Key For The Identification Of Mediterranean Brachyuran Megalopae

Based on larval literature, an identification key has been constructed for the megalopae of 55 species of Mediterranean Brachyura. This key is based mainly on external morphological characteristics visible, by using a microscope, limiting the necessity for dissection of specimens. Characteristics used include presence/absence of ornamentation on the carapace, number of abdominal somites, number and position of setae and/or spines on antennula, antenna, pereiopods and structure of uropods, etc. Partial dissection is only required to count the setae on the scaphognathite margin. Using the above characters, it is also possible to gather almost all the families into groups. However, the megalopae of Portunidae as well as those of the three species of Brachynotus genus are similar to each other and their identification at a specific level requires the use of features somehow variable and difficult to count. In the Majidae, the megalopae of 14 species are already known. The complexity of morphological characters typical of this family makes it difficult to define characters common to all spider crab megalopae. Nevertheless, the key may be an aid for carcinology studies, especially those including sorting and identification of megalopae from plankton samples

Morphology of the megalopa of the mud crab, Rhithropanopeus harrisii (Gould, 1841) (Decapoda, Brachyura, Panopeidae), identified by DNA barcode.

The morphology of the megalopa stage of the panopeid Rhithropanopeus harrisii is redescribed and illustrated in detail from plankton specimens identified by DNA barcode (16S mtDNA) as previous descriptions do not meet the current standard of brachyuran larval description. Several morphological characters vary widely from those of other panopeid species which could cast some doubt on the species’ placement in the same family. Besides, some anomalous megalopae of R. harrisii were found among specimens reared at the laboratory from zoeae collected in the plankton. These anomalous morphological features are discussed in terms of problems associated with laboratory rearing conditions

Modelling habitat requirements of white-clawed crayfish ( Austropotamobius pallipes

The white-clawed crayfish’s habitat has been profoundly modified in Piedmont (NW Italy) due to environmental changes caused by human impact. Consequently, native populations have decreased markedly. In this research project, support vector machines were tested as possible tools for evaluating the ecological factors that determine the presence of white-clawed crayfish. A system of 175 sites was investigated, 98 of which recorded the presence of Austropotamobius pallipes. At each site 27 physical-chemical, environmental and climatic variables were measured according to their importance to A. pallipes. Various feature selection methods were employed. These yielded three subsets of variables that helped build three different types of models: (1) models with no variable selection; (2) models built by applying Goldberg’s genetic algorithm after variable selection; (3) models built by using a combination of four supervised-filter evaluators after variable selection. These different model types helped us realise how important it was to select the right features if we wanted to build support vector machines that perform as well as possible. In addition, support vector machines have a high potential for predicting indigenous crayfish occurrence, according to our findings. Therefore, they are valuable tools for freshwater management, tools that may prove to be much more promising than traditional and other machine-learning techniques