Summary:For 113 species of Oligochaeta living in Europaean freshwaters data on the saprobic valence, the indicative weight of species and the individual saprobic index were given. The big majority of Oligochaeta is hardly determinable and needs special morphological and anatomical studies. The few easily recognizable species were figured. Oligochaeta show a relatively wide ecological valence so that their application for determining the degree of saprobity should be conplcd with the specific determination of the other members of the benthic community. General descriptionAquatic oligochaetes (OligochaetaLimicola) are not a taxonomical but an ecological group of annelid worms. There are strictly or "primary" aquatic (in the sense of ~EKANOVSKAJA, 1972) families as Aelosomatidae, Naididae, Tubificidae and Lumbriculidae and only few "secondary" aquatic genera and species from the families Enchytraeidae, Lumbricidae, which are considered semiaquatic or amphibious.The body is clearly divided into segments separated externally by distinct groves. The number of segments is variable: Aelosomatidae arid Naididae have between 7 and 40, Tubificidae 40 and BOO, Haplotaxidae u p t o 500. On each of the segments (except of the first ones = peristomiurn) there are chitinoid setae arranged into 4 bundles, two dorsolateral and two ventrolateral. The detailed shape and structure of the setae and their arrangement serve for determination. A bundle consists of one to 20 setae.The majority live i n or on the mud, sludge, sediments and debris on the bottom, among the macrophytes and within filamentous algae in standing and running waters. They show a crftwling movement on the superficial layers, but many Naididae (Dero, Nuis, Pristinu, Styluriu) are able to swim for a short period, but always in the vicinity of the substrate.Usually the Oligochaeta possess no respiratory organs and respirate by the whole body surface. Only few species have gills either at the posterior end (Dero, Aulophwus) or along the sides of the segnients(Bmnchiziru). The gills must be observed in theliving state, since they contract during fixation. Many oligochaets build tubesfrom organic material and fine debris and live inside, projecti~g over the posterior ends. Theless oxygen is in the water, the more vigorous are their waving moverneiits t o circulate the water and make more oxygen available for respiration. Some species are able to withstand the complete lack of oxygen perhaps rip to 4 weeks.

Freshwater leeches (Annelida: Clitellata: Hirudinida) of the Czech Republic were studied on the basis of recent literature, information in selected databases, and results of recent surveys conducted by the authors. The objectives of this study were to summarize recent taxonomic information, and to update the check-list of leeches using records collected during an eleven-year study (1998 through 2008). Altogether, twenty-four species representing 12 genera and five families are reported for the Czech Republic, including the first reports of Piscicola cf. haranti Jarry, 1960 and Dina punctata Johansson, 1927 for the country. A detailed description of the distributions of rare species and characterization of localities from which they are reported are presented. Plausible modes of dispersal and propagation of species in Central Europe are discussed. According to recent records, leech species are divided into three groups: indigenous species with stable and strong populations (12 species), indigenous species with weak populations known from a limited number of localities (9 species), and species only recently recorded in the Czech Republic (3 species). For scarce or rare species, a category of threat in the Czech Republic according to the International Union for Conservation of Nature is recommended. Most of threatened species are inhabitants of lowland wetlands and lowland larger rivers—habitats that are negatively impacted, often catastrophically, by human activities throughout Central Europe. The protection of suitable habitats is the most effective way to protect extant populations of endangered leech species. Six species of leeches are recommended for permanent addition to the Red list of threatened species in the Czech Republic.

Summary: For the 33 species of Hirudinea in the fresh waters of Central Europe the following saprobiological data are given : saprobic valency, indicative weight and specific saprobic index.A detailed key is established for determining the 33 species, with a large number of pictures. All the species have a relatively wide range of ecological valency, so that their application for determining the degree of saprobity is meaningful only in connection with different types of indicators. General descriptionThe leeches (Hirudinea) are annelid worms with a phylogenetical relation t o Oligochaeta. They lead a predatory or parasitic way of life and possess two terminal suckers which serve in attachment, locomotion and feeding. All leeches are composed of 34 true segments, but each segment is subdivided into a definite and constant number of superficial annuli =rings ranging from 3 to 14 in different species. The annulus can be easily seen on the body surface, but the true segments are hidden andcan bedetected by a study of the nervous system. Each of the 34 segments is represented by a ganglion and paired nerves, but these structures can be crowded together andpartially fused at both ends of t h e animal. The anterior or head sucker surrounds the mouth and bears the principal eyes. The caudal or subanal sucker is larger than the head, is complexly muscular, discoid and capable of great changes in shape when detached (MOORE; PXNNAK; MANN 1564; SFEGOLEV; LUXIN 1577). The pharynx of the families Glossiphonidae and Piscicolidae is modified to form an eversible proboscis. I n the families Hirudinidae and Erpobdellidae the mouth is a wide aperture occupying the whole of the anterior sucker. The Hirudinidae have cuticular teeth in their mouths, Erpobdellidae do not have them. The alimentary canal has a crop, which is dilated for the storage of food. I n the sanguivorous leeches it is drawn out into lateral diverticula, which can be clearly seen in smaller and more transparent species after a meal of blood.The individual species are characterized by the colour, although it is quite variable, and it is very useful for determination. Many species show bright colours with a characteristic pigmentation pattern, e. g. dots, spots, lines and stripes. The ventral surface is almost paler than the dorsal one. Young leeches range from translucent t o opaque and the characteristic pigmentation is not yet developed, adults show bright colours. After preservation the colours quickly fade mainly if kept in alcohol or on light. 32*

The leech Dina punctata JOHANSON, 1927 inhabits various types of running waters. This species appeared in Slovakia probably after the first Rhine-Main-Danube canal was built. Because little is known about its ecology, the aim of our study was to analyze the life cycle, individual growth rate, reproduction parameters and food composition of D. punctata in the Vydrica Stream. Samples of leeches were taken mainly each month from April 2003 to November 2004. The leech D. punctata had maximal 2-year life cycle there. Mature leeches, which were recognized by the presence of clitella, were present from April to the end of August. The most individuals mature at the age of 1 year. The breeding season of D. punctata peaks in June. The number of eggs per one cocoon is from 3 to 12. The mean successfulness of development of egg to embryo is 58%. Larvae from the family Chironomidae (28%), Gammarus fossarum (20%) and oligochaetes from the subfamily Naidinae (17%) are the dominant components of the feeding niche.