ARACHNOLOGISCHE GESELLSCHAFT

Heft 43 (2012)

Observations on web-invasion by the jumping spider Thyene imperialis in Israel (Araneae: Salticidae)

Observations on web-invasion by the jumping spider Thyene imperialis in Israel (Araneae: Salticidae)

Abstract

Observations on Thyene imperialis (Rossi, 1846) in Israel, Negev desert, invading a web of Cyclosa deserticola Levy, 1998 are reported. The female leapt into the orb-web to catch Cyclosa spiders. Photographs are provided, and a link to additional film material is given.

The sejugal furrow in camel spiders and acariform mites

The sejugal furrow in camel spiders and acariform mites

Abstract

Camel spiders (Arachnida: Solifugae) are one of the arachnid groups characterised by a prosomal dorsal shield composed of three distinct elements: the pro-, meso- and metapeltidium. These are associated respectively with prosomal appendages one to four, five, and six. What is less well known, although noted in the historical literature, is that the coxae of the 4th and 5th prosomal segments (i.e. walking legs 2 and 3) of camel spiders are also separated ventrally by a distinct membranous region, which is absent between the coxae of the other legs. We suggest that this essentially ventral division of the prosoma specifically between coxae 2 and 3 is homologous with the so-called sejugal furrow (the sejugal interval sensu van der Hammen). This division constitutes a fundamental part of the body plan in acariform mites (Arachnida: Acariformes). If homologous, this sejugal furrow could represent a further potential synapomorphy for (Solifugae + Acariformes); a relationship with increasing morphological and molecular support. Alternatively, outgroup comparison with sea spiders (Pycnogonida) and certain early Palaeozoic fossils could imply that the sejugal furrow defines an older tagma, derived from a more basal grade of organisation. In this scenario the (still) divided prosoma of acariform mites and camel spiders would be plesiomorphic. This interpretation challenges the textbook arachnid character of a peltidium (or ‘carapace’) covering an undivided prosoma.

Geography-related sub-generic diversity within the Mediterranean trapdoor

spider genus Nemesia (Araneae, Mygalomorphae, Nemesiidae)

Geography-related sub-generic diversity within the Mediterranean trapdoor

spider genus Nemesia (Araneae, Mygalomorphae, Nemesiidae)

Abstract

Three different male and female super-specific types are distinguished according to variations in the morphology of the bulb and spermathecae within the genus Nemesia Audouin, 1826. Plotting the distributions of these sexual types on a map of the Mediterranean indicates the existence of geography-related sub-generic diversity in which the Nemesia fauna of the eastern Mediterranean differs markedly from that of the western Mediterranean. While the eastern Mediterranean Nemesia fauna is highly homogeneous, the fauna of the western Mediterranean is very diverse. The eastern and western Nemesia faunae appear to overlap in the central Mediterranean. Efforts to relate the specific bulb types to the particular types of spermathecae described here were only partly successful.

Spiders in Fauna Europaea: dual use of the database

Spiders in Fauna Europaea: dual use of the database

Abstract

The history and current work of the project Fauna Europaea is outlined. The different sources used for building up the database and the efforts to keep it updated are described. Available models of national checklists are discussed and the ideal checklist is described. The double use of the database as a matrix behind the official site of Fauna Europaea – as well as a directly visible document on the website of the European Society of Arachnology – are indicated and the differences in transparency, links to literature sources, and facilities such as distribution maps and calculations of numbers of scores per species or of species per country are discussed. The future of the project is briefly outlined. The need for a European identification tool for spiders is stressed.

The scorpion collections (Arachnida, Scorpiones) held in the Museo Regionale di Scienze Naturali of Turin (Italy)

The scorpion collections (Arachnida, Scorpiones) held in the Museo Regionale di Scienze Naturali of Turin (Italy)

Abstract

Data and considerations about the history and contents of the scorpion collection housed in the Museo Regionale di Scienze Naturali of Turin (MRSN) are reported. Information on type material and important historical specimens are provided, as well as biographical notes about the major zoologists of the museum.

On the spider species described by L. Koch in 1882 from the Balearic Islands (Araneae)

On the spider species described by L. Koch in 1882 from the Balearic Islands (Araneae)

Abstract

Examination of the L. Koch collection of the Zoological Museum in Berlin allows us to propose the following new synonyms and combinations: Erigone marina L. Koch, 1882 = Oedothorax fuscus (Blackwall, 1834) n. syn.; Theridion elimatum L. Koch, 1882 = Enoplognatha diversa (Blackwall, 1859) n. syn.; Liocranum variabilis Wunderlich, 2008 = Zora inornata L. Koch, 1882 n. syn. = Liocranum inornatum n. comb.; Lycosa perspicax L. Koch, 1882 = Arctosa fulvolineata (Lucas, 1846) n. syn.; Alopecosella Roewer, 1960 = Arctosa C. L. Koch, 1847 n. syn.; Lycosa subhirsuta L. Koch, 1882 = Arctosa lacustris (Simon, 1876) n. syn.; Philodromus vegetus L. Koch, 1882 = Thanatus vulgaris Simon, 1870 n. syn.; Ozyptila bicuspis Simon, 1932 = Ozyptila furcula L. Koch, 1882 n. syn.; Haplodrassus maroccanus Denis, 1956 = Drassus parvulus L. Koch, 1882 n. syn. = Haplodrassus parvicorpus (Roewer, 1951) n. comb. (replacement name); Zelotes ruscinensis Simon, 1914 = Zelotes semirufa (L. Koch, 1882) n. syn.; Phlegra simoni L. Koch, 1882 = Phlegra bresnieri Lucas, 1846 n. syn.; Trochosula conspersa (L. Koch, 1882), Lycorma fraisnei (L. Koch, 1882), Lycorma insulana (L. Koch, 1882), Arctosa misella (L. Koch, 1882) and Pirata simplex (L. Koch, 1882) are all retransferred to their original genus Lycosa stat. rev. Cheiracanthium occidentale L. Koch, 1882, Ozyptila furcula L. Koch, 1882 and Zelotes callidus (Simon, 1878) are redescribed.

Behavioural analysis of web building anomalies in the orb-weaving spider Zygiella x-notata (Araneae, Araneidae)

Behavioural analysis of web building anomalies in the orb-weaving spider Zygiella x-notata (Araneae, Araneidae)

Abstract

Among animal constructions, spider’s orb webs represent regular geometrical architecture models. Their construction is the result of successive, simple and reproducible behavioural patterns, often considered as stereotyped. It has recently been shown that spider’s building behaviours vary, which can alter web regularity. The final capture spiral results from the laying of successive threads between two radii, here termed ‘spiral units’. We defined a theoretical normal web, as a web in which each turn of the final spiral should be parallel to the preceding one. Weaving of the spiral units sometimes leads to anomalies in the orb web. Anomalies were identified and analysed in the orb-weaving spider Zygiella x-notata (Clerck, 1757). From video recordings of web construction, we noted the displacements of the legs and of the abdomen of the spider. We compared the frequency of displacements, and their duration, between the construction of spiral units that produce a normal turn and ones that produce an anomalous turn. The position of the legs on the web’s threads was also analysed. Results showed that anomalies were not the consequences of a modification in activity but more likely the result of the position on the radii of the fourth leg. These results suggest that spiders use local information to build the final capture spiral.

Tests for attraction to prey and predator avoidance by chemical cues in spiders of the beech forest floor

Tests for attraction to prey and predator avoidance by chemical cues in spiders of the beech forest floor

Abstract

Spiders leave draglines, faeces and other secretions behind when traveling through their microhabitat. The presence of these secretions may unintentionally inform other animals, prey as well as predators, about a recent and possible current predation risk or food availability. For a wolf spider, other spiders including smaller conspecifics, form a substantial part of their prey, and larger wolf spiders, again including conspecifics, are potential predators. We tested two hypotheses: that large wolf spiders may locate patches of potential spider prey through the presence of silk threads and/or other secretions; and that prey spiders may use secretions from large wolf spiders to avoid patches with high predation risk. We used large (subadult or adult) Pardosa saltans to provide predator cues and mixed dwarf spiders or small (juvenile) P. saltans to provide prey cues. Subadult wolf spiders were significantly attracted to litter contaminated by dwarf spiders or small conspecifics after 6 hours but no longer after 24 hours. In contrast, neither dwarf spiders nor small P. saltans showed significant avoidance of substrate contaminated by adult P. saltans. However, small P. saltans showed different activity patterns on the two substrates. The results indicate that wolf spiders are able to increase the efficiency of foraging by searching preferentially in patches with the presence of intraguild prey. The lack of a clear patch selection response of the prey in spite of a modified activity pattern may possibly be associated with the vertical stratification of the beech litter habitat: the reduced volume of spaces in the deeper layers could make downward rather than horizontal movement a fast and safe tactic against a large predator that cannot enter these spaces.

Maintenance of polymorphism in the orb weaving spider species Agalenatea redii (Araneae, Araneidae)

Maintenance of polymorphism in the orb weaving spider species Agalenatea redii (Araneae, Araneidae)

Abstract

The maintenance of polymorphism within populations may be the consequence of several elements of species life history such as use of space, activity rhythms, predation, parasitism and reproduction. The present study focuses on the latter aspect using an orb weaving spider, Agalenatea redii, which presents five different morphs of the opisthosoma pattern in the adult stage. Over the course of four years, from 2008 to 2011, adult spiders (males, females and pairs) were observed at different sites. In 2011, we also conducted a six-week survey of a single population, observing the number of spiders of each morph and the morph of paired spiders. We collected field data on the spatial and temporal distribution of spiders based on their sex and morph. Using a distance analysis, we compared the field distribution with a simulated one in which pairs were associated at random. The results showed that although there were changes over time and space in the proportions of females of the different morphs, as well as in the proportion of the pair associations, pairing according to morphs probably occurs at random.

Spiders (Araneae) of Chernivtsi Сity (Ukraine)

Spiders (Araneae) of Chernivtsi Сity (Ukraine)

Abstract

The spider fauna of buildings and other urban habitats (city parks, green areas of industrial enterprises, and housing estates) of Chernivtsi city was surveyed. In the period 2002-2011, 212 species belonging to 26 families were recorded. Previous studies found a total of 173 species of spiders belonging to 26 families from the territories which are now included in the city limits of Chernivtsi. Currently, the total spider species list for Chernivtsi includes 260 species of 30 families, of which 125 species (21 families) were recorded both by earlier researchers and by ourselves. The most important reasons for changes in urban spider assemblages are as follows: species habitat change, introduction of alien species, and description of new species unknown in the late 19th – early 20th centuries.

Assemblages of herb-dwelling spiders (Araneae) of various steppe types in Ukraine and Central Chernozem of Russia

Assemblages of herb-dwelling spiders (Araneae) of various steppe types in Ukraine and Central Chernozem of Russia

Abstract

A total of 107 spider species from 15 families were recorded in the herbaceous vegetation of the steppe ecosystems of Ukraine and the Central Chernozem region of Russia. Araneidae, Thomisidae, Salticidae and Theridiidae were the most species-rich. The species composition depended on the steppe type; adjacent forest habitats influenced steppe fauna in the forest-steppe and northern part of the steppe natural zone. The number of generalist, forest and wetland dwelling species in the steppe vegetation showed a tendency to decrease towards the south. Dominance of herb-dwelling spiders was specific to each steppe type; no single species was found to predominate in all the steppe habitats.

26th ECA Midreshet Ben-Gurion, Sede Boqer, Israel: preface

26th ECA Midreshet Ben-Gurion, Sede Boqer, Israel: preface

Abstract

Preface: Lubin, Y., E. Gavish-Regev, T. Blick & O.-D. Finch (Eds) (2012): European Arachnology 2011. Proceedings of the 26th European Congress of Arachnology, Midreshet Ben-Gurion, Sede Boqer, Israel, 4-9 September 2011

Cover/Contents Arachnologische Mitteilungen 43, 2012 = European Arachnology 2011. Proceedings of the 26th European Congress of Arachnology, Midreshet Ben-Gurion, Sede Boqer, Israel, 4-9 September 2011

Cover/Contents Arachnologische Mitteilungen 43, 2012

Arachnologische Mitteilungen 43, 2012 = European Arachnology 2011. Proceedings of the 26th European Congress of Arachnology, Sede Boqer, Midreshet Ben-Gurion, 4-8 September 2011

Arachnologische Mitteilungen 43, 2012 = European Arachnology 2011. Proceedings of the 26th European Congress of Arachnology, Sede Boqer, Midreshet Ben-Gurion, 4-8 September 2011