The temperature experienced by micro-invertebrates in extreme environments (such as those of Antarctica) is a pivotal parameter regarding these animals' ecology and physiology. However, at present, detailed knowledge of microhabitat physical conditions in Antarctica is limited, as well as being biased towards sub-Antarctic and Maritime Antarctic regions. To better understand the temperature conditions experienced in the microhabitats of Continental Antarctica by the native microfauna, we recorded temperatures year round in ponds and soils in an area of the Victoria Land coast and compared these measurements with air temperature data from the closest automatic weather station. We identified an important difference in temperature dynamics between the air, soil and pond datasets. Ponds were the warmest sites overall, differing by up to 7.5°C in comparison with the air temperature due to their greater thermal capacity, which also drove their patterns of freeze-thaw cycles and mean daily thermal excursion.

Pourriotia carcharodonta gen. et sp. nov. is described from freshwater plankton collected at the subantarctic Kerguelen islands. The new taxon is provisionally placed in the Notommatidae. Main diagnostic characters separating the new taxon and the other genera of the family are provided by the morphology of the trophi. Apical rami chambers with toothed inner margin and blunt projection on outer margin. Apical rami teeth and subuncinal teeth with accessory spines. Proximal margin of major uncinal teeth firmly connected to distal margin of apical chambers, forming grasping unit. Fulcrum dumb-bell-shaped. Information is presented on the trophi structure of the genus Pleurata (Notommatidae).

Limnognathia maerski, class Micrognathozoa, so far known only from Arctic Greenland, is reported from the subantarctic Crozet Islands. Fine morphology of the trophi is redescribed using scanning electron microscopy. Results show that the trophi are composed of the same functional units, i.e. incus, paired mallei and epipharynx, as found in Rotifera Monogononta. The zoogeography of the species is briefly discussed.

This study represents the first systematic investigation of long-term anhydrobiotic survival in tardigrades, rotifers and nematodes inhabiting mosses and lichens. Sixty-three different samples from public and private collections, kept dry for 9–138 years, were examined. Rotifers of the genus Mniobia and the eutardigrade Ramazzottius oberhaeuseri (hatched from eggs) were found alive from one of the samples (9 years old). These observations represent the longest record for rotifers in the anhydrobiotic state. For tardigrades, our results confirm previous reports on the upper limit of anhydrobiotic survival under atmospheric oxygen conditions. This study suggests the possibility that tardigrade eggs are able to withstand longer periods in anhydrobiosis than animals. Some problems related to the evaluation of long-term anhydrobiotic survival, such as contamination and chemical treatments of samples, are reported. The possible role of the microenvironment in which the anhydrobiotic animals are kept is discussed.

A preliminary study of the rotifer fauna of Ile Amsterdam (T.A.A.F.), southern Indian Ocean, yielded seven taxa. Brachionus amsterdamensis sp. nov. is described. Information on the morphology of the trophi of Brachionus dimidiatus is presented.

As part of a survey of the rotifer fauna of Burundi, Lecanidae from Kashira and the floodplain of the river Rusizi in Northwest Burundi are reported. Thirty-four species of Lecane were found. Twenty-five of them are new to Burundi, raising the total Burundian Lecane record to thirty-five. Three species, Lecane aeganea Harring, 1914, L. eswari Dhanapathi, 1976 and L. subulata (Harring & Myers, 1926) are new to the African fauna, the presence of L. baimaii Sanoamuang & Savatenalinton, 1999 in Africa is confirmed. The fauna consists mainly of cosmopolitan and tropicopolitan taxa, accompanied by several Eastern Hemisphere taxa, and one each of pantropical, endemic and arctic-temperate taxa. The latter, occurring in a high-altitude locality, may be a glacial relict.

Keratella mexicana is a recently described species, known from a few localities only. Here we present new information on the distribution and morphology of the species based on a survey of 104 water bodies in Central Mexico. The ultra structural morphology of the trophi and lorica of K. mexicana is studied using scanning electron microscopy (SEM).

We report on a comparative scanning electron microscopical study of trophi morphology of the two species making up the Class Seisonidea of Phylum Rotifera. The trophi of the two are generally similar, with morphological differences being interpreted as the result of adaptations to different food sources: the trophi of Seison nebaliae are adapted to particle-feeding, that of Seison annulatus probably functions by piercing the integument of the host using the fulcrum tip, and subsequently sucking out haemolymph. This difference in feeding ecology is believed to contribute to the co-occurrence of both species on the same host. A new hypothesis on the evolution of rotifer trophi is proposed.

The rotifer fauna present in Thale-Noi Lake, Pattalang Province, Thailand on the 16th September 1995 is reported. A total of 106 species, the majority of which belong to the genera Lecane (31 %), Lepadella (13 %) and Brachionus (9 %) are recorded. Cephalodella songkhlaensis n.sp. and Trichocerca siamensis n.sp. are described, Lecane calcaria Harring & Myers is redescribed. An additional fourteen rotifer species are recorded for the first time from Thailand. The genera Metadiaschiza Fadeew and Paracephalodella Berzins are synonymized with Cephalodella Bory de St. Vincent.

The rotifer fauna of twenty five localities (mainly shallow lakes) from Corrientes, Argentina was studied. 136 taxa were identified, 20 ofwhich, from the genera Lecane, Lepadella, Ploesoma, Ptygura, Squatinella, Testudinella and Trichocerca are new to the Argentine fauna. Most of these are (sub)tropical in distribution, and 8 % are endemic to South America. Ploesoma africana Wulfert, Ptygura kostei n.sp., Testudinella brevicaudata Yamamoto and Trichocerca vernalis Hauer are recorded from the Neotropical region for the first time. The rotiferan species richness of this area, is remarkable. The highest diversity was recorded from vegetated lakes, with acid waters, where one locality yielded 56 species.

Les rapports volumétriques entre l'œuf amictique (V0) et la femelle adulte (VA) sont établis et discutés chez 21 populations naturelles ou expérimentales appartenant à 15 espèces.Chez les Rotifères herbivores, la relation allométrique est décrite par l’équation : V0 = 3,62 VA 0,816. L'exposant de celle-ci est très proche de la valeur générale 0,75 reliant l'investissement reproductif à la taille. Une relation intraspécifique similaire est observée chez B. calyciflorus. Le ratio V0/VA est moins variable chez les Asplanchna ovovivipares dont le rapport du poids sec au poids frais (4 %) est notablement inférieur à celui des autres espèces ( > = 10 %).En outre, des relations allométriques similaires ont été calculées entre le volume des œufs de durée et celui des œufs mâles d'une part, et le volume de la mère d'autre part, chez, respectivement, sept et trois des espèces précédentes. Les écarts observés sont interprétés comme le résultat de contraintes sélectives différentes.

Stomach content analyses were performed on dwarf specimens of Asplanchna sieboldi collected on different dates in a shallow floodplain lake of the Orinoco River system. The results showed that the dwarf forms of A. sieboldi were highly selective on small Brachionids (Brachionus caudatus and Keratella americana). This observation confirmed on the carnivore status of these forms of the species. Considering the aleatory character of prey capture in rotifers, the high selectivity observed in A. sieboldi may be controlled by the abundance of the favoured small-sized prey. Under the conditions of the study, Asplanchna may be considered a stenophagous predator. The prédation pattern exhibited by the dwarf A. sieboldi under our tropical conditions was similar to the pattern exhibited by larger species of Asplanchna in temperate regions. In both regions, size and abundance of prey seem to control the food preferences of this planktonic predator.