Abstracts to Articles

The Journal of Arachnology

Volume 27 Number 1

The Proceedings of the 14th Internal Congress of Arachnology

 HISTORIC OVERVIEW OF PAST CONGRESSES OF ARACHNOLOGY AND OF THE CENTRE INTERNATIONAL DE DOCUMENTATION ARACHNOLOGIQUE (C.I.D.A.)

Otto Kraus: Zoologisches Institut und Museum, Universitat Hamburg, Martin-Luther-King-Platz 3, D-20146 Hamburg, Germany

ABSTRACT. In 1959, Hermann Wiehle encouraged junior colleagues to arrange a meeting for arachnologists. This was held in 1960 at the University of Bonn, Germany, and is counted as the first in the senes of international congresses. After a second conference, held just one year later in Saarbrucken, Germany, a third truly international congress followed in 1965 in Frankfurt am Main. On this occasion, Max Vachon presented his idea to form what was later called the C.I.D.A. This institution was formally established at the occasion of the 4th congress, held in Paris in 1968. Detailed information on the origins, the series of congresses, and the C.I.D A. up to 1968 is presented.

The Journal of Arachnology 27:3-6

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THE GENUS ATTIDOPS (ARANEAE, SALTICIDAE)

G.B. Edwards: Curator, Arachnida & Myriapoda, Florida State Collection of Arthropods, Division of Plant Industry, RO. Box 147100, Gainesville, Florida 32614-7100 USA

ABSTRACT. The genus Attidops is resurrected from Ballus based on its strongly excavate cymbial tip, transverse embolar groove, flatter carapace with extended postocular area, and single retromarginal cheliceral tooth, which indicate a closer relationship to the genus Admestina. The type species, Ballus youngii Peckham & Peckham 1888, again transferred, becomes Attidops youngi (Peckham & Peckham). Two new species, Attidops nickersoni (sister species to A. youngi) and Attidops cutleri, are described. Icius cinctipes Banks 1900, previously transferred to Ballus, becomes a new combination, Attidops cinctipes (Banks). Lectotypes and paralectotypes are designated for Ballus youngii and Icius cinctipes. The genus is recorded from south-central Canada, eastern U.S. and eastern Mexico.

The Journal of Arachnology 27:7-15

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A NEW DISEMBOLUS (ARANEAE, LINYPHIIDAE) FROM CAPE COD, MASSACHUSETTS AND LONG ISLAND, NEW YORK

Robert L. Edwards: Research Associate, United States National Museum, Box 505, Woods Hole, Massachusetts 02543 USA

ABSTRACT. Disembolus bairdi new species is described from the coastal region of northeastern United States. Notes on the habitat, natural history and its associated spiders are provided.

The Journal of Arachnology 27:16 18

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SINOPODA, A NEW GENUS OF HETEROPODINAE (ARANEAE, SPARASSIDAE) FROM ASIA

Peter Jager: Institute for Zoology, Johannes Gutenberg-University, Saarstr. 21, 55099 Mainz, Germany

ABSTRACT. Sinopoda new genus (Araneae, Sparassidae, Heteropodinae) is described from Asia It is recognizable only from genital characters. At present, the new genus comprises 25 species from Japan Korea, China, Thailand, Malaysia and east India. Heteropoda campanacea, H. forcipata, H. hamata, H. koreana, H. Iicenti, H. marsupia (?), H minschana, H. serrata, H. shennonga, H. stellata and Panaretidius microphthalmus are placed in Sinopoda new genus. Relationships to other heteropodine genera are discussed.

The Journal of Arachnology 27:19-24

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CARBINEA, A NEW SPIDER GENUS FROM NORTH QUEENSLAND, AUSTRALIA (ARANEAE, AMAUROBIOIDEA, KABABININAE)

Valerie Todd Davies: Queensland Museum, P.O. Box 330O, South Brisbane, Australia

ABSTRACT. The distnbution of four species of Carhinea new genus in the Wet Tropics region of northern Queensland documents the species' richness and local endemism. The new species are C. Iongiscapa, C. breviscapa, C. wunderlichi and C. robertsi. They are placed in the sub-family Kababininae which is removed from the Amphinectidae (Davies 1995) as there is evidence that it does not belong there. The placement of this clade remains problematical.

The Journal of Arachnology 27:25-36

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SPIDERS OF THE GENUS HEPTATHELA (ARANEAE, LIPHISTIIDAE) FROM VIETNAM, WITH NOTES ON THEIR NATURAL HISTORY

Hirotsugu Ono: Department of Zoology, National Science Museum, 3-23-1 Hyakunin-cho, Shinjuku-ku, Tokyo, 169-0073 Japan

ABSTRACT. Spiders of the family Liphistiidae collected from northern Vietnam are taxonomically studied. Two new species of the genus Heptathela are described under the names, H. abca (from Yen Bai) and H. cucphuangensis (from Cuc Phuong National Park). Some natural history and zoogeographic notes of the new species are given.

The Journal of Arachnology 27:37-43

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ON THE PHYLOGENETIC RELATIONSHIPS OF SISICOTTUS HIBERNUS (ARANEAE, LINYPHIIDAE, ERIGONINAE)

Jeremy Zujko-Miller: Department of Biological Sciences, The George Washington University, Washington, D.C. 20052, and Department of Entomology, National Museum of Natural History, NHB-105, Smithsonian Institution, Washington, D.C. 20560

ABSTRACT. Carorita hiberna NEW COMBINATION, a species with many putative autapomorphies known from one sex and few specimens, is transferred from Sisicottus. This transfer is based on a modified version of a cladistic analysis of erigonine relationships by G. Hormiga which incorporated 43 spider taxa scored for 73 characters. The modified analysis features 46 taxa scored for 74 characters. The resulting cladogram placed C. hiberna sister to C. Iimnaea, the type species of Carorita. It is concluded that C. hiberna is better placed in Carorita than in either a new monotypic genus or in Sisicottus. Carorita hiberna is redescribed and the monophyly of Carorita as currently circumscribed is discussed.

The Joumal of Arachnology 27:44-52

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TOWARDS A PHYLOGENY OF ENTELEGYNE SPIDERS (ARANEAE, ARANEOMORPHAE, ENTELEGYNAE)

Charles E. Griswold (1), Jonathan A. Coddington (2), Norman I. Platnick (3) and Raymond R. Forster (4):
(1) Department of Entomology, California Academy of Sciences, Golden Gate Park, San Francisco, California 94118 USA;
(2) Department of Entomology, National Museum of Natural History, NHB-105, Smithsonian Institution, Washington, D.C. 20560, USA;
(3) Department of Entomology, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024 USA;
(4) McMasters Road, R.D. 1, Saddle Hill, Dunedin, New Zealand

ABSTRACT. We propose a phylogeny for all entelegyne families with cribellate members based on a matrix of 137 characters scored for 43 exemplar taxa and analyzed under parsimony. The cladogram confimms the monophyly of Neocnbellatae, Araneoclada, Entelegynae, and Orbiculariae. Lycosoidea, Amaurobiidae and some included subfamilies, Dictynoidea, and Amaurobioidea (sensu Forster & Wilton 1973) are polyphyletic. Phyxelidinae Lehtinen is raised to family level (Phyxelididae, NEW RANK). The family Zorocratidae Dahl 1913 is revalidated. A group including all entelegynes other than Eresoidea is weakly supported as the sister group of Orbiculariae.

The Joumal of Arachnology 27:53-63

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HYPOTHESES FOR THE RECENT HISPANIOLAN SPIDER FAUNA BASED ON THE DOMINICAN REPUBLIC AMBER SPIDER FAUNA

David Penney: Invertebrate Zoology, Manchester Museum, University of Manchester, Oxford Road, Manchester M13 9PL United Kingdom

ABSTRACT. The Dominican Republic amber fossil spider record is examined and hypotheses generated concerning the Recent Hispaniolan spider fauna which is, at present, poorly known. The families Cyrtaucheniidae, Microstigmatidae, Nemesiidae, Ochyroceratidae, Tetrablemmidae, Palpimanidae, Hersiliidae, Symphytognathidae s.l., Anapidae, Mysmenidae, and Hahniidae, known ffom the fossil, but not Recent, fauna are predicted to be components of the Recent fauna of Hispaniola. Based on a terrestrial invertebrate species longevity of less than ten million years, the presence of endemic and non-endemic species, and the assumption that Hispaniola has suffered no major ecological disruption that would cause the amber lineages to become extinct, the following hypotheses are made: Filistatidae and Desidae colonized Hispaniola after the Miocene amber formation; Drymusidae, Amaurobiidae, and Deinopidae were present on Hispaniola dunng the Tertiary, but avoided capture, or have yet to be found in the amber; and Scytodidae, Oecobiidae, Uloboridae, Dictynidae and Clubionidae have colonized Hispaniola since the Miocene amber formation but these families, which were present on Hispaniola dunng the period of amber formation, contain undiscovered endemic species.

The Joumal of Arachnology 27:64-70

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AN ADAPTIVE RADIATION OF HAWAIIAN THOMISIDAE: BIOGEOGRAPHIC AND GENETIC EVIDENCE

Jessica E. Garb: Zoology Department, University of Hawaii at Manoa, Honolulu, Hawaii 96822

ABSTRACT. The Hawaiian Thomisidae are noted for being extremely species rich, as well as diverse in morphology and ecology This exceptional diversity led early systematists to place the species into several genera with cosmopolitan distributions It has been recently suggested that these species compose a single large adaptive radiation, Species-area relationships for all thomisid species and for Misumenops EO, Pickard-Cambridge 1900 (Thomisidae) species for various island areas were generated, Further, a phylogenetic hypothesis was constructed based on genetic distances between the Hawaiian thomisids and various outgroups using a 450 bp region of the mitochondrial cytochrome oxidase I (COI) gene to test for close genetic relationships Despite the extraordinary isolation of the Hawaiian islands, the numbers of Misumenops and total thomisid species were found to be significantly higher than predicted for an island system of its size, Phylogenetic analysis of COI suggests the Hawaiian thomisids are more closely related to each other than to representatives of genera to which they have been previously assigned. These results support the existence of a Hawaiian thomisid adaptive radiation, and ment further investigation using comparative methods.

The Journal of Arachnology 27:71-78

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COMPARISON OF RATES OF SPECIATION IN WEB-BUILDING AND NON-WEB-BUILDING GROUPS WITHIN A HAWAIIAN SPIDER RADIATION

Rosemary G. Gillespie: Department of Zoology & Center for Conservation Research and Training. University of Hawaii, 3050 Maile Way, Honolulu, Hawaii 96822 USA

ABSTRACT. The isolation of the Hawaiian archipelago has resulted in a fauna that shows high levels of endemism I examined the role of lifestyle, as inferred from web-building versus non-web-building behavior, in dictating the rate of differentiation and species formation within a lineage of spiders in the genus Tetragnatha from the Hawaiian Islands. This genus compnses a group of morphologically, ecologically and behaviorally diverse taxa. Included in the radiation is a 'spiny-leg' clade which never builds webs and is relatively loosely associated with a specific habitat, and a large group of web-building species which are generally more tightly associated with a given substrate and habitat. Sequences of mitochondrial cytochrome oxidase DNA provided relative estimates of the age of a clade. Both linear and logarithmic models were used to estimate rates of speciation and the relative time required for speciation for each clade. The results showed that several small clades of web-building species have a greater rate of speciation as compared to the 'spiny-leg' clade. One explanation is that the web-building species may be capable of differentiation between more closely contiguous habitats, which would be consistent with the hypothesis that ecological differentiation promotes diversification and species formation. Possible altemative explanations for the results include differences in rates of molecular evolution, for example as a consequence of differences in metabolic activity.

The Journal of Arachnology 27:79-85

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FOSSIL EVIDENCE, TERRESTRIALIZATION AND ARACHNID PHYLOGENY

Jason A. Dunlop: Institute fur Systematische Zoologie, Museum fur Naturkunde, D-10115 Berlin, Germany
Mark Webster: Department of Earth Sciences, University of California, Riverside, California 92521 USA

ABSTRACT. Geological and morphological evidence suggests that the earliest scorpions were at least partially aquatic and that terrestnalization occurred within the scorpion clade. Scorpions and one or more other arachnid lineages are therefore likely to have come onto land independently. The phylogenetic position of scorpions remains controversial and we question Dromopoda, in which scorpions are placed denved within Arachnida, as this is not supported by scorpions' lateral eye rhabdomes, embryology and sperm morphology. We propose a synapomorphy for scorpions + eurypterids, a postabdomen of five segments as part of an opisthosoma of 13 segments. Scorpions and tetrapulmonates must have evolved their book lungs convergently while fossil evidence indicates that a stomotheca, synapomorphic for Dromopoda, is probably convergent too. 'Arachnid' characters such as Malpighian tubules, the absence of a carapace pleural margin, and an anteriorly directed mouth may also be convergent, although their status as synapomorphies can be defended using parsimony. Convergence is difficult to prove unequivocally, but when there are strong grounds for suspecting it, such characters are questionable evidence for arachnid monophyly.

The Joumal of Arachnology 27:86 93

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CEPHALOTHORACIC SULCI IN LINYPHIINE SPIDERS (ARANEAE, LINYPHIIDAE, LINYPHIINAE)

Gustavo Hormiga: Department of Biological Sciences,George Washington University, Washington, D.C. 20052, USA

ABSTRACT. Pore-bearing cephalothoracic sulci (pits) are described and illustrated for the first time in several linyphiine spiders (Linyphiidae, Linyphiinae). Sulci are reported in members of the genera Bathyphantes Menge, Diplostyla Emerton, Kaestneria Wiehle, Pacifiphantes Eskov & Marusik, Porrhomma Simon, and Vesicapalpus Millidge. The phylogenetic implications of the presence of sulci in linyphiines are discussed.

The Journal of Arachnology 27:94-102

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SPERMATOPHORES AND THE EVOLUTION OF FEMALE GENITALIA IN WHIP SPIDERS (CHELICERATA, AMBLYPYGI)

Peter Weygoldt: Albert-Ludwigs-Universitat, Institut fur Biologie I (Zoologie), Hauptstrasse 1, D-79104 Freiburg, Germany

ABSTRACT. Whip spiders use stalked spermatophores for sperm transfer. These are complex structures, and their morphology varies among genera and farnilies. Usually, the paired sperm masses hidden within the spermatophores are small, and there has been a co-evolution of spermatophores and those parts of the female genitalia which are used to pick up the spermatozoa and to store spermatozoa. These are structures like specialized sclerotizations, glands or, in a few species, seminal receptacles which are hidden inside the genital atrium (or uterus externus). In most species there are paired erectile bodies, homologous to genital appendages, which are attached to the dorsal side of the genital operculum which also is part of an appendage homologon. All these structures vary among genera and families. The comparison of spermatophores and genitalia of different species belonging to most genera and families suggest that the female gonopods consist pumarily of paired cushion-like structures, each equipped with a small finger-like appendage vestige. These appendage vestiges are retained in many species, particular in the Charinidae and Charontidae. They are erectile by increase in blood pressure, and they are thereby probably bent in characteristic ways and thus can pull off the sperm masses from the spermatophore. In some Charinidae, and in some species of Damon and Phrynichus (Phrynida, Phrynichidae) these appendage vestiges are totally lost. In the Phrynidae, on the other hand, they have become sclerotized and hard. They form the well-known claw-like sclerites, and an invagination at the base of each sclerite has been shaped to form a true seminal receptacle. Similar genitalia have evolved convergently in the genus Trichodamon (Phrynida, Phrynichidae). Spermatophores and the corresponding female genitalia and their mechanisms of a number of genera from most farnilies are described and illustrated.

The Journal of Arachnology 27:103-116

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ONTOGENY OF CHARACTERISTIC LEG MACROSETAE IN MIMETUS (ARANEAE, MIMETIDAE)

Bruce Cutler: Electron Microscopy Laboratory and Department of Entomology, University of Kansas, Lawrence, Kansas 66045-2106 USA
Hank Guarisco: RO. Box 3171, Lawrence, Kansas 66046 USA
Daniel J. Mott: Department of Biological and Physical Sciences, Lincoln Land Community College, 5250 Shepherd Road, Springfield, Illinois 62794-9256 USA

ABSTRACT. The distinctive prolateral spination of the metatarsi and tibiae of the first two legs in Mimetus is obscure in the first post-eggsac eclosion instar. Only one of the small, acuminate tipped macrosetae appears in the first instar, small macroseta numbers increase in the second instar, and outnumber the large macrosetae by the third instar. The high variability in adult macroseta counts occurs in the third instar as well. The characteristic macrosetae have a socketed base and longitudinally grooved shafts. The large macrosetae are characterized by numbers of small pustules on the base below the emergence of the shaft and the tips of the macrosetae are round. The small macrosetae have fewer pustules or none, and the tips of the macrosetae are falcate and acuminate. Both the large and small macrosetae morphologically resemble presumptive mechano-receptive setae on the legs, and may have a sensory function.

The Joumal of Arachnology 27:117-122

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VENTRAL MESOSOMAL CHANGES IN EMBRYOS FROM THREE SCORPION FAMILIES: IURIDAE, BUTHIDAE AND VAEJOVIDAE

Roger D. Farley: Department of Biology, University of California, Riverside, California 92521 USA

 

ABSTRACT. The scanning electron microscope was used to examine embryos at a stage when booklungs and spiracles are forming. Earlier studies with scorpion fossils suggest there was ventral mesosomal transition from gills or booklungs above ventral plates to stemites, booklungs and spiracles. In Hadrurus arizonensis (Iuridae), ventral plates and then sternites are formed on the ventral surface of mesosomal segments before spiracles appear. Bilateral invaginations in body segments XII-XV apparently give rise to the booklungs, with spiracles formed lateral to the site of invagination. Sternites with bilateral depressions were also present before spiracles in embryos of the buthid Centruroides exilicauda. In the developmental stages herein examined, spiracles were formed in embryos of Paruroctonus mesoensis (Vaejovidae); but there was no indication of ventral plates or sternites on the ventral mesosoma. Spiracles appear in the intersegmental area posterior to body segments XIII-XV. Booklungs may form later from pumordia associated with bilateral depressions observed in a later stage in these segments.

The Journal of Arachnology 27:123-128

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THE USE OF MORPHOMETRIC CHARACTERISTICS FOR THE RECOGNITION OF SPECIES AMONG GONIOSOMATINE HARVESTMEN (ARACHNIDA, OPILIONES, GONYLEPTIDAE)

Pedro Gnaspini: Departamento de Zoologia, Instituto de Biociencias, Universidade de Sao Paulo, Caixa Postal 11461, 05422-970, Sao Paulo, SP, Brasil

ABSTRACT. Morphometric data from males of six species of Goniosoma are presented and their importance in characterization and recognition of the species is discussed. Data presented show that it is important to use intraspecific variation during descriptions of these harvestmen.

1999 The Journal of Arachnology 27:129-134

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SEXUAL SELECTION IN PHOLCID SPIDERS (ARANEAE, PHOLCIDAE): ARTFUL CHELICERAE AND FORCEFUL GENITALIA

Bernhard A. Huber: Department of Entomology, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024 USA

ABSTRACT. Two aspects of pholcid reproductive biology are reviewed and appear best explained by sexual selection by female choice: the rapid and divergent evolution of male chelicerae (and clypei in some groups) which contact the female epigynum during copulation and probably act as copulatory courtship devices; and the often exceptionally strong pedipalps in males, which possibly function in correlation with the 'valve' in the internal female genitalia.

The Joumal of Arachnology 27:135-141

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A COMPARISON OF THE RESPIRATORY SYSTEMS IN SOME CAVE AND SURFACE SPECIES OF SPIDERS (ARANEAE, DYSDERIDAE)

Matjaz Kuntner (1), Boris Sket (1), and Andrej Blejec (2)
(1) Department of Biology, Biotechnical Faculty, University of Ljubljana, SI-1111 Ljubljana, Slovenia
(2)National Institute of Biology, POB 141, SI-1001 Ljubljana, Slovenia

ABSTRACT. We tested the hypothesis that the respiratory system of hypogean spiders is subject to regressive evolution by examining representatives of the family Dysderidae. This comparison included the epigean species Dysdera ninnii Canestrini 1868, and Harpactea lepida (C.L. Koch 1838), and the hypogean species Stalita toenaria Schiodte 1847, and Parastalita stygia (Joseph 1882). Both tube tracheae and book lungs of these species were measured and compared using 10 indices. Both the tracheal system and book lungs of the hypogean species were less developed than those of the epigean ones. We suggest that the cause is reduction of the respiratory system as a part of general structural reductions in the troglobites. This is consistent with the lower respiratory rates that characterize many troglobites.

The Journal of Arachnology 27:142-148

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A NEW ALL-FEMALE SCORPION AND THE FIRST PROBABLE CASE OF ARRHENOTOKY IN SCORPIONS

Wilson R. Lourengo: Laboratoire de Zoologie (Arthropodes), Museum National d'Histoire Naturelle, 61 rue de Buffon 75005 Paris, Erance
Orlando Cuellar: PO. Box 17074, Salt Lake City, Utah 84117-0074 USA

ABSTRACT. A new parthenogenetic species of scorpion, Ananteris coineaui Lourenco, is reported from French Guyana. Parthenogenesis is based on the production of an all-female brood (thelytoky) by a wild virgin female. Conversely, the first probable case of male parthenogenesis (arrehnotoky) in scorpions is reported based on the production of two successive all-male broods by a wild caught virgin female of Tityus metuendus Pocock from Peru. Both species were found in isolated palm trees within the rain forest, conforming with the insular theory of parthenogenesis.

The Journal of Arachnology 27:149-153

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DISCOVERY OF A SEXUAL POPULATION OF TITYUS SERRULATUS, ONE OF THE MORPHS WITHIN THE COMPLEX TITYUS STIGMURUS (SCORPIONES, BUTHIDAE)

Wilson R. Lourengo: Laboratoire de Zoologie (Arthropodes), Museum National d'Histoire Naturelle, 61 rue de Buffon 75005 Paris, France
John L. Cloudsley-Thompson: 10 Battshill Street, Islington, London N1 1TE, United Kingdom

ABSTRACT. Tityus serrulatus Lutz & Mello 1922 (in fact, the form confluenciata within the Tityus stigmurus complex) is an extremely toxic scorpion of considerable medical importance in Brazil. Its rapid spread is partially due to parthenogenesis. Speculation regarding the occurrence of sexual individuals has been resolved by the discovery of a population, described here, having a male-female sex ratio of 1/2.5. Four color morphs of the T. stigmurus complex are described, and it is concluded that T. serrulatus and Tityus lamottei Lourenco 1981 are junior synonyms of T. stigmurus (Thorell 1877).

The Journal of Arachnology 27:154-158

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ACTIVITY RHYTHMS AND BEHAVIORAL CHARACTERIZATION OF TWO EPIGEAN AND ONE CAVERNICOLOUS HARVESTMEN (ARACHNIDA, OPILIONES, GONYLEPTIDAE)

Sonia Hoenen and Pedro Gnaspini: Departamento de Zoologia, Instituto de Biociencias, Universidade de Sao Paulo, Caixa Postal 11461,05422-97O, Sao Paulo, SP, Brasil

ABSTRACT. The activity rhythms, feeding behavior, and reaction to light of two epigean (surface inhabitant) species of harvestmen (Iporangaia pustulosa and Iguapeia melanocephala) and of one cavernicolous species (Pachylospeleus strinatii) have been recorded. Both the epigean and the cavernicolous species showed a highly pronounced circadian rhythmicity. The cave species showed a bimodal pattern. Whereas the epigean species carried food away to feed, the cave species fed where they found the food. The time of reaction to light did not differ statistically between species. However, when exposed to light, the cave species walked much longer distances after it started walking. These differences are probably due to cave adaptation. The cave species may have to wander further for food (and maybe mates) because of the scarcity of resources and, therefore, show greater activity and also a tendency to exploit a resource wherever they find it.

The Journal of Arachnology 27:159-164

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COURTSHIP AND MATING BEHAVIOR OF BRACHYPELMA KLAASI (ARANEAE, THERAPHOSIDAE)

Martha Yarlez and Arturo Locht: Laboratorio de Acarologia, Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, Coyoacan 0451O, D.E Mexico

Rogelio Macias-Ordoriez: Departamento de Ecologia y Comportamiento Animal, Instituto de Ecologia, A.C., Xalapa, Veracruz 9100O, Mexico

ABSTRACT. Courtship and mating behavior of Brachypelma klausi, heretofore unknown, is described on the basis of three courtship and mating sequences, one in captivity and two in the field. Adult males perform courtship movements (pedipalp drumming, leg drumming, push-up and shaking) when they locate a female's burrow, probably in order to avoid female aggression. After some physical contact, the female raises the prosoma and extends her chelicerae. The male then grasps her chelicerae with his tibial apophyses and the female arches her body backwards leaving the epigyoum exposed. The male starts boxing the female's sternum and presumably inserts his pedipalps and inseminates the female. In two cases the female vigorously attacked the male immediately after mating and probably would have killed him had observers not intervened; the other pair separated more slowly and peacefully. Males appear to use chemical and/or tactile cues from the female's silk around the burrow during short-range searching behavior. Males begin courtship behavior by drumming on the silk to signal to the female that he is present. One male of B. klausi observed in the field laid silk over the female's silk around the burrow, possibly to prevent subsequent matings by other males. A second male did not detect the burrow after this act.

RESUMEN. Se describe el cortejo y apareamiento de Brachypelma klausi, hasta ahora desconocidos con base en tres secuencias de cortejo y apareamiento, una en cautiverio y dos en campo. Los machos adultos realizan movimientos de cortejo (tambonleo con pedipalpos, tamborileo con patas, lagartijas y temblado) cuando localizan nidos de hembras, probablemente para evitar la agresion de las mismas. Despues de un periodo de contacto fisico la hembra levanta el prosoma y evierte los queliceros. El macho prende los queliceros de la hembra con sus apofisis tibiales y la hembra se arquea hacia atras exponiendo el epigineo. El macho boxea contra el esterndn de la hembra y se asume que inserta sus pedipalpos y la insemina. En dos casos la hembra ataco al macho inmediatamente despues del apareamiento y probablemente lo hubiera matado de no haber intervenido el observador, la tercera pareja se separ6 mas lenta y pacificamente. Aparentemente los machos utilizan senales quimicas o tactiles de la seda de la hembra alrededor del nido durante la bCsqueda de corto alcance. Los machos inician el cortejo tamborileando en la seda, probablemente para anunciar su presencia a la hembra. Un macho de B. klaosi observado en el campo depbsito seda sobre la de la hembra alrededor del nido, posiblemente para evitar copulas subsecuentes de otros machos. Un segundo macho no parecio detectar el nido despues de la conducta mencionada.

The Journal of Arachnology 27:165-170

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LOCATION OF SUCCESSFUL STRIKES ON PREY BY JUVENILE CRAB SPIDERS MISUMENA VATIA (ARANEAE, THOMISIDAE)

Douglass H. Morse: Department of Ecology and Evolutionary Biology, Box G-W, Brown University, Providence, Rhode Island 02912 USA

ABSTRACT. Second-instar crab spiderlings Misumena vatia (ca. 0.6 mg) that had never previously fed made killing attacks on pomace flies Drosophila melanogaster (ca. 1.0 mg) in direct proportion to the surface areas of the flies' body patts: abdomen, 50%; thorax, 29%; head, 20%. They retained this pattern over their next six encounters with these flies. They also attacked the different surfaces of these body parts (front, side, above, below, behind) with a frequency predicted by the respective areas of these surfaces. All of the spiderlings tested more than once successfully attacked prey on more than one body part. Fifth and sixth-instar Misumena (ca. 7-15 mg) attacked small (4 mg) syrphid flies Toxamerus marginatus more frequently on the head than the second instars attacked Drosophila heads. This difference may result from subsequent experience, greater activity of the syrphid flies than the Drosophila, or maturation of the spiders.

The Journal of Arachnology 27:171-175

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SAMPLING METHOD AND TIME DETERMINES COMPOSITION OF SPIDER COLLECTIONS

Jan Green: Department of Zoology and Entomology, The University of Queensland, Brisbane, Queensland, Australia 4072

ABSTRACT. Sampling methods and times can misrepresent components of spider assemblages found in tree crops. I collected 2561 spiders, including 20 families, 77 genera and 140 species, from inland and coastal south-east Queensland citrus orchards maintained under Integrated Pest Management programs. Spider assemblages, collected diurnally and nocturnally using vacuum and pit-trap sampling methods over four seasonal penods (spring, summer, autumn and winter), were compared using Simpson and ShannonWiener diversity indices and Morisita-Horn similarity index. Significantly different spider assemblages were collected by the two sampling methods in all orchards and seasons. Nocturnal and diurnal sample data differed for spider abundance (similarity) and diversity for several orchards. These results indicate the need to conduct nocturnal and diumal sampling using a combination of sampling methods to reduce misinterpretation of the composition of spider assemblages. Such misinterpretations may underestimate the predatory importance of spiders in agricultural ecosystems.

The Journal of Arachnology 27:176-182

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NOTES ON THE BIOGEOGRAPHY AND NATURAL HISTORY OF THE ORBWEAVING SPIDER CAREPALXIS (ARANEAE, ARANEIDAE), INCLUDING A GUMNUT MIMIC FROM SOUTHWESTERN AUSTRALIA

Barbara York Main: Department of Zoology, University of Western Australia, Nedlands, Western Australia 6907 Australia

ABSTRACT. The biogeography of the Gondwanan orbweaving spider Carepaixis is reviewed. The genus occurs in Central and northern South America, Australia and New Guinea. It is recorded for the first time from Western Australia. Mimicry of a gumnut (eucalypt seed capsule) is described and illustrated for a southwestern Australian species. It is postulated that the mimicry protects the spiders from bird predation.

The Journal of Arachnology 27:183-188

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EFFECTS OF SHORT-TERM SAMPLING ON ECOLOGICAL CHARACTERIZATION AND EVALUATION OF EPIGEIC SPIDER COMMUNITIES AND THEIR HABITATS FOR SITE ASSESSMENT STUDIES

Uwe Riecken: Federal Agency for Nature Conservation, Mallwitzstrasse 1-3, D-53177 Bonn, Germany

ABSTRACT. Epigeic invertebrates such as spiders are of increasing importance for habitat characterization and for assessments within environmental plannings in Germany and other European countries. Due to high costs for spider sampling (e g., with pitfall traps), proposals for a limited sampling effort are required for the practical use The results of a two-year study with continuous sampling are compared to results of short-term sampling and to results of a reduced number of traps The same data set is used for all evaluations Decreasing sampling effort generally reduced the number of recorded species and led to a biased ecological charactenzation of the spider communities. Reducing the number of pitfall traps used provided a more representative sample than did reducing the duration of sampling. In general, errors based on reduced sampling were lower for agricultural than for natural habitats. These results offer practical use of spiders for bioindication in future environmental planning.

The Journal of Arachnology 27:189-195

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DISTRIBUTION AND NATURAL HISTORY OF MEXICAN SPECIES OF BRACHYPELMA AND BRACHYPELMIDES (THERAPHOSIDAE, THERAPHOSINAE) WITH MORPHOLOGICAL EVIDENCE FOR THEIR SYNONYMY

A. Locht, M. Yanez and I. Vazquez: Laboratorio de Acarologia "Anita Hoffmann," Facultad de Ciencias, Universidad Nacional Authnoma de Mexico, Coyoacan 04510, D.F, Mexico

ABSTRACT. This comparision of Brachypelmides and Brachypelma species is based on newly collected spiders and more than 100 specimens from five museum collections. The results show that there are six endemic species of Brachypelma in western Mexico (B. auratum, B. baumgarteni, B. boehmei, B. emilia, B. pallidum, B. smithi), presenting a gap in their distribution only where Brachypelmides klaasi is found. Brachypelma vagans is distributed along both coasts of Mexico and Brachypelmides rahnaui is found in the central part of Mexico. Notes on natural history, a morphological comparison of 27 characters of these genera, and a discussion of the genenc affinities are included.

RESUMEN. De junio de 1997 a Octubre de 1998 se hizo un estudio comparativo de Brachypelmides y de las especies de Brachypelma. Se revisaron especimenes de ambos generos obtenidos en el campo recientemente y mas de 100 especimenes de cinco diferentes colecciones para realizar este estudio. Los resultados muestran que hay seis especies endemicas al Paclfico mexicano de Brachypelma (B. auratum, B. baumgarteni, B boehmei, B. emillia, B. pallidum, B. smithi), presentando una distribucidn continua a lo largo de la costa del Pacifico, siendo interrumpida por la distribucion de B. klausi. Brachypelma vagans se distribuye en ambas costas y Brachypelmides ruhnaui en el centro del pais. Se incluyen notas de historia natural, una comparacion morfologica de 27 caractensticas de estos generos y una discusion de las afinidades genencas.

The Journal of Arachnology 27:196-200

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COMMON GROUND-LIVING SPIDERS IN OLD TAIGA FORESTS OF FINLAND

Seppo Koponen: Zoological Museum, University of Turku, FIN-20014 Turku, Finland

ABSTRACT. Spiders living on the forest floor in six old taiga forests were studied using pitfall traps in 1994 (in Suomussalmi) and 1995 (in Puolanka), central-eastem Finland, ca. 65° N. Seventy-seven species belonging to eleven families were caught. Linyphiidae (s. lat.) dominated both in species and individual numbers. The most common species were Lepthyphantes alacris, Agyneta ramosa, Lepthyphantes antroniensis, Centromerus arcanus and Agyneta subtilis. The fauna found is, in general, typical of old Finnish boreal forests.

The Joumal of Arachnology 27:201-204

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ABUNDANCE AND PHENOLOGY OF SCHIZOMIDA (ARACHNIDA) FROM A PRIMARY UPLAND FOREST IN CENTRAL AMAZONIA

J. Adis (1), J. Reddell (2), J. Cokendolpher (3) and J.W. de Morais (4)
(1) Max-Planck-lnstitute for Limnology, Tropical Ecology Working Group, Postfach 165, D-24302 Plon, Germany
(2) Texas Memorial Museum, University of Texas, Austin, Texas 78705, USA
(3) 2007 29th St., Lubbock, Texas 79411 USA
(4)1nstituto Nacional de Pesquisas da Amazonia (INPA), C P. 478, 69.011-970 Manaus, AM, Brazil

ABSTRACT. There were 193 schizomids (hubbardids) collected from the soil (0-7 cm depth) during a 12 month study of a primary upland forest (37.5 +/- 16.8 ind/m2/month) near Manaus. They were represented by Surazomus brasiliensis (Kraus 1967) and an undescribed species of a new genus (96% and 4% of the total catch, respectively). About 68% of all specimens of S. brasiliensis inhabited the organic soil layer (0-3.5 cm depth) where monthly catches of juveniles were positively correlated with soil temperature. Females were twice as abundant as males. The lack of a distinct reproductive period and the presence of juveniles (in particular the first nymphal instar) and adults (both sexes) throughout the year indicate a plurivoltine mode of life. Few specimens were caught on the soil surface, and none were on tree trunks or in the canopy. Abundance of S. brasiliensis is compared to that of the Palpigradi (microwhip scorpions) and Thelyphonida (vinegaroons) from the same study site.

The Journal of Arachnology 27:205-210

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RELATIONSHIP OF HABITAT AGE TO PHENOLOGY AMONG GROUND-DWELLING LINYPHIIDAE (ARANEAE) IN THE SOUTHEASTERN UNITED STATES

Michael L. Draney: Department of Biology, P.O. Box 30001, New Mexico State University, Las Cruces, New Mexico 88003 USA

D.A. Crossley, Jr.: Institute of Ecology, University of Georgia, Athens, Georgia 30602 USA

ABSTRACT. Ground-dwelling Linyphiidae from eight South Carolina inner coastal plain habitats were sampled for one year using pitfall traps Habitats formed an age gradient, from a field disturbed yearly and pine stands aged 5, 25 and 40 years, to xeric, mesic and hydric hardwoods (50-75 years) and an oldgrowth forest (200 years) Sixteen of the 55 trapped species were represented in sufficient numbers (n adults > = number of sampling periods, 26) to examine patterns of correlation between phenology and habitat distribution Half of the species are multivoltine, characterized by adults present throughout the year, continuous reproduction, and overlapping generations. Adult abundance of these species peaked during spring through autumn. Other species were univoltine, with adults present briefly, indicating synchronous reproduction and non-overlapping generations. Adult abundance of these species always peaked dunng winter months. This study examines relationships between observed voltinism pattems and characteristic habitat (distribution among the habitats) among the 16 most abundant species. Species from older habitats tend to be univoltine, whereas species inhabiting more recently disturbed habitats were more likely to be multivoltine. Stenochronous winter reproduction (univoltines) probably increases survivorship by limiting individuals' exposure to the harsh conditions of the southeastern summer during vulnerable penods of immatunty and reproduction. This phenological specialization appears optimal in this region except in frequently disturbed habitats, where rapid multivoltine reproduction is most advantageous.

The Journal of Arachnology 27:211-216

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HOUSE SPIDERS OF KANSAS

Hank Guarisco: Kansas Biological Survey, University of Kansas, Lawrence, Kansas 66047 USA

ABSTRACT: Spiders found in and around buildings may be divided into three categories: 1) true synanthropes, which can establish breeding populations in houses, seldom occur locally in the natural environment, and have broad ranges because they may be accidentally transported to new locations, 2) spiders which are seasonally abundant in natural habitats as well as in houses, but don't establish breeding populations in houses, 3) spiders which are rarely found in houses because they are locally rare or spiders that are locally common but are rarely found indoors. Fifteen species, including the venomous Loxosceles relusa and Cheiracanthium mildei are true synanthropes in Kansas. Category 2 contains 26 species, including the venomous species Latrodectus hesperus, L, mactans, and L, variolus. There are 33 species which are rarely found indoors in Kansas. Most species listed have been reported from buildings across the United States.

The Journal of Arachnology 27:217-221

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SPIDER AND HARVESTMAN COMMUNITIES ALONG A GLACIATION TRANSECT IN THE ITALIAN DOLOMITES

Vito Zingerle: Institute of Zoology and Limnology, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria

ABSTRACT. Arachnid communities of alpine grassland, of screes and woodlands near the timberline and of the nival zone have been compared along a transect from the northern to the southern border of the Dolomites. The region is zoogeographically interesting because of differences of the ice cover during glaciation, which was less severe in the southern area. Along the whole transect spider communities in grasslands and at the timberline zone show approximately the same composition. Endemic species, e.g, Harpactea grisea (Canestuni 1868), Amaurobius ruffoi Thaler 1990, Coelotes mediocris Kulczynski 1887, Cybaeus intermedius Maurer 1992 and Eudasylobus ligusticus Roewer 1923 occur mostly on the southernmost station, which remained free of ice. Re-immigrants over short distance are scarce, e.g., Coelotes mediocris at Passo Rolle and Coelotes solitarius L. Koch 1868 in the Puez area. Endemic species were not found in the alpine grassland of the northern Dolomites, which suggests severe impact of glacial events on the local fauna. Central alpine species, i.e., Erigonella subelevata (L. Koch 1869), Metopobactrus nadigi Thaler 1976, Meioneta orites (Thorell 1875), Pardosa blanda (C.L. Koch 1833) and Pardosa mixta (Kulczynski 1887) are still present at the southernmost boundary of the Alps. Nunataks in the northern and central area of the Dolomites allowed speciation effects within the nival fauna: Lepthyphantes brunneri Thaler 1984, Lepthyphantes merretti Millidge 1974, Megabunus armatus (Kulczynski 1887). Further zoogeographically interesting records are Cryphoeca nivalis Schenkel 1919 and Xysticus bonneti Denis 1938.

RIASSUNTO. E stata studiata la composizione della fauna aracnologica della zona subalpina, alpina e nivale lungo un transetto che parte dalle Dolomti settentrionali (Parco Naturale Puez-Odle) e porta fino al bordo meridionale delle Alpi (Monte Grappa). II versante meridionale delle Alpi e di grande importanza ai fini di studi zoogeografici, essendo queste regioni in parte rimaste libere dai ghiacciai durante le epoche glaciali. Sul Monte Grappa sono state riscontrate piu specie endemiche p.es. Harpactea grisea (Canestrini 1868), Amaurobius ruffoi Thaler 1990, Coelotes mediocris Kulczynski 1887, Cybaeus intermedius Maurer 1992 e Eudasylobus ligusticus Roewer 1923. Alcune specie reimmigranti a breve distanza hanno riconquistato parti delle Dolomiti raggiungendo regioni piu a nord: Coelotes mediocris Kulczynski 1887 e stato catturato anche a Passo Rolle, Coelotes solitanus L. Koch 1868 anche nel Parco Naturale Puez-Odle. Specie endemiche sembrano essere assenti nella prateria alpina delle Dolomiti settentnonali, dimostrando l'effetto distruttivo dei ghiacciai sulla fauna del suolo. In questa zona si possono trovare specie endemiche sulle cime piu alte nmaste libere dai ghiacciai: Lepthyphantes merretti Millidge 1974, Lepthyphantes brunneri Thaler 1984 e Megabunus armatus (Kulczynski 1887). Altre specie rare e di notevole interesse zoogeografico catturate nell'ambito di questo studio sono Cryphoeca nivalis Schenkel 1919 e Xysticus bonneu Denis 1938. E particolarmente sorprendente la presenza sul Monte Grappa di specie tipiche delle Alpi centrali che sembrano spingersi fino al bordo piu meridionale delle Alpi, p.es. Erigonella subelevata (L. Koch 1869), Metopobactrus nadigi Thaler 1976, Meioneta orites (Thorell 1875), Pardosa blanda (C.L. Koch 1833) e Pardosa mixta (Kulczynski 1887).

The Journal of Arachnology 27:222-228

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SALTICIDAE (ARACHNIDA, ARANEAE) OF ISLANDS OFF AUSTRALIA

Barbara Patoleta and Marek Zabka: Zaklad Zoologii WSRP, 08-1 10 Siedlce, Poland

ABSTRACT. Thirty nine species of Salticidae from 33 Australian islands are analyzed with respect to their total distribution, dispersal possibilities and relations with the continental fauna. The possibility of the Torres Strait islands as a dispersal route for salticids is discussed.

The Journal of Arachnology 27:229-235

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PSEUDOSCORPIONS IN FIELD MARGINS: EFFECTS OF MARGIN AGE, MANAGEMENT AND BOUNDARY HABITATS

James R. Bell, Simon Gates, Alison J. Haughton, David W. Macdonald, and Helen Smith: Wildlife Conservation Research Unit, Department of Zoology, Oxford University, South Parks Road, Oxford OXI 3PS, U.K.

C. Philip Wheater and W. Rod Cullen: Department of Environmental and Geographical Sciences, Manchester Metropolitan University, Manchester Ml SGD, U.K.

ABSTRACT. Pseudoscorpions (Chthonius ischnocheles (Hermann) and C. orthodactylus (Leach) sensu strictus) were collected using a D-Vac over two-years from 60 field margins at Oxford University farm at Wytham, U.K. Old and new grassland margins were subjected to six different treatments involving spraying, non-intervention and four different cutting intensities. Significantly more pseudoscorpions were found in old compared to new margins, suggesting they may be attracted to litter build-up over time. Pseudoscorpion numbers were reduced on treatments subjected to two cuts annually, particularly when a summer cut was included, although this effect was ameliorated when the cuttings were left. However, pseudoscorpions were most numerous on treatments which involved no management because of the increase in leaf litter which may replicate a woodland environment. Adjacent hedges appear to buffer the effects of management: margins with adjacent hedges (rather than ditches or tracks) having more individuals In contrast to results for other invertebrate groups, sowing wildflower seed did not significantly increase the abundance of pseudoscorpions The effect of different treatments on pseudoscorpion numbers demonstrates that they are useful indicators of the effects of management practice

The Joumal of Arachnology 27:236-240

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COMPARATIVE ANALYSES OF EPIGEIC SPIDER ASSEMBLAGES IN NORTHERN HUNGARIAN WINTER WHEAT FIELDS AND THEIR ADJACENT MARGINS

Ferenc Toth and Jozsef Kiss: Godollo University of Agricultural Sciences, Department of Plant Protection, H-2103 Godollo, Hungary

ABSTRACT. Pitfall trapping was carried out in northern Hungarian winter wheat fields and their adjacent margins dunng the growing seasons of three consecutive years, 1992-1994. The dominant species of both habitats was the wolf spider Pardosa agrestis (Westring). A total of 8403 adult individuals of 19 families of 149 spider species was identified: 118 species from the winter wheat and 118 from the margins with fewer traps. The efficiency of detecting species by trapping was 90%, according to the BauleMitscherlich extrapolation model. Provided that the sampling effort is the same in both habitats, traps in the margin may catch higher number of individuals and species, than traps located within the field. Calculations, however, indicate that the field, with an area more than a hundred times larger than that of the margins, has a higher total number of species. Although the spider species spectrum of the field and of the margin had a considerable overlap, the Renkonen similarity index indicates that the spider fauna of the two types of habitats were different. Spider assemblages of the margins were more diverse (Renyi diversity), than those of the fields. The species richness of epigeic spiders in our Hungarian winter wheat fields was high, and it was increased by the presence of margins. Thus, for the purposes of the protection of our fauna and promotion of integrated pest management, establishment and maintenance of margins is strongly desirable.

The Journal of Arachnology 27:241-248

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THE EFFECTS OF DIFFERENT RATES OF THE HERBICIDE GLYPHOSATE ON SPIDERS IN ARABLE FIELD MARGINS

Alison J. Haughton (1), James R. Bell (2), Nigel D. Boatman (3) and Andy Wilcox (1)
(1) Crop & Environment Research Centre, Harper Adams University College, Newport Shropshire TF10 8NB UK
(2) Department of Environmental & Geographical Sciences, Manchester Metropolitan University, Chester St., Manchester M1 5GD. UK
(3) Allerton Educational & Research Trust, Loddington House, Loddington, Leicestershire LE7 9XE. UK

ABSTRACT. Field margins are susceptible to agro-chemical spray dnfl, and the effects of herbicide on spiders in semi-natural habitats have been little studied In this experiment, an arable field margin was sprayed with three rates of glyphosate (90 g active ingredient/hectare (a.i/ha), 180 g a.i./ha & 360 g a.i./ ha) and control plots leh unsprayed. Spiders were sampled monthly (June-October) using a converted garden-vac and adult spiders were identified to species. A total of 23,393 spiders was sampled with the web-spinners representing more than 90% of the individuals. The effects of glyphosate application on the abundance of wandering and web-spinning prey-capture guilds, and the two most abundant species (Gonatium rubens and Lepthyphantes tenuis) were analyzed using ANOVA F tests. The highest rate of glyphosate consistently reduced the total number of spiders, the numbers of web-spinners, G. rubens and L. tenuis but not numbers of wandering spiders. Changes in vegetation structure and microclimate caused by the glyphosate are implicated in the reduction of numbers of spiders in plots receiving the highest rate of glyphosate. We conclude that glyphosate drift at rates of more than 360 g a.i./ha (active ingredients per hectare) into arable field margins could result in significant losses of important arthropod predators in farmland and a reduction in spider biodiversity in agroecosystems.

The Joumal of Arachnology 27:249-254

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A FAUNISTIC AND ZOOGEOGRAPHICAL REVIEW OF THE SPIDERS (ARANEAE) OF THE BALKAN PENINSULA

Christo Deltshev: Institute of Zoology, Bulgarian Academy of Sciences, Blvd. Tsar Osvoboditel 1, 1000-Sofia, Bulgaria

ABSTRACT. The Balkan Peninsula is home to 1409 species, included in 337 genera and 47 famulies. This number was established after a critical review of the existing literature and taxonomic revlsion of some available collections containing spider material from this region. The highest number of specles is recorded for the territories of Bulgaria (775), Greece (642), Croatia (615) and Serbia (508). This biodiversity depends not only on the size of the regions, but also on the degree of exploration by researchers. The territories of Albania, Turkey, Montenegro and Bosnia are less well investlgated. Accordmg to thelr current distribution, the established 1409 species can be classified into 24 zoogeograpical categories, grouped into four complexes (widely distributed, European, Balkan endemics, and Mediterranean). The largest number of species belongs to the widely distributed complex, but the most characterlstlc are the Balkan endemics. Their established number (379 species) is high and reflects the local character of the fauna. This phenomenon can be attributed to the relative isolation of the mountains compared with the lowlands, in the context of paleo-environmental changes since Pliocene. Thelr high percentage (26.9%) suggests an important process of autochtonous speciation. Thus, the Balkan Peninsula can be considered as a main center of speciation for the European araneofauna.

The Journal of Arachnology 27:255-261

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GUILD STRUCTURE OF SPIDERS IN MAJOR CROPS

George W. Uetz: Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio 45221-0006, USA
Juraj Halaj and Alan B. Cady: Department of Zoology, Miami University, Oxford, Ohio 45056 USA

ABSTRACT. The ecological guild concept has been of great interest to arachnologists, and the different manner in which spiders forage for a common resource-prey arthropods-has led to numerous attempts to classify them into guilds. However, questions have been raised about the validity of guilds and the taxon-centered basis of their definition. Here, we propose an altemative approach to guild classification, using quantitative analysis of ecological characteristics of spider families. While generalizations may not apply to all species within a taxon, results from this approach suggest eight major spider guilds similar to earlier guild assignments by some authors and provide a reasonable framework for future studies. We used this classification in a comparison of spider guild composition across several major crops (from published studies). While total species richness varied widely among crops, the proportion of the total species within each guild was remarkably even across crops. The relative abundance of guilds (based on numbers of individuals) varied greatly, which may reflect availability of resources within a crop type. Pattems of similarity in guild composition suggest the possibility of plant habitat structure as an influence on the spider community. Further detailed analyses of spider guilds in various crops have been constrained by both a lack of comparable quantitative data and the paucity of behavioral and natural history information available for many taxa. As recent studies have shown that assemblages of spiders can impact pest populations and reduce crop damage, a better understanding of spider guild composition and variation in spider community structure among crops is essential in future studies of the arthropod fauna in agroecosystems.

The Journal of Arachnology 27:270-280

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AN AERIAL LOTTERY: THE PHYSICS OF BALLOONING IN A CHAOTIC ATMOSPHERE

Robert B. Suter: Department of Biology, Vassar College, Poughkeepsie, New York 12604 USA

ABSTRACT. The annual recolonization of many agroecosystems by spiders is accomplished more by aerial deposition of ballooning spiders than by cursonal invasion from refugia such as forests and fence lines. The resulting spider communities can have major direct impacts on prey populations and can therefore strongly influence crop productivity. In this paper I first review what we know about ballooning in the broad sense, and then explore the influence of localized atmospheric structure on the physics and dynamics of ballooning. I used relatively high frequency measurements of air movement (speed and inclination) to develop a statistical characterization of the aerial microclimate at the top of the canopy in a field dominated by goldenrod (Solidago sp.), and analyzed the known physics of ballooning in the context of that statistical characterization The major findings are (1) that the spider's perception of the current state of its microclimate at least with respect to air direction and speed, has almost no predictive value and can only contribute to the spider's decision-making in a statistical sense, and (2) that the size distribution of the population of aeronauts is well explained by constraints imposed by aerodynamics and the probabilistic structure of the turbulent atmosphere.

The Joumal of Arachnology 27:281-293

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DIFFERENTIAL AERIAL DISPERSAL OF LINYPHIID SPIDERS FROM A GRASS AND A CEREAL FIELD

C.F.G. Thomas and P.C. Jepson: Department of Biology, University of Southampton, Bassett Crescent East, Southampton SO9 3TU, U.K.

ABSTRACT. Ground and aerial populations of linyphiid spiders were sampled in and above a grass and a cereal field, weekly from June-August 1991. Aerial activity of immature, adult male and adult female spiders was significantly higher over the senescing cereal field than the grass field. Water-trap catches and wind-speed data were used to calculate indices of aenal activity to show differences in the timing of dispersal by adult male, female and immature spiders. Some aerial dispersal occurred every week with highest adult dispersal in July and highest immature dispersal in August. Aerial activity indices were higher for males than females, and the dispersal peak occurred earlier for males than females. Immatures dispersed from the cereal field in July and August, and from the grass field mainly in August Differences in aerial activity are discussed with reference to dispersal strategies that might maximize spider survival in the patchy, disturbed agricultural landscape.

The Journal of Arachnology 27:294-300

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PREY CHOICE AND SPIDER FITNESS

Soren Toft: Department of Zoology, University of Aarhus, Building 135 DK-8000 Arhus, Denmark

ABSTRACT. Although spiders in general are polyphagous, indiscuminate feeding is not advantageous because prey vary enormously in quality due to toxicity or nutrient deficiency. Active prey selection serves to find the optimal compromise between three "nutritional goals": maximize energy intake, balance nutrient composition of the body, and minimize toxin consumption. Consumption of toxic prey is reduced by more or less specific induced aversions, probably associated with both prey taste and behavior. Spiders' ability to avoid toxic prey seems limited because aversions are short-lasting and some toxic prey do not induce an aversion. Such prey may be lethal. Toxic prey in a mixed diet may inhibit feeding on and utilization of good prey Induced tolerance to toxic prey may be possible, however. Nutritional balance may be obtained through consumption of high-quality prey or through mixing of prey types. It is argued that nutrient balance is more important than maximization of energy intake for fitness.

The Journal of Arachnology 27:301-307

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MECHANISMS UNDERLYING THE EFFECTS OF SPIDERS ON PEST POPULATIONS

Keith Sunderland: Department of Entomological Sciences, Horticulture Research International, Wellesboume, Warwick CV35 9EF, U.K.

ABSTRACT. Assemblages of spider species can make significant reductions in pest numbers that are of value to the farmer. A group of spider species with complementary niches leaves few refuges for the pest in space or time. Spiders usually exert an influence on pest numbers in concert with other natural enemies, and spiders are sometimes the dominant component. In addition to killing pests by direct attack, spiders cause pest mortality by dislodging them from plants or trapping them in webs. If the pest is distasteful, or if it is the dominant prey type available, spiders may kill more than they consume, which increases the rate of pest kill per unit of spider food demand. The implications for pest control, of various types of interaction between spiders and other natural enemies, are explored in this paper. Interactions with specialist natural enemies usually result in complementary effects, enhancing pest control. Specialists reduce the density of pests to levels where spiders can prevent resurgence. Specialists foraging on the crop may flush pests off the plant to be hlled by ground-zone spiders. Although hyperpredation (i.e., predators killing other predators) may disrupt biological control occasionally, it is considered that the wide range of competitive interactions between natural enemies, in general, promotes diversity and stability of the natural enemy community and generates a robust basis for pest control.

The Journal of Arachnology 27:308-316

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PREY SELECTION OF SPIDERS IN THE FIELD

Martin Nyffeler: Zoological Institute, Division of Ecology, University of Berne, Baltzerstr. 3, CH-3012 Berne, Switzerland

ABSTRACT. In this article, an overview of the general feeding patterns of common agroecosystem spiders is presented. Five groups of web-weavers (Tetragnathidae, Araneidae, Theridiidae, Linyphiidae, Dictynidae) and five groups of hunters (small-sized Oxyopidae, large-sized Oxyopidae, Thomisidae, Salticidae, Lycosidae) are analyzed comparatively (based on 40 prey analyses previously published by various European and US authors). Fewer than 10 insect orders, as well as the order Araneae, make up the bulk of the prey of these spiders. Web-weavers and hunters both basically feed on the same prey orders, but in different proportions. The observed differences reflect in part the very diverse range of life styles and foraging modes exhibited by the various spider groups and, to some extent, differences in prey availability. Web-weavers are almost strictly insectivorous (insects constituting > 99% of total prey). Hunters, however, exhibit a mixed strategy of insectivorous and araneophagic foraging patterns (insects constituting ~75-90% of total prey). Diet breadth computed with the Inverted Simpson Index was, on average, significantly higher in the hunting spiders than the web spiders. There seems to be a consistent trend of greater diet breadth of the hunters compared to the web-weavers in agroecosystems. Overall, spider individuals of small size (including large percentages of immatures) numencally dominate the faunas of field crops, and these feed primarily on tiny prey (< 4 mm in length).

The Journal of Arachnology 27:317-324

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SCALE-DEPENDENT DISPERSAL AND DISTRIBUTION PATTERNS OF SPIDERS IN AGRICULTURAL SYSTEMS: A REVIEW

Ferenc Samu: Department of Zoology, Plant Protection Institute, Hungarian Academy of Sciences, Budapest, RO.B. 102, H-1525 Hungary
Keith D. Sunderland: Horticulture Research International, Wellesbourne, Warwick CV35 9EF, U.K.
Csaba Szinetar: Berzsenyi College, 4 Karolyi Gaspar Sqr., Szombathely, H-9700 Hungary

ABSTRACT. A conceptual framework is presented for the study of the factors affecting the distribution, dispersal and abundance of spiders in agricultural systems. It is useful to consider how factors operate at three levels of a spatial hierarchy, namely micro-habitat, habitat and landscape. The size and distribution of spider populations are determined by factors influencing survival, reproduction and dispersal. Modes of dispersal vary in terms of the efficiency of sampling new habitats and the level of risk. A literature survey of proximal factors (micro-climate, habitat structure, disturbance, prey availability, predation, and territoriality) affecting micro-habitat usage by spiders showed that the relative importance of these factors varied according to spider species. Spider abundance and diversity were found, in general, to be positively correlated with environmental diversity at different spatial scales. Within-field habitat diversifications were found to be more effective in increasing spider populations when interspersed throughout the crop (e.g., polycultures and reduced tillage) than when spatially segregated (e.g., strip management). Two approaches (modeling and experimental) to studying the effects of landscape level phenomena on spider distribution and abundance are discussed. Manipulation of habitats at the edge of fields has not, in the main, resulted in increased spider density within fields. Opportunities were identified for increasing regional populations of spiders, and optimizing pest control, by management of the annual shift in the crop mosaic to maximize spider transfer rates from senescing crops to young crops.

The Journal of Arachnology 27:325-332

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SPIDER PREDATION: HOW AND WHY WE STUDY IT

Matthew H. Greenstone: USDA-ARS Plant Sciences and Water Conservation Laboratory, 1301 N. Western Street, Stillwater, Oklahoma 74075 USA

ABSTRACT. Predation is of great ecological, evolutionary and behavioral interest. For our present purposes the primary reason for studying it is to determine the role of spiders in suppressing pest populations. Research approaches have included laboratory studies of preference, feeding rate, and fitness; direct observation of predation events or accumulations of prey carcasses; gut analysis; and field experiments. Laboratory studies provide some uniquely useful kinds of information but cannot give reliable indications of the "biological control potential" of spiders against a given pest. Direct observation can be powerful; it has provided the best data on dietary range and predation rates in the field. Gut analytical methods include the use of radionuclides, electrophoresis, chromatography and serology. Serological techniques are preferred: antibodies can be made specific down to the level of prey stage or instar, and assays are simple, sensitive, and reliable. They can determine the relative importance of different predator species, and may be the most efficient methods to document predation on eggs. Problems in quantitation remain. Field experiments have demonstrated unequivocally that spiders can effectively reduce pest populations and the crop damage they cause.

The Journal of Arachnology 27:333-342

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SPIDER COMPETITION IN STRUCTURALLY SIMPLE ECOSYSTEMS

Samuel D. Marshall: Department of Zoology, Miami University, Oxford, Ohio 45056 USA
Ann L. Rypstra: Department of Zoology, Miami University, 1601 Peck Boulevard, Hamilton, Ohio 45011 USA

ABSTRACT. Spider competition has long been an elusive phenomenon for ecological study. Because most spiders are generalist predators, they are predicted to overlap in resource use wherever they overlap in space use and activity periods However, despite this obvious potential for competition, the empirical evidence for competition has been weak. Spider competition could potentially limit densities in agricultural ecosystems, which would limit their effectiveness as biological control agents. We summarize the results of five studies in a type of ecosystem which may be considered to be analogous to row crops in both the physiognomy of vegetation and cyclic disturbance regimes, namely, wetlands In addition, we summarize the results of our own work in a soybean ecosystem

The Journal of Arachnology 27:343-350

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THE IMPLICATIONS OF INTRAGUILD PREDATION FOR THE ROLE OF SPIDERS IN BIOLOGICAL CONTROL

Margaret A. Hodge: Department of Biology, The College of Wooster, Wooster, Ohio 44491 USA

ABSTRACT. Evidence is growing that spiders can be effective biological control agents, particulary assemblages of several species. Other evidence finds that spiders prey on each other and other generalist predators, and as such are of limited value in biological control Such predatory interactions between species which use similar resources have been dubbed intraguild predation (IGP) due to their potential to modify competition as well as cause direct mortality. IGP interactions can have unexpected effects at other trophic levels, and sometimes result in enhancement of a pest population. In this paper I review the evidence for intraguild predation interactions involving spiders in natural systems, and other generalist predators in agroecosystems. To date not much research has examined whether such interactions influence spider biological control potential. Some suggestions as to how we might begin to address these issues are presented.

The Journal of Arachnology 27:351-362

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SPIDERS IN DECOMPOSITION FOOD WEBS OF AGROECOSYSTEMS: THEORY AND EVIDENCE

David H. Wise, William E. Snyder and Patchanee Tuntibunpakul: Department of Entomology, University of Kentucky, Lexington, Kentucky 40546 USA
Juraj Halaj: Department of Zoology, Miami University, Oxford, Ohio 45056 USA

ABSTRACT. The involvement of spiders in decomposition food webs has the potential to affect agricultural productivity through two quite different types of interactions: (1) cascading, top-down effects of spider predation on rates of nutrient mineralization -- spider-initiated trophic cascades in the detrital food web that could alter rates of decomposition and release of nutrients to plants; and (2) a bottom-up linkage, through spiders, between decomposition and grazing food webs -- energy from the detrital web contributing to elevated spider densities, which in tum might reduce pests and enhance net primary production Scant expenmental evidence exists to refute or support either hypothesis, The first set of interactions is most likely to be of significance in no-till and conservation tillage farming, In theory, spiders have the potential to enhance productivity by increasing rates of mineralization, but theory also predicts that spiders, by preying on important detritivores and fungivores, depress rates of litter decomposition, Field expenments by Kajak and her colleagues have uncovered such negative effects of spiders in mown pastures, Although this negative effect could reduce plant growth, the expected time lags in most types of crops suggest that the overall impact of spiders on plant production will be determined more by the interactions comprising the second hypothesis However, the later hypothesis, that bottom-up control processes in the decomposition web affect crop productivity via energy subsidies to spiders and other generalist predators in the grazing web, remains conjecture without clear expenmental confirmation. This hypothesis should be tested in agroecosystems in which detritus-based food webs can feasibly be manipulated.

The Joumal of Arachnology 27:363-370

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ARCHITECTURAL FEATURES OF AGRICULTURAL HABITATS AND THEIR IMPACT ON THE SPIDER INHABITANTS

Ann L. Rypstra: Department of Zoology, Miami University, 1601 Peck Blvd., Hamilton, Ohio 45011 USA
Paul E. Carter, Robert A. Balfour, and Samuel D. Marshall: Department of Zoology, Miami University, Oxford, Ohio 45056 USA

ABSTRACT. The density and diversity of the spider community has been closely tied to the structural complexity of the local environment. For instance, soil dwelling spiders increase dramatically when the litter layer is enhanced because there are more retreats and hiding places and because temperature and humidity extremes are moderated. Web-building spiders are directly linked to the configuration of the vegetation because of specific web attachment requirements. Both correlative and experimental data support a tight relationship between spider density and habitat structure Most of the available data show that agricultural practices which enhance the structural complexity of the environment (such as intercropping, mulching, and conservation tillage practices) enhance the density and diversity of the spider community The key question regarding spiders in agroecosystems is, of course, whether they are in any way suppressing the activity of herbivores, Some studies uncovered a strong link between habitat complexity, spider abundance and plant productivity; but others have not, and the mechanisms by which spiders could exert a top-down effect are not clear More investigation into the specifics of how habitat structure influences the predator-prey interactions in agroecosystems is needed in order to truly understand and manage agricultural production in a responsible manner

The Journal of Arachnology 27:371-377

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AN INDIVIDUAL-BASED MODEL FOR DISPERSIVE SPIDERS IN AGROECOSYSTEMS: SIMULATIONS OF THE EFFECTS OF LANDSCAPE STRUCTURE

C.J. Topping: Department of Landscape Ecology, NERI, Kalo, Grenavej 14, DK-8410 R0nde, Denmark

ABSTRACT. A general individual-based model of spiders in agricultural land was constructed. The populations of spiders were simulated on landscapes which were defined from a set of landscape descriptors based on a Danish agricultural landscape These descriptors gave the types of habitats present in the landscape together with their area and a frequency distribution of the size of individual habitat patches. The agricultural land was divided into crop types each with its own array of crop managements which were considered to influence the spiders via mortality. The dimensions of the model are relatively large, with the spider population able to grow to a size of one million individuals and with a spatial resolution of 108 landscape units. The effect of altering the spatial organization of the landscape elements was investigated together with the influence of the size of fields in the agocultural landscape. Results showed that the spatial arrangement of landscape elements did not affect spider population sizes, but that the effect of increasing habitat patch size, whilst maintaining a constant habitat area, was to increase population sizes, especially where dispersal was minimal. Thus stochastic events (e.g., mortality and the placement of set-aside), were not significant factors in the simulation results. Simulation results indicated that the optimal dispersal strategy for spiders in this system was one of high juvenile dispersal, although the extent to which these results can be translated to other systems is not yet known. These results indicate the potential for using models of this type for theoretical investigations of the life-history strategies used by spiders, especially where landscape heterogeneity and limited dispersal ability could result in complex spatial dynamic patterns.

The Journal of Arachnology 27:378-386

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THE HOWS AND WHYS OF SUCCESSFUL PEST SUPPRESSION BY SPIDERS: INSIGHTS FROM CASE STUDIES

Susan E. Riechert: Department of Ecology & Evolutionary Biology, University of Tennessee, Knoxville Tennessee 37996-1610 USA

ABSTRACT. We can identify agricultural systems in which spiders might best be applied in pest suppression from study of the mechanisms by which spider populations influence prey in natural ecosystems. Theory predicts that prey control is achieved through the development of a stable interaction between predator and prey populations. Two models have been applied to predator control of prey, limit cycle and equilibrium point or focal control. Limit cycle control is exerted on a prey species population by a predator species that tracks the densities of its prey. Although the limit cycle approach is commonly applied to pest control situations, the long life cycles and generalist feeding habits of spiders limit their abilities to exhibit density-dependent tracking of their prey. Crops with short growing seasons and species-depauperate systems are the best candidates for limit cycle influences of spiders on prey. Spider populations that exhibit an uneven age-structure and have strong migratory/aggregational tendencies would offer the greatest pest suppression in these simple systems. Equilibrium point/focus control involves the limiting effects of an assemblage of polyphagous feeders on an assemblage of prey species. Spiders fit this model to a greater extent than they do a limit cycle model of prey control. Agricultural systems that conserve spider densities and species representation through minimal chemical application and the maintenance of ground cover are good candidates for equilibrium point control of prey by spiders. It is also important to recognize that many success stories in agroecosystems do not involve stable interactions between predator and prey populations. Indirect effects (e.g., the cessation of feeding in the presence of a predator) and superfluous killing of prey are two factors that augment the influence of spiders on targeted insect populations.

The Journal of Arachnology 27:387-396

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This page was posted 12 / 21 / 2000 and modified 11 / 27 / 2009