Anapistula ataecina 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Arthropoda Arachnida Araneae Symphytognathidae

Scientific Name: Anapistula ataecina Cardoso & Scharff, 2009
Taxonomic Notes: This newly described species was discovered in 2005. It is the single representative of the family Symphytognathidae in Europe with its closest relatives occurring in Cote D’Ivoire.

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v) ver 3.1
Year Published: 2010
Date Assessed: 2009-05-27
Assessor(s): Cardoso, P.
Reviewer(s): Pollock, C.M. & Snazell, R.
Anapistula ataecina is one of the smallest spiders described to date. In spite of relatively intensive searches, this species is known only from four caves in the Frade cave system, Sesimbra, Portugal, with an estimated extent of occurrence (EOO) of less than 3 km² and an area of occupancy (AOO) around 1 km².

Although all four caves occupied by this species occur within a nature park, limestone quarries in the area are expanding and about 20% of the Frade cave system has already been destroyed by nearby quarrying activities. A survey of one cave in the system that has been legally protected since 1979 failed to find any individuals of A. ataecina. The species has very specific habitat requirements and it is suspected that changes to the geological structure of this cave caused by its opening during mining activities may have caused the local extinction of the spider from this cave. Tourism may also have an impact on this species as tourist activities have recently been authorized inside the cave system.

Since the main threats to this species (quarrying and tourism) are likely to affect each cave separately, currently the species is estimated to occur in four locations. Dispersal ability for this species is not known, but since this is a very small cave-dwelling invertebrate, it is assumed that it has a very low dispersal ability, and the population is suspected to be severely fragmented.

This spider is assessed as Critically Endangered based on its restricted range (EOO <100 km², AOO <10 km²), severe fragmentation, and continuing decline in EOO, AOO, habitat quality, number of locations and population size caused by the ongoing threat from quarrying and tourist activities in the cave system.

Geographic Range [top]

Range Description:This spider is known from only four caves in the Frade cave system, Sesimbra, Portugal. Relatively intensive searches in and around the region have failed to find the spider; surveys have been carried out over the last 3–4 years, and surveys of over 100 caves in the 1940s by Barros Machado, a specialist in minute spiders, did not find this species (Cardoso and Scharff 2009). Its estimated extent of occurrence (EOO) and area of occupancy (AOO) are both extremely small (EOO <3 km², AOO = 1 km²).
Countries occurrence:
Portugal (Portugal (mainland))
Additional data:
Estimated area of occupancy (AOO) - km2:1Continuing decline in area of occupancy (AOO):Yes
Estimated extent of occurrence (EOO) - km2:1-3
Continuing decline in extent of occurrence (EOO):Yes
Number of Locations:4
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This spider is rare. Population size is not known, but only four subpopulations are known (occurring in four caves), with only three of those subpopulations considered to be viable; in one of the occupied caves, only one individual has been found despite several collecting trips to the cave (Cardoso and Scharff 2009).
Current Population Trend:Decreasing
Additional data:
Continuing decline of mature individuals:Yes
Population severely fragmented:Yes
Continuing decline in subpopulations:Yes
All individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:This is one of the smallest spiders described to date (female size of 0.43 to 0.57 mm). It is a troglobiont (cave-dwelling) species, only found in calcareous formations in areas with very restricted microhabitat characteristics. Although it is a very small species, this spider can easily be seen in its web as it appears as a white spot dangling in mid-air; the web itself is invisible (Cardoso and Scharff 2009). Its tridimensional web, with a sheet-like structure, seems atypical for the family and for the genus.

No males have yet been found despite many collecting trips to the caves over more than three years. The species may reproduce asexually (through parthenogenesis), which probably implies a very low genetic variability. This spider is a K-strategist, with each female producing only 2–3 eggs per year, which, compared with other arthropods, is a very low reproductive capability.
Continuing decline in area, extent and/or quality of habitat:Yes

Threats [top]

Major Threat(s): The species occurs inside a Nature Park, but despite that it is not adequately protected. Limestone quarries prevail in the area and these expand mostly without reliable environmental impact assessment studies prior to exploitation inside the protected area. Approximately 20% of the cave system where the species is found has already been destroyed by nearby limestone quarries.

Within this cave system and the limestone quarries lies the Gruta do Zambujal, a cave protected by national laws since 1979 (Decreto-Lei no. 140/79). A single visit to this cave did not reveal any individuals of Anapistula ataecina, even though the geological structure of this cave seems suitable for the species. Unfortunately, the cave is now much degraded. Changes in the internal microclimate caused by the exposure of the cave during mining activities may have caused the species to go locally extinct.

In addition to quarrying activities, tourism may also have an impact on the species. The Portuguese Institute for Nature Conservation has recently authorized tourist activities inside Gruta do Fumo, where most specimens of this spider were found. This authorization was granted in the absence of any previous environmental impact assessment studies.

Conservation Actions [top]

Conservation Actions: Despite the cave system being located inside a Nature Park the stone quarries are expanding. Numerous conservation initiatives were proposed by a local speleology association, but these have not been implemented or authorized by the national authorities:
  1. To force the limestone quarries to obey the existing laws imposing the minimum distance that any quarry should be from protected areas or the ocean (500 m).
  2. To close Gruta do Zambujal in order to restore the natural air flow and microclimate.
  3. To protect the cliffs opened by the limestone quarries surrounding Gruta do Zambujal from erosion and to guarantee their geological stability.
  4. To establish and enforce strict guidelines for the future touristic visits to the Frade cave system.

Citation: Cardoso, P. 2010. Anapistula ataecina. The IUCN Red List of Threatened Species 2010: e.T176265A7207415. . Downloaded on 15 July 2018.
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