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Fauna Europaea provides a public web-service with an index of scientific names (including important synonyms) of all living European land and freshwater animals, their geographical distribution at country level (up to the Urals, excluding the Caucasus region), and some additional information. The Fauna Europaea project covers about 230,000 taxonomic names, including 130,000 accepted species and 14,000 accepted subspecies, which is much more than the originally projected number of 100,000 species. This represents a huge effort by more than 400 contributing specialists throughout Europe and is a unique (standard) reference suitable for many users in science, government, industry, nature conservation and education. Gastrotricha are a meiobenthic phylum composed of 813 species known so far (2 orders, 17 families) of free-living microinvertebrates commonly present and actively moving on and into sediments of aquatic ecosystems, 339 of which live in fresh and brackish waters. The Fauna Europaea database includes 214 species of Chaetonotida (4 families) plus a single species of Macrodasyida incertae sedis. This paper deals with the 224 European freshwater species known so far, 9 of which, all of Chaetonotida, have been described subsequently and will be included in the next database version. Basic information on their biology and ecology are summarized, and a list of selected, main references is given. As a general conclusion the gastrotrich fauna from Europe is the best known compared with that of other continents, but shows some important gaps of knowledge in Eastern and Southern regions.

During a survey of the Italian marine meiofauna, several specimens of the rare gastrotrich genus Xenodasys were found in a submarine cave along the Ionian coast of Apulia. The finding represents the first record of the genus for the Mediterranean Sea and reinforces the consideration of marine caves as habitats of high naturalistic value. The specimens, analysed using different microscopy techniques, showed a new species, named Xenodasys eknomios. Scanning electron microscopy, unveiling the astonishing morphology of this unusual gastrotrich, indicates that, due to technical artefacts, light microscopy may generate unreal features, which in the past may have led to the misinterpretation of the anatomical traits of these creatures. Transmission electron microscopy indicated that the ‘Seitenfüsschen’, are genuine elements of the adhesive apparatus, in contrast with previous investigation, which attributed an exclusive sensorial function to these organs. Confocal laser scanning microscopy, combined with actin-binding fluorochromes, revealed muscular elements in a region where originally the muscular chordoid organ was reported for gastrotrich species belonging to the genus Chordodasys. A taxonomic revision of the species currently allocated to the genus Xenodasys led to the establishment of Chordodasiopsis gen. nov. to integrate the former Xenodasys (=Chordodasys) antennatus and to the drafting of emended diagnosis of the genus Xenodasys. An overview of the high-rank systematization of these genera is also provided, with the establishment of Xenodasyidae fam. nov. to allocate both Xenodasys and Chordodasiopsis.

Geometric morphometrics was applied in a quantitative analysis of the morphology of the yellow-bellied marmot mandible. Five age classes were recognised by premolar toothwear, and the size and shape of the lower jaw were compared between sexes and among ages. Although the social role of adult males and females is markedly distinct, with the former mainly engaged to defend a territory with a female harem and the latter taking care of the young, mandible sexual dimorphism was moderate. On the contrary, form differences among age classes were conspicuous, and ontogenetic scaling, aimed at increasing mandible robustness, accounted for the majority of the shape change during growth. At least one mandibular shape modification, however, was related to the different behavioural ecology of immature and adult marmots. The mechanical efficiency of the superficial masseter and, thus, the strength of the incisor bite become so much greater in the sexually mature individuals that it cannot be interpreted as size-related adjustment. The need for stronger incisive bites is not explained by diet change, as the yellow-bellied marmot adults feed on the same grasses and forbs as the young and yearlings. Increasing the strength of the incisor bite is likely to be adaptive in order to provide adults with more efficient 'weapons' for intraspecific conflicts, and self- and kin-defence from predators. Morphological remodelling in the yellow-bellied marmot mandible seems to be more concerned with changes in size and behaviour during growth than with ethological differences between adults of the two sexes.

The morphology of the reproductive apparatus of several species of Turbanellidae, which are sequential hermaphrodites, has been studied for a comparison with that of other Gastrotricha Macrodasyida, which are simultaneous hermaphrodites. The common structural plan of the genital system of Turbanellidae includes two testes which extend into two sperm ducts turning anteriorly and fusing in a midventral pore, two ovaries with oocytes maturing in a cephalic direction and only one accessory organ, a seminal receptacle, provided with an external pore. A possible sperm transfer modality alternative to that described in the literature is advanced. Spermatological characters of Paraturbanella teissieri have been compared with those of the two Turbanella species studied up to date. Turbanellidae share with other Macrodasyida the general model of spermatozoon, but are the only representatives of this taxon known so far which have sperm devoid of the striated cylinder around the axoneme. Both the structure of the reproductive apparatus and the fine morphology of the spermatozoa of Turbanellidae species agree with the evolutionary view, recently supported by morphological and molecular data, which puts this taxon on a separate clade, early divergent from the stem lineage of Macrodasyida.

A faunistic analysis of the sandy sediment collected from 10 locations along the east (four) and west coasts (six) of Corsica, western Mediterranean Sea, yielded a rich and diverse range of gastrotrichs: 42 species of 18 genera and seven families from the orders Chaetonotida (17 species) and Macrodasyida (25 species). Sublittoral samples were always more species-rich than those from littoral sites; 37 versus nine spp. The gastrotrich fauna from the east coast was more diverse than that from the west coast, both in terms of the total species number (35 spp.: 13 Chaetonotida ‡ 22 Macrodasyida versus 23 spp.: 12 Chaetonotida ‡ 11 Macrodasyida) and the number of species per location (13 §4.2 versus 7.5§ 4.0). All but three of the species have previously been reported from other Mediterranean locations. The exceptions are two as yet unidentieed species of the genera Cephalodasys and Macrodasys, and Tetranchyroderma inaequitubulatum sp. nov., a thaumastodermatid with pentancrous covering, showing a cluster of ventral adhesive tubes peculiarly located only on the right side and an unusually conspicuous sexual caudal organ. Aspidiophorus paramediterraneus, Chaetonotus apechochaetus, Acanthodasys aculeatus, Paraturbanella teissieri, Pseudostomella etrusca and Tetranchyroderma thysanophorum, present at 50% or more of the investigated locations, are the most common species on the third largest island of the western Mediterranean basin.

During 1996–1997 a systematic sampling programme was carried out in brackish coastal lakes and lagoons and in the delta of the River Po. In six of the nine collecting locations, 12 species of Gastrotricha were identified. One species, Chaetonotus ichthydioides, is new to science; another three species, the chaetonotidans Heterolepidoderma foliatum and the macrodasyidans Dendrodasys ponticus and Turbanella cf. pontica, and one macrodasyidan genus, Paradasys (P. subterraneus), were found in Italy for the first time. The unusual morphology of some of the species identified shows that Gastrotricha colonized brackish waters from both marine and freshwater habitats.

Twenty‐four macrodasyid and thirteen chaetonotid species of marine Gastrotricha are reported. Two of these species ‐ Urodasys apuliensis and U. bucinastylis ‐ are new, while the macrodasyid genus Crasiella is reported for the first time in Italy and the Mediterranean basin. Samples were taken at depths varying from 1 to 34 metres. Altogether, the number of species found was relatively high and comparable with the range of fauna found on the major Italian islands. A possible evolution of the reproductive system in the genus Urodasys is briefly discussed.

Twenty-three species of gastrotrichs were found in samples collected from 10 of the 19 water-courses examined. The richness of species and the faunistic composition are comparable with those in lentic sediments, even if specimens are more numerous in the latter. The Zambra riverlet in the Pisa Mountains is the richest (17 species) of the sampling biotopes. As in freshwater lentic environments, the presence of organic detritus causes an increase in both the number of specimens and species, whereas the fine fraction of the sediment (silt) leads to their sharp decrease. Lepidodermella squamata, Chaetonotus maximus and C. persetosus have proved to be ubiquitous species, while C. fluviatilis and Ichthydium squamigerum were only found in sand. Most species show a cuticular covering with a particular morphology which has probably favoured their moving from the surface of sediment towards interstitial spaces.

Four species new to science are described and figured from the Italian coastline of the Mediterranean Sea and its adjacent waters: the Mediterranean Dactylopodola mesotyphle n. sp. in the family Dactylopodolidae, a neotenous sibling species of the more geographically ubiquitous D. typhle Remane, 1927, is differentiated from the latter both morphologically and biogeographically. Of three species of Tetranchyroderma: T. aphenothigmum n. sp., T. psilotopum n. sp., and T. sympborochetum n. sp. in the family Thaumastodermatidae, the first and third have a complete dorsal covering of tetrancres, while the second has an incomplete covering of pentancres. The species Dendrodasys affinis Wilke, 1954 in the family Dactylopodolidae is redescribed, and figured for the first time, from specimens collected in littoral and shallow sublit‐toral sediments near Naples.

Most species of Urodasys bear a clearly structured cuticular stylet in the caudal organ, that constitutes a powerful diagnostic feature. On the basis of the morphology of this stylet, two new species, Urodasys acanthostylis and U. uncinostylis, are described. Urodasys acanthostylis is diagnosed by a stylet with the tubular portion clearly bent at a slightly obtuse angle, U. uncinostylis by a stylet with the tubular portion which develops in about one and a half coils. The former was found along the Apulian coast (southern Italy) and in Malta, and the latter at the Maldives.

Of the thaumastodermatid gastrotrichs that were collected in the years 1989–1991, during a faunistic survey of the Italian coasts, several have been placed in the genus Tetranchyroderma. On the basis of their distinctive morphological characters, four that bear pentancres are being described as new species, three with a complete dorsal covering of ancres: T. kontosomum, T. polyprobo‐lostomum, T. tanymesatherum, and one with an incomplete covering: T. anomalopsum.

Forty‐one species (25 Macrodasyida and 16 Chaetonotida) are reported from the coasts of Sicily. Among the Chaetonotida, Chaetonotus sp. 3 Valbonesi & Luporini, 1987 is redescribed and redrawn from specimens collected from sublittoral sediments of Giardini Naxos (Taormina), and is named Chaetonotus luporinii.

Twenty‐eight macrodasyid and twenty‐eight chaetonotid species of marine Gastrotricha are reported. Of these species, two ‐Halichaetonotus clavicornis and H. genatus ‐ are new, and three are described for the first time for to the Italian fauna. The influence of various physical and chemical environmental factors on gastrotrich distribution along the peninsular and island coasts of the Tyrrhenian Sea are analysed and discussed.

BackgroundBiogeographical and macroecological principles are derived from patterns of distribution in large organisms, whereas microscopic ones have often been considered uninteresting, because of their supposed wide distribution. Here, after reporting the results of an intensive faunistic survey of marine microscopic animals (meiofauna) in Northern Sardinia, we test for the effect of body size, dispersal ability, and habitat features on the patterns of distribution of several groups.Methodology/principal findingsAs a dataset we use the results of a workshop held at La Maddalena (Sardinia, Italy) in September 2010, aimed at studying selected taxa of soft-bodied meiofauna (Acoela, Annelida, Gastrotricha, Nemertodermatida, Platyhelminthes and Rotifera), in conjunction with data on the same taxa obtained during a previous workshop hosted at Tjärnö (Western Sweden) in September 2007. Using linear mixed effects models and model averaging while accounting for sampling bias and potential pseudoreplication, we found evidence that: (1) meiofaunal groups with more restricted distribution are the ones with low dispersal potential; (2) meiofaunal groups with higher probability of finding new species for science are the ones with low dispersal potential; (3) the proportion of the global species pool of each meiofaunal group present in each area at the regional scale is negatively related to body size, and positively related to their occurrence in the endobenthic habitat.Conclusion/significanceOur macroecological analysis of meiofauna, in the framework of the ubiquity hypothesis for microscopic organisms, indicates that not only body size but mostly dispersal ability and also occurrence in the endobenthic habitat are important correlates of diversity for these understudied animals, with different importance at different spatial scales. Furthermore, since the Western Mediterranean is one of the best-studied areas in the world, the large number of undescribed species (37%) highlights that the census of marine meiofauna is still very far from being complete.

Marine and freshwater gastrotrich fauna from the Island of Montecristo (Tuscan Archipelago) is reported. Thirteen macrodasyid and six chaetonotid species were found in marine sandy sediments from four collecting sites. The new species Lepidodasys unicarenatus and Tetranchyroderma insulare ate described. Nine chaetonotid species were collected from the inland waters of the island, and the new species Chaetonotus (Schizochaetonotus) oplites is described. A comparison between the gastrotrich fauna of Montecristo and that of other islands in the archipelago and of the Tuscan littoral is drawn.

A new genus, Dendropodola, and species, D. transitionalis, are described in the family Dactylopodolidae. Three new species, Cephalodasys hadrosomus, Mesodasys adenotubulatus, and Mesodasys ischiensis, are described in the family Lepidodasyidae. And, six new species, Pseudostomella etrusca, Ptychostomella tyrrhenica, Tetranchyroderma heterotubulatum, Tetranchyroderma hypopsilancrum, Tetranchyroderma pachysomum, and Tetranchyroderma thysanophorum, are described in the family Thaumastodermatidae. All were collected in littoral and shallow sublittoral sediments along the Italian coastline of the Mediterranean Sea and its adjacent waters.

Owing to technical problems and difficult taxonomic identification, meiofauna have been generally less studied than macrofauna. However, the role of meiofauna in marine ecosystem functioning, and their effective and rapid response to anthropogenic alterations and climatic changes have recently been acknowledged, leading to increasing scientific and applied interest. At present, systematic and biogeographic knowledge of the meiofauna of the Adriatic Sea is extremely heterogeneous, because most of the data are limited to a few taxa and the sampled areas are scattered, being located mainly in the coastal areas of the northern basin. Analysis of the composition and distribution of meiobenthic groups in the Adriatic Sea highlights the presence of several endemisms. Meiofauna also include bioindicator taxa, which allow assessment of the quality of marine sediments; this is particularly useful in systems characterised by the synergistic effect of different forms of anthropogenic impact, such as the Adriatic basi...

Twenty‐three species of chetonotid gastrotrichs are reported from three islands of the Tuscan Archipelago (Tyrrhenian Sea, Italy). The island of Elba is the largest in the archipelago and has the most sand beaches. It possesses the greatest diversity of gastrotrich fauna, with 17 known species. The island of Capraia ranks second with 12 species, and the island of Giglio is third with 8 species. Chaetonotus napoleonicus from the island of Elba and Chaetonotus aegilonensis together with Halichaetonotus marivagus, both from the island of Capraia, are described as new species. A clarification of the diagnostic characters of C. atrox, C. dispar and C. neptuni is given. Xenotrichula carolinensis is synonymized with X. intermedia.

During the past 5 decades, the large-sized biota inhabiting dark marine caves has attracted the attention of many marine biologists; in contrast, studies concerning the meiofaunal organisms of these peculiar biotopes remain scanty and mostly with a taxonomic aim. In this study, the nature and abundance of meiofaunal taxa living in a Mediterranean, semi-submerged sea cave was surveyed in relation to distance from the entrance and over two different seasonal periods. Particular attention was paid to the Gastrotricha taxocene. Research was carried out in a cave along the Ionian coast of Apulia (southern Italy), the “Grotta Piccola del Ciolo” which opens for approximately 120 m on the north-eastern side of a shallow fjord and has a bottom blanketed by fine to very fine sand, occasionally rich in detritus. Quantitative samples in four replicates were collected by SCUBA diving, in November 2000 and June 2001, coring the sediment with a hand-held piston corer in three light-free sites (stations 1–3) located at increasing distances from the entrance. At each site, two additional 500-ml sediment samples were collected for an in vivo study of the Gastrotricha. Faunistic analysis found a fairly high meiobenthic diversity, identifying representatives of more than 12 major groups, with total abundances ranging from 656 ind./10 cm2 (10 cm2) in November to 1,069 ind./10 cm2 in June. Station 1, the closest to the entrance invariably hosted the most abundant meiofaunal community (851 ind./10 cm2 in November and 1932 ind./10 cm2 in June), followed by station 2 or 3 depending on the season. While nematodes and harpacticoids appear as the most abundant taxa when the cave is considered as a whole, other taxa may prevail numerically in selected stations, e.g. priapulids, which are the second most abundant taxon at station 1 (30 ind./10 cm2 in November and 83 ind./10 cm2 in June). Although the density of total meiofauna and that of the single groups may not be very high, the cave is interesting by virtue of the peculiarity of the hosted fauna, e.g., species and genera new to science or new to the Mediterranean Sea. Regarding the Gastrotricha, we found 16 species, accounting for 1.3–2.6% of the total meiobenthos (density = 8.4 ind./10 cm2 in November and 27.4 ind./10 cm2 in June). Analysis of the gastrotrich community found, particularly in June, an assemblage of taxa quite different from those found in open habitats, even at the family level; differences that are probably due to the exploitation of different food resources by animals populating the two environments, i.e. algae in the open sea versus bacteria in the caves. Results indicate that for meiofauna, as happens for macrofauna, the marine caves may represent hotspots of biodiversity and endemism; the driving forces at the base of the trophic depletion hypothesis seem to be responsible for structuring the meiofauna community inside the cave.

Gastrotrichs are meiobenthic invertebrates of obscure origin and unclear phylogenetic alliances. Uncertainties also plague the intra-group relationship with major contrasts between the evolutionary scenarios inferred from morphology or molecules. In this study we analysed partial sequences of the 18S rDNA gene of 18 taxa (14 new and 4 published) to test morphological estimates of gastrotrich phylogeny and to verify whether controversial interrelationships from previous molecular data are due to poor sampling. Data were analysed using both maximum parsimony and maximum likelihood. MP topology was then forced to reflect published morphological estimates and the most parsimonious solutions from each constraint analysis was statistically compared against the unconstrained solution. MP analysis yielded a single tree with few nodes well supported by bootstrap resampling. These included the monophyly of the Chaetonotidae and the internal relationships of the members of this family, with Aspidiophorus appearing as the most basal member. The monophyly of the Turbanellidae was also well supported with some suggestion that its sister group might be Mesodasys . Lepidodasyidae was found to be an unnatural taxon with Lepidodasys forming a separated clade but unrelated also to the Thaumastodermatidae. With the exception of genera Lepidodasys and Neodasys , the Macrodasyida appeared to be resolved separately from the Chaetonotida, and Dactylopodola was resolved as the most basal macrodasyid. ML analysis yielded a tree not too dissimilar from MP, although Dactylopodola and Xenodasys were resolved as a clade. Statistics indicate that the output from our MP analysis is compatible with the classical view placing representatives of the two orders within two distinct evolutionary lines. Most of the constrained solutions, except the shortest, corroborate the monophyly of the two orders, whereas all five constrained solutions support also the notion that sees Neodasys as an early divergent clade along the Chaetonotida branch. Thus, results are generally compatible with the hypothesised evolutionary scenario based on morphological data, but are in contrast with previous findings from molecules. Future research should consider using the complete SSU rDNA gene sequence in their analysis and additional genes for deeper resolution.

Biogeographia vol. XXIV - 2003 (Printed October, 31st 2003) Marine biogeography of the Mediterranean Sea: patterns and dynamics of biodiversity Faunistics and zoogeographical overview of the Mediterranean and Black Sea marine Gastrotricha M. ANTONIO TODARO*, LUCIA MATINATO**, MARIA BALSAMO***, PAOLO TONGIORGI** *Dz'pzzrrz'mem‘o di Bio/ogirz /lnimzzle, Uni:/ersitiz (ii Marian/1 E Reggio Emilirz, Vizz Czzmpi 213/cl’, [~41 I 00 Madcna (Juli)/),' e—mzzz'/: todzzro. zzntonio @zmimo. it **Dzj7zzrti7neI2to di Scierzze Agnzrie, Urziz/erritiz di Marlena e Reggia Emilia, Via Kennmfiz 17, 142100 Reggie Emz'lz'zz (Italy) ***[5tz'tLiz‘0 di Scimze Maifblogic/ye, Universitfz di Ureirzo, Via Oddi 21, I-61029 M~bz'no (Italy) Key words: Gastrotrichs, Biogeography, Meiofauna, Taxonomy, Mediterranean Sea, Black Sea. SUMMARY The paper provides an updated overview of the knowledge regarding the marine gastrotrich fauna of 10 Mediterranean and 2 Black Sea countries. Taxonomic account and species distribution come from published records, including electronically disseminated information, as well as original data from 18 localities (16 western and 2 levantine), investigated by the authors between 1990 and 2002. Since the description of the first marine Mediterranean gastrotrich, Hera)/zlzzijir izgzzm Claparede, 1867, discovered in the Gulf of Naples (Italy), 273 additional species, from 417 locations have been recorded in the basin so far. Of the gastrotrichs found, 143 species, in 24 genera and 6 families, belong to the order Macrodasyida and 131 species, in 11 genera and 3 families, belong to the order Chaetonotida; these statistics include several species as yet not described. The number of species per location is variable, ranging from 1—37, with a global mean of 8.041” 6.69 spp/location. Egypt and Israel show mean values well above the average, with 12.8 and 10.8 spp/loc. respectively, whereas mean values for Algeria, Tunisia, Bulgaria, Croatia, and France are below average (1— 5.43 spp / location); data For Cyprus, Greece, Romania and Italy are within the average value. Arttzzr/Jorlzzrys (Ictz/mtm‘, recorded in 28% of the investigated locations is the most Frequently found macrodasyidan; Htz/it/Jzzetmzatur am/zfi'r, also recorded in 28% of the investigated localities, is the most common chaetonotidan. Data analysis indicated substantial differences among countries, regarding sampling effort and, consequently, faunistic knowledge. In comparison with the generally good information concerning the Italian fauna (177 species from 246 localities), gastrotrichs from other Mediterranean nations are much less known; along with Italy, only few other Nations have been investigated to a sufficient extent (i.e., Greece: 44 sampled localities, 77 recorded species; France: 37 L, 70 spp; Egypt: 28 L, 81 spp; Israel: 15 L, 55 spp; Cyprus: 9 L, 41 spp), whereas investigation carried out in several other countries can be considered, to a variable degree, incomplete (i.e., Algeria: 16 investigated localities and 11 species found; Romania: 7 L, 30 spp; Tunisia: 5 L, 2 spp; Bulgaria: 3 L, 11 spp; Croatia: 1 L, 12 spp, Spain: 1 L, 3 sp, Malta; 2L, 2 spp.), or nil (e.g., Morocco, Libya, Turkey, Albania). All marine gastrotrich Families and most marine genera have representatives in the Mediterranean Fauna, notable absences regard the genera Demzoz/zzryr, Dirzadmjyr, Plzzizat/rziyx, Prostabucttzntizl and perhaps Prezzzfart/1‘brz71e[/zz; on the other hand representatives of two genera, En2_ytI'mji: and Dezzdmpar/01:1, are unknown elsewhere in the world except the western Mediterranean. At species level, about 140 taxa have so Far been found only in the Mediterranean area, whereas the

The barrier islands and coast south and east of Venice, Italy, were sampled in parallel to the work of Schrom two decades ago. Where he found 49 site records for 24 species of gastrotrichs at 8 sites, 5 littoral and 3 shallow sublittoral, we found 5 site records for 2 species at 9 sites, 5 littoral and 4 shallow sublittoral. We had no site records from littoral sites; one species, Dolichodasys elongatus, occurred at all sublittoral sites. From other locations (n=15) in our present survey of the Italian coastline, where we have paired littoral: sublittoral sites, we have found 6.7 (±0.9) species in the former and 8.0 (±0.9) in the latter. The absence of gastrotrichs in samples from all five littoral sites and the dominance of D. elongatus in sublittoral sites is clear evidence as to the severity of pollution in this area. However, five species were found in a sample from the top of a longshore bar at one location, indicating that a type of local refugium exists from which future recolonization of the remaining habitat could proceed, if the input of pollutants can be reversed.

The new species Tetranchyroderma esarabdophorum is characterized by having two pairs of cephalic tentacles and three pairs of dorsolateral rod-like processes. T. esarabdophorum is close to T. enallosa and more so to T. antennatum, which has also been found in the Mediterranean.

An overall picture of the European elver's behaviour during coastward migration and entrance into inland waters emerges from a survey of the literature. The factors influencing trophic migration are discussed. In particular, the data relevant to the Mediterranean area are taken into account. The observations by the authors over the course of one year at the outlet of the River Arno confirm that the behaviour of elvers there is similar to that described for the North Atlantic coast. The ascent of the elvers at the sampling point (located approximately 1100 m upstream from the outlet) is greater in the hours immediately following sunset. A clear-cut influence upon the amount of the ascent is due to tidal movements, and catches are larger after the peaks registered with flood tide. Temperature of the waters appears to have some effect, but no fluctuations in the ascent are attributable to the flow of the river and to the phases of the moon. The increase in the demand for elvers to replace stocks and...

Viene segnalata la presenza sulle coste della Toscana di due specie di Gastrotrichi Macrodasioidei nuovi per i mari italiani: Paraturbanella teissieri e Turbanella thiophila; per la seconda specie e il secondo rinvenimento in assoluto. P. thiophila e un tipico componente delle biocenosi di sabbie poco ossigenate (the sulfide system) ed e notevole anche per le sue dimensioni.

Tetranchyroderma sardum, a new species of macrodasyid gastrotrich, was found in litoral sand from Sardinia. It is characterized by: 1. two pairs of cephalic tentacles, one rod‐like and the other knob‐like; 2. twenty‐two pairs of ventrolateral adhesive tubes; 3. three furcal adhesive tubes and 4. thirteen longitudinal rows of pen‐tancres. T. sardum closely resembles T. esarabdophorum and T. anten‐natum, both collected from the Mediterranean Sea.

(1961). Sulle relazioni tra habitat ed orientamento astronomico in alcune specie del gen. Arctosa. (Araneae - Lycosidae) Bollettino di zoologia: Vol. 28, No. 2, pp. 683-689.

The shell‐boring gastropod Ocinebrina edwardsi sustains itself by preying on mussels. In the laboratory these drills, when presented with a choice between well fed and starved prey, were attracted to a statistically significant degree (P < 0.01) towards the well fed mussels. Chemical signals, i. e. attractant and/or repellent substances which were being continually emitted by the mussels, informed the predators from a distance as to the physiological condition of their prey. Results of any predation tests which fail to take this aspect into consideration may be biased and tests carried out on animals which have been kept for a long time in captivity are to be avoided.

Samples of mullet fry were taken hourly, for 24h, once a month, from September 1979 to October 1980. Five species were found to enter the estuary of the Arno river: Mugil cephalus, Liza ramada, Liza aurata, Liza saliens and Chelon labrosus. Seasonal occurrence and migrational peaks were determined for each species. Variations of standard length and of condition factor were studied during the migrational phase. Hourly samples gave further information on daily variations in the catches of juvenile mullets, on the influence of tidal movements and on feeding activity during the 24-h cycle. Our results showed that the greatest number of fry was caught at sunset, a second peak occurring in the morning hours. Furthermore, the catches seem to be affected by tidal movements, being higher during high tide. The variations of the vacuity coefficient (the percentage of empty stomachs in the total sample) related to dial rhythm, were considered to indicate the daily feeding activity of each species. The analysis showed that the trophic activity of L. saliens, L. ramada and L. aurata occurs mainly during daylight. On the contrary, M. cephalus seems scarcely to feed in this condition, but increases its activity slightly at dusk and in the first part of the night.

The daily feeding rhythms of five species of mullet fry (Liza ramada, Liza aurata, Liza saliens, Mugil cephalus and Chelon labrosus) were investigated by analyzing their stomach fullness during 24‐hour cycles. Light is the major abiotic factor influencing the feeding rhythm of the fry. Feeding activity occurs prevalently during day‐time with a clear unimodal feeding cycle. Only L. saliens fry show a bimodal feeding cycle, with a secondary peak around sunset. Differences in the feeding activity rhythm are probably due to larger individuals which, unlike the smaller individuals, show preferential twilight feeding. Tides and temperature play a secondary role and their influence is probably masked by the light effect.