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http://www.nsrl.ttu.edu/publications/specpubs/sps/SP54.pdf
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... record .—Torrence (2007) encountered examples of this widow spider in her bucket traps on the edge of playas in Floyd County (county record), Texas. Because of the potential for bites of this toxic spider, only sight records were noted. Distribution .—Sissom (2003) found this species in the grassland above Pantex Lake and Playa 2, Car- son County (first county record), Texas. Dean (2007) recorded this spider from Bastrop, Culberson, Johnson, Kent, and from the Southern High Plains in Lubbock and Garza Counties. It is a common spider in Lubbock County and the only species present based on casual observations (JCC pers. obs.). Studies by Zhang et al. (2004) suggest to us that Latrodectus from east of about the 100th Meridian are Latrodectus mactans (Fabricius 1775) and those west are L. hesperus in Texas. Kaston (1970) noted L. hesperus was the only widow spider occurring from about the middle of Texas, Oklahoma, and Kansas west and north to the Canadian provinces. Latrodectus are notorious for being transported by commerce and therefore it is possible both species might overlap ranges. Dean (2007) listed L. mactans from the High Plains of Texas in Lubbock and Randall Counties, but it is possible those were based upon old records that need to be reexamined. Our records from Floyd and Carson Counties are new High Plains records for L. hesperus. Comment .—There are volumes written on widow spiders (see citations in Kaston 1970). As illustrated in Fig. 14, immatures of this spider do not have the solid black body that so many people believe is characteristic for widow spiders, but like adults immatures do have an hour-glass mark of orange or red on the ventral surface of the abdomen. Numerous specimens of adult females observed in western Texas have red/orange patterns retained along the dorsum of the abdomen (especially posteriorly) (JCC pers. obs.; Photo. ...
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Frequency and duration of playa inundation (i.e., hydroperiod) are major influences on the spatial and temporal distribution of flora and fauna in the western Great Plains. We used a 10-year data set of 221 playa wetlands to develop models of factors influencing the probability of a playa being flooded during January. We evaluated the relative influence of landscape and precipitation variables on the probability of a playa being inundated during January. Of the surveyed playas, 67% were inundated in ≥1 year and 33% never contained water in January. Our selected model indicated that the proportion of grassland in the watershed, mean annual rainfall, the previous year’s total rainfall, and playa size as variables in the top ranked models for the probability of a playa being inundated during January. Proportion of grassland in the watershed had the largest positive effect. The probability of a playa being inundated during January increased from west to east across the THP and on average, we would expect individual playas to be inundated approximately once every 11 years, with ~30% of the playas inundated at a frequency greater than 1 year out of 10. Playas with cropland watersheds had diminished hydrologic function.
Estudiamos la fauna de las arañas de Ash Meadows National Wildlife Refuge en seis expediciones de colecta de octubre 2004 a agosto 2005. Encontramos ≥81 especies de 60 géneros y 26 familias. La diversidad fue dominada por Salticidae (≥13 especies en siete géneros), seguida por Lycosidae (ocho especies en siete géneros), Araneidae (ocho especies en siete géneros), Gnaphosidae (siete especies en siete géneros), y Philodromidae (cuatro especies en cuatro géneros), con Thomisidae, Linyphiidae, Dictynidae, Theridiidae, Miturgidae, Pholcidae y Tetragnathidae representadas por dos a siete especies de uno a tres géneros cada una. Un total de14 familias fue representado por una sola especie en un solo género. La familia Lycosidae se encontró en más sitios que ninguna otra familia y tuvo los más individuos colectados. En la escala de todo el paisaje, registramos una densidad de especies de sólo 0.96 especies/ km2 y aunque 45.7% de las especies fueron representadas por un solo espécimen, concluimos que la fauna es pobre en diversidad. Esto es consistente con otros hábitats desérticos de bajas alturas y los dominados por lagos playas en Norteamérica y quizás se atribuye a la formación limitada de suelo.
