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Iberus gualtieranus

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA MOLLUSCA GASTROPODA STYLOMMATOPHORA HELICIDAE

Scientific Name: Iberus gualtieranus
Species Authority: (Linnaeus, 1758)
Common Name(s):
Spanish Chapa
Taxonomic Notes: Iberus is an Iberian Peninsula endemic genus, that comprised 20 morphospecies of uncertain validity (traditional classifications conflicted with each other mostly in the number of species), some of them occupying a very restricted geographical area. They were characterized mostly on the basis of the shell morphology because the reproductive system shows no diagnostic features at the specific level (Puente 1994, Arrébola 1995). Recently, Elejalde, Madeira, Arrébola et al. (2008) have studied partial DNA sequences of two mitochondrial genes (COI and 16S rRNA) from different specimens of Iberus, to test the validity of the described morphospecies of the genus. The analysis have revealed 11 main phylogroups, being genetically unique lineages that are allopatrically distributed and considered to have full species status. One of them is I. gualtieranus, composed by three subspecies:  I.g. gualtieranus, I.g. mariae and I.g. ornatissimus. The first has a keeled and flattened shell with marked ornamentation of spiral and radial costulae (synapomorphy), while the other two show rounded and globose shells with soft ornamentation. I.g. mariae and I.g. ornatissimus have distinct and very restricted range and their shells clearly differ one from another. Both taxa were phylogenetically very closely related to I. g. gualtieranus, in contrast with the opinion of other authors who considered them to be more closely related to I. alonensis s.l., on the basis of shell morphology (Alonso and Ibáñez 1981).

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(iii,v)+2ab(iii,v) ver 3.1
Year Published: 2013
Date Assessed: 2010-09-01
Assessor(s): Arrébola, J.
Reviewer(s): Martínez-Ortí, A., Gomez, B., Neubert, E. & Cuttelod, A.
Justification:
The large size of Iberus makes them the best candidates for food harvesting, most of them being locally consumed in their particular distribution areas, specially the flattened I. gualtieranus (“chapa”) and the rounded I. alonensis group (“serrano”) which represent a true traditional, natural and economic resource to rural population. Unfortunately, the impact caused by uncontrolled and excessive snail harvest, accumulated over a long time, as well as other pressures originated by human activities (the increase of agriculture, habitat degradation, fire, etc.) have produced a significant reduction in the number of snails in the environment and the necessity to take urgent actions to mitigate the threats. This species is therefore listed as Endangered (EN) B1ab(iii,v)+2ab(iii,v).

Geographic Range [top]

Range Description: The original distribution area of Iberus gualtieranus gualtieranus is the eastern third of Sierra de Gádor (Almería, Andalucía, south of the Iberian Peninsula), although it is also known from several narrower, isolated and restricted sites in eastern Andalucía: at least Sierra de Jaén (Jaén), Sierra Elvira (Granada) and even Almanzora (NE Almería). According to Elejalde et al. (2005, 2008) the subpopulation of Sierra de Gador is the only native population, having originated the others by recent anthropogenic introductions (due to its gastronomic use) carried out from this only autochthonous population. There are slight conchological differences between Sierra Gádor shells and others, specially in relation with the greater size of  the original subpopulation shells. The data in this assessment (such as the extent of occurrence (EOO) and area of occupancy (AOO)) refer to the original and only subpopulation in Sierra de Gador, where the EOO would be continuous and have the same surface as the AOO, if there was no anthropic habitat destruction and fragmentation. The other subespecies I.g. mariae and I.g. ornatissimus are restricted to Los Alcores de Punta Entinas (type locality) and Barranco Fuerte in Huecija (type locality) and surroundings (Ruiz et al. 2006).
Countries:
Native:
Spain (Spain (mainland))
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The first census for this species has been done in Sierra de Gádor (unpublished data) and the results were not very optimistic: I.g. gualtieranus could be under the minimum density threshold for population viability, so that the density of adults would not be enough for positives or nulls growth rates (Arrebola and Ruiz 2008; unpublished data). As there are no previous census data, it is not possible to estimate the rate of the population decline. However, indirect evidences support the hypothesis of a population decline (loss of habitats, harvest increase, fires, motorways construction, etc.). Back in 1979, Cobos already indicated that this population was declining and now, the subspecies in Almeria is already commercially extinct. Another census has been done in Sierra Elvira (Moreno-Rueda and Pizarro 2007).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: Iberus gualtieranus gualtieranus is a calcicolous, drought tolerant and thermophilic species living in limestone mountain areas of rocky substrate and sun exposure sub-desert environments with sparse vegetation. It can also occur in areas with more vegetation cover in Sierra Elvira (Moreno-Rueda 2002). It avoids earthy and shady places. During dry weather, it takes refuge inside the crevices of the rocks and under stones. Studies on its biology (unpublished data) indicated a low reproductive success, dispersal and predation rates, high rates of adult resistance, synchronization of the activity, absence of predators and/or good defence against them and juvenile mortality due to adverse environmental conditions. With its flattened shell is well adapted to living in strict climates of drought and insulation for long periods, allowing it to penetrate deeper into the fissures of the rock and displace I. alonensis sensu lato in the native range of I. g. gualtieranusThe subpopulations of the species living in areas of low rainfall, have developed a fast and accurate behavioural response to the rare rainy moments of the year. Aestivation is the time of year when more juveniles die because of high temperatures that produce animal dehydration.The active periods of feeding, movement, growth and reproduction are mainly occurring during two times of the year: spring and specially in autumn. During cold and dry winters, its activity is reduced (unpublished data).
Systems: Terrestrial

Use and Trade [top]

Use and Trade: Irrational and uncontrolled catches of I.g. gualtieranus are going on a long-standing and a traditional way. This has led to the practically commercial extinction of this snail known as "chapa", but the same has not happened with captures. Due to the natural scarcity of product, sales prices have increased dramatically and the snail is actually sold for human consumption per unit (not per kilo), reaching a price of 1-1.5 euros each specimens.

Threats [top]

Major Threat(s): Highway construction has meant that 8.7% of the area of occupancy is divided into 14 fragments physically separated by insurmountable barriers for snails. Three important fires have happened in the area of occupancy since 2003 (affecting 9,5% of the extent of occurrence) producing a comparatively lower density of individuals at present. Irreversible loss of the area of occupancy occurred between 1991 and 1999 (3.4 km2) due to urban and agriculture development (2.43% of the total EOO in 1991). Habitat loss reaches 8.7% of the EOO from 1956 (no agriculture or urban pressure) and 2004. From a biologic point of view, poor recruitment and population reproduction and regeneration index, high juvenile mortality and low density are also impacting the species survival. Analysis of fronts of hybridization between the subpopulations of I. g. gualtieranus and other Iberus species indicate that they are in a dynamic equilibrium, and no evidence has been found that these fronts are a threat to the conservation of the subspecies. Traditional harvesting has produced a strong impact on population intrinsic factors (low rates of recruitment, reproduction and regeneration population, aggravated by high juvenile mortality) and the current density may have reached a point where the population viability would be naturally compromised (unpublished data). The indiscriminate and uncontrolled collection made in recent decades derives from its great gastronomic appreciation, and even though it has been considered commercially extinct, it is still collected due to its high market value. Furthermore, the catches are made in times of activity, when most individuals are visible to collectors, causing an irreversible impact on the population (unpublished data).

Conservation Actions [top]

Conservation Actions: Since the low population density is the most pressing problem, it is necessary to manage/stop the catch and reinforce the population with individuals reared in captivity. The species should be included in the National and Regional Endangered Species Catalogue, which would legally prohibit its harvest. Because of its popularity in Andalusia and its great appeal in the world of amateur malacology would be possible to use. Since 2005, a Conservation Plan for Iberus g. gualtieranus is developed within the Programme for Conservation and Sustainable Use of Land Snails of Andalusia, sponsored by the Ministry of Environment of the Junta de Andalucía and led by the Physiology and Zoology Department (University of Seville). At present, breeding in captivity (laboratory scale in Seville University) has been obtained to complete cycle (Arrébola, Ruiz, and Cárcaba, unpublished data). In this sense, it is crucial to begin the half-scale breeding of the species (this will be done in 2011).

Citation: Arrébola, J. 2013. Iberus gualtieranus. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 20 December 2014.
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