In 2006 an unusual find of Procambarus clarkii, today considered one of the most dangerous exotic crayfish, was made within the preserved brackish Mediterranean biotope ''Palude di Torre Flavia'' (Rome, Italy). Here the investigation on the population structure and dynamics of P. clarkii inhabiting this brackish wetland is presented in an attempt to describe the life history pattern in this type of habitat. The present study showed that this species has a lower growth rate and higher longevity than other studied European P. clarkii populations, and that it can damage brackish habitats and human livelihoods. The main results of this study chiefly concern the differences found between several lifehistory parameters of the studied population and those obtained in previous studies. These results showed the high ecological plasticity of P. clarkii, indicate the need to intervene before the species spreads further in brackish water, for the conservation of Mediterranean coastal habitats.

This study aimed to improve our knowledge of the population status and dynamics of Austropotamobius pallipes, by applying length-based fish stock assessment approaches based on the analysis of polymodal size-frequency distributions and mark-recapture datasets. Analysis of nearly 8000 crayfish collected from May to October of the years 2001-2004 showed a well-structured population and a low growth rate, the latter showing evident seasonality in both sexes (with high value of amplitude and winter point). Moreover, sexual differences were found, because females have higher growth rates than males. This analysis also showed that A. pallipes is a long-lived species, with an expected lifetime of 10 years, and a mortality rate affected by illegal harvesting. The results obtained in this study by length-frequency analysis are the same as those obtained by approaches based on recapture. Statistical evidences showed that the growth rate is affected by latitude, the former increasing with a decrease of the latter, probably as a result of the associated different environmental and climatic conditions. Dynamics studies are useful for planning monitoring, and could have a role in introduction programmes and control of reintroduced individuals during any restocking project. Considerations of population dynamics can be used to derive generalizations on the stress and exploitation grade of a stock, based on the concept that dynamics are strictly related to biological processes and to the adaptation of a species to its habitat. Through a survey of a body size, it is possible to avoid the use of invasive techniques for ageing crayfish and recapture methods that can cause a certain degree of stress. We discuss and underline the importance of using polymodal frequency analysis in order to determine important parameters in population structure and dynamics and further population properties of great usefulness for the monitoring and preservation of threatened crayfish.

A geometric morphometric analysis was carried out on the crania of 13 species of elephant-shrews (Macroscelidea), a group of African mammals whose phylogeny is still debated. The material examined consisted of 313 crania and included all the genera of Macroscelididae, the unique family recognized by taxonomists. The results obtained from the analysis of the cranium shape and size, either from dorsal or lateral view, were very similar. The Wrst one appeared more reliable because of the higher number of intersection points Wxed between the cranial sutures. All the cranial features that distinguished the genus Rhynchocyon were a consequence of the extreme enlargement of frontal bones. Instead, within the subfamily Macroscelidinae, the diVerences between genera were based on modiWcation involving other bones, mainly mastoids and nasals, as shown by the deformation grids. A cluster analysis conWrmed the traditional subdivision in two subfamilies (Rhynchocyoninae and Macroscelidinae) but suggested a diVerent relationship among the recognized genera belonging to Macroscelidinae. Our results are congruent with data obtained from previous biochemical research and support the traditional subdivision in two subfamilies, the monophily of the genus Elephantulus and its closeness with Petrodromus, relating to their similar cranium shapes. The latter presumably is a case of gigantism as adaptation to forest habitats. Further studies on all the species of Elephantulus could provide new evidence for assessing the relationships within this clade, including Macroscelides that by the present analysis appeared as a well-distinguished taxonomic entity.

Biological invasions inflict damage to the ecology, economy, and human health, and pose serious threats to the native communities. Among the many invasive taxa, crayfish have attracted much attention by scientists and policy makers. Recently, an established population of an alien species of crayfish, new for Italy, was found in the Natural Preserve of ''Laghi di Ninfa'' (central Italy). Based on morphological and genetic evidence (molecular barcoding of COI and 16S rDNA), we classified it at subspecies level as the Parastacidae Cherax destructor destructor, native to Australia. Its introduction possibly occurred at the end of the 1980s but the species seems to be still confined in the preserve. The low temperature of the adjacent waters may be a barrier against its natural spreading but not against its intentional translocation into natural waters by man. Because of the invasive history of C. destructor, eradication of this population is urgent and still economically profitable.

Attributing the term bioindicator to a species complex such as Austropotamobius pallipes is complicated, considering that the meaning given to a bioindicator can vary according to the geographic position, and that A. pallipes species complex has been divided into 2 species and 5 subspecies, the possibility of using A. i. meridionalis as a bioindicator in watercourses of Central Italy was evaluated. To this end, we analysed the structure and abundance of a number of crayfish populations and then compared them to the water quality of the corresponding watercourses, using E.B.I. (Extended Biotic Index). This index provides information on water quality through an analysis of the macrobenthos community. The watercourses are assigned to various classes (from I to V, increasing the degrees of alteration). This study was carried out in several watercourses near Rome. The abundance of crayfish was found to be greatest in those tracts that are assessed as class I, where the populations seem well structured with individuals of various sizes and the sex ratio is approximately 1:1. In contrast, in class II we found a reduced presence of specimens, mostly in bad conditions. No crayfish specimens were observed in watercourses designated as class III. In light of these preliminary results, it does not seem possible to consider A. i. meridionalis as a bioindicator, given that one of the typical characteristics of a biological indicator (wide distribution) is not met. Though these results illustrate the possibility of using A. i. meridionalis populations as an excellent monitoring instrument in Central Italy. Key-words:Austropotamobius italicus meridionalis, bioindicator, monitoring instrument, water quality. AUSTROPOTAMOBIUS ITALICUS MERIDIONALIS PEUT-ELLE ÊTRE UTILISÉE COMME INSTRUMENT DE SURVEILLANCE EN ITALIE DU CENTRE? OBSERVATIONS PRÉLIMINAIRES RÉSUMÉ