Abstracts to Articles

The Journal of Arachnology

Volume 28 Number 3

 

A NEW SPECIES OF THE GENUS KIMULA(OPILIONES:MINUIDAE) FROM THE DOMINICAN REPUBLIC

Abel Perez Gonzalez and Luis Armas Departmento de Ivertebrados, Instituto de Ecologia y Sistematica, A.P. 8029, C.P. 10800, Habana, 8 Cuba

ABSTRACT. Kimula cokendolpheri new species is described from the Central Range of the Dominican Republic, West Indies. It is the first non-fossil species of this genus recorded from Hispaniola.

Keywords: Opilionids, Kimula, West Indies, Dominican Republic

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SYSTEMATICS OF THE GENUS DYSDERA (ARANEAE, DYSDERIDAE) IN THE EASTERN CANARY ISLANDS

Miquel A. Arnedo: Departament de Biologia Animal, Universitat de Barcelona. Av. Diagonal 645, E08028 Barcelona, Spain
Pedro Oromi: Departamento de Biologia Animal, Universidad de La Laguna, Tenerife, Spain
Carles Ribera: Departament de Biologia Animal, Universitat de Barcelona. Av. Diagonal 645, E08028 Barcelona, Spain

ABSTRACT. The circum-Mediterranean spider genus Dysdera has undergone an outsanding species radiation in the volcanic archipelago of the Canary Islands. The present study deals with the endemic species that inhabit the older and ecologically distinct islands of Fuerteventura, Lanzarote and their nearby islets. A new species, Dysdera sanborondon, is described. The male of D. spinidorsum Wunderlich 1991, is described for the first time. Five species are redescribed: D. alegranzoensis Wunderlich 1991; D. Iancerotensis Simon 1907; D. Ionga Wunderlich 1991; D. nesiotes Simon 1907, and D. spinidorsum Wunderlich 1991. The species D. Iiostethus Simon 1907 is proposed to be a senior synonym of D. clavisetoe Wunderlich 1991 and its presence in the eastern islands is considered to be doubtful. A neotype is designated for D. nesiotes. The distribution of D. alegranzoensis is extended to Lanzarote and the other northern islets. Dysdera nesiotes is reported for the first time in the eastern Canaries. Morphological affinities and distribution patterns are discussed. The remarkably lower number of endemic species harbored by the eastern islands, when compared with other Cananan islands similar in size but younger in age, is proposed to be the result of a major extinction event in the eastern Canaries due to climatic change.

Keywords: Spider taxonomy, oceanic islands, colonization, extinction


Journal of Arachnology 28:261-292

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NEW SPECIES AND RECORDS OF KLEPTOCHTHONIUS FROM INDIANA (PSEUDOSCORPIONIDA, CHTHONIIDAE) William B. Muchmore: Department of Biology, University of Rochester, Box 27021 1, Rochester, New York 1 4627-02 1 1 USA

ABSTRACT. New records and supplemental data are given for the troglobitic species Kleptochthtmius packardi; and two new epigean or troglophilic species are described, K griseomanus and K. Iewisorum. Some comments are made on the status of the genus.

Keywords: Pseudoscorpionida, Kleptochthonius, cavernicoles, Indiana

Journal of Arachnology 28:293-299

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SPIDER SIZE AND LOCOMOTION ON TH1E WATER SURFACE (ARANEAE, PISAURIDAE)

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

ABSTRACT. Newly emerged fishing spiders, Dolomedes triton (Walckenaer 1837), can achieve rowing velocities as high as those of adults despite an approximately 600-fold difference in mass (1.7 mg vs. 1.1 g) In contrast, when velocity is measured in relative terms (body lengths/sec), small spiders move much more rapidly than adults, with V(rel )proportional to mass^ - 0.31. This surprising performance of very small spiders can be attabuted both to their very high stride frequency (stride frequency is proportional to mass^ (- 0.43)) and to the high angular velocity of their propulsive legs (anugular velocity is proportional to mass^ (33)). Calculations of leg tip velocities, based on measurements of both angular velocities and leg lengths, reveal that maximum leg tip velocities are achieved by spiders of about 33 mg, nineteen times more massive than the smallest spiders we tested. Some very small spiders perform conspicuously and consistently less well than do others of the same size. A detailed dissection of the motion of these underachievers reveals that a disproportionate amount of their rowing effort goes into vertical as opposed to horizontal work: the ratio of vertical to horizontal work during rowing is 1.03 +/- 0.89 to1 in norrnal fishing spiders and 5.18 +/- 1.73 to 1 in the underachievers.

Keywords: Allometry, locomotion, size, spider, aquatic

Journal of Arachnology 28:300-308

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CHEMICAL CUES FROM ANTS INFLUENCE PREDATORY BEHAVIOR IN HABROCESTUM PULEX, AN ANT-EATING JUMPING SPIDER (ARANEAE, SALTICIDAE)

Robert J. Clark and Robert R. Jackson: Department of Zoology, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
Bruce Cutler: Electron Microscope Laboratory, Haworth Hall, University of Kansas, Lawrence, Kansas 66045-7534 USA

ABSTRACT. The ability of Habrocestum pulex, a myrmecophagic jumping spider, to detect olfactory and contact chemical cues from ants was investigated experimentally. When given a choice between walking over clean soil or soil that had housed ants, H. pulex spent significantly more time on ant-treated soil. However, H. pulex did not appear to discnminate between clean blotting paper and blotting paper over which ants had walked. In tests using a Y-shaped olfactometer, when given a choice between an experimental arm containing air from a cage containing ants, or 6-methyl-5-hepten-2-one, and a control arm containing clean air, H. pulex moved into the experimental arm significantly more frequently than the control arm. When on soil that had previously housed ants, agitated walking, undirected leaping, posturing with body raised, and perching on top of corks were each significantly more prevalent than when H. pulex was on clean soil. Chemical cues left by ants on soil also affected H. pulex's attention to visual cues from ants: when on treated soil, H. pulex initiated and completed stalking sequences more often, and after shorter latency, than when on control soil.

Keywords: Prey detection, myrmecophagy, kairomone, Salticidae, Habrocestum pulex

Journal of Arachnology 28:309-318

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LIFE HISTORY OF PARDOSA MOESTA AND PARDOSA MACKENZIANA (ARANEAE, LYCOSIDAE) IN CENTRAL ALBERTA, CANADA

Christopher M. Buddle: Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9 Canada

ABSTRACT. The density, fecundity, and life-cycle of Pardosa maesta Banks 1892 and Pardosa mackenziana (Keyserling 1877) were studied in a deciduous forest in central Alberta, Canada. Density estimates were lower than reported for other Pardosa species; they ranged from 0.46 per square meter for male P. mackenziana to 2.99 per square meter for immature P. mackenziana. Adult female densities were below I per square meter for both species. Clutch sizes were highly vanable and averaged (+/- SE) 33.06 +/- 1.29 for P. moesta and 48.37 +/- 1.67 for P. mackenziana. Although clutch size was positively related to female size, little of the variation was adequately explained by female size alone. Several lines of evidence suggest that P. moesta and P. mackenziana require two years to mature in central Alberta, with a peak reproductive period in May and June. Females carry egg sacs into the summer months and immature spiders overwinter following the first growing season when they are still less than 5 mg in weight. After a second summer of growth, subadults overwinter and maturation occurs early in the spring.

Keywords: Lycosidae, density, fecundity, phenology, life-cycle

Journal of Arachnology 28:319-328

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A STRUCTURED INVENTORY OF APPALACHIAN GRASS BALD AND HEATH BALD SPIDER ASSEMBLAGES AND A TEST OF SPECIES RICHNESS ESTIMATOR PERFORMANCE

Douglas S. Toti, Frederick A. Coyle, and Jeremy A. Miller: Department of Biology, Western Carolina University, Cullowhee, North Carolina 28723 USA

ABSTRACT. The current rate of species attrition necessitates the development of quick and accurate sampling protocols and species richness estimators. Four time-based and one area-based methods were used to sample spiders of a grass bald and a heath bald in the Great Smoky Mountains National Park in late spring and early fall of 1995. Eighty-four samples were collected at each site; 1853 adults and 91 species were found in the grass bald, 573 adults and 60 species in the heath bald. The data were analyzed with 11 species richness estimators: Chao & Lee 1, Chao & Lee 2, ACE, ICE, bootstrap, Chao 1, Chao 2, first-order jackknife, second-order jackknife, Michaelis-Menten runs, and Michaelis-Menten means. A11 but the Chao & Lee estimators generated richness estimates that clustered within a reasonable range, 106160 species for the grass bald and 68-90 species for the heath bald. The failure of the observed species accumulation curve to level off for our data sets showed that more sampling would be needed to determine the number of species present as adults during the two sampling seasons. Although this prevented us from rigorously testing richness estimator performance, we found that the Michaelis-Menten means estimator performed better than the other estimators when judged by two indirect criteria of good estimator performance-the estimator curve should reach an asymptote with fewer samples than are required for the observed species accumulation curve to reach an asymptote, and the estimates should be close to reasonable visual extrapolations of the asymptote of the observed species accumulation curve. We postulate that the differences we found in species richness and taxon and guild composition between the spider assemblages of these two bald communities are, at least in part, a consequence of striking differences in the physiognomy, richness, and taxonomic composition of the plant associations of the two communities.

Keywords: Spiders, species richness, richness estimators, Appalachian balds

Journal of Arachnology 28:329-345

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DOES THE PRESENCE OF POTENTIAL PREY AFFECT WEB DESIGN IN ARGIOPE KEYSERLINGI (ARANEAE, ARANEIDAE)?

Marie E. Herberstein, Anne C. Gaskett, Deborah Glencross, Simon Hart, Sue Jaensch and Mark A. Elgar: Department of Zoology, University of Melbourne, 3010, Victoria, Australia

ABSTRACT. Orb-web spiders may anticipate their future prey environment by detecting the presence of prey and adjusting their web building behavior accordingly. Here we investigate the effect of different prey sizes and density on the web size and mesh height of the orb webs constructed by Argiope keyserlingi. The experimental design allowed the transmission of prey vibrations but prevented any capture. We found that A. keyserlingi constructed webs more frequently in the presence of prey, but did not alter the web size or mesh height of their webs.

Keywords: Orb web, mesh height, foraging, behavior

Journal of Arachnology 28:346-350

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This page was posted 12 / 19 / 2000 and modified 11 / 27 / 2009