Structure, Bioadhesive Distribution and Elastic Properties of the Agglutinated Test of Astrammina rara (Protozoa: Foraminiferida)

ABSTRACT. The fine structure, elastic properties, and distribution of the fibrous, meshlike cement (bioadhesive) were studied for the test of the antarctic agglutinated foraminiferan Astrammina rara. Grain-size analysis of particles incorporated into the test compared with adjacent sediment indicates that A. rara is grain-size selective. Fractured tests curl inward, suggesting that the test is under tension—an impression substantiated by micromanipulation observations. Changes in test appearance were examined by scanning electron microscopy after sequential chemical treatments combined with ultrasonication. Organic fibrils securing fine-grained particulates on the test exterior were removed during initial sonication. A veil of fibrous organic material lining the test interior (i.e. inner organic lining) was removed by treatment with a nonionic detergent, revealing ligamentous cables of bioadhesive securely joining large grains. These cables are partially disrupted by treatment with sodium dodecyl sulfate, and further disrupted by disulfide reducing agents, suggesting that protein is an integral adhesive component. The large detrital grains incorporated into the test are arranged in an interlocked, optimally packed fashion. Together, these observations indicate that the seemingly simple spherical architecture of A. rara's test is in fact quite complex, consisting of large grains compressed by tensile cables of a proteinaceous bioadhesive, with additional rigidity supplied by fine particulate "mortar" deposited externally.     

Field experiments on the relationship between drift and henthic densities of aquatic insects in tropical streams (Ivory Coast). III Trichoptera

SUMMARY. 1. Based on in situ gutter trials we related the drift of caddis flies to their benthic densities and to various abiotic factors in streams in the Ivory Coast (West Africa). Members of the families Hydropsychidae, Philopotamidae. Hydroptilidae and Leptoceridae were considered in detail.
2. The drift of larvae peaked at night in both early and late larval instars.
3. Drift of a larval group (a certain instar, species or higher taxon) was more often related to the benthic density of other larval groups than to its own benthic density.
4. Self-regulation of an upper benthic density of a larval group by emigration through drift was not statistically evident.
5. There was no straightforward relationship between drift and abiotic factors.
6. Drift rates differed between taxa as well as between larval instars (size groups) within a taxon. Newly hatched larvae had very high drift rates, whereas the last larval instar usually had the lowest drift rate.
7. We related these results to the violently fluctuating discharge of the streams in the study area and the consequent variability of space for lotic insects.
8. Drift estimates, made at the same time as a monitoring programme on possible side-effects of insecticides (Onchocerciasis Control Programme), failed to reflect benthic densities except in the night drift of Hydropsychidae.     

On the distinction between Modisimus and Hedypsilus (Araneae, Pholcidae), with notes on behavior and natural history

Evidence is presented that the genera Hedypsilus Simon, 1893 and Modisimus Simon, 1893 are subjective synonyms. Precedence is given to Modisimus over Hedypsilus. The type species of both genera (M. glaucus Simon, 1893 and H. culicinus Simon, 1893) are redescribed. Hedypsilus lawrencei Lessert, 1938 is synonymized with Hedypsilus culicinus Simon, 1893. It appears to be a pantropical, synanthropic species. Preliminary notes on its natural history are presented. Two closely related new species are described, Modisimus simoni sp. n. (Venezuela) and Modisimus david sp. n. (Central America). Modisimus globosus Schmidt, 1956 (Colombia?) is redescribed and illustrated for the first time. Notes on the usefulness of the curvature of eye rows and of leg formulae for the systematics of pholcids are given.     

MOLECULAR PHYLOGENY AND THE GEOGRAPHIC ORIGIN OF HALIOTIDAE TRACED BY HAEMOCYANIN SEQUENCES

Phylogenetic relationships of 12 species of the vetigastropodfamily Haliotidae were analysed on the basis of partial haemocyanincoding genes. Both protein-coding and genomic sequence data,of which the latter includes one ancient intron, were analysed.We were able to distinguish two genetically different monophyleticgroups with high bootstrap support: (i) the abalones from Europe,South Africa, Australia, Taiwan and Japan group together andare separated from (ii) five California and two Japanese abalones.The usefulness of haemocyanin as a phylogenetic character andthe origin of the Haliotidae are discussed. (Received 4 March 2005; accepted 4 July 2005)