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Grammostola vachoni 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Arthropoda Arachnida Araneae Theraphosidae

Scientific Name: Grammostola vachoni Schiapelli & Gerschman, 1961

Assessment Information [top]

Red List Category & Criteria: Vulnerable B2ab(i,ii,iii,v) ver 3.1
Year Published: 2012
Date Assessed: 2012-05-16
Assessor(s): Ferretti, N.E. & Pompozzi, G.
Reviewer(s): Gerlach, J. & West, R.C.
Justification:
This species is widely distributed in Central Argentina from east to west. Although the extent of occurrence (EOO) or distributional range is vast in this country, the species' area of occupancy (AOO) is small due to its restriction mainly to hilly and rocky areas at about 500–1,500 meters above sea level. These separated populations could be regarded as seven separate locations. Moreover, the threats that face this species (continuing habitat loss, habitat fragmentation and collection for the international pet trade) have been increasing over recent decades. Regarding habitat loss, in the mountain grassland of central Argentina a long history (over 300 years) of cattle grazing has altered plant communities by increasing their diversity, while reducing both their structural complexity and the frequency of tall grasses (Pucheta et al. 1998). Moreover, in a mountainous system occupied by this  species (Pampa de Achala, Córdoba), a sustained, high-density cattle presence was associated with a noticeably reduced insect community (Cagnolo et al. 2002). The species remains abundant in a Nature Reserve in Buenos Aires (Ferretti et al. 2012), but this area shows a situation of overgrazing mainly by feral horses changing the vegetation structure, reflecting changes on the richness and diversity of animal taxa (Zalba and Cozzani 2004). The species is considered to be threatened by these factors throughout its range.

Geographic Range [top]

Range Description:This species is found in western Argentina in the provinces of La Rioja, Santiago del Estero, San Luis, Córdoba and Mendoza, in eastern Argentina in the provinces of La Pampa, Río Negro, Chubut and Buenos Aires. The inferred extent of occurrence is about 500,000 km² while the actual area of occupancy is less than 2,000 km².
Countries occurrence:
Native:
Argentina (Buenos Aires, Chubut, Córdoba, La Pampa, La Rioja, Mendoza, Rio Negro, San Luis, Santiago del Estero)
Additional data:
Estimated area of occupancy (AOO) - km2:1500Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):UnknownEstimated extent of occurrence (EOO) - km2:500000
Continuing decline in extent of occurrence (EOO):YesExtreme fluctuations in extent of occurrence (EOO):Unknown
Number of Locations:7Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:NoLower elevation limit (metres):500
Upper elevation limit (metres):1500
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Population information is scarce. This species is restricted mainly to rocky and hilly areas. There is one studied population in a natural reserve from Central Argentina that showed a moderate abundance of immature specimens in an area of approximately 0.5 ha of native grassland (Ferretti et al. 2012). However, the actual number of mature individuals tends to be much lower, for example, in the study mentioned above the mature individuals corresponded to only 4.5% of the total of individuals observed.
Current Population Trend:Decreasing
Additional data:
Continuing decline of mature individuals:Yes
Extreme fluctuations:UnknownPopulation severely fragmented:Unknown
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:UnknownAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:This species inhabits short burrows constructed under stones in hilly and mountainous areas. Adult males do not have fixed home ranges, and move frequently in search for females. The reproductive period is restricted to the spring season (from October to December). Males can live one year in captivity. Adult females remain within or close to their burrows at all times. The female lays a single egg sac per year containing 100–400 eggs in her shelter during December (beginning of summer in Southern Hemisphere). The female guards the egg sac for two to three months until spiderlings emerge during February and March (summer and beginning of fall). The reproductive biology, mating behaviour and agonistic interactions of this species are well known from laboratory studies (Ferretti and Ferrero 2008, Ferretti and Pérez-Miles 2011). In some areas, this species is sympatric and synchronic with another theraphosid species, Grammostola doeringi Holmberg 1881.
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes
Movement patterns:Not a Migrant

Use and Trade [top]

Use and Trade:

Members of this genus have become popular in the illegal pet trade in recent decades, for example, in Uruguay more than 300 individuals and 50 cocoons of Grammostola anthracina (Koch 1842) were confiscated from illegal trade (Panzera et al. 2009). From the internet (16 May 2012) a Google search for “Grammostola vachoni” found 4,160 entries including many  (mainly Argentinian web pages) were advertisements for the sale of spiders of this species ranging from 30 to 50 US$. The level of trade is not known.

Threats [top]

Major Threat(s): Habitat loss and fragmentation, and collection of the species for the international pet trade are the major threats. From our understanding, if the habitat is under many pressures such as habitat lost and fragmented by agriculture and grazing, urbanization, and mining activity, together with an additional threat to the species that involves collection by international pet traders (which could have an impact on wild populations) could result in the extinction of this species from known locations in the near future. Habitat fragmentation (for example, in a mountainous system in central-northern Argentina) produces a dramatic increase in the amount of edge habitat, which can influence critical ecological mechanisms by altering the nature of the species interactions (Fagan et al. 1999, Laurance et al. 2000). In addition, the results obtained by Valladares et al. (2006) shows the first evidence of a pervasive impact of habitat fragmentation on trophic processes in this mountainous system involving a hundred of species. According to the illegal pet trade, some species of the genus Grammostola in recent decades have become popular as pets in many countries. For example, in Uruguay more than 300 individuals and 50 cocoons of Grammostola anthracina (Koch 1842) were confiscated for illegal trade (Panzera et al. 2009). Rapid checks on the internet (16 May 2012) using Google tool (www.google.com) to search with the words “Grammostola vachoni” rendered 4.160 entries and many of them (mainly Argentinean web pages) were advertisements for the sale of spiders of this species ranging from US$ 30–50.

Conservation Actions [top]

Conservation Actions: This species is moderately abundant in the “Ernesto Tornquist” Provincial Park and is present in the “Lihue Calel” National Park from central Argentina.

Citation: Ferretti, N.E. & Pompozzi, G. 2012. Grammostola vachoni. The IUCN Red List of Threatened Species 2012: e.T18217620A18217711. . Downloaded on 14 December 2017.
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