BackRugathodes pico (Merrett & Ashmole, 1989)

Rugathodes pico (Merrett & Ashmole, 1989)

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

Countries of Occurrence:
Portugal - Azores


Russell, N.

Lamelas-Lopez, L.

Facilitators / Compilers/s:

Assessment Rationale:

Rugathodes pico is a cave adapted Azorean-endemic species known from Pico and Faial (Azores, Portugal). It has a small extent of occurrence (EOO = 302 km²) and area of occupancy (AOO = 24-28 km²). The species is particularly rare in most caves and only known from seven isolated natural subpopulations. The main current threat to this species is the impact of agriculture activities, namely the expansion of wine production and domestic pollution. However, each subpopulation is under several different future threats. The species is assessed as Vulnerable (VU), mostly due to its small area of occupancy (AOO), a decline of habitat quality and the many ongoing and future threats. We suggest as future measure of conservation the regular monitoring of the species (every ten years) and fencing the entrances of the caves where human intrusion and disturbance has been occurring.

Geographic Range:

Rugathodes pico is a cave-adapted species known from Pico and Faial (Azores, Portugal) (Borges et al. 2010), occurring in seven volcanic caves in Faial (Furna Ruim) and Pico (Furna dos Montanheiros, Gruta das Canárias, Gruta da Agostinha, Gruta do Henrique Maciel, Gruta do Mistério da Silveira I, Gruta do Soldão) (Pereira et al. 2016). The Extent of Occurrence (EOO) is c. 302 km2 and the maximum estimated Area of Occupancy (AOO) is 24-28 km2 

Portugal - Azores
Extent of Occurrence (EOO):
302 (km2)
Area of Occupancy (AOO):
24-28 (km2)
Elevation Lower Limit:
Elevation Upper Limit:
Biogeographic Realms:
Endemic Azores


Seven subpopulations of this species can be found across two islands, but most of them are very small and located in disturbed lava tubes. A single large subpopulation is located in Gruta da Agostinha, which is under future threat due to increasing possibility of land-use changes for wine production. Current Population Trend: Decreasing.

Habitat and Ecology

The species is a troglobite specialist, occurring only in humid lava tubes and volcanic pits. Rugathodes pico's adaptations related to cave life are the very pale colour, the long spines and hairs, and the extreme length of the legs (Merrett and Ashmole 1989). The species builds cobwebs in open spaces and across small holes in the volcanic basaltic rock. Usually it occurs in twilight conditions near cave openings to deep parts of the caves. In the cave with the larger subpopulation (Gruta da Agostinha) the species occurs in all sections of the cave. Systems: Terrestrial.

Major Threat(s):

The main current threats to this species are domestic pollution in caves near houses and the impact of agricultural activities (namely the expansion of wine production and cattle management). However, there are several future potential threats: climatic changes (see Ferreira et al. 2016) that can change the conditions inside the caves; urban development in coastal areas, changes in the road infrastructure around the caves; logging of Pittosporum undulatum exotic forests over the caves; potential human recreational activities with radical cave visitation; and increased frequency of geological events (volcanic activity). 

Conservation Actions

The species is not protected by regional law. Some of the caves are included in the Natural Park of Faial and Pico. Since land-use changes (for Pittosporum undulatum removal, urban development, wine production) is the main current and future threat, it might be important to safeguard the species survival in the future and conservation should be extended beyond the current area, possibly allowing the recovery of other caves to original conditions where the species might be reintroduced. Further research is needed into its ecology and life history in order to find extant specimens in additional caves. An area-based management plan is also necessary for the most disturbed caves including invertebrate monitoring to contribute to a potential species recovery plan.