Trochonerilla mobilis gen. et sp.n., a meiofaunal nerillid (Annelida, Polychaeta) from a marine aquarium in Moscow

A nerillid species new to science is described from the marine aquarium system of Moscow Zoo. Trochonerilla mobilis gen. et sp.n. is characterized by eight chaetigerous segments, three antennae, absence of palps, parapodia with two bundles of simple chaetae and pygidium with two anal cirri. In contrast to other eight-segmented nerillids, Trochonerilla mobilis are very active and mobile animals. They are also able to swim through the water column by means of the strong ring of cilia on the first chaetigerous segment. Their geographical origin is unknown.     

Intraspecific selective survival within variably uniplicate Late Devonian brachiopods

The central fold of the Late Devonian brachiopods Cyrtospirifer monticola, Cleiothyridina devonica, Rugaltorostrum madisonense, Sinotectirostrum banffense and Trifiodorostellum dunbarense (Three Forks Formation, Central Idaho) varies intraspecifically from nearly rectimarginate or weakly developed to chevron-shaped. Frequency of central fold morphotypes through succesSjve size classes indicates selective survival in favor of variants with a strongly developed central fold, although morphotypes with the most extremely developed central fold never numerically dominate the larger size classes of any species. Differential mortality among the morphotypes can be attributed to: (1) less resistance to shell fracture by morphotypes with weakly developed uniplicae which were preferentially culled out of the population by durophagous predators, (2) less efficiency of weakly uniplicate morphotypes in the generation of nutrient-bearing eddies against the downcurrent inhalant margins. Failure of the morphotypes with the most strongly developed uniplicae to numerically dominate adult (largest) size classes is attributed to the hydrodynamic instability of such shell geometries on current-scoured substrates.     

Impact of parasitic mite infection on a terrestrial snail

Summary

Although parasitic infections have been shown to be critical for growth, reproduction and survival of many vertebrates, little is known about the impact of parasites on invertebrate hosts and particular on molluscs. Therefore, it is of interest how parasites may affect their invertebrate hosts and how hosts can manage the detrimental effect of infections. In the present study, the naturally widespread parasitic mite Riccardoella limacum, which has been suggested to play an important role in the ecology of the land snail Arianta arbustorum, was artificially transferred to A. arbustorum. We experimentally examined the effect of the parasite on the food consumption, shell growth, and survival of its host. Surprisingly, we found minor impacts in some traits, i.e. we found that infected and uninfected snails similarly completed their shell growth, attained sexual maturity, and allocated equal energy into their albumen glands. However, infected snails consumed less and showed a significantly higher mortality after winter than uninfected snails.     

Isolation of five polymorphic microsatellite markers in Utetheisa ornatrix (Lepidoptera: Arctiidae)

We isolated five polymorphic microsatellite markers for the arctiid moth Utetheisa ornatrix as part of an effort to investigate the role of inbreeding in the degree of polyandry seen in natural populations of the moth. We tested the primers on 105 individuals collected from scrub habitat in central Florida. These microsatellite loci provide a new research tool for understanding the population structure and reproductive behaviour of U. ornatrix.