Abstracts to Articles

The Journal of Arachnology

Volume 33 Number 1

From the AAS webadmin: Please note that these abstracts are provided as a convenience. Species names are not italicized and except for authors names, accents have been removed from the text. The reason is that it has proved very difficult to move text from JoA's editorial files to html without numerous errors. So, these summaries are taken instead from the pdf for each article. In this process, italics and accents are lost and given that these are brief summaries of the articles. Moreover, the text still requires some cleanup, which must be done by hand. I regret that I cannot justify the time required to add italics and accents back to the text.

Behavior of web-invading spiders Argyrodes argentatus (Theridiidae) in Argiope appensa (Araneidae) host webs in Guam
by Alexander M. Kerr

ABSTRACT Most Argyrodes live in the webs of other spiders, stealing food from the host, scavenging small prey from the web or killing and eating the host. I observed the behavior of A. argentatus from Guam, where it is a frequent inhabitant of the large orb webs of Argiope appensa. I examined the proportion of time spent in different activities, whether behavior differed between the sexes and if population density of Argyrodes on a host web affects Argyrodes behavior. Argyrodes spent 55% of the time hanging immobile and inverted in the support strands at the webs' margin. This was significantly more time than that spent in stationary activity, forward movement at the web's margin, feeding, foraging on the sticky
spiral or in aggressive interaction. Females foraged significantly more often than did males, though the sexes spent about the same amount of time feeding and in other activities. Females also engaged in more bouts of feeding and 21% of these bouts were at prey bundles prepared by the host. In contrast, males invariably foraged for small insects unnoticed by the host.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Scytodes vs. Schizocosa: Predatory techniques and their morphological correlates
by Robert B. Suter and Gail E. Stratton

ABSTRACT Wolf spiders (Lycosidae) typically subdue prey using their legs for capture and their fangs for the injection of venom. Spitting spiders (Scytodidae), in contrast, subdue prey by entangling them, at a distance, in a spitted mixture of silk, glue, and venom that immobilizes and may also kill them. We selected individuals of Schizocosa duplex (Lycosidae) and Scytodes sp. (Scytodidae) of approximately the same mass and carapace width to provide a quantitative assessment of their relative allocations of biomass to morphological features that might be expected to vary with prey-capture technique. As expected, the wolf spiders allocated significantly more to legs, chelicerae, and fangs, and significantly less to the venom glands, than did the spitting spiders. Further comparisons of the legs and chelicerae of the two species provided surprises. First, the legs of Scytodes were 42% longer than those of Schizocosa despite smaller overall allocation to the legs in Scytodes. And second, although the relative sizes of the chelicerae differ greatly, the shapes of the chelicerae of Schizocosa and Scytodes were not significantly different despite the radically different tasks those structures must fulfill.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Mating frequency in Schizocosa ocreata (Hentz) wolf spiders: evidence for a mating system with female monandry and male polygyny
by Stephanie Norton and George W. Uetz

ABSTRACT Courtship behavior has been studied extensively in the wolf spider Schizocosa ocreata (Hentz) (Araneae, Lycosidae). While much research has tested predictions of sexual selection theory regarding male traits and female mate choice, some critical assumptions about female behavior remain untested. To determine if females mate more than once, and to what degree copulation influences subsequent female mating, a multiple mating experiment was conducted. Virgin females were paired randomly with males in laboratory containers. If mating occurred, females were paired with a second male within 24 hr, after 3 days, or after 30 days (enough time for an egg sac to be produced). Of the 101 females tested, 83 (82%) mated with the first male they encountered. The probability of a female mating the first time was not influenced by female size, male size, or male age, but varied significantly with female age post-maturity. Of the 18 males that failed to mate, 3 were cannibalized. Of the 83 males that did mate, 12 were cannibalized after mating. There was no difference between re-mating treatments (1 d, 3 d and 30 d), and analysis of pooled data showed a highly significant difference in the proportion of virgin and mated females accepting males; most females mated only once (93%). In contrast, males appeared to court and attempt mating with every female encountered (virgin and mated), and a majority of males paired with more than one virgin female mated more than once (64.5%). Results suggest that female S. ocreata are essentially monandrous, while males are polygynous, and are discussed in the context of potential
conflicts-of-interest between the sexes.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Day vs. night sampling for spiders in grape vineyards
by Michael J. Costello and Kent M. Daané

ABSTRACT We compared day sampling (between 0700 and 1100) and night sampling (between 1900 and 2300) of spiders on grapevines in a California vineyard in 1993 and 1994, shaking spiders from the vines onto a drop cloth and vacuuming them up. Pooled density of the seven most abundant spider species did not differ significantly between day and night sampling, nor did density of Cheiracanthium inclusum (Miturgidae), Trachelas pacificus (Corrinidae), Oxyopes spp. (Oxyopidae) or Neoscona oaxacensis (Araneidae). Under day sampling Metaphidippus vitis (Salticidae) was 60% more abundant and Hololena nedra (Agelenidae) more than 2.5 fold more abundant than under night sampling. Daytime sampling generally
resulted in a higher percentage of capture for each spider taxa analyzed, but neither of the diversity indices (Shannon-Wiener, Simpson or Bray-Curtis) showed any difference between day and night sampling. Parameters generated by Taylor's power law indicate a uniform distribution for most spider taxa, which was not affected by sampling time with the exception of H. nedra. We suggest that at vineyard sites in California with a similar spider community, sampling can be limited to daylight hours if a sampling method is used which is sufficiently vigorous to dislodge spiders from their resting places.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Determining a combined sampling procedure for a reliable estimation of Araneidae and Thomisidae assemblages (Arachnida, Araneae)
by Alberto Jiménez-Valverde & Jorge M. Lobo

ABSTRACT As the disappearance of species accelerates, it becomes extremely urgent to develop sampling protocols based on efficient sampling methods. As knowledge of the Iberian spider fauna is extremely incomplete, it is becoming necessary to facilitate reliable and complete species richness inventory collection. In this work the results from six sampling methods (sweeping, beating, pitfall traps, hand collecting at two different heights and leaf litter analysis) in three habitats with different vegetation structure are compared for the inventory of Araneidae and Thomisidae in 1 km2 sampling plots. A combination of
sweeping, beating and pitfall trapping prove to be necessary to achieve a reliable inventory of these two spider families. Hand collecting above knee level contributes to the improvement of the protocol in certain habitats where araneids, concentrated in patches of suitable vegetation, are easy to find.


RESUMEN A medida que se acelera la desaparicion de las especies se hace mas urgente el desarrollo de protocolos de muestreo basados en metodos eficientes. El conocimiento de la aracnofauna iberica es bastante escaso, por lo que es necesario desarrollar inventarios fiables y tan completos como sea posible, de una manera rapida y sencilla. En el presente trabajo se comparan seis metodos diferentes de muestreo (mangueo, batido, trampas de interceptacion, captura directa a dos alturas distintas y analisis de hojarasca) para el inventariado de las familias Araneidae y Thomisidae en parcelas de 1 km2, estudiando su comportamiento en tres habitats con diferente complejidad estructural de la vegetacion. Los resultados muestran que para conseguir inventarios fiables de estas dos familias es necesaria la combinacion del mangueo, batido y de las trampas de caida. En los habitats en los que la localizacion de los araneidos es sencilla debido a que se concentran en parches de vegetacion concretos, la captura directa a una altura por encima de las rodillas contribuye a mejorar el protocolo.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Surface ultrastructure of labial and maxillary cuspules in eight species of theraphosidae (Araneae)
by Fernando Pérez-Miles and Laura Montes de Oca

ABSTRACT Surface ultrastructure of labial and maxillary cuspules was studied in eight species of seven different genera of Theraphosidae. Cuspule ornamentation was observed through SEM images and comparisons were made among labial and maxillary cuspules of different species and different zones of each cuspule. Ornamentation patterns were different on the anterior face of the cuspule with respect to the posterior face. A significant correlation analysis between cuspule size and body size was found. The systematic use and the probable functions of the cuspules are discussed.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Natural history and karyotype of some ant-eating zodariid spiders (Araneae, Zodariidae) from Israel
by Stano Pekár, Jirí Král and Yael Lubin

ABSTRACT Natural history, including phenology, circadian activity, mimicry, reproduction, prey specialization and karyotype was studied in the zodariid spiders Trygettus sexoculatus, Zodarion cyrenaicum, Z. lutipes and Z. nitidum (Zodariidae, Zodariinae) found in Israel. The spiders were active throughout the year, with maximum seasonal activity in the summer. Two distinct reproductive periods were found for Z. cyrenaicum and Z. nitidum, one in May and the other in November. Individuals of all species studied were observed hunting only in the morning. Three zodariid species were found to generally mimic ants:
Trygettus sexoculatus mimicked tiny yellow-brown ants such as Monomorium niloticum, Z. cyrenaicum mimicked large black ants such as Messor arenarius, and Z. lutipes mimicked large yellow-brown ants such as Camponotus fellah. The zodariids observed were able to subdue various ant species, from the subfamilies Formicinae, Myrmicinae and Dolichoderinae. Trygettus sexoculatus appeared to specialize on Monomorium sp., Z. lutipes on Camponotus sp. and Z. cyrenaicum on Messor sp. ants, i.e., the same ant species they imitate. When bitten by zodariids, Formicinae and Dolichoderinae ants were paralyzed much more quickly than Myrmicinae. Female zodariid paralyzed ants faster than juveniles and males. Courtship and mating were observed only in Z. lutipes and were found to be similar to other Zodarion species. The mean fecundity for all three Zodarion species ranged from 38 - 45 eggs per egg sac, thus being higher than reported in central European species. Females of all three species guarded egg sacs inside of their retreats. Karyotypes of studied Zodarion spiders were similar to the karyotypes of other zodariid spiders in terms of the diploid number (26 in Z. cyrenaicum and 25 in both Z. lutipes and Z. nitidum), sex chromosome systems and morphology of chromosomes. Most of the data indicate that the Zodarion species of this study have a close affinity to a group of Western European Zodarion species.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


A new species of Apostenus from California, with notes on the genus (Araneae, Liocranidae)
by Darrell Ubick and Richard S. Vetter

ABSTRACT The genus Apostenus is newly recorded from the Nearctic region and a new species, Apostenus californicus, is described from California. Notes are presented on several morphological features of phylogenetic interest.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


The effect of perceived predation risk on male courtship and copulatory behavior in the wolf spider Pardosa milvina (Araneae, Lycosidae)
by Abraham R. Taylor, Matthew H. Persons and Ann L. Rypstra

ABSTRACT The wolf spider, Pardosa milvina (Hentz 1844), shows effective antipredator responses in the presence of chemotactile cues (silk and excreta) from a larger wolf spider, Hogna helluo (Walckenaer 1837). We examined the influence of these substratum-borne cues on male P. milvina courtship and copulatory behavior. Forty-one pairs of adult virgin male and female P. milvina were placed on substrates with or without silk and excreta from an adult female H. helluo. Using behavioral observation software (Noldus Observert 4.1), we recorded time until courtship, courtship duration, and intensity (leg raise and body shake rates). We also measured the total number of matings, the duration of each mating, and the number and rate of successful and failed palpal insertions. While we found no difference between treatments in mating success, courtship intensity or duration, there were significant increases in time until courtship and significant decreases in palpal insertion rates under predation risk. Males under predation risk also had significantly more failed palpal insertions than males not under risk. Results suggest that predation risk has a relatively minor impact on courtship displays and mating success, but could potentially impact mate searching, sperm transfer efficiency, or copulatory courtship.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Web orientation, stabilimentum structure and predatory behavior of Argiope florida Chamberlin & Ivie 1944 (Araneae, Araneidae, Argiopinae)
by Michael J. Justice, Teresa C. Justice and Regina L. Vesci

ABSTRACT This study was undertaken to describe the web orientation, stabilimentum structure and predatory behavior of Argiope florida Chamberlin & Ivie 1944 (Araneae, Araneidae, Argiopinae), a virtually unstudied orb-web spider of the southeastern United States. Adult female Argiope florida were sampled from five sandy ridge areas of Florida. Compass orientation of the spider's dorsum, incline of the web from vertical and hub height were measured. The presence of male A. florida, barrier webs, kleptoparasitic species of Argyrodes Simon 1864 (Araneae, Theridiidae), wrapped prey and large areas of web damage were noted. Predatory behavior was elicited by touching a radius with a 100 Hz tuning fork. The number of stabilimentum arms was measured, along with their arrangement, length and number of silk bands. On average, webs faced 1008 E of N, were inclined 198 from vertical and were 1 m from the ground at the hub. Responses to the tuning fork, which closely resembled the responses to actual prey, were more vigorous when Argyrodes spp. were present on the web, but were not different when wrapped prey were present on the web. Most webs had stabilimenta and most stabilimenta had four arms in a cruciate pattern. The upper arms tended to be smaller and spaced further apart than the lower arms. Spider size was related to the angle between the lower arms of the stabilimentum, but not to other measures of the stabilimentum.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


First fossil Filistatidae: A new species of Misionella in Miocene amber from the Dominican Republic
by David Penney

ABSTRACT Misionella didicostae new species is described from 15 - 20 Ma Miocene amber from the Dominican Republic as the first fossil record of the family Filistatidae. The biogeography of the extant (Brazil and Argentina) and the new fossil species supports the hypothesis that the developing northern Greater Antilles and northwestern South America were briefly (33 - 35 Ma) connected by a landspan centered on the emergent Aves Ridge. Undiscovered extant species of Misionella may exist on Hispaniola. The autospasized first pair of legs suggest that the spider was engulfed in a flowing resin seep of relatively low viscosity, rather than having wandered onto a sticky exudate, becoming stuck and then covered by a subsequent resin flow.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Diversity among ground-dwelling spider assemblages: habitat generalists and specialists
by Rachael E. Mallis and Lawrence E. Hurd

ABSTRACT We sampled assemblages of ground-dwelling spiders with pitfall traps in six terrestrial habitats representing a successional gradient in southwestern Virginia, during the summer of 2002. Approximately half of the 50 species trapped were habitat specialists with low abundance, found at only one of the sites, which is qualitatively consistent with the literature. Only four species, Schizocosa ocreata (Hentz 1844), Pirata insularis (Emerton 1885) Pirata aspirans (Chamberlain 1904) and Neoantistea magna (Keyserling 1887) were found at as many as four sites. A few species that were found in more than one study from disparate geographical communities, such as Trochosa terricola (Thorell 1856) tended also to be relatively abundant habitat generalists. In general, the majority of spider species found in studies such as ours that examined multiple sites were habitat specialists and had low abundance. For our sample sites, there was no relationship between any measure of spider diversity (S, H', J') and successional age. Our results, and those of most other published studies, are consistent with the hypothesis that spider assemblages do not undergo succession and except for a few very common generalist species the composition of these communities is unpredictable, and may depend more on stochastic colonization and specific resource requirements of specialists following immigration than on any predictable association with successional parameters.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Seasonal habitat shift in an intertidal wolf spider: proximal cues associated with migration and substrate preference
by Johanna M. Kraus and Douglass H. Morse

ABSTRACT During most of the year, the wolf spider Pardosa lapidicina Emerton 1885 occupies tidal cobble beaches surrounding Narragansett Bay, RI, USA, but in late autumn part of the population moves into adjacent forest litter to overwinter. We monitored these movements with drift fences and pitfall traps from 1996 - 1999 and evaluated the possible roles of ambient temperature, rainfall, humidity and storm events. We tested substrate choice over the season as a proxy for migratory tendency, both in the laboratory and the field, focusing on the roles of temperature and photoperiod. The timing of peak migration differed among years (S.D. 5 15.5 d). Minimum weekly temperature, weekly rainfall, percent relative humidity and storm events did not explain the variation in migratory times. However, significantly more spiders migrated during weeks with below-freezing temperatures than in weeks without them. Leaf litter, which has less variable temperatures than beach cobble, may provide a refuge from extreme temperatures during winter. Spiders maintained at cold temperatures in laboratory experiments chose leaves over beach cobble significantly more often than did those in warm temperatures. The time of year that spiders were collected also influenced their probability of choosing leaf substrate in the laboratory. Photoperiod, on the other hand, did not significantly influence substrate preference. This study helps to uncover how environmental cues influence seasonal movements across a habitat boundary.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Spatial distribution and microhabitat preference of Psecas chapoda (Peckham & Peckham) (Araneae, Salticidae)
by Gustavo Quevedo Romero and João Vasconcellos-Neto

ABSTRACT Although spiders generally do not have a strong association with the plants on which they live, the jumping spider Psecas chapoda inhabits and breeds on Bromelia balansae (Bromeliaceae). To understand the relationship between Psecas chapoda and Bromelia balansae, we investigated whether the type of habitat (forest or grassland), the size of the bromeliad and the inflorescence of the host plants affected the preference and/or density of P. chapoda. We also examined how spiders of different ages and their eggsacs were distributed on the leaf layers of the rosette of host plants and whether P. chapoda used other plants in addition to B. balanasae. Psecas chapoda occurred with higher frequency on bromeliads in grasslands to those in forest. In grassland, larger bromeliads had more spiders, but this was not true of bromeliads in the forest. This spider avoided bromeliads with inflorescence. Most of the spiderlings (70%) occurred in the central layer of the rosette leaves, and their distribution pattern suggested that they sought shelter to protect themselves from desiccation or cannibalism, both of which are commonly observed in this species. Older spiders, as well as females without eggsacs, occurred in the external layers whereas 90% of the females with eggsacs occurred close to the central layers. Deposition of the eggsacs near the center of the rosette can allow the spiderlings to reach their shelter rapidly and to be less exposed to desiccation and cannibalism. The non-detection of P. chapoda on non-bromeliad plants, and the stereotyped behaviors on the host-plant suggest that this jumping spider was strongly associated with B. balansae.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


A review of the Tasmanian species of Pararchaeidae and Holarchaeidae (Arachnida, Araneae)
by M.G. Rix

ABSTRACT The Tasmanian species of Pararchaeidae and Holarchaeidae are revised and higher speciesgroup relationships within the Pararchaeidae are examined. Three new species of Pararchaea Forster are described and the genitalia of P. corticola Hickman, P. ornata Hickman, P. saxicola Hickman and P. bryophila Hickman are redescribed, the receptacula of P. ornata, P. saxicola and P. bryophila for the first time. The male of P. ornata is newly described. With the addition of P. hickmani new species, P. lulu new species and P. robusta new species, the Tasmanian pararchaeid fauna is enlarged to include seven species. Holarchaea globosa (Hickman) is rediagnosed and the female genitalia and male are described and illustrated for the first time. Biological information is included where known.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Relationship between escape speed and flight distance in a wolf spider, Hogna carolinensis (Walckenaer 1805)
by Matthew K. Nelson and Daniel R. Formanowicz Jr.

ABSTRACT The relationship between running speed and flight distance is an important one in terms of escape from predators, especially in species that may have multiple defensive strategies. In the wolf spider Hogna carolinensis, one important antipredator mechanism is flight. We examined the relationship between sprint speed and flight distance in wolf spiders by measuring sprint speed on a running track and, in a separate set of experiments with the same individual spiders, measured the distance at which they fled from an advancing model predator. Sprint speed was not significantly correlated with mass, size, or sex of the spiders. Sprint speed was positively correlated with flight distance. This correlation may be the result of a trade-off between two competing modes of antipredator mechanisms: escape and crypsis. In individuals with higher sprint speeds, escape may be the more advantageous option. Slower individuals may have a greater chance of surviving an encounter with a predator simply by remaining still and relying on crypsis.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Seismic communication during courtship in two burrowing tarantula spiders: an experimental study on Eupalaestrus weijenberghi and Acanthoscurria suina
by Verónica Quirici and Fernando G. Costa

ABSTRACT During courtship, males of Eupalaestrus weijenberghi and Acanthoscurria suina performed body vibrations and palpal drumming after contacting conspecific female silk at the burrow entrance. Receptive females responded by leg tapping. To elucidate the communicatory channels involved in both species, courting males were placed in terraria with females that had burrowed. In the first experiment, the courting male was covered with a glass cup, minimizing airborne acoustic communication but allowing seismic communication. In the second, the male courted without the cup cover. In the third experiment, the male and the female were placed into two separated parts of the terrarium, greatly limiting seismic communication. In the fourth, these last parts were joined. Females of both species responded to the courtship with receptive behavior in all of the experiments except experiment 3. We conclude that male signals produced during courtship in these two species are mainly seismic. Male body vibrations (that would generate seismic signals) as well as female display, are a widespread phenomena in theraphosid spiders.

 

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Mating and self-burying behavior of Homalonychus theologus Chamberlin (Araneae, Homalonychidae) In Baja California Sur
by Karina Domínguez and María-Luisa Jiménez

ABSTRACT The spider Homalonychus theologus is endemic to desert zones from southwestern California to southern Baja California Peninsula. Until now little has been published about its biology. In this paper we describe the reproductive and self-burying behavior and some aspects of the ecology of the species. Courtship behavior is between levels I and II, and the copulation position is a modification of type III. The male wraps the female's legs in silk before mating. This behavior could help justify inclusion of the Homalonychidae in the superfamily Lycosoidea. Possible camouflage behavior was attributed to the observation that these spiders can camouflage themselves by adhered sand grains to their bodies and buried themselves in the substratum. Females constructed eggsacs two days on average after mating one eggsac contained 29 eggs and other zero. Females incorporated sand "collars'' to the egg sac with silk, probably as protection for the eggs against the dry environment as well as camouflage. This activity was carried out within 34 hours before oviposition. In the field, solitary spiders were found mainly under dead fallen cacti Pachycereus pringlei.


RESUMEN La arana Homalonychus theologus es endemica de las zonas deserticas del sur de California hasta el sur de la peninsula de Baja California. Hasta ahora se conoce poco acerca de su biologia. En este articulo describimos los habitos reproductores, conducta de enterramiento y aportamos algunos datos ecologicos de esta especie. La conducta de cortejo es intermedia entre los niveles i y ii y la posicion de copula corresponde a una modificacion del tipo iii. El macho envuelve las patas de la hembra con seda antes de la copula. Esta conducta puede contribuir a que las Homalonychidae puedan ser incluidas en la Superfamilia Lycosoidea. La posible conducta de enterramiento fue registrada cuando las aran╦ťas incorporaron granos de arena a sus cuerpos y se enterraron en el sustrato. Las hembras fabrican sus ovisacos pocos dias despues del apareamiento con un promedio de dos dias en su elaboracion y el numero de huevos observado fue de 0 - 29 por ovisaco. Las hembras incorporan "collares'' de arena con seda al ovisaco como una probable proteccion de los huevos a la desecacion del medio. Este evento fue llevado a cabo en 34 horas. En el campo, las aranas se encontraron principalmente solas y bajo cardones en descomposicion Pachycereus pringlei.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Notes on the genus Brachistosternus (Scorpiones, Bothriuridae) in Chile, with the description of two new species
by
Andrés A. Ojanguren Affilastro

ABSTRACT Two new species of Brachistosternus from Chile are described. Brachistosternus (Leptosternus) cekalovici new species can be distinguished from most other species of the genus because the divided dorsal gland of the telson. The closest species are B. (L.) artigasi Cekalovic 1974 and B. (L.) negrei Cekalovic 1975, for which redescriptions are provided. Brachistosternus cekalovici has only been collected in "Tres Cruces'', Coquimbo Province, Chile. Brachistosternus (Leptosternus) mattonii new species is also described. This species is most closely related to B. (L.) donosoi Cekalovic 1974, from which it can be distinguished by its more densely granular tegument (especially on the ventral surface of the metasoma), hemispermatophore with more developed internal spines, and the lack of a telson gland. A redescription of B. donosoi is also provided. Both species are related to the Argentine plains species, whilst B. (L.) artigasi, B. (L.) cekalovici and B. (L.) negrei seem to be more related to the Andean species of the subgenus Leptosternus.


RESUMEN Notas sobre el genero Brachistosternus (Scorpiones, Bothriuridae) en Chile, con la descripcio n de dos nuevas especies. En el presente articulo se describen dos nuevas especies del genero Brachistosternus de la Republica de Chile. Brachistosternus (Leptosternus) cekalovici new species puede diferenciarse de la mayoria de las especies descriptas del genero porque la glandula de la cara dorsal del telson, esta dividida en dos mitades separadas. Las especies mas relacionadas son B. (L.) artigasi Cekalovic 1974 y B. (L.) negrei Cekalovic 1975; en este trabajo se brindan tambien las redescripciones de ambas especies. Brachistosternus cekalovici solo ha sido colectada en la localidad de Tres Cruces, en la provincia de Coquimbo, Chile. Brachistosternus (Leptosternus) mattonii n. sp se encuentra estrechamente relacionada con B. (L.) donosoi Cekalovic 1974, puede diferenciarse de ella por poseer un tegumento mas granuloso, especialmente en la faz ventral del metasoma, por el mayor desarrollo de las espinas internas del hemiespermatoforo y por carecer de la glandula del telson. Tambien se brinda la redescripcion de B. donosoi. Ambas especies se encuentran relacionadas con las especies argentinas de llanura, mientras que B. (L.) artigasi, B. (L.) cekalovici y B. (L.) negrei parecen estar mas relacionadas con las especies andinas del subgenero Leptosternus.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


 

SHORT COMMUNICATION: Predation by Argyrodes trigonum on Linyphia triangularis, an invasive sheet-web weaver in coastal Maine
by Jeremy D. Houser, Daniel T. Jennings and Elizabeth M. Jakob

ABSTRACT A female Argyrodes trigonum (Theridiidae) was observed feeding on a female Linyphia triangularis (Linyphiidae), a recently established European immigrant in Maine. Multiple observations of Argyrodes spiders inhabiting L. triangularis webs suggest that this invasive sheet-web weaver is not immune to web invasions, kleptoparasitism or predation by A. trigonum. The potential impacts of A. trigonum on the invasion dynamics of L. triangularis are unknown, but likely to be
minimal.

  Download a copy of this article

Go to the top of this page

Go to Contents for this Issue


Go to:

This page was posted June 17, 2005 and moved to free access December 15, 2006; modified for tracking 11 / 27 / 2009