Abstracts to Articles

The Journal of Arachnology

Volume 31 Number 2

 

 

SPIDERS OF THE GENUS TETRAGNATHA (ARANEAE, TETRAGNATHIDAE) IN THE SOCIETY ISLANDS

by R.G. Gillespie: Division of Insect Biology, University of California Berkeley, 201Wellman Hall, Berkeley, CA 94720-3112, USA.

ABSTRACT. This study revises the status of knowledge of the spider fauna of the Society Islands. Until recently, the literature on the spider fauna in these islands has suggested that the genus Tetragnatha in particular is noticeable for its poor representation in comparison with the large radiation in the Hawaiian Islands. Expeditions were conducted to determine whether this genus is indeed poorly represented in the islands as the literature would suggest. The results indicate that the islands actually have a number of endemic Tetragnatha, although there is no noticeable adaptive radiation as is seen in the Hawaiian Islands. Results of field expeditions in 1999–2000 and studies on historical collections have shown that: (1) Reports of the cosmotropical species T. mandibulata in the Society Islands are probably not valid; these were misidentifications for either T. macilenta or T. nitens. (2) Tetragnatha huahinensis is a synonym of T. macilenta. (3) There are three new species of Tetragnatha, all of which are described here and appear to be endemic to middle and high elevations of the Society Islands (from Tahiti, Moorea and Raiatea). In total, there are six species of Tetragnatha in the Society Islands: in addition to the three endemic species there is one possibly indigenous (T. macilenta), and two that may be of more recent introduction (T. nitens and T. maxillosa).

Keywords: Tahiti, Moorea, Pacific, descriptions, biogeography

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PHYLOGENETIC ANALYSIS OF SANTINEZIA WITH DESCRIPTION OF FIVE NEW SPECIES (OPILIONES, LANIATORES, CRANAIDAE)

by Ricardo Pinto-da-Rocha: Departamento de Zoologia, Instituto de Biocièncias, Universidade de São Paulo, Rua do Matão, Travessa 14, n. 321, 05508–900, São Paulo, SP, Brazil. E-mail: ricrocha@usp.br
and
Adriano B. Kury
: Departamento de Invertebrados, Museu Nacional, Quinta da Boa Vista, São Cristóvão, 20.940-040, Rio de Janeiro, RJ, Brazil

ABSTRACT. The taxonomic status of all species of Santinezia Roewer 1923 is defined, and a catalogue is provided. Santinezia lucifer, S. gracilis, S. onorei (all from Ecuador), S. furva (from Colombia and Venezuela) and S. hermosa (from Peru) are newly described. Santinezia biordi González-Sponga 1991 is newly considered as a junior subjective synonym of S. serratotibialis Roewer 1932. Santinezia albilineata Roewer 1932, Goniosoma pavani Muñoz-Cuevas 1972, S. benedictoi Soares & Avram 1981, S. decui Avram 1987, S. orghidani Avram 1987 and S. francourbani Avram 1987 are newly considered as junior subjective synonyms of Inezia curvipes Roewer 1916. Nieblia Roewer 1925, Chondrocranaus Roewer 1932, Macuchicola Mello-Leitão 1943 and Carvalholeptes H. Soares 1970 are newly considered as junior subjective synonyms of Santinezia. Nieblia camposi Mello-Leitão 1942 is transferred to Spinicranaus Roewer 1913. Santinezia albimedialis Goodnight & Goodnight 1943 is transferred to Phareicranaus Roewer 1913. Nieblia magna Roewer 1932 is transferred to Neocranaus Roewer 1913. Santinezia micheneri Goodnight & Goodnight 1947 is newly considered as a junior subjective synonym of Phareicranaus ornatus Roewer 1932. A character survey is done including newly discovered characters of genital morphology, patterns of colored marks of dorsal scutum and armature of male leg IV. A phylogenetic analysis of the species of the genus for which males are known is provided allowing the definition of three new species groups. Comparative descriptions are given of the penial morphology of one species of Ventrivomer, one species of Phareicranaus and eight species of Santinezia. Distribution maps for all species of Santinezia are given. The type locality of S. serratotibialis Roewer 1932 is corrected from Trinidad (Bolivia) to Trinidad (Trinidad & Tobago).

Keywords: Laniatores, Neotropics, harvestmen, phalangids, taxonomy

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ON THE USE OF AMPULLATE GLAND SILKS BY WOLF SPIDERS (ARANEAE, LYCOSIDAE) FOR ATTACHING THE EGG SAC TO THE SPINNERETS AND A PROPOSAL FOR DEFINING NUBBINS AND TARTIPORES

by Mark A. Townley and Edward K. Tillinghast: Department of Zoology, Rudman Hall, University of New Hampshire, Durham, New Hampshire 03824 USA. E-mail: mtownley@cisunix.unh.edu

ABSTRACT. The means by which female wolf spiders attach an egg sac to their spinnerets was investigated using scanning electron microscopy. In four Pardosa species, we observed that silk fibers emerging from ampullate gland spigots had been affixed to the surface of the egg sac. More specifically, primary (1°) and secondary (2°) major ampullate (MaA) glands and 1° and 2° minor ampullate (MiA) glands all contributed fibers for this purpose. The diameters of the 2° MaA and 2° MiA fibers were greater than those of the 1° MaA and 1° MiA fibers and, correspondingly, the widths of the 2° ampullate spigots were clearly greater than those of the 1° ampullate spigots. Larger 2° ampullate spigots were also observed in adult females of species from three other lycosid genera. Thus, 2° ampullate glands, which in araneoids function only in juveniles during proecdysis, are not only functional in adult female lycosids (and adult females of several other families), but they appear to play a greater role than the 1° ampullate glands in egg sac attachment. Observations made on the 1° and 2° ampullate spigots of adult females from species belonging to several other families are also presented. Cuticular structures referred to as nubbins and tartipores are present in some spinning fields on spinnerets. A proposal is made for defining these terms by a criterion, namely their different origins, which differs from that applied previously.

Keywords: Ampullate silk gland, Pardosa, Hogna, Trochosa, Lycosoidea

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WHEN TO QUIT? ESTIMATING SPIDER SPECIES RICHNESS IN A NORTHERN EUROPEAN DECIDUOUS FOREST

by Nikolaj Scharff (1), Jonathan A. Coddington (2), Charles E. Griswold (3), Gustavo Hormiga (4) and Per de Place Bjørn (1)

(1) Dept. Entomology, Zoological Museum, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark
(2) Dept. Systematic Biology, National Museum of Natural History NHB 105, Smithsonian Institution, Washington DC, 20013-7012, USA
(3) Dept. Entomology,California Academy of Sciences, Golden Gate Park, San Francisco, CA 94118, USA
(4) Dept. Biology, George Washington University, Washington DC, 20052, USA

Address correspondance to: Nikolaj Scharff (145 35321107, fax 145 35321010; E-mail: nscharff@zmuc.ku.dk

ABSTRACT. Terrestrial arthropod surveys and inventories frequently suffer from undersampling bias; common species are over-represented and rare species may be missed entirely. This study compared a rapid (3 days) and intense inventory of spiders from one hectare of a mature beech forest (Fagus sylvaticus) in Hestehaven, Denmark, comprising 8,710 adult spiders of 66 species to a previous, much more thorough, bi-weekly survey of two years duration from the same site that comprised 42,273 spiders (adult and juvenile) of 141 species. Non-parametric species richness estimators were used to assess the degree of undersampling bias in various data partitions. The current study used five experienced, four novice collectors, and five semi-quantitative collecting methods. Method and time of day strongly affected numbers of species and adults per sample. Collector experience affected numbers of species but not numbers of adults per sample. Despite the intensive collecting, number of adults per sample did not decrease over the course of the study. At the end of the sampling, 31 species were still rare in the sample (singletons or doubletons). Non-parametric richness estimators suggest that the actual richness of adult spiders in the study plot at this time of year and susceptible to the methods used was about 80 species. Species turnover between the two surveys (ca 23 years) was remarkably small: the two lists were 92% identical. The baseline study suggests that the rarity of 12 of the 31 rare species was artifactual (10 due to phenology, one to method, another to spatial edge effects). The rarity of the remainder is unexplained and by default is interpreted as undersampling bias.

Keywords: Biodiversity, Araneae, inventory, species richness estimation, singletons, beech forest, Denmark

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OBSERVATIONS OF THEOTIMA MINUTISSIMUS (ARANEAE, OCHYROCERATIDAE), A PARTHENOGENETIC SPIDER

by: Robert L. Edwards: Box 505, Woods Hole, Massachusetts 02543, USA,
Eric H. Edwards
: 45 Canterbury Lane, East Falmouth, Massachusetts 02536, USA,
and
Annabel D. Edwards
: Massachusetts General Hospital, Department of Anesthesia, Boston, Massachusetts 02114, USA.

ABSTRACT. It has been suggested by several authorities that at least one species of spider of the genus Theotima, family Ochyroceratidae, occurring in tropical regions in South Africa, the Caribbean and Asia may be parthenogenetic. Theotima minutissimus is particularly abundant in the tropical rainforest leaf litter on El Yunque, Puerto Rico. While many hundreds of specimens have been collected over many years, none has been a male. To examine the possibility that this small species, 6 0.9 mm body length, is parthenogenetic, live specimens were collected and maintained in the laboratory. A second generation spiderling, raised separately, produced viable progeny.

Keywords: Parthenogenesis, spider, tropical rainforest, leaf litter, Wolbachia

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THE EFFECTS OF SIZE, SEX, AND REPRODUCTIVE CONDITION ON THERMAL AND DESICCATION STRESS IN A RIPARIAN SPIDER (PIRATA SEDENTARIUS, ARANEAE, LYCOSIDAE)

by: Jill DeVito and Daniel R. Formanowicz, Jr.: Biology Department, Box 19498 University of Texas at Arlington, Arlington, TX 76019. E-mail: devitoj@muohio.edu

ABSTRACT. Within a species, physiological tolerances and thermoregulatory behaviors may vary among ontogenetic stages or between sexes. Such different tolerances can strongly affect the ecology and life history of a species. In a laboratory study, we tested the hypothesis that Pirata sedentarius Montgomery 1904 is differentially susceptible to thermal/desiccation stress by size and sex. As predicted, male adults were more susceptible to thermal/desiccation stress than females. Unexpectedly, however, juvenile spiders survived longer under thermal/desiccation stress than adults. Furthermore, female adults without egg sacs displayed a trend toward higher thermal/desiccation tolerance than females carrying egg sacs. These results suggest that for P. sedentarius, microhabitat preferences and/or thermoregulatory behaviors may change over the course of development, and may vary between sexes and between females with and without egg sacs.

Keywords: Microhabitat partitioning, ontogenetic changes in physiological tolerances

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CLUTCH SIZE AND OFFSPRING SIZE IN THE WOLF SPIDER PIRATA SEDENTARIUS (ARANEAE, LYCOSIDAE)

by: Christopher A. Brown, Bridget M. Sanford and Rebekah R. Swerdon: Dept. of Biology, State University of New York College at Fredonia, Fredonia, New York 14063 USA

ABSTRACT. Wolf spiders in the genus Pirata are common, often locally abundant, inhabitants of many moist or mesic habitats. However, relatively little is known about the ecology or life history of these spiders. Here we present data collected during 2000–2001 on female size, offspring size and clutch size for two populations (Ball Gulf, Hardscrabble Creek) of Pirata sedentarius from western New York. In both populations, mean offspring size was less variable than was female size, clutch size or total clutch mass. At Ball Gulf, 67% of females produced two egg sacs and 48% produced three sacs. Clutch size declined across the egg sac sequence for all females. Female size, measured as cephalothorax length, was uncorrelated with mean offspring size in all cases. However, larger females produced larger and heavier clutches during 2001 for both populations; female size was uncorrelated with these variables during 2000 at Hardscrabble Creek. Larger clutches from both populations contained more offspring, and larger clutches contained smaller offspring at Hardscrabble Creek in 2001. We found a significant offspring size-number trade-off at Ball Gulf, while at Hardscrabble Creek this trade-off was marginally significant in 2001 and non-significant in 2000.

Keywords: Lycosidae, Pirata, life history, clutch size, offspring size

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NATURAL HISTORY OF MISUMENOPS ARGENTEUS (THOMISIDAE): SEASONALITY AND DIET ON TRICHOGONIOPSIS ADENANTHA (ASTERACEAE)

by: Gustavo Quevedo Romero and João Vasconcellos-Neto: Departamento de Zoologia, Universidade Estadual de Campinas (UNICAMP), C.P. 6109, Campinas, SP, 13083-970, Brazil, E-mail: gqromero@unicamp.br

ABSTRACT. Seasonal fluctuations, phenology and diet of Misumenops argenteus (Araneae, Thomisidae) on Trichogoniopsis adenantha (Asteraceae) were investigated in the Serra do Japi, southeastern Brazil, over a 2 year period. This spider population increased at the beginning of the rainy season, reaching a peak in March, and decreased in May, reaching its lowest density in the cold/dry season. In the rainy season (December–May), most of the individuals were in the young or juvenile phase (3rd–6th instars). The spiders reached adulthood between the end of the cold/dry season and the beginning of the hot/rainy season. Analysis of temporal displacement (with up to a 3 month delay) detected a one month delay between the blooming period of T. adenantha and the beginning of the rainy season. The number of arthropods (potential prey of M. argenteus) on the plants increased concomitantly with the increase in the number of reproductive branches. The M. argenteus population also increased numerically 2 months after the rise in arthropod density. These results indicate that the spiders require time to respond to changes in environmental conditions. Of the 595 spiders examined, 76 (12.8%) had prey. Prey items included arthropods belonging to several guilds, but spiders showed a preference for wingless prey or prey that remained on the branches for longer periods of time.

Keywords: Prey, seasonal distribution, plant-animal interactions

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SHORT COMMUNICATION

EFFECTS OF MATERNAL BODY SIZE ON CLUTCH SIZE AND EGG WEIGHT IN A PHOLCID SPIDER (HOLOCNEMUS PLUCHEI)

by: Christa D. Skow: Neuroscience and Behavior Program, Tobin Hall, University of Massachusetts, Amherst, Massachusetts 01002 USA
and Elizabeth M. Jakob
: Department of Psychology, Tobin Hall, University of Massachusetts, Amherst, Massachusetts 01002 USA

ABSTRACT. The pholcid spider Holocnemus pluchei (Scopoli 1763) competes for food with conspecifics, and spiders reared on high food levels are generally larger. In this study, we examined whether larger female body size (as estimated by tibia-patella length) translated into increased reproductive success in the form of increased clutch size, clutch weight, and average egg weight. Larger spiders had more eggs and thus heavier clutches, but there was no relationship between maternal size and average egg weight. We also looked for a tradeoff between average egg weight and egg number, and we found a weak relationship in which average egg weight was highest for intermediate-sized clutches. Larger female body size thus translates into increased reproductive success in terms of egg number and clutch weight, but not weight of individual eggs.

Keywords: Pholcidae, fecundity, egg size, clutch size, fitness

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SHORT COMMUNICATION

IS THE HAIRY GROOVE IN THE GIBBOSUS MALE MORPH OF OEDOTHORAX GIBBOSUS (BLACKWALL 1841) A NUPTIAL FEEDING DEVICE?

by: Danny Vanacker, Liesbeth Maes, Sylvia Pardo, Frederik Hendrickx: Laboratory of Animal Ecology, Zoogeography and Nature Conservation, Ghent University, Ledeganckstraat 35, 9000 Ghent, Belgium, E-mail: Danny.Vanacker@rug.ac.be
and
:
Jean-Pierre Maelfait: Laboratory of Animal Ecology, Zoogeography and Nature Conservation, Ledeganckstraat 35, 9000 Ghent, Belgium; Institute of Nature Conservation, Kliniekstraat 25, 1070 Brussels, Belgium

ABSTRACT. Oedothorax gibbosus (Blackwall 1841) (Erigoninae, Linyphiidae, Araneae) is a dwarf spider characterized by dimorphic males. There is a ‘‘gibbosus’’ male morph characterized by a hunch on the posterior third of the carapace, anterior to which is a hairy groove, and a ‘‘tuberosus’’ morph without these features. We observed several gustatorial courtship interactions by a gibbosus male morph and a conspecific female as well as a by a gibbosus male and a male of the closely related species, Oedothorax fuscus (Blackwall 1834). These interactions suggest that the hairy groove in the gibbosus male morph is a nuptial feeding device possibly under the influence of sexual selection. The interspecific interactions can possibly be interpreted as ‘robbings’ of the nuptial feeding. The interspecific interactions indicate that the cephalic structure of gibbosus probably does not function as a ‘‘lock and key’’ mechanism.

Keywords: Oedothorax gibbosus, Oedothorax fuscus, interspecific courtship, nuptial feeding, gustatorial courtship

 

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ERRATUM:

ERRATUM In Brookhart & Cushing (2002, Journal of Arachnology 39:84–97), the type locality for the male holotype of Eremobates gerbae was erroneously stated as: Rincon Mountains, Cochise County, Arizona, collected August–8 October 1995. The Rincon Mountains are in Pima county not Cochise County and the holotype was collected 30 August 1994. The female allotype of E. gerbae was also collected in the Rincon Mountains in Pima County and was collected on 8 October 1995.

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