In polar regions, apart from tundra and glaciers, geothermally active areas

with elevated temperatures are important elements of ecosystems. One such geothermally

active region characterized by mosaic ecosystems and vast areas covered by recent lava

fields is Iceland. The aim of our study was to explore the diversity of invertebrates

inhabiting geothermally active lava fields in the Krafla area (Iceland). Eight bryophyte

samples were collected from a warm surface, mainly from the steaming areas. We have

found Nematoda, Rotifera, Tardigrada and Oribatida in the samples. Habitat analysis

demonstrated there to be 12 bryophyte species (five liverworts and seven mosses).

The diversity of bryophytes in a single sample ranged from one to six species. The

most common bryophyte was Racomitrium lanuginosum (Hedw.) Brid. Four species

of tardigrades were found, including one that was new. Pilatobius islandicus sp. nov.

is described herein by morphological, morphometric and molecular approaches (COI,

28S rRNA, 18S rRNA). Oribatida mites were identified as two species (Malaconothrus

monodactylus (Michael, 1888) and Camisia foveolata Hammer, 1955). The average density

of invertebrates was 13.1 ind./g with a maximum of 40.8 ind./g calculated per dry

material. The tardigrades found in our study belonged to herbivores, microbivores and

omnivores, whereas the mites belonged to saprophages, which indicates complex trophic

networks in geothermally active lava fields.

Plant parasites of the genera Longidorus Micoletzky, 1922 and Paralongidorus Siddiqi, Hooper and Khan, 1963 comprise a group of plant root ectoparasites, some of which are known as pests of economic importance. Their importance is further augmented by the fact that several species are known to be vectors of nepoviruses. To date 16 species from the genus Longidorus and two from Paralongidorus have been recorded in Poland. Despite their economic importance in agriculture currently there is no regional key for species identification. This paper presents such a key. The key has many illustrations and is based mainly on traits which are easily observable even by less experienced users. Thus, it should provide a useful tool for both scientists and specialists working in the field of plant protection, soil ecology and zoology as well as for teaching purposes.

In total, 18 species and larval forms of endoparasitic worms were found in 19 newly examined notothenioid fishes of three species, Trematomus hansom, Notothenia coriiceps and Chionodraco hamatus, caught off Adelie Land. One digenean species, Neolepidapedon trema-tomi, was recorded in this area for the first time. A total list of endoparasitic worms prepared by Zdzitowiecki etal. (1998) increased from 20 to 21 species and larval forms and concerns 11 deter­mined and one determined species of Digenea (the most diverse group), three larval forms of Cestoda, three species (one identified only to genus) of Acanthocephala, two species (one in the larval stage) and one larval form of Nematoda. All these species and forms, with the exception of the indetcrmined digenean, occur also in the deep Antarctica, in the Ross Sea and/or in the Weddell Sea. The prevalence and relative density of infection with each parasite in three host species is given based on summarized previous and new data.

Nematoda, Tardigrada, Rotifera and Crustacea composition in different freshwater habitats on Spitsbergen (Arctic) and King George Island (Antarctic) was presented. In all surveyed groups more genera and species were recorded from Spitsbergen than from King George Island. Habitats richest in taxa were moss banks and thaw ponds, whereas streams were poorest in species. In all groups in both regions cosmopolitan species dominated, but higher number of endemic species was recorded on King George Island. Regarding species composition in surveyed groups it can be suggested that freshwater habitats on Spitsbergen are more similar to each other than those on King George Island.