The presence of different species of hydrophytes was investigated in relation to Secchi disk visibility, pH, dissolved oxygen,electrical conductivity, total Kjeldahl nitrogen, total phosphorus and chlorophyll-a concentration in two tropical ponds nearbyKolkata, India, during a three years period (June 1999 to May 2002). The dominant flora in the ponds namely, Alternantheraphiloxeroides, Nymphoides hydrophylla, Lemna aequinoctialis, and Vallisneria spiralis were found to subsist over a wide amplitudeof nutrient levels thereby showing their adaptability to highly eutrophic ecosystems, a common feature of the tropics.However, the presence of some minor species could be associated with a narrow range of specific limnological variables.

The concentrations of the Al, Co, Cr, Cu, Pb, Sn, Ni, and Zn trace metals were monitored in Lake Ipê (Brazil) during twohydrological sub-periods : June - December 1999 (low water period, LW), and January - April 2000 (high water period, HW).A detailed study of the physical and chemical state of the metals was performed through the MINTEQA2 computer programusing 15 abiotic parameters. An increase in concentration of many trace metals in July 1999 was due to the sudden entry ofallochthonous matter. The seasonal study showed that the metal concentrations in the lake were governed by the hydrologicalregime of the Paran· River (HW), and by the occurrence of occasional flood pulses and rainfall (LW).

Ten species of molluscs were identified in the freshwater tidal area of the River Minho estuary. Species richness per site rangedfrom 1 to 9. Abundance ranged from 230 to 4130 individuals per m², with an average of 1412 individuals per m2. Corbiculafluminea(Müller, 1774) presented the highest density, corresponding to 88.7 % of the total specimens gathered, followed byPisidium amnicum (Müller, 1774) with 5.8 %. Biomass ranged from 17.0 to 249.6 g AFDW m-2, with an average of 99.8 gAFDW m-2. C. fluminea was the species dominating the total biomass (95.4 %), followed by Bithynia tentaculata (Linnaeus,1758) with 1.6 %. A multivariate analysis revealed a community with two distinct groups : one group almost or exclusivelyrepresented by C. fluminea, and another group with a more diverse assemblage.

Macunahyphes, gen. nov. is proposed to include Tricorythodes australis (Banks). In the present paper, the new taxon is describedan illustrated from imagos and nymphs. The unique characters present in Macunahyphes gen. nov. are: in the male imago,(1) forceps tri-segmented with first segment distomedially projected, (2) penis with very wide base, becoming thinner toward asubapical constriction, and then slightly widening again, penis lobes of each side almost completely fused except apical insicion,(3) penes with a ventral projection covered with spines, and in the nymph, (4) glossae and paraglossae almost completelyfused, with a circular outline, and (5) femora with numerous robust serrate setae.

A new genus of hypogean Ostracoda, Marococandona nov. gen. from wells and springs in the Guelmin and Agadir regions(Southern Morocco) is described. This genus is close to the genus Candonopsis, but can be distinguished from this latter by severalcharacteristics : the rectangular shape of the carapace, the reduction of the antenna chaetotaxy, the lack of sexual dimorphismin the male antenna, the lack of setae on the protopodite of the second thoracopod, and on the two first articles of the third thoracopodendopodite. M. danielopoli n. sp. has primitive characters, with a normally segmented antennula, a ‘t’ seta on the antenna,and normally developed furcal claws. In contrast, the morphology of M. nicolae n. sp. is regressed, with a 5 segmentedantennula, no ‘t’ setae on the antenna, and a reduced furca. The two species live in highly mineralised water and seem poorlysensitive to groundwater pollution.

Blooms of Ceratium hirundinella (O. F. Müller) Bergh. have been detected in different water bodies in the Neotropical Regionsince 1990. The colonization began in southern lakes, and during the last decade the dinoflagellate arrived and bloomed in subtropicalreservoirs. In this context the colonization of C. hirundinella and its population development have been analyzed fromits first record in the Río Tercero Reservoir (February 1999 to February 2001). Phytoplankton and physicochemical sampleswere obtained from three sampling stations at the Reservoir, one in the outlet of the water cooling channel of the nuclear powerplant, and one in the nearest tributary (Quillinzo River). Two blooms of C. hirundinella were detected during the warm seasonswith temperatures higher than 18°C, and pH ranging between 8.5 and 8.9. Environmental conditions such as certain light intensityrange and percentage of dissolved oxygen mentioned as favorable for Ceratium development were always recorded in RíoTercero Reservoir. Cysts were observed in spring and summer months. Another dinoflagellate (Peridinium gatunense Nygaard)bloomed in previous summer in this water body but its population density decreased during the invasive phase of colonizationof C. hirundinella. Asplanchna girodi, became the dominant zooplankter after the first bloom of C. hirundinella. We believe thatthe presence of this dinoflagellate in the Neotropical Region could be a regional phenomenon associated with some dispersalmechanisms and favorable local conditions for its proliferation like those recorded in the Rio Tercero Reservoir.

Three males of Cryptocandona vavrai were discovered in geographically distant sites (UK, France, Romania), representingdifferent environments (surface and underground waters). The species may be considered a parthenogen with rare occurrence ofsingle males, the morphology of which was hitherto poorly known. The first complete description of males is given, which, togetherwith comparative descriptions of females from surface waters at the UK site and underground waters at an additional sitein eastern France, as well as consideration of the shape and size of the last juvenile stages, permits the presentation of a morecomplete description and an amended diagnosis of the species. Cryptocandona vavrai takes an intermediate position in thegenus, lodged between stygobitic species and the cluster of more primitive C. reducta and C. brehmi. Due to a number of traits(broad calcified inner lamella of the valves, 3rd ramus podomere of the antennule lacking the posterior seta, hook-like shortestterminal seta of the cleaning leg, specific morphology of the male prehensile palps and hemipenis lobes) C. vavrai is fairly easilyrecognised, although there seems to be considerable intraspecific variation. The comparison between females from surfaceand underground waters revealed substantial elongation of the apical antennal claws, aesthetascs and the distal claw of the walkingleg in the latter population. The major difference recorded among the compared males is the underdevelopment of the externalclaw z2 on the 3rd endopodial podomere of the antenna in the male from the underground waters in Romania. The revealedvariation could indicate that some populations may deserve a separate (sub-specific) taxonomic status. Finally, available data onthe distribution and ecology of this species are summarised.