Species

BackDysdera aneris Macías-Hernández Arnedo, 2010

Dysdera aneris Macías-Hernández Arnedo, 2010

Aranha-tenaz-das-Selvagens

  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Class: Arachnida
  • Order: Araneae
  • Family: Dysderidae
VU Vulnerable
IUCN Red List Status:

Countries of Occurrence:
Portugal - Madeira

Archipelago(s):
Madeira

Assessor/s:
Luis Crespo
Mario Boieiro
Paulo A.V. Borges
Pedro Cardoso
Cardoso, P., Crespo, L.C., Silva, I., Borges, P. & Boieiro, M.

Reviewer/s:
Henriques, S. & Russell, N.

Contributor/s:

Facilitators / Compilers/s:


Assessment Rationale:

Dysdera aneris is restricted to the small Selvagens archipelago that lies between Madeira and the Canary Islands, where it possibly occupies all islets. This species has a restricted geographic range with an extent of occurrence (EOO) of 15 km² and an area of occupancy (AOO) of 12 km². It is possible that a future reintroduction of the invasive Dysdera crocata on Selvagem Grande might lead to competition for resources with D. aneris with unpredictable consequences, as was already suggested for the extinction of at least one endemic Dysdera in the Azores. Therefore this species is assessed as Vulnerable (VU) under Criterion D2. More research on population trends and life history is needed.

Geographic Range:

Dysdera aneris is restricted to the small Selvagens archipelago (Portugal) that lies between Madeira and the Canary Islands, where it possibly occupies all islets: Selvagem Grande, Selvagem Pequena and Ilhéu de Fora (Macías-Hernández et al. 2010).

Regions:
Portugal - Madeira
Extent of Occurrence (EOO):
15 (km2)
Area of Occupancy (AOO):
12 (km2)
Elevation Lower Limit:
0 (m)
Elevation Upper Limit:
160 (m)
Biogeographic Realms:
Palearctic
Presence:
Extant
Origin:
Endemic Madeira
Seasonality:
Resident

Population:

Population size is not known for this species. Cardoso et al. (2017a) record the population as stable.

Habitat and Ecology

The Selvagens archipelago is dominated by barren areas with low herbaceous vegetation and rocky outcrops. The natural vegetation of Selvagem Grande has been largely recovered by successful projects coordinated by the Madeira Natural Park devoted to the eradication of invasive species. This species is found across the islands. Its diet is unknown, although most congeners are specialized hunters feeding on woodlice.

Major Threat(s):

Although not currently a threat, the invasive Dysdera crocata has been found on Selvagem Grande in the past (Macías-Hernández et al. 2010). It is possible that a future reintroduction of the species might lead to competition for resources with D. aneriswith unpredictable consequences, as was already suggested for the extinction of at least one endemic Dysdera in the Azores (Cardoso et al. 2010).

Conservation Actions

The entire range of this spider is within the Selvagens Nature Reserve. Monitoring of population trends should be conducted to confirm this spider's status. In addition, some information on its life history (particularly its feeding regime) should be collected as it might be restricted to very few prey types with implications for its conservation.