Cyrioctea (Araneae, Zodariidae) in Africa: temperate Gondwanaland relict, recent radiation, or both?

Two new species of the zodariid genus Cyrioctea Simon, 1889 are described: C. sawadee sp. nov. and C. lotzi sp. nov., both only known from males. The genus now contains seven Afrotropical species and this abundance is discussed in the context of its basal situation in the family and its apparent temperate Gondwanaland distribution, which implies a much greater age of the Zodariidae than presently accepted. Unlike most taxa with a temperate Gondwana distribution, Cyrioctea boasts a high number of species with small distribution areas. This points in the direction of a recent radiation initiated after a long period of stasis

Studies in Liocranidae (Araneae): a new afrotropical genus featuring a synapomorphy for the Cybaeodinae

Cteniogaster, a new genus of small ground spiders is described from Kenya and Tanzania. It encompasses seven new species, three of which are known from both sexes: C. toxarchus sp. nov., the type species, C. conviva sp. nov. and C. hexomma sp. nov. Three species are known from females only: C. lampropus sp. nov., C. sangarawe sp. nov. and C. taxorchis sp. nov. and one only from males: C. nana sp. nov. The new genus can be recognised by the presence of a posterior ventral abdominal f eld of strong setae and anterior lateral spinnerets with enlarged piriform gland spigots in males. A cladistic analysis attributes the genus to Liocranidae, Cybaeodinae. The results of the analysis performed do not produce an unequivocal autapomorphy for Liocranidae, but provide a combination of non-homoplasious character changes that offers significant potential for recognising genera as Liocranidae. Moreover, robust apomorphies are determined within Liocranidae for the subfamilies Liocraninae and Cybaeodinae. Based on these fi ndings Toxoniella Warui & Jocqué, 2002 is transferred from Gallieniellidae to Liocranidae, Cybaeodinae. Jacaena Thorell, 1897, Plynnon Deeleman-Reinhold, 2001 and Teutamus Thorell, 1890 are transferred to Corinnidae, Phrurolithinae and Montebello Hogg, 1914 to Gnaphosidae. Itatsina Kishida, 1930 is synonymised with Prochora Simon, 1886

A new species of Hortipes (Araneae, Corinnidae), the first spider with an insertable retrolateral tibial apophysis on the male palp

Hortipes gigapophysalis (Araneae, Corinnidae) is a new species described from both sexes from montane forest on Mt Nimba, eastern Guinea. The species is remarkable for its long, whip-shaped retrolateral tibial apophysis (RTA) on the male palp. The structure apparently has an insertable function as the epigyne of the female contains a separate set of ducts starting from a central concavity that is unique in the genus. This duct system is apparently meant to receive the supple RTA. This type of structural arrangement has never previously been found in spiders

Platform for digital voice communication with channel-based key generation

This paper proposes a novel method for the integration of channel-based key generation in a real-time digital voice communication system. For this purpose, a specific hardware platform was developed. To obtain the keys for the cipher, channel-based key generation is used to generate identical keys on both sides of the channel, based on the unique reciprocal channel characteristics. Hamming code key reconciliation drastically reduces the probability of remaining key errors, while a cyclic redundancy check (CRC) is used as a final checking mechanism. As a proof of concept, the generated key is used to encrypt as well as decrypt the audio by means of an XOR operation at both sides of the link. Several measurements were performed, showing that new keys are continuously being formed and replaced. Additional measurements also create more insight into the key update rate and key entropy for different parameter settings in the algorithm

An introductory study of house spiders (Araneae) in Belgium

More than 800 spiders were collected in 43 houses heated in winter, distributed mainly in the northern part of Belgium. Information required for the collections to be eligible for the project was: address, construction year, type of house, and surroundings. The spiders were qualified as ‘house spiders’ or ‘garden spiders’. Of the 93 species collected, 19 could be defined as house spiders. Pholcus phalangioides was the most common, followed by Eratigena atrica and Steatoda triangulosa. Garden spiders enter the house much more often in houses in a rural environment than in those situated in clusters, and mainly in spring. The spiders are most common in autumn when many of them are breeding. The common house spiders colonize houses shortly after their construction

Food-web structure in relation to environmental gradients and predator-prey ratios in tank-bromeliad ecosystems

Little is known of how linkage patterns between species change along environmental gradients. The small, spatially discrete food webs inhabiting tank-bromeliads provide an excellent opportunity to analyse patterns of community diversity and food-web topology (connectance, linkage density, nestedness) in relation to key environmental variables (habitat size, detrital resource, incident radiation) and predators: prey ratios. We sampled 365 bromeliads in a wide range of understorey environments in French Guiana and used gut contents of invertebrates to draw the corresponding 365 connectance webs. At the bromeliad scale, habitat size (water volume) determined the number of species that constitute food-web nodes, the proportion of predators, and food-web topology. The number of species as well as the proportion of predators within bromeliads declined from open to forested habitats, where the volume of water collected by bromeliads was generally lower because of rainfall interception by the canopy. A core group of microorganisms and generalist detritivores remained relatively constant across environments. This suggests that (i) a highly-connected core ensures food-web stability and key ecosystem functions across environments, and (ii) larger deviations in food-web structures can be expected following disturbance if detritivores share traits that determine responses to environmental changes. While linkage density and nestedness were lower in bromeliads in the forest than in open areas, experiments are needed to confirm a trend for lower food-web stability in the understorey of primary forests

Environmental determinants of macroinvertebrate diversity in small water bodies: insights from tank-bromeliads

The interlocking leaves of tank-forming bromeliads (Bromeliaceae) collect rainwater and detritus, thus creating a freshwater habitat for specialized organisms. Their abundance and the possibility of quantifying communities with accuracy give us unparalleled insight into how changes in local to regional environments influence community diversity in small water bodies. We sampled 365 bromeliads (365 invertebrate communities) along a southeastern to northwestern range in French Guiana. Geographic locality determined the species pool for bromeliad invertebrates, and local environments determined the abundance patterns through the selection of traits that are best adapted to the bromeliad habitats. Patterns in community structure mostly emerged from patterns of predator species occurrence and abundance across local-regional environments, while the set of detritivores remained constant. Water volume had a strong positive correlation with invertebrate diversity, making it a biologically relevant measure of the pools' carrying capacity. The significant effects of incoming detritus and incident light show that changes in local environments (e.g., the conversion of forest to cropping systems) strongly influence freshwater communities. Because changes in local environments do not affect detritivores and predators equally, one may expect functional shifts as sets of invertebrates with particular traits are replaced or complemented by other sets with different traits

An ant-plant mutualism induces shifts in the protist community structure of a tank-bromeliad

Although ants may induce community-wide effects via changes in physical habitats in terrestrial environments, their influence on aquatic communities living in plant-held waters remains largely underexplored. The neotropical tank-bromeliad Aechmea mertensii (Bromeliaceae) occurs along forest edges in ant-gardens initiated by Camponotus femoratus or by Pachycondyla goeldii. Its leaves form wells that hold rainwater and provide suitable habitats for many aquatic organisms. We postulated that these ant-plant mutualisms indirectly affect the microbial community structure via changes in the environmental conditions experienced by the plants. To test this hypothesis, we analyzed the protist communities from 63 tank-bromeliads associated with either C. femoratus or P. goeldii (hereafter Cf-Aechmea and Pg-Aechmea) along a forest edge in French Guiana. For each plant, a large number of environmental variables (including habitat structure, food resources, incident radiation and the presence of aquatic invertebrates) were quantified to determine their relative importance in driving any observed differences across ant-associated plants. Pg-Aechmea are located in sun-exposed areas and hold low volumes of water and low amounts of detritus, whereas Cf-Aechmea are located in partially shaded areas and accumulate higher amounts of water and detritus. Protists (i.e., protozoa and algae) inhabiting Cf-Aechmea exhibit greater richness and abundances than those in Pg-Aechmea. Variations in detritus content, number of leaves, incident radiation, and the epiphyte richness of the ant-garden were the main factors explaining the variation in protist richness. A shift in the functional group composition of protists between bromeliads tended by different ant species suggested that mutualistic ants indirectly mediate changes in the microbial food web

Global Patterns of Guild Composition and Functional Diversity of Spiders

The objectives of this work are: (1) to define spider guilds for all extant families worldwide; (2) test if guilds defined at family level are good surrogates of species guilds; (3) compare the taxonomic and guild composition of spider assemblages from different parts of the world; (4) compare the taxonomic and functional diversity of spider assemblages and; (5) relate functional diversity with habitat structure. Data on foraging strategy, prey range, vertical stratification and circadian activity was collected for 108 families. Spider guilds were defined by hierarchical clustering. We searched for inconsistencies between family guild placement and the known guild of each species. Richness and abundance per guild before and after correcting guild placement were compared, as were the proportions of each guild and family between all possible pairs of sites. Functional diversity per site was calculated based on hierarchical clustering. Eight guilds were discriminated: (1) sensing, (2) sheet, (3) space, and (4) orb web weavers; (5) specialists; (6) ambush, (7) ground, and (8) other hunters. Sixteen percent of the species richness corresponding to 11% of all captured individuals was incorrectly attributed to a guild by family surrogacy; however, the correlation of uncorrected vs. corrected guilds was invariably high. The correlation of guild richness or abundances was generally higher than the correlation of family richness or abundances. Functional diversity was not always higher in the tropics than in temperate regions. Families may potentially serve as ecological surrogates for species. Different families may present similar roles in the ecosystems, with replacement of some taxa by other within the same guild. Spiders in tropical regions seem to have higher redundancy of functional roles and/or finer resource partitioning than in temperate regions. Although species and family diversity were higher in the tropics, functional diversity seems to be also influenced by altitude and habitat structure