Phaleria

Abstract: The spatial distribution of the following five nocturnal tenebrionid species was studied along a beach dune system: Phaleria provincialis Fauvel, Phaleriabimaculata Linnaeus, Halammobia pellucida Herbst, Xanthomus pallidus Curtis and Xanthomus pellucidus Mulsant. An integrated system of traps was used to sample the beetles during their active and resting phases. Environmental parameters were recorded locally during the experiments. Preference experiments were performed under controlled laboratory conditions. The aim of the study was to understand the environmental constraints influencing the species' spatial distribution and the mechanisms involved in zonal maintenance. The results indicate that beetles exploit chemical and physical gradients of the beach dune system; and the mechanisms used for zonal recovery and/or maintenance are based on behavioural responses to visual and environmental stimuli. Controlled laboratory experiments showed that sand salinity was a limiting factor for all five species. For the two Phaleria species, which had a relatively seaward distribution, sand moistures were also important. In contrast, for the two Xanthomus species, which were distributed more landwards, grain size was a regulating factor. In the present study gradients in beetle responses to different environmental factors were observed.

Abstract: A study on the spatial distribution of two tenebrionids and an isopod species was conducted at a small extent. Two species of the genus Phaleria were chosen because of their sympatric distribution and apparently similar adaptations to the beach environment. These scavenger species were studied in association to Tylos europaeus. Distributions, both perpendicular and parallel to the shoreline, were studied simultaneously with a grid of 20 × 20 pitfall traps arranged at a distance of 1 m from each other. Faunal samples were collected at two different hours of the night and core samples of sand were taken next to each pitfall trap for successive laboratory analysis. An index of dispersion was applied to test for aggregation of all species and of environmental parameters on the total, across- and long-shore. Kolmogorov–Smirnov two-sample test was used to compare the distributions between species. Regression analyse were applied to evaluate relationships between environmental parameters and species distributions. The study showed that the distribution of Phaleria species and T. europaeus was scale-dependent. The species and the values of the environmental parameters showed aggregated distributions both across- and long-shore. Aggregations of each Phaleria species differed according to their resting and foraging phases. For all species, sand moisture and salinity were the most important parameters explaining distribution. Granulometric parameters were correlated with the choice of the resting areas of both Phaleria species, whereas the spatial distribution of T. europaeus was correlated to the distribution of the organic matter.

Abstract: Two species, Phaleria prolixa Fairmaire and Phaleria bimaculata Linnaeus were compared. The first species lives on a Somalian beach with large tidal fluctuations, while the second inhabits a beach on the Tyrrhenian littoral of Italy where tidal excursions are negligible. For Ph. prolixa the data were collected in two different climatic seasons, the dry and the wet season. Instead for Ph. bimaculata the data refer to a 4 month survey. Zonations and activity patterns were obtained from the capture frequencies of directional cross and wall traps. Both species prefer the seaward part of the sandy beach with slight variations in the different seasons for Ph. prolixa. Both species are nocturnal but only Ph. prolixa, being largely tied to a tidal rhythm, shows activity even throughout the day.

Abstract: Two sympatric species of the genus Phaleria living on the beach of Burano (GR, Italy) were studied. Fortnightly samplings were made for a period of an entire year (from January to December 1996). Two transects of pitfall traps, spanning from mean sea level to the unvegetated limits of the beach, were arranged perpendicular and parallel to the shoreline so as to capture spontaneously active individuals. So as to better understand the life cycle of the Phaleria genus, another locality (Collelungo), where only Phaleria provincialis was present, was chosen. Samplings were fortnightly from January to December 1999. Sand patches of 0.25 m 2 were sieved every 2 m along a transect from mean sea level to the base of the dune. Organic detritus was collected and weighed in the laboratory. Through such a method, darkling beetles could be sampled during their resting phase so as to obtain information on their zonation. In the laboratory, all adults were dissected, sexed, ovarioles extracted and oocytes measured. For adults and larvae from Collelungo, morphometric measurements were made and larvae were classed. Annual distributions in both study localities indicated that the species are typically univoltine, with over-wintering adults and emergence of the new generation from summer to autumn. The life cycle of P. bimaculata was shifted in comparison to that of P. provincialis , showing greater eurythermal characteristics for the first species. Numerical differences in captures found between the two species are also discussed.