Abstract:We characterized soil communities in the Mojave Desert across an elevation gradient. Our goal was to test the hypothesis that as soil quality improved with increasing elevation (due to increased productivity), the diversity of soil prokaryotes and nematodes would also increase. Soil organic matter and soil moisture content increased with elevation as predicted. Soil salinity did not correlate to elevation, but was highest at a mid-gradient, alluvial site. Soil nematode density, community trophic structure, and diversity did not show patterns related to elevation. Similar results were obtained for diversity of bacteria and archaea. Relationships between soil properties, nematode communities, and prokaryotic diversity were site-specific. For example, at the lowest elevation site, nematode communities contained a high proportion of fungal-feeding species and diversity of bacteria was lowest. At a high-salinity site, nematode density was highest, and overall, nematode density showed an unexpected, positive correlation to salinity. At the highest elevation site, nematode density and species richness were attenuated, despite relatively high moisture and organic matter content for the soils. Our results support emerging evidence for the lack of a relationship between productivity and the diversity of soil nematodes and prokaryotes.

Two new species, Begonia bracteolata and Begonia keralensis, are described from the Western Ghats of India. They are placed in the newly created Begonia sect. Flocciferae, along with B. albo-coccinea Hook. and B. floccifera Bedd. Lectotypes are designated for three names within this section. Colour photoplates, illustrations and an identification key to Begonia sect. Flocciferae are also provided.

The history, taxonomy, distribution, habitat and cultivation of thc widespread Eulophia pulchra (Orchidaceae) is discussed and a full description of the species is provided.

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The genus Ischaemum Linnaeus (1753: 1049) was established with two species, viz. I. muticum Linnaeus (1753: 1049) and I. aristatum Linnaeus (1753: 1049). At present, the genus comprises ca. 71 species distributed in warm and tropical regions of the world (Mabberley 2008). It is represented by 56 species in India of which 43 species are endemic (Srivastava & Nair, 2010). In recent years, the genus has attracted the attention of many researchers for novelties in taxonomy (Gorade et al. 2016, Sunil et al. 2017), distribution (Datar et al. 2014) and nomenclature (Tiwari et al. 2016).