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An attempt was made to recover identifiable spider sub-fossils from peat cores taken from a post-glacial basin mire in Cheshire, north-west England. Although the features normally required to identify specimens to species level in taxonomic keys were rarely preserved, carapace morphology and cheliceral dentition allowed unequivocal identification to species level in many cases. Current lack of knowledge of the autecology of wetland spiders prevents any conclusion regarding the paleoecological conditions, but the technique could reveal insights into the post-glacial development of the spider faunal assemblage of mires.
This study continues documentation of the adaptive radiation of species in the genus Tetragnatha in the Hawaiian archipelago. The four new species described here are similar in gross appearance, all being brown and elongate. They all build orb webs low down in shrubby vegetation, and have disjunct or abutting ranges. The new species are T. limu, T. lena, T. palikea, and T. uluhe. Different species occur in middle and high elevations, and in wet and dry habitats. Similar to other representatives of Hawaiian Tetragnatha, they are strictly nocturnal web-builders.
The first species of the genus Austropsopilio is described from South America. The species, A. sudamericanus, closely resembles those from Australia and Tasmania but lacks the elongate ocular tubercle previously regarded as diagnostic for the genus. Problems in the taxonomy of the genus are discussed.
Two novel sampling techniques were used to survey the spider community of the leaf litter in a deciduous forest in Kentucky, USA. Using modified pitfall traps and litter-grab techniques, we sampled separately the top, middle and bottom litter layers from April–October. Our sampling program captured over 3,000 spiders encompassing 18 different families. Both techniques revealed that the web-spinning families were more abundant in the lower litter layers. In contrast, the non-web building cursorial spiders, which actively pursue their prey, were more abundant in the top litter layer. Cursorial spiders, on average, were larger than the web-building spiders found in the leaf litter. Web-building spiders from the top litter layer were also larger than the web-building spiders caught in the middle and the bottom litter layers.
Comparison between the two sampling techniques revealed that the spider community profile is greatly influenced by the sampling method employed. The stratified litter-grab technique revealed the numerical dominance of Dictynidae (38% of the spiders captured) and Linyphiidae (32%), families that are predominately minute web-building spiders. In contrast, the pitfall-trap technique suggested Lycosidae (24%), a family of active foragers, to be numerically dominant, with Dictynidae representing only 1% of the spiders captured. The results indicate that major groups of spiders differ in their vertical distribution within deciduous leaf litter, and that sampling method can dramatically affect inferences about spider community structure.
Juvenile Anyphaena sp. were collected from overwintering traps placed on the lowest limbs of white oak, Quercus alba, in South Carolina. Multiple regression analysis was used to determine that the number of juvenile Anyphaena sp. found can be predicted by the circumference of the limb, the distance from the trunk and the distance from the ground. This study helps demonstrate that the limbs of trees, although often neglected in overwintering studies, can provide a refuge for arthropods.
We investigated the pattern of molecular variation with respect to secondary structure in the 16S ribosomal RNA gene and its phylogenetic implications for arachnids with a focus on spiders. Based on a model by Gutell et al. (1996), secondary structures were proposed for the 3′ half of 16S in the mygalomorph spider Aptostichus atomarius. Models were also constructed for a hypervariable length of the 16S in three other arachnids, which revealed a trend of stem and loop reduction in more advanced arachnids. Using a simple statistical approach to compare functional regions, we found that internal and external loops are more variable than stems or connection regions. Down-weighting or excluding regions which code for the more variable loops improved tree topologies by restoring the monophyly of the genus Aptostichus, a group supported by combined 16S, COI, and morphological data in other analyses. This study demonstrated the utility of considering secondary structure for DNA sequence alignment and phylogenetic reconstruction in spiders.
The new species Bothriurus jesuita is described. This species belongs to the bonariensis species group and is closely related to Bothriurus chacoensisMaury & Acosta 1993 from which it can be distinguished by its thicker and taller chela and because of it is almost 30% larger. It can be distinguished from Bothriurus bonariensis (C.L. Koch 1842) because it has an apical filament on the basal lobe of the right hemispermatophore and because the frontal ridge reaches the frontal fold. Bothriurus jesuita has been collected in the northern region of Corrientes Province and in Misiones Province in an area that belongs to the “Paranaense” Phytogeographic Province.
This study revises the status of knowledge of the spider fauna of the Marquesas Islands in French Polynesia. In particular, the genus Tetragnatha was noticeable for its poor representation in the Marquesas Islands by comparison with the large radiation in the yet more remote Polynesian archipelago of the Hawaiian Islands. Expeditions were conducted to determine whether Tetragnatha was indeed poorly represented in the Marquesas Islands, as the literature would suggest. In addition, specimens were studied from historical collections from this archipelago. The results indicate that the islands do indeed have a number of endemic Tetragnatha, and the genus does appear to have undergone adaptive radiation, although not nearly on the same scale as in the Hawaiian Islands. Results indicate that: (1) in addition to T. marquesiana Berland there are four new species, described here, each of which are endemic to the islands. Tetragnatha marquesiana is widespread in the northern islands, including Nuku Hiva. There are two additional species on Nuku Hiva: T. punua and T. oomua. Two new species are described from the southern islands of Hiva Oa (T. kapua) and Tahuata (T. tahuata). Tetragnatha kapua from Hiva Oa appears to be related to T. marquesiana. (2) Tetragnatha macilenta L. Koch does not occur on these islands. Reports of its widespread distribution through the Pacific can only be substantiated as far as the Society Islands. (3) Tetragnatha nitens (Audouin), which may not be indigenous, occurs in disturbed areas at high elevations in Nuku Hiva. In total, there are six species of Tetragnatha in the Marquesas Islands.
Habitat ranges of ground-dwelling spiders were studied by pitfall trapping in and around a freshwater pond during the spring and summer of 1998 in central Alberta, Canada. Sixty species from 14 families were collected, and catches of several species suggested distinct habitat affinities along transects between the pond and adjacent terrestrial habitats. Variation in the catches of Pirata piraticus (Clerck 1757), Pardosa moesta Banks 1892, Pardosa fuscula (Thorell 1875), and immature Pirata species were partially explained by soil moisture at trap locations extending from the shore. We devised a “floating” pitfall trap that captured several species, including mature and immature Dolomedes triton (Walckenaer 1837), Pirata piraticus, and other immature Lycosidae, directly on the water surface. A DCA ordination revealed distinct spider assemblages were associated with three habitat types: 1) the water surface; 2) the moist habitats closely associated with the water's edge; and 3) the drier, terrestrial grassland habitats located >2 m from the shore. A new, more inclusive definition of semi-aquatic spiders was developed, based on knowledge about both male and female activity near the shore, and affinities towards soil moisture. Thus, Pirata piraticus, Dolomedes triton, and Pardosa fuscula were defined as semi-aquatic spiders.
We report for the first time the existence of eggsac recognition and maternal care in Loxosceles gaucho. Spiders confronted simultaneously with their own and foreign eggsacs stay closer to their own eggsacs. This is unexpected since eggsac recognition should evolve among species with clumped distributions, high maternal investments and few breeding opportunities, features not present in this species. Despite this recognition, spiders with a single eggsac make no distinction between their own and foreign eggsacs: they adopt eggsacs from sympatric, conspecific females, and take care of them as their own. It seems that there is a readiness to perform maternal care that overrules the recognition system. We describe oviposition behavior and compare it with other descriptions in the literature. Seven behavioral characters related to eggsac building and/or guarding are mapped onto available phylogenies. Maternal care behaviors are quite conservative among spiders, useful for the grouping not only of families, but also of higher order ranks.
The genus Uliodon L. Koch is reviewed. It now includes only the type species, Uliodon albopunctatus L. Koch 1873, Uliodon cervinus L. Koch 1873, and Zora frenatusKoch 1873, and the genus is transferred to the Zoropsidae. Uliodon is known only from New Zealand. Through an original misreading of the type specimen locality data, both species were erroneously reported from Australia. Forster and Homann previously referred to Uliodon species as Miturga, which is endemic to Australia. The subfamily Uliodoninae Lehtinen 1967 was founded on the characters of Zora tarantulina L. Koch 1873, later transferred to Uliodon by Simon. The diagnostic character of the subfamily, the very long path of the embolus, is not found in Uliodon. The subfamily is here diagnosed from the genus; its validity is unclear. In any case, both Uliodon and Uliodoninae are transferred to the Zoropsidae along with the Australian HuntiaGray & Thompson 2001. Zora tarantulina is made the type species of a new monotypic genus, Mituliodon, included in the Miturgidae; the genus is known only from Australia and Timor. Mituliodon tarantulinus (L. Koch 1873) now newly includes in its synonymy, Uliodon australiensis (L. Koch 1873), Uliodon torvus (L. Koch 1873), Miturga maculataHogg 1900, Syspira rubicundaHogg 1900 and Miturga veloxHickman 1930. The New Zealand genus Zealoctenus is transferred from the Ctenidae to the Miturgidae because it is very similar to the Australian genus DiaprograptaSimon 1909; the other New Zealand “ctenid” genus, NemoctenusForster & Wilton 1973, along with the Australian zorid HorioctenoidesMain 1954 are synonymized with the zorid genus Argoctenus L. Koch 1878, found in Australia, New Zealand and New Caledonia. The New Zealand “psechrids” PoakaForster & Wilton 1973 and HaurokoaForster & Wilton 1973 are transferred to the Amaurobiidae and T
Afrarchaea grimaldii new species (Archaeidae, Archaeinae) from 88–95 Ma (Cenomanian–Turonian) Upper Cretaceous amber (Burmite) from Myanmar (Burma) is described. This is the first spider to be described from this deposit and is the oldest known Archaeidae sensu stricto extending the known range of the family by approximately 50 Ma from the previously oldest recorded specimens in Baltic and Bitterfeld ambers, and provides further evidence that spiders were not severely affected by the end-Cretaceous mass extinction event. It represents the oldest fossil record of an araneophagic spider. This species could be used to argue for both the theory of mobilistic biogeography and ousted relicts to explain the zoogeography of the genus, but until new data become available, supports neither reliably.
We extend detection of arthropod predator gut contents by polymerase chain reaction (PCR), heretofore restricted to insect predators, to spiders. Single individuals of the corn lead aphid, Rhopalosiphum maidis, were detected in the guts of spiderlings of Oxyopes salticus up to 12 h after feeding; individuals of the congeneric bird cherry oat aphid, R. padi, were not detected. Unfed O. salticus and Misumenops sp. were also negative.
We report a case of cohabitation between an adult male and a conspecific subadult female Lycosa tarantula (Linnaeus 1758) (Araneae, Lycosidae). Cohabitation was observed during a field study in a population near Madrid city (central Spain). The male was first observed in the female burrow four days before the female maturation molt. Both individuals remained together until female maturation occurred. Mating occurred two days after female maturation, at a much younger age than non-cohabiting females. The possible mechanisms by which adult males find subadult female burrows are discussed.
We collected 75 immature Pardosa milvina and maintained them in a laboratory until death or maturity to determine whether P. milvina in our population were harboring endoparasites. Nine mermithid nematodes emerged from P. milvina hosts, with each nematode emerging from a separate spider. One dipteran parasite, an acrocerid, emerged from P. milvina. This study provides the first published record of nematodes emerging from P. milvina and documents an additional record of acrocerid parasitism of P. milvina.
A new subspecies of Philodromus rufus, P. r. jenningsi is described from the south central and southeastern United States. It is characterized by a light brown unicolorous carapace, except for dark semicircular marks at the central rear carapace edge.
Austrochilus forsteri new species, (Araneae, Austrochilidae, Austrochilinae) is described and illustrated based on specimens collected in Malleco Province, Chile.
Whip spiders (Amblypygi) are a small and understudied group of arachnids characterized by long antenniform legs and raptorial pedipalps. Due to their nocturnal habits, secretive nature and geographical distribution there have been very few studies of feeding behavior in this group. Here, we report a remarkable foraging strategy adopted by the giant tropical whip spider Heterophrynus cheiracanthus (Gervais 1844) inhabiting rocky outcrops adjacent to mountain streams running through primary tropical rainforest on the Caribbean island of Tobago. Heterophrynus cheiracanthus positions itself close to the stream edge on a vertical rock surface with pedipalps fully extended and antenniform legs frequently entering the shallow water. Freshwater prawns of the genus Macrobrachium are caught while still submerged in the water despite the whip scorpion being unable to use the trichobothria on the walking legs. Possible mechanisms of prey detection are discussed.
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