Mollusca

Wiwaxia is a bizarre metazoan that has been interpreted as a primitive mollusc and as a polychaete annelid worm. Extensive material from the Burgess Shale provides a detailed picture of its morphology and ontogeny, but the fossil record outside this lagerstätte is scarce, and complete wiwaxiids are particularly rare. Here we report small articulated specimens of Wiwaxia foliosa sp. nov. from the Xiaoshiba fauna (Cambrian Stage 3, Hongjingshao Formation, Kunming, south China). Although spines are absent, the fossils' sclerites – like those of W. corrugata – are symmetrically arranged in five distinct zones. They form rows across the body, and were individually added and shed throughout growth to retain an approximately symmetrical body shape. Their development pattern suggests a molluscan affinity. The basic body plan of wiwaxiids is fundamentally conserved across two continents through Cambrian Stages 3–5 – revealing morphological stasis in the wake of the Cambrian explosion.

"Mollusks are fascinating organisms, present in almost all ecosystems, and part of human history since pre-historic times. They are eaten, cultivated, and their shells are used in all kind of purposes, from tools to decoration and collection. Despite this importance, the biological knowledge on the mollusks is proportionally weak. The systematics of some groups, in particular, is so problematic that precludes the advance of other biological fields.The knowledge on the malacological reproductive strategy is vital, as it is essential part of the organism’s continued existence. The understanding and comparison of strategies gives important clues at least on the
adaptation to the environment, phylogeny and to perform policy for Nature conservation. This scenario is just the main goal of this volume, in such the reproductive strategy of some key Brazilian species are described and fine illustrated, in order to provide to the interested readers a rich database for identification and to improve their knowledge. In most cases, both the egg capsules and the larval-young phases are included. This is inedited in Brazil and is an indiscussible advance to the local and global Malacology. Securely, this book, which reunites an impressive assemblage of malacologists, is a mark, and will raise a lot of new studies and workings on so
fascinating members of our devastated ecosystems."

The distribution, body composition, growth rate, and population structure of Unio terminalis were measured at different sites of Lake Kinneret (Israel). Maximum clam density was found on the muddy sand between 0.3–6 m depth. Clams were most abundant in the River Jordan inlet zone, where they showed the highest growth rate. This was probably related to both highest food availability and the highest density of fish hosting Unio glochidia in this area. U. terminalis in Lake Kinneret has a more massive shell and ash content as compared with the European Unio species. The annual P/B ratios of U. terminalis populations at different sites were similar and ranged within 0.17–0.18. The computated filtration capacity and energetic budget permit the assumption that the U. terminalis population plays a substantial role in removal of organic particles from the water in the Kinneret shallow inshore zone (up to 15 m depth), and in nutrient recycling.

"The globally significant Caucasus hotspot of biological diversity holds a rich and largely endemic fauna of land molluscs. Georgia holds the majority of these regional endemics. Land molluscs are particularly sensitive indicators of habitat quality and faunal diversity. In this study, we examine the extent to which the existing network of protected areas (PAs) within Georgia captures the hotspots of endemic molluscan diversity. We collected and mapped the records of Georgian and Caucasian endemic species onto a 20 × 20 km2 UTM grid to identify the most important endemic areas in Georgia. We related these to the existing network of PAs. Less than half of the richest grid cells included significant PAs. Although those endemics with the smallest known ranges were better protected than the remainder, the incomplete state of knowledge means that our estimates of existing protection are surely optimistic. To date, the designation of PAs in Georgia has not used distributional data for invertebrates, although elsewhere they have been shown to be an effective aid to planning and management for conservation. Further surveys of molluscs and their monitoring in existing PAs can and should inform a systematic conservation strategy in Georgia.
"

"The Mediterranean area is the locus of a variety of deep-sea chemosynthetic environments that have been exploited by bivalves of the family Solemyidae during Cenozoic to present time. Large solemyids represented by the Solemya doderleini group were widely distributed in Neogene deep-sea reducing habitats, including cold vent hydrocarbon sites. Based upon the diagnostic structure of the ligament, Solemya doderleini (Mayer), 1861 and S.
subquadrata (Foresti), 1879 are moved to the genus Acharax Dall, 1908. After the Messinian Salinity Crisis Acharax doderleini re-colonized deep-sea sulphide environments up to the Pliocene at least. At present, Acharax occurs in similar settings in the adjacent eastern Atlantic Ocean. Thus far, large solemyids are not documented from the present deep Mediterranean Sea in spite of a vast number of seep and reducing habitats with chemosynthetic biota, especially concentrated in its Eastern basin. Promisingly, however, a single live juvenile specimen of Solemyidae has
been recently found at bathyal depth associated with a pockmark in the Nile Deep Sea Fan."