Nelson Ferretti

Historical biogeography of mygalomorph spiders from the peripampasic orogenic arc based on track analysis and PAE as a panbiogeographical tool

A panbiogeographical analysis of Mygalomorphae spiders was undertaken in order to determine generalized tracks and biogeographical nodes in the peripampasic orogenic arc. This arc comprises mountainous systems that harbour a high number of endemic species, while they exhibit biotic connections that have become fragmented probably during Tertiary tectonics. They are considered relevant areas for biodiversity conservation. A total of 1078 records of 51 Mygalomorphae species were analysed and ten areas were delimited based on geological data. We used track analysis and parsimony analysis of endemicity as a panbiogeographical tool. Five generalized tracks and three nodes were recovered. The tracks recovered in Argentina could be explained as a consequence of two events: (i) Atlantic marine transgressions during the Middle and Late Miocene; and (ii) changes in the climate of southern South America from the Miocene to Pliocene, caused by the gradual raising of the Andean chain and also, the additional uplift of Pampean and Subandean ranges. The southeastern Brazil and Uruguayan generalized tracks could be explained by the Rio de La Plata Craton.

Mygalomorph Spider Community of a Natural Reserve in a Hilly System in Central Argentina

Abstract The diversity, abundance, spatial distribution, and phenology of the mygalomorph spider community in the “Ernesto Tornquist” Strict Nature Reserve were analyzed in this study. Located in southwestern Buenos Aires, Argentina, the Reserve is representative of the Ventania system, which is a sigmoidal mountain belt 180 km in length. This exceptional hilly ecosystem is home for many endemic species and rich native fauna and flora. Spider abundance was sampled monthly from October 2009 to October 2010 by hand capture and pitfall traps on grassland slopes. The species recorded in the study area were: Actinopus sp.1 (Actinopodidae); Grammostola vachoni and Plesiopelma longisternale (Theraphosidae); Acanthogonatus centralis (Nemesiidae); and Mecicobothrium thorelli (Mecicobothriidae). Grammostola vachoni and Acanthogonatus centralis were the dominant species in hand capture and pitfall traps, respectively. The seasonal variation, diversity, and abundance of the mygalomorph community are analyzed and discussed here. The Mygalomorphae of the Ventania system comprises an important group of sedentary and cryptozoic spiders that seem to be highly dependent on habitat type and environmental factors.

Sexual behavior of Acanthogonatus centralis (Araneae: Mygalomorphae: Nemesiidae) from Argentina, with some notes on their burrows

Abstract Acanthogonatus centralis Goloboff 1995 is a Neotropical nemesiid distributed in hilly zones of central Argentina. The biology of the Nemesiidae is almost unknown. We describe the courtship and mating of A. centralis based on eight observed matings (three males and five females). Male courtship involved scratching and beating the ground. These behaviors have not been observed in other mygalomorph spiders and are here described for the first time. After contacting female silk, males stretched the web. Males manipulated their pedipalps and spasmodically beat their legs over the female. The mating position was typical of mygalomorph spiders. Females remained active during copulation by making body jerks and struggling. The body jerks of females could be stimulating the male to renew palpal insertion. In addition to describing this spider familys mating behavior, we also include some notes on their shelters. The tunnel-webs observed in the field had no branches, only one entrance, and a short burrow. Adult males are capable of constructing tunnel-webs, but they are quite different from those of juveniles and females, lacking the short burrow.

Historical relationships among Argentinean biogeographic provinces based on mygalomorph spider distribution data (Araneae: Mygalomorphae)

The present study used the previously defined biogeographic provinces from Argentina as the starting point for a parsimony analysis of endemicity and cluster analysis. The goal of the study was to use a dataset of distributional patterns of mygalomorph spiders from Argentina to evaluate the historical relationships of the biogeographic provinces. The analyses showed the following relationships: Yungas and Puna; Pampa and Chaco, Monte and Prepuna; Parana Forest and Araucaria angustifolia Forest; Central and Subandean Patagonia. Biogeographical regionalizations are useful as general reference models and their heuristic value should be explored by examining the geographical distribution of other taxa.

Aerial dispersal by Actinopus spiderlings (Araneae: Actinopodidae)

Abstract Ballooning, a form of dispersal rarely seen in mygalomorph spiders, was observed in 13 individuals of an undetermined species of Actinopus under laboratory conditions. After ascending a stick, each spiderling initiated ballooning from either the horizontal lines between sticks or from the sticks edges. They became airborne by dropping and dangling from a dragline, which then gradually lifted and lengthened to 10–15 cm in the breeze, broke at its attachment point, and served as a ballooning thread. This method of ballooning has also been observed in araneomorphs and other species of mygalomorphs, and this is probably a more primitive and shorter distance form of ballooning than that typically practiced by higher araneomorphs, which produce airborne silk lines that are pulled from the spider by air currents and are used either as spanning lines or as balloon lines that allow the spider itself to become airborne.

Sexual Behaviour of Mygalomorph Spiders: when Simplicity Becomes Complex; an Update of the Last 21 Years

Summary A generally common impression seems to be that the mygalomorphs have simple repertoires of behaviours, but many authors have concluded that this traditional portrayal of mygalomorph behaviours is misleading. An increasing number of studies of reproductive behaviour of mygalomorphs have revealed intricate and complex mechanisms of communication employed by this group. Our objective was to provide a synthetic treatment of the literature published in the last 21 years about sexual behaviour of mygalomorph spiders, in order to contribute in improving our understanding on the widespread and unique behaviours they exhibit. We provide a brief introduction to reproductive behaviour of mygalomorph spiders, and then examine some of the general patterns of courtship and mating behaviours known on some mygalomorph families.

Copulatory behavior of Microstigmatidae (Araneae: Mygalomorphae): a study with Xenonemesia platensis from Argentina

Abstract Microstigmatidae are small ground-dwelling and free-living spiders. The present study reports on the copulatory behavior of Xenonemesia platensis Goloboff 1989, constituting the first report on sexual behavior of the Microstigmatidae. Our findings in X. platensis did not show evidence of pheromones associated with silk. The courtship behavioral units of males was comprised of quivers by legs I and II, brusque movements of the palps, and leg tapping with legs II. During mating, a novel courtship behavior by males was observed that consisted of tapping and scraping with legs II on the female legs. The present study not only gives a description of mating behavior in Microstigmatidae for the first time, but also reports strong evidence of nongenital copulatory courtship activity in mygalomorph spiders.

On Puan, a New Genus of Goblin Spiders from Argentina (Araneae, Dysderoidea, Oonopidae)

ABSTRACT A new genus of Oonopidae, Puan, is described from Argentina. The genus exhibits several features also found in orsolobids, including a well-sclerotized sperm duct and an H-shaped eye pattern. Puan resembles the oonopid genus Unicorn Platnick and Brescovit but differs in male palpal morphology. In addition, males lack the clypeal horn characteristic of Unicorn. Two new species, P. chechehet and P. nair, are described from the southwestern mountains of Buenos Aires province. Complex copulatory bulbs are the principal characteristic of these species and could be a synapomorphy for the genus.

The first Hapalotremus Simon, 1903 (Araneae: Theraphosidae) from Argentina: description and natural history of Hapalotremus martinorum sp. nov.

A new species of Hapalotremus Simon, 1903 from northern Argentina is described and illustrated. Hapalotremus martinorum sp. nov. differs from all other congeners by the colour pattern of live specimens. Males differ in the male palpal bulb morphology, with thickened and less curved embolus having a blunt subapical keel and less-developed apical keel. Females differ in the shape of the spermathecae, with the lateral bases more pronounced than the superiors and the upper edge more rounded. Specimens were captured inhabiting short burrows or crevices under stones in high cloud forests. Hapalotremus cyclothorax (Mello-Leitão 1923) is a junior synonym of Homoeomma montanum (Mello-Leitão, 1923), Hapalotremus scintillans (Mello-Leitão 1929) is a junior synonym of Pachistopelma rufonigrum Pocock, 1901, Hapalotremus exilis (Mello-Leitão 1923) and Hapalotremus muticus (Mello-Leitão 1923) are considered species inquirenda. http://zoobank.org/urn:lsid:zoobank.org:pub:1758F6FD-8883-445D-A757-0AC7E120DCF6

Diversity and seasonal composition of the scorpion fauna from a mountainous system on pampean grasslands in central Argentina

ABSTRACT Scorpions are one of the most important taxa for ecological, conservation, and biogeographic studies. Biodiversity in the pampean grassland hilly environment is relevant because of the high number of native plant and animal taxa. We studied the diversity, abundance and phenology of a scorpion community in a natural reserve from central Argentina. Samples were taken monthly using 10 pitfall traps. Five species of scorpions (269 individuals) were observed in the study site (Bothriuridae). Bothriurus prospicuus was the most abundant species with 40.15% of the total individuals captured. The Shannon index was H´ = 0.69 and the evenness index was 0.83. Scorpion abundance was significantly different between months and was significantly correlated with monthly mean temperature. The knowledge on the scorpion fauna in “Ernesto Tornquist” Provincial Park could help in the preservation of natural grassland habitats.