white spots. This phenotype characterises the Apalachicola and Escambia lineages, which current evidence suggests are paraphyletic. We reject taxonomies that place these two lineages in N. lodingi because the type specimen of this species appears to be a melanistic member of N. beyeri. Therefore, we describe the Apalachicola and Escambia lineages as independent new species.

http://ww.zoobank.org/urn:lsid:zoobank.org:act:C8508CCB-F54F-4DC8-B61D-56966A3F1CC8

http://www.zoobank.org/urn:lsid:zoobank.org:act:F044B2CC-55F0-4FFA-A312-9CAD9E73CD69