Ecology of Pinnidae(Mollusca: Bivalvia) from the Gulf of Thailand

The ecology of the family Pinnidae was studied by sampling three pinnid species from 36 sampling sites across four different microhabitats in the Gulf of Thailand. The species spatial distributions were mostly uniform, with some populations having random distributions. Species abundances differed between sandy and coral habitats according to non-metric multi-dimension scaling analyses. Although the Gulf of Thailand is a relatively small geographic area, habitats are varied enough to provide variable shell densities. Small islands are important distribution areas, and coral reefs provide both direct and indirect shelter which support high abundances,densities and increased shell size. The highest density was recorded in sand beds within coral reefs. Low density and small shell size in sand beaches might be related to high mortality in shallow water or to adaptations for survival in shallow waters. A clear correlation between sediment composition and species abundance was found in Pinna atropurpurea; abundance increased with the sand content of the sediment. For P. deltodes, abundance increased as the rock fraction of the sediment increased. These results suggest that adaptations in Pinnidae, such as shell size, shell morphology, and the exposure of the shell above the sediment-water interface, are responses for survival in different habitats.

Flat-footed Females and Missing Males:A New Genus and Species of Pleciofungivoridae(Diptera:Bibionomorpha)Represents the First Record of the Family from Mid-Cretaceous Kachin Amber

A new genus and species,Cretopleciofungivora simpsoni gen.et sp.nov.,from the extinct family Pleciofungivoridae(Diptera:Bibionomorpha),is discovered in mid-Cretaceous Kachin amber.Previously,this family was known only from imprints in sedimentary rocks of the Jurassic and the Lower Cretaceous.Discovery of a representative of Pleciofungivoridae in Kachin amber confirms the presence of the family in the Upper Cretaceous.The new species has a unique structure of fore tarsus,with lobed and extended tarsal segments Ⅱ to Ⅳ,a feature hitherto known only in a few species of extant Sciaroidea.Although not particularly rare,the new species is currently known only from female specimens.Possible reasons for this phenomenon,very unusual in Sciaroidea,are briefly discussed,including parthenogenesis as a potentially plausible hypothesis.

A New Species Group in the Genus Tanytarsus van der Wulp (Diptera:Chironomidae) Based on a Fossil Record from Baltic Amber

A new fossil chironomid, Tanytarsus serafini, found in Baltic amber is described and illustrated based on adult males. The new species and similar extant species of the genus Tanytarsus van der Wulp are compared. Due to several distinct characters of wing, legs and bypopygium, a new species group for Tanytarsus serafini is proposed, and its diagnostic features are evaluated.

What is the difference between marine and limnetic-terrestrial associations of nematodes with invertebrates?

Zoo-and phyto-parasitic nematodes of the order Rhabditida and zooparasites of the subclass Dorylaimia are well known,due largely to their medical,veterinarian and agricultural significance.However,there have been many switches from a free-living to a symbiotic(including parasitism)mode of existence in the evolutionary trajectories of various nematode clades.Here,we attempt to summarize all known cases of symbioses(from commensalism to true parasitism)between marine nematodes representing nonparasitic taxa and various larger animals,ranging from protists to vertebrates.Most cases are of nematodes relating to dwelling on crustaceans(ectocommensalism)or living in the body cavity and internal organs of various invertebrates(endoparasitism or parasitoidism).Ectocommensal species may differ from their free-living relatives in their longer filiform bodies and enlarged ventral and caudal glands,which may be interpreted as adaptations for the purpose of fixation on the body surface of a motile host.Endoparasitic species are characterized by deep anatomical modification,including rudimentation of the alimentary tract and hypertrophy of reproductive organs.Unlike terrestrial and limnetic invertebrates,marine invertebrates have almost no intestinal nematode dwellers.The evolutionary trajectories of nematode dwellers of marine and nonmarine invertebrates are compared.

Spatial avoidance of patches of polluted chernozem soils by soil invertebrates

Soil invertebrates and heavy metal concentrations are heterogeneously distributed in the soil of steppe plots surrounding an iron mining enterprise in southern Russia. This study assesses whether patches of high soil invertebrate abundance coincide with patches of low concentrations of pollutants. For this aim, spatial analysis by distance indices （SADIE） was applied. Three valleys in Belogorye Nature Reserve were chosen. One valley faced the tailing pond to the north and the other two faced south-east or south-west. Two sampling plots were chosen in each valley, 60 m apart from each other. On every plot 16 soil cores were collected from a grid of 4 × 4 units with a 5-m distance between each sample unit. Each soil core had an area of 76 cm2 and was 12-15 cm deep. All macroinvertebrates were hand-sorted and identified to family. Abundance of soil invertebrates was not controlled by patches of metal concentration in the soil. Epigaeic groups, like insects and other invertebrates inhabiting the litter layer, were not directly associated with local parameters of the soil. On the contrary, belowground invertebrate abundance （elaterid larvae and earthworms） showed significant dissociation with some heavy metal （Fe, Pb, Zn） concentrations in the soil. The patchiness of soil pollution may act as a leading factor ofbelowground soil invertebrate distribution. The spatial structure of animal populations in industrially transformed soils needs further research.

Competing for Space: Factors That Lead to Sponge Overgrowth When Interacting with Octocoral

The overgrowth of octocorals by sponges is generally disadvantageous for the octocorals. When the growth of octocoral populations increases the reefs’ structural complexity, more substrate space becomes available for epibionts to grow. One of these epibionts is the sponge Desmapsamma anchorata, known to grow exponentially faster than other sponges, and for its ability to overwhelm the substrate over which it grows. Our objective in this study is to determine if the overgrowth of branching octocorals by varying sponges is defined only by species-specific interactions, or if some physical attributes make this octocoral more susceptible to being overgrown than others. To determine this, on a reef south of Carrie Bow Cay, Belize, we monitored the attachment of various demosponges to branching octocorals in a series of experiments to assess the response effect of the interactions and properties leading to attachment and subsequent sponge overgrowth on branching octocorals. Substrate effects, species-specific reactions, and time of exposure were considered. Additionally, following successful-attachment, preliminary growth rates of two sponge species epizoic on two octocoral species were monitored. Differences in the observed interaction between species and treatments were analyzed with a multinomial response model to isolate a species-specific effect from other interacting effects of the properties tested. Results indicate that time of exposure of a sponge in direct contact with the octocoral fragment significantly affects the outcome of the interaction;secondly, physical properties and species-specific interactions also influence the attachment. Following the successful attachment to an octocoral, the growth of the sponge varies as a function of the sponge’s differential growth rate and the substrate species over which it grows. In the context of species successions, understanding interactions between coralreef organisms is important as these interactions explain species composition and diversity, and provide a basis for the prediction of future changes in complex reef communities.

On the importance of concomitant conditions: Light and conspecific presence modulate prey response to predation cue

Assessment of individual costs of the anti-predator defence translating into changes in population parameters is meagre.This is because prey responses are likely to be modulated by additional factors,commonly present in the environment,but often neglected in experimental studies.To evaluate the effect of external factors on prey behavior and physiology,we exposed amphipods Dikerogammarus villosus and Gammarus jazdzewskii to the predation cue of Perca fluviatilis in different densities and light conditions.Singletons of both species exposed to the predation cue in light modified their oxygen consumption(D.villosus:reduction,G.jadzewskii:increase)compared to their respiration in predator-free conditions.However,in the presence of conspecifics or in darkness,their respiration became insensitive to the predation cue.On the other hand,the swimming activity of prey was reduced in the presence of the predation cue irrespective of prey density and light conditions,but singletons were consistently more active than groups.Thus,external factors,such as conspecifics and darkness,constantly or periodically occurring in the field,may reduce the costs of predator non-consumptive effects compared to the costs measured under laboratory conditions(in light or absence of conspecifics).Moreover,we showed that behavioral and physiological parameters of prey may change differently in response to predation risk.Thus,conclusions drawn on the basis of single defence mechanisms and/or results obtained in artificial conditions,not reflecting the environmental complexity,strongly depend on the experimental design and endpoint selection and therefore should be treated with care.

Why on the snow？ Winter emergence strategies of snow-active Chironomidae （Diptera） in Poland

A long-term study of adult non-biting midges （Chironomidae） active in winter on the snow in mountain areas and lowlands in Poland yielded 35 species. The lowland and mountain communities differed significantly in their specific composition. The mountain assemblage was found to be more diverse and abundant, with a substantial contribution from the subfamily Diamesinae, whereas Orthocladiinae predominated in the lowlands. Orthocladius wetterensis Brundin was the most characteristic and superdominant species in the winter-active chironomid communities in both areas. Only a few specimens and species of snow-active chironomids were recorded in late autumn and early winter. The abundance ofchironomids peaked in late February in the mountain and lowland areas with an additional peak in the mountain areas in early April. However, this second peak of activity consisted mainly of Orthocladiinae, as Diamesinae emerged earliest in the season. Most snow-active species emerged in mid- and late winter, but their seasonal patterns differed between the 2 regions as a result of the different species composition and the duration of snow cover in these regions. Spearman＇s rank correlation coefficient tests yielded positive results between each season and the number of chironomid individuals recorded in the mountain area. A positive correlation between air temperature, rising to ＋3.5 ~C, and the number of specimens recorded on the snow in the mountain community was statistically significant. The winter emergence and mate-searching strategies of chironomids are discussed in the light of global warming, and a brief compilation of most important published data on the phenomena studied is provided.

Northwestward range expansion of the bumblebee Bombus haematurus into Central Europe is associated with warmer winters and niche conservatism

Species range expansions are crucial for understanding niche formation and the interaction with the environment.Here,we studied the bumblebee Bombus haematurus Kriechbaumer,1870,a species historically distributed from northern Serbia through northern Iran which has very recently started expanding northwestward into Central Europe without human-mediated dispersal(i.e.,it is a natural spread).After updating the global distribution of this species,we investigated if niche shifts took place during this range expansion between newly colonized and historical areas.In addition,we have explored which climatic factors may have favored the natural range expansion of the species.Our results indicated that Bombus haematurus has colonized large territories in 7 European countries outside the historical area in the period from the 1980s to 2018,a natural expansion over an area that equals 20%of the historical distribution.In addition,this bumblebee performs generalism in flower visitation and it occurs in different habitats,although a preference for forested areas clearly emerges.The land-use associated with the species in the colonized areas is similar to the historical distribution,indicating that no major niche shifts occurred during the spread.Furthermore,in recently colonized localities,the range expansion was associated with warming temperatures during the winter and also during both queen overwintering and emergence phases.These findings document a case of natural range expansion due to environmental change rather than due to niche shifts,and specifically they suggest that warmer winters could be linked to the process of natural colonization of new areas.

Differences in predator-avoidance behavior between two invasive gobies and their native competitors

Globally,fish are frequently introduced beyond their native range.Some,like Ponto-Caspian gobies,are becoming invasive,achieving high colo-nization rates and constituting frequent prey for native predators.However,little is known about the effectiveness of antipredator behaviors of the invaders,which may shape their role in the invaded community and contribute to the invasion success.We compared antipredator behaviors of invasive gobies and native fish species after their detection by the predator,when the danger becomes direct.We studied 2 fish pairs,each consisting of an invasive and native species co-occurring in the environment and belonging to the same prey guild:(1)the racer goby Babka gymnotrachelus versus European bulhead Cottus gobio,(2)the monkey goby Neogobius fluviatilis versus gudgeon Gobio gobio,facing a naive predator(the Eurasian perch Perca fluviatilis).We analyzed behaviors of single prey individuals(escaping,staying in shelter,and activity)and sin-gle predators(activity,searching,following,capturing,and latency to prey consumption).In the predator presence,the bullhead was less active and more often managed to escape after capture than the racer goby.The gudgeon escaped before the capture more often than the monkey goby.The predator succeeded later with the bullhead compared to racer goby,whereas no differences in ingestion time occurred between the gudgeon and monkey goby.The results suggest that,in terms of hunting effort of native predators,the invasive gobies are equivalent to or more profitable prey than their native analogs,which can facilitate the integration of the gobies into local food webs.

缅甸北部克钦白垩纪中期琥珀中的蜡蝉化石一新属新种:Ayaimatum trilobatum gen.et sp.nov.(半翅目:蜡蝉总科:拟蛛蜡蝉科)

根据缅甸北部克钦地区产出的白垩纪中期琥珀中保存的蜡蝉,建立了1新属1新种--三瓣残缺蜡蝉(Ayaimatum trilobatum gen.et sp.nov.),该新属新种属于白垩纪的拟蛛蜡蝉科(Mimarachnidae)。本文对拟蛛蜡蝉科的属种记录进行了综述,同时探讨了这一灭绝科属种的多样性和形态分异。