The effect of environmental stability on hyporheic community structure

Interstitial water samples were collected from two well depths (30 and 60 cm) from 8 rivers in the Cass-Craigieburn region, South Island (New Zealand) during January 1998 to assess the hyporheos in streams of differing stability. Hyporheic water chemistry was more similar to surface water chemistry at unstable sites than at stable sites. The greatest diversity of both epigean and hypogean animals occurred at intermediate levels of disturbance; however, invertebrate density declined with increasing bed movement. Abundance of epigean animals also increased with declining environmental stability (i.e., increasing bed movement). Water chemistry was most like the river channel at unstable sites, probably because less stable substrates had increased interstitial flow facilitating a greater supply of water from the surface channel. In contrast, stable sites were spring fed and groundwater had a greater influence. Thus, substrate stability may influence hyporheic water chemistry and porosity by changing the interaction between ground and surface waters. Epigean taxa may be less abundant at stable sites because the chemical nature of the water is least like the river channel (e.g. low dissolved oxygen, higher temperature and higher conductivity), while the abundance of hypogean animals is greater, as these taxa are more tolerant of this water chemistry, and are thus capable of persisting in the stable substrates.     

Novelty and phylogenetic affinities of a new family of tapeworms (Cestoda: Rhinebothriidea) from endangered sawfish and guitarfish

The parasites of hosts of conservation concern are often poorly known. This is the case with the iconic group of elasmobranchs known as the sawfish of the genus Pristis, all four species of which are considered as Endangered or Critically Endangered by the International Union for Conservation of Nature (IUCN, Switzerland). Examination of cestodes from three species of sawfish (Pristis pristis, Pristis clavata, and Pristis zijsron) in Australia and one of their close relatives, the also critically endangered widenose guitarfish, Glaucostegus obtusus, in India, collected over the past 25 years, yielded four new species of tapeworms which are described herein. All four belong to the previously monotypic Mixobothrium; the diagnosis of the genus is revised to accommodate the new species. Among the new taxa is a species that had been included in previous molecular phylogenies but whose identity and affinities within the order Rhinebothriidea, and thus also its familial placement, were unclear. This species exhibits the morphological features of Mixobothrium and thus its identity is, at long last, revealed. Sequence data generated for the 28S rDNA gene for three of the new species, as well as an additional new but yet undescribed species from Pristis pectinata from Florida (USA), confirms the uniqueness of this group among the rhinebothriideans. The new family Mixobothriidae is established to house these taxa. The members of this family differ from all but one of the five other families of rhinebothriideans in lacking apical suckers on their bothridia. They are also distinctive in that their bothridia are divided into three regions. The anterior and posterior regions have similar locular configurations to one another and differ from the locular configuration of the middle region. As a consequence, the bothridia are symmetrical along both their vertical and horizontal axes. We predict that a focus on species of guitarfish in the genus Glaucostegus will be the most productive approach for discovering additional diversity in this family of cestodes.     

Mongol names in the nomenclatural designations of the fossil Cenozoic fauna and flora of Central Asia

Mongol names and toponyms are most often used by paleontologists for designation of new forms of fossil fauna and flora from the Cenozoic of Central Asia.