The invasive sabellid Branchiomma bairdi (McIntosh, 1885) was collected in the Estany des Peix lagoon (Formentera Island, Balearic Sea, Western Mediterranean). This species is native to Bermuda (Western Atlantic Ocean), being widely distributed through the Caribbean Sea. However, it has been described as invasive worldwide, being also present in the Indo-Pacific region, the Eastern Atlantic Ocean and the Mediterranean Sea. We here provide the first record of the species for the Balearic Sea, together with a comparison to other morphologically similar alien species, Branchiomma boholense (Grube, 1878), which is supposed to have also been introduced in the Mediterranean basin. We also include comprehensive taxonomic descriptions of both taxa based on the type material, a dichotomous key for the Mediterranean species of Branchiomma and hypothesize the most likely way of introduction of B. bairdi in the Balearic region.

A multiple access key, or polyclave, and a traditional dichotomous key were constructed for the identification of 40 species of weed seedlings. The polyclave contained 3.4 times more information than the dichotomous key; however, there was no difference in the frequency of accurate identifications or in the time required to make accurate identifications using either system. The relative values of traditional keys and polyclaves for weed seedling identifications are discussed.

Eight new species of Lecideaceae are described from the southern subpolar region: Bryobilimbia coppinsiana Fryday, a saxicolous species with one septate ascospores (Campbell Island, New Zealand); Immersaria fuliginosa Fryday, with a thallus composed of thalloconidia (Falkland Islands); Lecidea aurantia Fryday, with an orange thallus (Auckland Islands, New Zealand); L. campbellensis Fryday, with an endolithic thallus and apothecia resembling those of a species of Porpidia (Campbell Island); Poeltiaria ochyrae Hertel, which is similar to P. subincongua but with a thick areolate thallus (South Orkney and South Shetland Islands); P. tasmanica Fryday, which is similar to P. urbanskyana but with smaller ascopores (Tasmania); Poeltidea inspersa Fryday with an enolithic thallus and a hymenium with large oil globules (Falkland Islands); and Porpidia vulcanoides Hertel & Fryday with immersed apothecia with a thick margin and large ascospores (SW Chile). Lecidea kalbii Hertel is resurrected from the synonymy of L. mannii Tuck. and treated as a distinct species. The circumscription of genera within the Lecideaceae is also discussed: Poeltiaria is shown to be heterogeneous, and the genera Labyrintha and Notolecidea are reduced to synonymy with Poeltidea and Poeltiaria respectively, and the new combinations Poeltidia implexa (Malcolm et al.) Hertel & Fryday and Poeltiaria subcontinua (Hertel) Hertel & Fryday made. A key to the genera of Lecideaceae s. lat. is provided.

The aquatic larvae of the Diptera are often the most abundant and most diverse group of the benthic macroinvertebrate fauna.They are able to survive in and colonise practically all freshwater habitats, and some species can tolerate harsh environmentalconditions. They are therefore both a qualitatively and quantitatively important group of biological indicators for assessing freshwatersystems. On the other hand their determination at the species level is very difficult. This is in part due to a lack of taxonomicwork in the group, but also the absence of comprehensive determination keys, that meet the needs of water managers. Asa result, the aquatic larvae of the Diptera often play a subordinate role in water management. In light of the EU Water FrameworkDirective the present work is a first step in improving the integration of the important group of the Diptera in water managementpractice: a comprehensive determination key, which is geared at water managers. The key includes 60 taxa, largely at the familyand genus level. In contrast to already existing keys the present work tries to differentiate the taxa on the basis of simple anduser-friendly characters. Numerous figures allow for easy checking of determination results. The key is applicable in Germany,Scandinavia, Great Britain and the Benelux states. Mainly taxa from running water systems are considered, but the key can alsobe used at the family level to determine taxa from standing water bodies.

Computer programming is ideal for the identification of ticks. This is due to the ability of computers to make rapid, repeated and complete searches of a large database of features in answer to a series of questions which lead to a single species. The program can allow the search to start in any order and to avoid difficult questions. It enables illustrations to be displayed when a question is asked. In contrast, classical dichotomous keys need to be used in a fixed sequence in which it is difficult to avoid questions, and often use vaguely defined characters and obscure language. To program an electronic key a character state matrix is constructed of rows of precisely defined characters with the two or more states in which they may occur and of columns in which the species are placed. Each state is recorded as being positive or negative. This corresponds to the binary system needed for computing and this need enforces a discipline on the identification method that has to define in illustrations and precise standardized language the characters and their states. These concepts are illustrated by the development of ‘Multikey’ program for the identification of ticks of domestic animals in Africa. The advantages of Multikey are its ease of use, its compatibility with comprehensive tick guides on compact discs and the ability to expand it with more information. The disadvantages are the requirement for a computer next to the laboratory microscope and the difficulty in browsing the contents. These disadvantages can be overcome by a printed version and there is use for both the printed and the electronic versions of such guides.