We documented the existence of a population of the southern Caribbean pontarachnid mite Litarachna caribica for the first time on the Pacific coast of Panama. Based on morphological observations, this is the first record of a pontarachnid mite with a trans-isthmian distribution, which can be explained by either modern biological dispersal or historical vicariance hypotheses. Litarachna caribica had either passed through the Panama Canal, successfully colonizing the opposite coast, or previously continuously distributed populations had become disjunct after the rise of the Central American land.

The morphology of the larval stages of Arrenurus biscissus, A. pugionifer and A. bisulcicodulus is described. The three species belong to the subgenus Micruracarus and share several characters. The larvae of the three species differ in the shape of the dorsal plate, shape of the excretory pore plate, ratio between length of coxal plate median margins, and the numbers of pectinating setae on fifth palpal segment (PV). The larva of A. biscissus is very similar to the closely related A. sinuator. Larvae of A. pugionifer and A. bisulcicodulus resemble other Micruracarus species (A. bifidicodulus, A. inexploratus, A. integrator).

A catalogue of the water mites of the genus Neumania Lebert is given for the countries surrounding the Mediterranean Sea. Morphological details and taxonomical position are discussed. For each species, geographical distribution and habitat preference are given. The following synonyms are established: Neumania algeriensis Bader, 1989 = N. seurati Walter, 1931; N. atlantida Lundblad, 1942 = N. uncinata Walter, 1927. The synonymization of N. agilis Koenike, 1916 with N. limosa (Koch, 1836) is confirmed. Due to incomplete description and lack of type material, N. vietsi Husiatinschi, 1937 should be considered a species incerta. The following first records are given for national faunas: Neumania elliptica (France, Italy); N. phreaticola (Italy, Slovenia); N. uncinata (Greece, Israel, Italy, Bosnia and Herzegovina, Montenegro).

The larval morphology of 20 water mite species from Alpine springs is described, with that of Protzia distincta, Tartarothyas romanica, Sperchon mutilus, S. resupinus, S. violaceus, Bandakia concreta, Lebertia cuneifera, L. lativentris, L. sefvei, Atractides adnatus, A. panniculatus, A. macrolaminatus and A. walteri being presented for the first time. For the other 7 species (Panisus michaeli, Panisopsis curvifrons, Thyas palustris, Partnunia steinmanni, Sperchon thienemanni, Lebertia zschokkei and Hygrobates norvegicus), old descriptions exist but, in most cases are not accurate enough to be usable in taxonomy. These species have therefore been re-described. Some general observations on larval morphology and taxonomy are discussed. A short survey of the larval descriptions of West-Palaearctic water mites in general and of spring-living taxa in particular is given, together with a perspective for future research into larval morphology in this geographical area.

The author reports new collections of 10 water-mite species from the Peloponnes (Greece), Sardinia (Italy), Corsica (France), and Andalusia (Spain). Barbaxonella reverendissima is described as a new species ; first descriptions are given of the male of Bandakia Corsica, the larva of Monotonia tegulata and the deutonymphs of Psammotorrenticola gracilis, Utaxatax ventriplax and Momonides lundbladi. Momonisia phreatica and Bandakia concreta were found for the first time in the Mediterranean region. The zoogeographical significance of the new records is briefly discussed.

Eleven species of the water mite family Torrenticolidae Piersig are reported from interstitial waters of Sicily. The male, female and deutonymph of Torrenticola hyporheica n.sp. are described. The morphological traits of the new species suggest adaptation to life in groundwaters and indicate affinities with other hyporheobiont species of the genus such as T. ramigera Szalay and T. jeanneli Motas & Orghidan. The high number of Torrenticolid-species found in interstitial habitats may be related to the adaptive morphological features of members of this family and more directly to hydrogeological conditions on the island. Torrenticola lativalvata, Torrenticola hyporheica and Torrenticola trinacriae were the most abundant species collected. Marked differences between the distributions of species of the family in Sicily and Corsica are pointed out.

The seasonal and bathymetric occurrence of water mites in the sublittoral and profundal zones of lake Banyoles were studied in 1986-1987. Four species were found in the mud substrate : Neumania deltoides (Piersig, 1894), Neumania imitata Koenike, 1908, Unionicola crassipes (Müller, 1776) and Arrenurus sinuator (Müller, 1776). The maximum depth that water mites reached was 12 m, but they were more frequent and abundant at 5 m depth, mainly in the March-May period (41 individuals per m2). This group represents only 0.08-0.39 % of the total macrobenthic fauna in the sublittoral of lake Banyoles. N. deltoides is the most abundant and widely distributed species. For N. imitata this is the first record in the Iberian peninsula.

Ce travail concerne les données faunistiques et écologiques relatives aux espèces italiennes du genre Torrenticola recueillies dans l'Apennin. Treize espèces ont été signalées, cinq sont nouvelles pour la faune italienne (T. similis, T. lativalvata, T. brevirostris, T. ungeri et T. amplexa). L'étude des caractères dimensionels a permis d'individualiser quelques indices morphologiques de valeur discriminante à un niveau spécifique et a permis de mettre en synonymie quatre espèces. Une distribution différente des espèces entre les secteurs de l'Apennin abruzzin et calabrais a été aussi mise en évidence. L'importance du microhabitat, déterminée par la typologie du cours d'eau, a été soulignée afin d'expliquer la distribution géographique des espèces dans le bassin méditerranéen.