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Adult swarms of non-biting pestiferous midges (Chironomidae: Diptera), primarily Chironomus plumosus, prevail over and around Lake Trasimeno (Italy) during the summer season. The current field survey (2018–2021, 33 sampling occasions) was carried out in the central area of the lake. It revealed a macrobenthic community consisting of Chironomidae (40.72%) and Oligochaeta (59.23%). Chironomus plumosus was the dominant chironomid species (98.84%). A previous survey (2000–2002, 11 sampling occasions) had highlighted a similar community, although C. plumosus had a lower density, comprising a maximum of 295.0 ind. m−2. This density was five times lower than the maximum densities of 2018–2021. A survey (2018–2021, 58 sampling occasions) conducted in the littoral zone revealed much greater chironomid biodiversity, with C. plumosus abundance of only 24.35% among all chironomids. This species showed an average density (88.1 ind. m−2) five times lower than its density (467.9 ind. m−2) in the central zone (2018–2021). Therefore, the central area of the lake, constituting about 90% of its total surface area, is the main region for the origin of C. plumosus adults and, consequently, during the summer months, it is the primary source of the annoying swarms that affect residents and tourists of the lake vicinity.

In some Porifera (Demospongiae: Keratosa), prototypes of the connective system are almost exclusively based on collagenic networks. We studied the topographic distribution, spatial layout, microtraits, and/or morphogenesis of these collagenic structures in Ircinia retidermata (Dictyoceratida: Irciniidae). Analyses were carried out on a clonal strain from sustainable experimental mariculture by using light and scanning electron microscopy. Histology revealed new insights on the widely diversified and complex hierarchical assemblage of collagenic structures. Key evolutionary novelties in the organization of sponge connective system were found out. The aquiferous canals are shaped as corrugate-like pipelines conferring plasticity to the water circulation system. Compact clusters of elongated cells are putatively involved in a nutrient transferring system. Knob-ended filaments are characterized by a banding pattern and micro-components. Ectosome and outer endosome districts are the active fibrogenetic areas, where exogenous material constitutes an axial condensation nucleus for the ensuing morphogenesis. The new data can be useful to understand not only the evolutionary novelties occurring in the target taxon but also the morpho-functional significance of its adaptive collagenic anatomical traits. In addition, data may give insights on both marine collagen sustainable applied researches along with evolutionary and phylogenetic analyses, thus highlighting sponges as a key renewable source for inspired biomaterials. Therefore, we also promote bioresources sustainable exploitation with the aim to provide new donors of marine collagen, thereby supporting conservation of wild populations/species.

Field sampling of littoral macrobenthos of the shallow Lake Trasimeno was conducted along 17 years (2005–2021) on 129 different occasions. This long-term field study deepens the knowledge concerning the life cycle of Chironomus plumosus (Diptera), the main responsible for summer chironomid swarms that adversely affect human littoral activities, providing useful information for its management. About 108,000 macrobenthic specimens were collected, belonging to Oligochaeta (Naididae) (62%), Diptera (Chironomidae) (37%), and only 1.5% to other invertebrate taxa. Eighteen chironomid taxa were found. The trend of chironomid density was not affected by C. plumosus, which showed a maximum increase in September. This peak is justified by the presence of large swarms of C. plumosus in late August in which the populations of the central area of Lake Trasimeno consistently participate. The larval density of this species did not increase over the 17 years. A detailed analysis of the sampled larvae and adult biomass catches from 2017 to 2020 reveals that four annual swarmings occurred: in April, July, August, and September–October. The water temperature remains higher than 20 °C during the night hours from the end of May to mid-September, strengthening the hypothesis of the three midge swarming cycles in the summer period until early autumn.

Both physical–chemical and biological indicators are used to assess the ecological health of ecosystems. The functional trait composition of communities has the potential to predict the impact of environmental change on ecosystems, yet, we miss evidence that information on pollution can be used to forecast the functional responses of freshwater communities. We used chemical and ecological data collected in the Nestore river basin (Central Italy) to test whether (i) there are generalities in the response of macroinvertebrate functional diversity to river pollution; (ii) water pollution filters certain functional traits and (iii) traits do better than chemical analyses at revealing ecological stress in rivers. Due to interactions with hydrology, chemical variables showed higher seasonal variation at impacted sites, so occasional water samples represented snapshots. Functional traits did well at detecting water pollution by various chemicals, and there was a clear shift of trait combinations from unimpacted to impacted sites. Anthropogenic disturbances homogenized benthic communities in terms of taxonomic and functional composition, both in space (impacted sites) and time (seasons). Traits related to feeding habits (mainly reliance on fine particulate organic matter) and tolerance to organic pollution were prevalent at impacted reaches, and functional trait compositions were more stable than water chemistry over seasons because they integrate environmental conditions over longer time periods. Functional traits can play a relevant role in the bioassessment of polluted river ecosystems, even under low to moderate disturbance. Trait-based assessment can be complemented by chemical analyses, notably at highly polluted sites where biological diversity drops to its lowest levels. Copyright © 2016 John Wiley & Sons, Ltd.

This work is concerned with the ultrastructural organization and some histochemical features of the vacuolar cells of the demosponge Oscarella lobularis. Vacuolar cells are characterized by large clear vacuoles containing an aqueous fluid. They are commonly found in the mesohyl of this sponge and tend to constitute a sort of parenchyma in the choanosome. Mobile cells of the mesohyl appear to differetiate into vacuolar cells through the progressive formation of wide cytoplasmic lacunae. We have identified four types of cells showing progressive transformation toward the vacuolar cell type. Precursors (types 1-4) of the vacuolar cells probably derive from endopinacocytes, since they share several histochemical and ultrastructural characteristics with them. Our data support the notion that vacuolar cells are involved in the synthesis of collagen, act as a mechanical support of the sponge body, and are eventually extruded from the sponge through the canals of the aquiferous system.

Introduction of alien species is one of the major threats to aquatic biota and knowledge of the major correlates of their occurrence is pivotal in planning reliable conservation strategies. 2. To understand whether specific freshwater habitats are more likely to be invaded than others, a dataset on the occurrence of 1604 species in 54 taxonomic groups from 181 sites across the Italian peninsula was gathered. 3. TheEUNIShabitatclassificationwas used, selectingfor the study's seven habitat types at thesecondEUNIS level, including lentic (EUNIS C1; 64 sites), lotic (EUNIS C2; 99 sites) and highly artificial (EUNIS J5; 18 sites) habitats. 4. The aim of the study was to test whether the overall number of alien species and the proportion of alien species for each taxonomic group differed between habitat types and could be explained by environmental, human-mediated, or climatic factors. 5. Using generalized linear mixed effect models to account for potential confounding factors, only average air temperature of the site was a significant positive predictor of the occurrence of alien species, regardless of habitat type, species richness, and other climatic variables. 6. A direct effect of temperature could be excluded given the origin of alien species, mostly from colder areas than Italy. Thus, an indirect effect could be hypothesized at the Italian latitudes, with warmer areas potentially

Dragonflies and damselflies are among the most ancient winged insects. Adults belonging to this order are visually oriented and are considered anosmic on the basis of neuroanatomical investigations. As a consequence, the chemical ecology of these predatory insects has long been neglected. Morphological and electrophysiological data demonstrated that dragonfly antennae possess olfactory sensilla. Additionally, a neuroanatomical study revealed the presence of spherical knots in the aglomerular antennal lobe that could allow for the perception of odour. However, the biological role of the antennal olfactory sensilla remains unknown, and no bioassay showing the use of olfaction in Odonata has been performed thus far. Here, we demonstrate through behavioural assays that adults of Ischnura elegans are attracted by olfactory cues emitted by prey; furthermore, using electrophysiological single-cell recordings, we prove that the antennal olfactory sensilla of I. elegans respond to prey odour. Our results clearly demonstrate the involvement of antennal olfactory sensilla in Odonata predation, thus showing, for the first time, the use of olfaction in Odonata biology. This finding indicates that the nervous system of Odonata is able to receive and process olfactory information, suggesting that the simple organisation of the antennal lobe does not prevent the use of olfaction in insects.

The mentum deformity incidence in Chironomus plumosus larvae to assess the environmental contamination level in Lake Trasimeno, Central Italy, was investigated. The survey lasted from May 2018 to August 2019. Fifty-one samplings were carried out: 34 in the littoral zone and 17 in the central zone. The deformity assessment was based on 737 and 2767 larval specimens of C. plumosus collected from the littoral and central zones, respectively. Comparison of the larval morphometric variables between normal and deformed specimens highlighted that the deformities did not cause alterations of the larval growth. The deformity incidence amounted to 7.22% in the whole Trasimeno&rsquo, s ecosystem, reaching 8.28% in the littoral zone and 6.94% in the central zone. Among the different seasonal cohorts, the spring cohort had overall the highest deformity value (11.41%). The deformity type assessment protocol highlighted that the most common deformity type was &ldquo, round/filed teeth&rdquo, (64%). The results of this 2018&ndash, 2019 survey revealed a low deformity incidence, within the background range of relatively low-impacted freshwaters. Comparison with previous investigations (2000&ndash, 2010) of the same habitat showed a clear decrease of the deformity incidence. This study further contributes to the evaluation of the mentum deformity in chironomids that represent an indicator endpoint of the anthropogenic contamination level in freshwaters.

The reproductive cycle of the demosponge Sarcotragus spinosulus from two dif-ferent shallow environments (La Pierta and La Strea) of the Ionian coasts ofApulia (SE Italy) was studied from February 2006 to February 2007 in 20tagged specimens. The sponge is viviparous. All the monitored specimensshowed sexual reproduction, even if the process usually involved small portionsof the sponge tissue. Most of the specimens showed hermaphroditism, withcontemporaneous production of oocytes and spermatic cysts in the samereproductive season. Young oocytes occurred from June to September in speci-mens from La Pierta and from June to October in those from La Strea. Largemature eggs, measuring up to 200 lm, showed a peak in August to September,concomitant with the appearance of spermatic cysts, whose density values wereabout 100 times higher than those estimated for female elements. At La Pierta,embryos were present for 11 months, whereas at La Strea they were very scarceduring the first 4 months of observation, with the results that there was a sig-nificant difference in the production of embryos between the two groups ofsponges. Embryo development occurred in patches inside the choanosomalregion. Cleavage started in September and led in June to a solid stereoblastula,which, only at La Pierta, produced parenchymella larva (371.3 + 31.3 lmonaverage) from June to July. In the specimens from La Strea, larvae were neverobserved. The slight differences in the reproductive cycle between the twogroups of sponges may be explained in the light of the major variability of theenvironmental parameters which could have affected the specimens from LaStrea negatively.IntroductionSarcotragus spinosulus Schmidt 1862 is a demosponge typ-ical of Mediterranean coastal environments, very com-mon in shallow waters and also just below the tide line.Among the Mediterranean demosponges, this species canbe considered one of the most tolerant of light, beingscreened by the thick layer of superficial pigmented tissue(pinacoderm) containing a large number of melanocytesand a dense bacterial simbiocortex. The species is consid-ered of wide ecological value, being able to live in differ-ent ecological conditions, from cliffs exposed to highwater movement to semi-enclosed bays with a high sedi-mentation regime (Corriero 1990; Mercurio et al. 2001;Corriero et al. 2004; Baldacconi et al. 2007).Members of the order Dictyoceratida are viviparousand the incubated larvae are parenchymellae (Cook BMihopouloset al.1999;Tsoukatou et al. 2002; Liu et al.2006;BenKahla-Nakbiet al. 2010). The only reports concerning the reproduction

We present a data set on the biodiversity of Italian freshwaters, including lakeshores and riverbanks of natural (N=379: springs, streams and lakes) and artificial (N=11: fountains) sites. The data set belongs partly to the Italian Long Term Ecological Research network (LTER-Italy) and partly to LifeWatch, the European e-Science infrastructure for biodiversity and ecosystem research. The data included cover a time period corresponding to the last fifty years (1962-2014). They span a large number of taxa from prokaryotes and unicellular eukaryotes to vertebrates and plants, including taxa linked to the aquatic habitat in at least part of their life cycles (like immature stages of insects, amphibians, birds and vascular plants). The data set consists of 6463 occurrence data and distribution records for 1738 species. The complete data set is available in csv file format via the LifeWatch Service Centre.

This study reports the description, at ultrastructural level, of some steps of the spermatogenesis up to spermatozoa differentiation in the stylasterid Distichopora sp., from Indonesia. The most outstanding aspect is represented by the late spermatids, which are initially included in the same cytoplasmic matrix, thus forming a “syncytium”. The syncytial elements coexist with discrete spermatids. Individual spermatids have an elongate compact electron-dense nucleus, and several mitochondria located at its base. Elimination of the cytoplasmic matrix, together with the tapering of the nucleus leads to spermatozoa, simply delimited by a curled membrane, and provided with a flagellum with a 9 + 2 tubular pattern, a pericentriolar anchoring fibre apparatus and several mitochondria. No apparent acrosome or pro-acrosomal vesicles are observed.

Recent ultrastructural investigations on Odonata antennal flagellum describe two types of sensilla styloconica, T1 and T2. The styloconic sensilla are located in pits, at the bottom of deep cavities, and share common features typical of thermo-hygroreceptors. In order to ascertain if the Odonata antennae are involved in hygroreception and thermoreception, we carried out electrophysiological recordings (single cell recordings, SCR) from adult males and females of Libellula depressa L., 1758. After contact was established, the antenna was stimulated by rapid changes in temperature and humidity. The present research shows the occurrence of a dry (DC), a moist (MC) and a cold (CC) receptor neurons on the antennal flagellum of L. depressa. These data demonstrate for the first time the presence of functional thermo-hygroreceptors on the antennal flagellum of dragonflies. The present results extend our knowledge of the not visual sensory modalities of Odonata, a field of research unexplored so far.

The class Anthozoa is the largest meta- zoan group forming mutualistic symbioses with mi- croalgae. These algal symbionts (most commonly dino - flagellates of the genus Symbiodinium) are distributed across most anthozoan orders. Records of algal cells in antipatharian (black coral) tissues have been reported, but no detailed descriptions of a mutualistic endosym- biosis exist. Here we report on zooxanthellate speci- mens of an unidentified black coral species within the genus Cirrhipathes that were collected from reef slopes at depths of 15 to 38 m in the Indonesian Archi- pelago. Symbionts were abundant (~10 7 symbionts cm -2 ) and ultrastructural analysis revealed the presence of a distinct symbiosome surrounding the algae, as well as algal reproduction inside the gastrodermal layer. Mol- ecular analysis revealed the algae to be closely related to the symbionts (Symbiodinium clade G) of clionid sponges. There was also evidence for additional sym- bionts in clade C at low abundance. Taken together, these findings (high abundance, taxonomic identity, presence of symbiosome, in situ reproduction, and depth distribution) strongly suggest that these algae are functioning as mutualists. This study confirms and describes the symbiosis between Symbiodinium and a black coral species of the genus Cirrhipathes, supports the pervasiveness of mutualisms among anthozoan taxa, and highlights the diversity and flexibility of these symbiotic associations in a poorly studied group.

Clionaids are excavating sponges, which live in and grow into calcareous substrates. We studied the sexual reproductive cycles of two clionaid sponges coexisting in a Mediterranean coastal basin (Porto Cesareo, Italy), Cliona viridis and Cliona celata, by analyzing monthly tissue samples of ten specimens of each species collected over a 2-year period. From May to June of the second study year, supplementary samples were taken weekly. Up to 90% of the specimens of C. viridis and 70% of those of C. celata sampled were reproductive during the study. In both species, but particularly in C. viridis, reproductive investment, measured as the percentage of sponge tissue occupied by gametes, was high. Oocytes were present almost year-round in both species, except for a 1–4-month period after zygote release. In contrast, spermatogenesis occurred most frequently in May in both species, when (May–June) oocytes reached their greatest diameters. Cliona viridis and C. celata are hermaphrodites, with oocytes and spermatic cysts coexisting in 10% of the studied individuals in the first year of the study, and in 30% during the second. No developing embryos or larvae were incubated in the sponge tissues, and fertilization was not observed. Temperature may play a role in triggering some important phases of the reproduction of these Cliona, such as oocyte maturation and spermatogenesis, which occurred when water temperature increased from 17°C to 25°C between May and June.

Fertile male polyps of three colonies of the black coral Rhipidipathes reticulata (Aphanipathidae) from Togian Islands (Indonesia) have been the source of the sperm investigated at ultrastructural level, in order to compare their organization with that of other members belonging to the family Antipathidae and Myriopathidae. The extension of the studies to a representative of the family Aphanipathidae stresses once more the structural similarity of the male gametes in antipatharians. A sketch of the sperm model reports the similarity and differences in the examined taxa. Among the micro-characters, the cup-like body linked to the pericentriolar apparatus, is exclusive of the antipatharians. Other inclusions concern the more common pro-acrosomal vesicles or the acrosomelike structure observed only in Antipathella subpinnata and Myriopathes japonica. Lipid vesicles are occasionally present. A typical inclusion, the electron-dense content of which has a C-shaped configuration, is restricted to Rhipidipathes reticulata and is associated to the cup-like body or to the mitochondrion.

The reproductive cycle of the demosponge Hymeniacidon perlevis (Montagu) was investigated at the Mar Piccolo di Taranto (Ionian Sea, Apulian). According to the distribution of the specimens, along a bathymetric gradient, sponges have been subdivided in two groups, named group A and group B. The former was made up of specimens that are usually exposed in the air when there is a low water level and the latter by specimens that are constantly submerged. Monthly monitoring (February 2006 - January 2007) of twenty tagged specimens (ten in each group) was carried out in order to compare the reproductive efforts in the two groups. The reproductive pattern differed slightly between the two groups; the majority of the females in group B restrict oocyte production till May. In addition, group A exhibits a significantly higher density of sexual elements, than those belonging to group B. It was hypothesised that the sexual activity of the submerged specimens, living close to the soft bottom, could be influenced by severe anoxic crises due to periodic algal decay, whereas the intertidal specimens, located some decimetres off the soft bottom, and subjected to the moderate water movement, were not affected. The thick algal assemblage associated with the intertidal specimens gives protection against dehydration and solar irradiation during the prolonged periods of air exposure. By September, none of the monitored specimens had survived. The finding of newly developing small specimens in late winter supports a possible colonisation from residual sponge fragments dispersed before mass mortality.

Black coral colonies belonging to Antipathella subpinnata (Myriopathidae), found in Adriatic Sea (off the Tremiti Islands) and in Tyrrhenian Sea (Mezzo Canale), were inspected with the aim of investigating their reproductive activity. The small colony (about 42 cm tall) from Adriatic Sea was sexually immature, whereas the larger (about 120 cm tall) five colonies from Tyrrhenian Sea were fertile. Four colonies were males and one was a female, thus confirming the gonochoric condition already known for the black coral. Semithin sections proved that most of the egg and sperm masses flow out through the pharynx, even though small gamete masses were also observed emerging from the tentacles. In the female polyps, egg masses were enveloped by parental tissue derived from the breakage of the mesenterial septa, as observed in the male polyps for the sperm cysts masses. Ultrastructural observations provided details on the characteristics of egg and sperm in this taxon. Sperm stood out for the presence of an acrosome-like structure derived from the merging of pro-acrosomal vesicles. On the whole, the fine organization of the sperm recalled previous descriptions reported for some tropical black coral taxa.

The present study focuses on the reproductive success of transplants of the bath sponge Spongia officinalis Linnaeus, 1759, with the aim of investigating the possibility of restocking this species, one of the most endangered organisms of the Mediterranean sessile zoobenthos. Transplants of S. officinalis, collected from a wild population along the Apulian coasts (Ionian Sea, Italy), have been moved into an area where the species was present in the past. The transplants consisted both of specimens in toto and of fragments of different sizes, obtained after having cut the mother sponge into pieces. All transplanted sponges showed complete cicatrisation of the cut surfaces within a month of the initial manipulation and had a survival rate of 100% throughout the 12 months of the study. From the present investigation, it has emerged that the reproductive effort and the larval release by the transplants do not differ significantly from those shown by the source population. This successful technical approach supports its application as a strategy for restocking the population of this endangered species.

The relevance of the budding process in a population of Tethya citrina inhabiting an unpredictable environment subjected to frequent anoxic crisis (Mar Piccolo di Taranto) is described, and new data about the fate of the buds after their release are provided. At the individual level, for the first time in natural conditions, it has been demonstrated that several budding events follow each other, alternating with short periods (1–2 months) of rest. At the population level, budding proved to be a continuous process, being detected throughout the 13 months of study, with a short summer decrease both in the frequency of budding specimens and bud density. This trend was markedly different from that reported for conspecific populations inhabiting stable environments, in which budding is a seasonal process. It is hypothesized that the sudden and unpredictable variations of the ecological conditions could be responsible for the onset of repeated budding events, thus stressing the role of environmental factors in affecting the asexual reproductive pattern. T. citrina buds, here investigated, tend to detach from the adult sponge within 7/15 days of their differentiation, a feature coherent with experimental data carried out under laboratory conditions. A significant relationship between the size/age of the post-buds and the onset of the asexual reproduction has been proved: in particular, the first budding event was observed in nine-month-old sponges, measuring about 7 mm in diameter. As reported for other demosponges, in T. citrina post-buds the growth rate was positively related to the water temperature, with a significant increase during the summer. In addition, a negative effect of the budding process on the sponge growth, is hypothesized for a post-bud subjected to repeated budding events. Growth rate, however, proved highly variable.

Females of Habrophlebia eldae release eggs into the water by penetrating the surface with the ovipositor. Ultrastructural investigations (SEM, TEM) confirm that at rest the ovipositor of H. eldae is composed of a proximal sclerous region and a distal membranous region. During oviposition, the membranous region unfolds a telescopic tube made up of a thin cuticle. At rest, this telescopic structure is kept folded inside the ovipositor. The extension of the structure seems to be passive, caused by the passage of the eggs, pushed out by the peristaltic movements of the net of muscle fibres surrounding the oviducts. The contact of the membranous distal region of the ovipositor with water triggers egg laying through extension of the telescopic tube. Numerous mechanoreceptors, in the form of short bristles, are located ventrally in the membranous region of the ovipositor and seem to be involved in water perception.

The buds of the sponge Tethya seychellensis, collected in May 2006 from South Male Atoll (Maldives), have been processed for histological and ultrastructural investigations. Buds show three stages, different in morphology and size, reflecting different steps of their differentiation: round-shaped buds (stage I), cylindrical-shaped buds (II) and thin-stalked spearshaped buds (III). Cells with inclusions, belonging to the category of spherulous cells, are the main components of these buds. At stage I, some irregularly shaped cells, probably precursors of the choanocytes, are able to engulf and remove portions of the collagen matrix, a feature which could be interpreted as an initial step in choanocyte differentiation. Tethya seychellensis stands out among the other congeneric species owing to the occurrence of choanocyte chambers in the unreleased buds, as observed at stages II and III. The precocious differentiation of the choanocyte chambers allows the detached bud to act as a young functional sponge, thus enhancing the survival chances of these filter-feeding organisms. The structure of the buds of T. seychellensis stresses once more that in the genus Tethya the organisation of the buds represents a species-specific process, which varies according to the plasticity and the morphogenetic potentiality expressed by a single species.

An ultrastructural investigation (SEM, TEM) on the antennal flagellum of the adult of the dragonfly Libellula depressa (Odonata:Libellulidae) revealed sensilla located in pits on the lateral-ventral side of the antenna. These sensilla are represented by sensilla coeloconica and by deeply sunken sensilla. The sensilla coeloconica are innervated by three unbranched dendrites, which enter the peg and show a dendrite sheath ending at the base of the peg. The peg has no socket and its cuticle is irregular with wide pore-like structures at the base of which actual pores are visible. The structure of these coeloconic sensilla is in agreement with that reported for single-walled insect chemoreceptors. The deeply sunken sensilla are represented by two kinds of sensilla styloconica, named type-1 and type-2, located at the bottom of deep cavities appearing as simple openings on the antennal surface. These sensilla are no-pore sensilla with inflexible socket and unbranched dendrites and, notwithstanding their structural differences, share common features typical of thermo/hygroreceptors. The presence of chemoreceptors in adult dragonflies sheds light on evolutionary trends in insect perception; the previously unknown occurrence of thermo/hygroreceptors in dragonflies is very important in view of the reported ability of Odonata to thermoregulate heliothermically.

Summary Female polyps of Cirrhipathes cfr. anguina were collected in August 2007 from the coral reef of Siladen Island in the Bunaken Marine Park (North Sulawesi, Indonesia). The primary transverse mesenteries, which separate the adjacent lateral tentacles from one another, were filled with oocytes developing within the mesoglea. Cross-sections of the oral region revealed that young gametes were located both at the emergence of the primary transverse mesenteries from the gastroderm lining the coelenterons, and at the point where the mesenteries were linked to the pharynx. By contrast, at a lower level, where the mesenteries gave rise to mesenterial filaments, young gametes were limited to the initial part of the mesenteries. Oocytes were lodged in individual chambers, and were separated from one another by mesogleal elements. On occasion, oocytes were found in proximity to cells with short microvillous-like processes that interdigitated with those emerging from the oocyte surface. Oocytes varied in size a...

This study investigated the development of the larvae of Spongia officinalis in experimental conditions, after settlement on plastic substrates, using electron and light microscopy. The released larvae show a dark pigmented ring distinguishes the posterior larval pole. The youngest larvae, covered with a flagellate epithelium, move onwards by rotating on their longitudinal axis. Over time a creeping-like motion prevails, probably linked to the need for settlement. After a free-swimming period of 24-48 h, larvae settle on the artificial substrate by the anterior pole. At settlement, the flagellate epithelium is substituted by flattened cells, which delimit the outermost surface. Post-larvae were reared to about three months. The early phase of post-larval differentiation shows a solid interior mainly consisting of granular cells varying in shape and size. They are included in a dense collagen matrix that contains a conspicuous amount of bacteria. Lacunae are already evident in the initial phase of metamorphosis. In several of them, cell debris and nucleate cells are visible. This feature is consistent with a progressive reduction of the cell mass (autolysis). Neither choanocyte chambers nor canals differentiate. The morphogenetic process leads to a metamorph only consisting of vacuolated cells and collagen fibrils included in a thin fibrous coat.

The reproductive cycle of the bath sponge Spongia officinalis L. has been studied over 1 year on 11 tagged specimens of different sizes (from 82 to 886 ml, in volume) from Ionian coasts of Apulia (SE Italy). According to literature data, the sponge is viviparous. All the monitored specimens showed sexual reproduction, even if the process usually involved small portions of the sponge tissue. Ten specimens were gonochoric (sex ratio 1:1), one specimen showed successive hermaphroditism, with alternate production of oocytes and spermatic cysts in the same reproductive season. Young oocytes occur almost all year round, whereas large mature eggs show a peak in October–November, concomitantly with the appearance of spermatic cysts. No relationships were observed between the sponge size and the presence of sexual elements within the range of the sponge size considered in this research. Embryo development occurs in patches of choanosomal tissue, which contain four or more elements. Cleavage is total and equal; it starts in November and in May leads to a solid stereoblastula, which develops into a parenchymella larva, from May to July. The stereoblastula lacks flagella and its surface is delimited by elongated cells well segregated from the internal ones. Parenchymella larvae are released from June to July, asynchronously, either at the individual or population level, with a few days of de-phasing. Up to 523 larval elements/48 h for a sponge specimen were counted. The free-swimming larvae are ovoid and uniformly flagellated. Flagella are longer at the posterior region, than on the rest of the larval body. Flagellated cells form a pseudo-stratified epithelial layer, delimiting the outermost larval surface, and are filled with electron-lucent vesicles showing a homogenous content. No choanocyte chambers, pinacocytes or skeletal elements are present in the newly released larvae.

Spermatogenesis of the marine sponge Halichondria semitubulosa (formerly Pellina semitubulosa) has been investigated at the ultrastructural level. This process can be observed in March when, among the choanocyte chambers of the aquiferous system, spermatic cysts are visible. They are delimited by pinacocyte‐like cells and include elements in progressive development: spermatocytes of the first and second order, spermatids and spermatozoa. The early phase of spermatogenesis was not detected. Spermatocytes of the first order show an elongated shape, several small mitochondria and patched chromatin; spermatocytes of the second order, frequently connected by bridges, show denser chromatin, a single large mitochondrion with numerous tightly adherent cristae, glycogen, and round‐shaped inclusions with a central electron‐dense core. In the spermatids the chromatin tends to be packed in the central region. Spermatozoa have a uniformly dense nucleus in close association with the large mitochondrion. Sperm maturatio...

The reproductive cycle of Geodia cydonium in a semi-enclosed Mediterranean bay (Porto Cesareo, SW Apulia) was studied with monthly frequency over a 3-year period. The investigation was carried out by uti- lizing a technique consisting of tagging ten individuals with a PVC stick and cutting oV, by means of a metal cork borer, small samples (cylinders about 5 cm 3 in vol- ume) from each of them for histological analysis. Sex- ual reproductive elements were detected in all individuals, but in the third year some specimens showed reduced reproductive activity or complete infertility. Spermatogenesis occurred in a short period (from June to August) whereas oogenesis lasted longer (from spring to late summer). Spermatic cysts occurred when the frequency of specimens with oocytes reached its maximum values. A relationship between water temperature and the onset of gamete diVerentiation was observed. G. cydonium is here conWrmed ovipa- rous and gonochoric with a sex ratio in favour of the females. However, in contrast with current literature on Porifera—which suggests that only a limited num- ber of sponges, all belonging to the same species are sexually active—the sexual reproduction of this species involves all the examined individuals. This Wnding can be explained by the methodological approach used in this research, which diVers from the traditional way of assessing the sponge reproductive cycle by analysing randomly collected specimens within a population. The study of a series of individuals over time represents a better "model technique" for investigating sponge sex- ual reproduction and the eVect of environmental parameters on gamete diVerentiation.

We used self-organizing maps (SOM, neural network) to bring out patterns of benthic macroinvertebrate diversity in relation to river pollution. Fourteen stations were sampled over various seasons in the Nestore drainage basin (Central Italy) and characterized for macroinvertebrate communities, nutrient and heavy metal concentrations. Physicochemical variables were introduced into a SOM previously trained with macroinvertebrate data. Patterns of communities matched spatial and seasonal changes in environmental conditions, including water chemistry related to economic activities in the catchment. Although our analyses did not allow us to establish the specific effect of any given environmental parameter upon macroinvertebrate community composition based on the field study, they enabled us to map the ecological health of river ecosystems in a readily interpretable manner.

In lower metazoans, the aggregative properties of dissociated cells leading to in vitro stable multicellular aggregates have furnished a remarkable experimental material to carry out investigations in various research fields. One of the main expectations is to find good models for the study in vitro of the first steps of biomineralization processes. In this study, we examined five common Mediterranean gorgonians (Paramuricea clavata, Corallium rubrum, Eunicella singularis, Eunicella cavolinii, and Eunicella verrucosa) using mechanical cell aggregate production techniques. In particular, we investigated the conditions of aggregate formation, their number and survival in experimental conditions, the DNA synthesizing activity using 5'-bromo-2'-deoxyuridine (BrdU) tests, and the response to calcein addition and observed the secretion of newly formed sclerites. The BrdU tests showed that cell proliferation depends on the size of aggregates and on the presence/absence of symbiotic zooxanthellae. With epifluorescent and confocal imaging from calcein addition assays, we observed the presence of calcium ions within cells, a possible clue for prediction of sclerite formation or calcium deposition. The species-specific efficiency in production of cell aggregates is correlated to the size of polyps, showing that the higher density of polyps and their diameter correspond to higher production of cell aggregates. Regarding the long-term maintenance, we obtained the best results from E. singularis, which formed multicellular aggregates of 0.245 mm ± 0.086 mm in size and maintained symbiotic association with zooxanthellae throughout the experimental run. Formation of sclerites within aggregates opens a wide field of investigation on biomineralization, since de novo sclerites were observed around 30 d after the beginning of the experiment.

Monthly monitoring over one year (June 2003–May 2004) allowed us to evaluate the distribution of the Eurasian invader Dreissena polymorpha along the shores of Lake Trasimeno (Central Italy) and to shed light on the reproduction of these zebra mussels. Sampling was carried out on 12 study sites, 10 with hard substrata and 2 with soft sediments. The mollusk colonized different substrata, a feature that affected its density: from 40 on wooden boat keels to 200,000 individuals/m2 on concrete. In all months, gonad and gamete development was investigated by means of histological examination. The gonad of both sexes consisted of a single Y‐shaped organ, which increased in volume during maturation until it occupied the whole visceral mass in ripe individuals. Only one period of successful reproduction seemed to exist, and the gonadal development of males and females coincided fairly closely. Gamete development seemed to depend on a rapid increase in water temperature (from 4.3°C to 13.4°C). Inactive gonads were o...

The freshwater sponge Ephydatia fluviatilis and the zebra mussel Dreissena polymorpha were found to compete for space in Lake Trasimeno, because they colonize the same hard substrata (rocks and concrete). Photographic monitoring was carried out over one year, from June 2003 to May 2004, at particular sites located along the coasts, namely: Monte del Lago, Passignano sul Trasimeno, Spiaggia Comunale di Castiglione del Lago, Tuoro sul Trasimeno. Sponge overgrowth was observed monthly by comparing images of sponge/mussel interaction. Sponges tend to be encrusting but they can give rise to massive forms on concrete. In both cases, sponges grow and can gradually envelop the valves up to the final encapsulation of the mollusc. Asexual reproduction by means of resistant bodies, or gemmules, allows sponges to withstand the environmental stress, such as desiccation of the habitat or temperature values beyond the limit that are acceptable for mollusc survival. The suppressive influence of E. fluviatilis al...

Lake Piediluco (Central Italy) displays a discontinuous reed-belt along its shore, the dominant macrophyte being Phragmites australis (Cav.) Trin ex Steud., the reeds of which support the growth of the spongeEphydatia fluviatilis (L.). Samplings were carried out at ten stations located along the reed-belt with the aim of investigating the ‘consortium’, which is the result of the association between the edificatory E. fluviatilis and the related organisms. These last were considered at three different levels: (a) spatial localisation (epibionts, endobionts); (b) kind of association (occasional, strictly linked); (c) model of organisation (unicellular, multicellular). The associated fauna was investigated by considering both sponge biomass and life-cycle. The faunal composition of associated organisms and their quantitative rates were determined, and statistical differences among stations were tested by using 1-way ANOVA (p

Cues used for the detection of prey by the larva of Libellula depressa (Odonata Libellulidae) were investigated. Nymphs (alive and recently dead) of the mayfly Cloeon dipterum (Ephemeroptera Baetidae) and dummies were used as prey models. The responses of the larva to stimulations of different kinds and intensity, in different areas around the body, were tested in the laboratory in six different behavioural experiments. From the statistical analysis of the data (Pearson Chi-square and one-way ANOVA) it emerged that: (i) chemical cues seem not to be involved in the detection of the prey or, if they are involved, they are negligible in comparison with other kinds of stimuli; (ii) the larva of L. depressa utilizes mechanical and visual cues for the release of the predatory labial strike, and either one of these cues is effective for labial strike elicitation; (iii) mechanical stimuli have a predominant role in predation; (iv) the larva of L. depressa can rely on a non-contact mechanical sense for the detecti...

The ultrastructure of the globular papillae located along the inner side of the forceps of the two flying stages, imago and subimago, of male mayflies belonging to Ecdyonurus venosus (F.) is described. The external shape of the globular papillae varies with their position on the forceps’ segments and the stage. In longitudinal section, the globular papillae of the imago and subimago have a single dendrite ending in a tubular body, a feature consistent with their function as mechanosensory sensilla. During mating, the mechanical pressure on the forceps may be sensed by the cuticular surface of the papillae and transmitted to the tubular body. In the subimago, the globular papillae have a pointed apex and are less numerous. Another kind of sensillum, hairs having the typical organization of mechanoreceptive bristles, are scattered on the forceps of both imago and subimago.

Freshwater oligochaetes are studied worldwide because of their relevance as bioindicators in aquatic ecosystems. Nevertheless, species identification is still difficult because it is mainly based on the male reproductive system. The morphology of the chaetae offers an additional set of characters and the fine organization of these elements can help in solving crucial aspects allowing specific attribution. In spite of this, somatic chaetae are poorly investigated under scanning electron microscopy (SEM). A SEM analysis of the chaetae has been carried out on the tubificids Branchiura sowerbyi, Limnodrilus hoffmeisteri, Tubifex tubifex, and Psammoryctides barbatus from Trasimeno and Piediluco lakes (Central Italy). In particular, the chaetal pattern of B. sowerbyi is comparable to that described for specimens from the tropical regions of Asia, and T. tubifex shows the chaetal pattern typical of the nominal species; the palmate chaetae of P. barbatus are characterized by 15-20 fringes, each of them with a distal end thinner and folded backwards. In addition, B. sowerbyi is the dominant species in Lake Trasimeno, whereas it is lacking in Lake Piediluco, where the tubificids are primarily represented by T. tubifex.

The knowledge on Odonata adult mouthparts sensilla is scanty and, notwithstanding the epipharynx in the labrum is considered an organ of taste, no ultrastructural investigation has been performed so far on this structure in Odonata. The labrum of the adult of the damselfly Ischnura elegans (Odonata, Coenagrionidae) shows on its ventral side the epipharynx with sensilla represented by articulated hairs and by small pegs located at the apex of slightly raised domes. Under scanning and transmission electron microscope, the articulated hairs, with a well developed socket and tubular body, have the typical structure of bristles, the most common type of insect mechanoreceptors, usually responding to direct touch; the pegs, showing an apical pore together with a variable number of sensory neurons (from two to five), the outer dendritic segments of which show a dendrite sheath stopping along their length, have features typical of contact chemoreceptors.

L'obiettivo principale di LifeWatch, un'infrastruttura europea di e-Science sulla biodiversità e sugli ecosistemi, consiste nel rafforzare la ricerca scientifica sulla biodiversità attraverso la creazione di laboratori virtuali sul web, flessibili e avanzati. Tre casi di studio sono stati proposti da LifeWatch a livello europeo per facilitare lo sviluppo di ricerche integrate su questioni scientifiche fondamentali: dati già esistenti sono stati utilizzati, organizzati e migliorati con l'aggiunta di ulteriori informazioni e resi accessibili alla comunità scientifica e al grande pubblico. L'Italia coordina il caso di studio sulle specie aliene d'acqua dolce per valutare la vulnerabilità di questi ecosistemi alla loro invasione. A causa della stretto legame con le attività umane, le acque dolci sono soggette da secoli all'invasione di specie aliene e stanno soffrendo una perdita di biodiversità a tassi anche superiori a quelli registrati nei biomi terrestri. Le specie aliene sono estremamente difficili da gestire una volta entrate in un ambiente nuovo, quindi lo sforzo scientifico per comprendere i meccanismi che causano il loro successo e per trovare mezzi adeguati per la loro prevenzione dovrebbe essere elevato. Diversi studi hanno analizzato le cause forzanti della loro presenza, il ruolo dei cambiamenti climatici nel facilitare il loro arrivo e la loro diffusione, o l'impatto causato a livello di ecosistemi. Questi sono alcuni dei problemi che questa sessione affronta per capire meglio il processo delle invasioni biologiche al fine di ridurre il loro aumento e per applicare misure di conservazione della biodiversità più efficaci.

Consecutive underwater observations carried out in shallow waters of Pontetto (Ligurian Sea) from June to the end of November 2013 revealed the presence of purple areas on the white surface of the asconoid calcareous sponge Clathina coriacea. Histological and ultrastructural investigations performed on the purple areas of the sponge showed the occurrence of a network of hyphae of an indeterminate fungus permeating the sponge tissues and presumably responsible for the unusual colour of the sponge. The hyphae, varying in size and morphology according to their location in the sponge body, are visible on the outermost sponge surface and, after crossing the mesohyl, penetrate inwards into the choanodermal layer, being mainly located along the apical border of the choanocytes. The occurrence of undamaged flagella and microvillar fringes, which are the organelles characterising the choanocyte cells, is consistent with a normal functionality of the sponge tissues, notwithstanding the presence of the funga...

Nanomechanical properties, nanohardness and elastic modulus, of an Antarctic spongeRosella racovitzeawere determined by using a vertical indentation system attached to an atomic force microscope. The Rosella spicules, known to have optical waveguide properties, are 10–20 cm long with a circular cross section of diameter 200–600 μm. The spicules are composed of 2–10-μm-thick layers of siliceous material that has no detectable crystallinity. Measurements through the thickness of the spicules indicated uniform properties regardless of layering. Both the elastic modulus and nanohardness values of the spicules are about half of that of either fused silica or commercial glass optical fibers. The fracture strength and fracture energy of the spicules, determined by 3-point bend tests, are several times those of silica rods of similar diameter. These sponge spicules are highly flexible and tough possibly because of their layered structure and hydrated nature of the silica. The spicules offer bioinspired lessons for potential biomimetic design of optical fibers with long-term durability that could potentially be fabricated at room temperature in aqueous solutions.

The genus Proboscidoplocia is endemic to Madagascar and recent studies revealed that it is not monospecific. The eggs of four newly described species, namely P. billi, P. leplattenierae, P. ruffieuxae, and P. vayssierei, were investigated by scanning and transmission electron microscopy. Eggs were flattened and showed two distinct sides joining along their peripheral border. In P. billi, a deep groove separated the two sides, whereas only a slight rim was evident in the eggs of the other three species. The chorionic decorations varied from irregular uplifted ribs, as in P. billi, to regularly arranged depressions, wider in P. leplattenierae (8–10 μm in diameter) than in P. ruffieuxae (2–3 μm in diameter). In P. vayssierei, the chorion showed irregularly arranged micropores (about 1 μm in diameter). Mucous material covered the egg surface and tended to accumulate in the spaces between ribs or inside the chorionic depressions. The chorion was formed by two layers (endo‐ and exochorion) that showed ...

Healthy specimens of the Mediterranean Petrosia ficiformis har bour endocellular cyanobacteria (Aphanocapsa feldmanni) caus ing a violet pigmentation of the sponge. Necrosis in P. ficiformis can be easily detected by the occurrence of white patches scat tered over the surface. Necrotic specimens were examined along the Gallinara Island coasts (Western Ligurian Sea), in coincidence with environmental stress (heavy rainfall, land run‐off, high sea‐water temperature). The appearance of white patches is due to the gradual sloughing of the pinacodermal covering, as evidenced by scanning electron microscopic observations. Sloughing leads to progressive tissue degeneration in the deeper parts. Histologi‐cal sections showed that, concomitantly with the loss of the su perficial layer, internal sponge tissues degenerate and the sponge body becomes exposed to the invasion of ciliates. Spicule bun dles of the skeletal network separate damaged tissues from the healthy ones, thereby slowing down spread of necr...

The sexual reproductive cycle of the Tetractinomorpha Spirophorida Cinachyra tarentina was studied mainly using light microscopy on samples collected in South Italy over a 2‐year period. Some aspects of the egg morphology were observed using transmission electron microscopy. Each year, young oocytes in pre‐vitellogenesis appeared in May and coexisted with growing oocytes. Yolk‐filled eggs were present in June and July. Oogenesis preceded spermatogenesis which occurred only in June. Cinachyra tarentina is an oviparous species having small eggs ranging from 40 to 50 pm in diameter which are scattered in the mesohyl and have a nucleolated nucleus surrounded by dictyosomes of the Golgi apparatus. Growing oocytes and yolk‐filled eggs have an irregular surface because of the presence of numerous pseudopodia which protrude into the mesohyl. Even though apparently gonochoric individuals were mostly observed, the rare specimens with sperm clusters and young oocytes proved the occurrence of successive herm...

The ultrastructure of the Malpighian tubules of the final instar nymph of the mayfly Baetis rhodani is described. Numerous Malpighian tubules enter the alimentary canal at the transition from midgut to hindgut. Each of them is made up of a cylindrical distal portion and a proximal narrow duct emptying into the gut. At the junction between the two regions, the cylindrical portion enlarges and curves, to continue into the thin duct. The wall of the cylindrical portion consists of primary cells characterized by typical features of the secretory/absorbing epithelia. These cells show a large polytene nucleus, an apical microvillated border, a high number of mitochondria and basal infoldings. The narrow duct is formed of large cells joined by highly convoluted junctions, and their cytoplasm is filled with electron‐translucent vesicles. The apical border of the cells of narrow duct lacks microvilli but bears several finger‐like extensions. Each narrow duct empties into a canal interposed between groups ...

The temporal sequence of eggshell organization (vitelline envelope and chorion) in Silo mediterraneus saturniae (Trichoptera, Goeridae) is highlighted by means of ultrastructural investigation on ovarioles of newly emerged females. Precursors of the vitelline envelope, initially accumulating in the space around egg microvilli, merge together to give rise to a striated border. Discrete striae fuse into the final electron‐dense vitelline envelope. Choriogenesis takes place along the apical region of the follicle cells facing the egg, throughout the progressive release of precursor material synthesized by the follicular epithelium. The onset of chorionic layer deposition is marked by irregular patches which gradually interconnect. As choriogenesis progresses, the follicular epithelium reduces in thickness. An epichorion, with a fibrillar texture, becomes gradually distinct from the follicle cell cytoplasmic matrix and is superimposed on the chorion. At the end of choriogenesis (chorion and epichorio...

An overview of larval antennal sensilla in hemimetabolous and holometabolous water-living insects is given by updating current knowledge on the fine structure of these sensory systems. In the absence of successful electrophysiological studies, the possible function of sensilla is deduced from their architecture. Various kinds of sensilla are described in hemimetabolous insects, such as Ephemeroptera, Odonata, and Plecoptera, and holometabolous insects, such as Diptera Nematocera (Culicidae, Simuliidae, Psychodidae, Chaoboridae) and Trichoptera. Their possible function in responding to stimuli from the freshwater environment is illustrated and discussed. The importance of sensilla as taxonomic and phylogenetic traits is reported in Baetidae (Ephemeroptera) and in Diptera Nematocera. Some homologies outlined in Diptera Nematocera give evidence of a link between species, such as Chaoboridae and Psychodidae, whose antennae are highly modified, prehensile in the former and very reduced in the latter. Particular features, such as cuticle without pores in chemosensory sensilla and naked perikarya, are so far found exclusively in some water-living arthropods, thus reflecting a possible adaptation to the aquatic habitat. The structure of sensilla and chloride cells, which have a similar external morphology, is presented and discussed in various insect groups, considering the possible derivation of the chloride cells from sensilla.

The study of cell-cell and cell-substratum adhesion in vitro is useful for understanding cell behavior in a three-dimensional pattern. We have used dissociated cells (choanocytes represent the main fraction) from the calcareous sponge Clathrina, namely C. cerebrum and C. clathrus, to illustrate our present understanding on three main aspects of cell-cell and cell-substratum adhesion in vitro: (1) cytoskeletal protrusions; (2) cell behaviours on organic substrata; and (3) paths of locomotory sponge cell. Cell locomotion occurs by the extensions of scleropodial and lamellipodial protrusions, by way of actin polymerization. The extent to which cells produce these cytoplasmic processes varies according to the substratum (e.g., collagen, fibronectin, laminin, polylysine). It was found that more cell extensions were produced on collagen substrata, and this led to greater cell movement. Advancing choanocytes are not polarized. Their paths are particularly complicated, showing linear segments, which produce a more efficent cellular translocation, and winding tracts with frequent turns or loops. Small amoeboid cells describe more linear paths with a wide range of speed variation than larger cells. The presence of cell-derived substratum reduces the progressive dispersion of cells and allows cells to encounter one another in such a way that the initial random walking later turns into non-random displacement. Even though cAMP-treated cells exhibit different aggregative tactics, cAMP 10-8 M remarkably enhances cell encounters and supports the existing information that this cyclic nucleotide represents a signal that affects cell morphology and locomotion. The bulk of data on sponge cell-cell and cell-substratum adhesion has been evaluated by mentioning the significant advances and references concerning studies of other cell systems. Microsc. Res. Tech. 44:279–292, 1999. © 1999 Wiley-Liss, Inc.