The present edition of the “Polish Red Data Book of Animals” was based on the same criteria and principles as those recommended recently by the IUCN/WCU (e.g. Species, 1999 no. 31-32, 2004 no. 41) and adopted in the first volume of the PRDBA concerning vertebrates (Głowaciński ed. 2001). Differences exist only in the layout of species accounts (description of population state and threats), which has been adapted to the specific character of the group. As compared to the first part of the PRDBA (2001) the layout of species accounts has been simplified and the cartographic record limited exclusively to the area of Poland. The categorisation of taxa within the group of Extinct species and species of Lower Risk was also slightly simplified. The present volume of the PRDBA concentrates on the three phyla of invertebrates: molluscs Mollusca, arthropods Arthropoda and annelids Annelida. Most attention is paid to the arthropods, and particularly to insects Insecta.
The Book covers principally native and autochtonous taxa. The only exception is Lithoglyphus naticoides, an allochtonous species, whose range has notably increased during the last several centuries, and which appeared in Poland as the result of expansion enabled by man (construction of canals linking the drainage basins of rivers; development of water transport). However, this snail has recently been observed to withdraw from the occupied area, primarily due to water pollution, becoming the example of a species which at first profited from civilisation changes, expanding its area, and next, declined due to the destructive influence of anthropogenic factors.
Certain doubts may concern the inclusion of some species which have relatively strong populations and occur at many locations in our country but quickly retreat from other areas of Europe. A good example may be the large copper Lycaena dispar, a butterfly which has become extinct or is on the brink of extinction in many Western European countries. Therefore, relatively large and not threatened Polish populations of this butterfly may fulfil an important role in the species restitution and should be treated as a source of individuals which may strengthen dying populations. In view of this, they deserve special attention and care. Similar is the case of a beetle Aulonothroscus laticollis.