IUCN SSC Mid-Atlantic Island Invertebrates Specialist Group


BackTrechus picoensis Machado, 1988

Trechus picoensis Machado, 1988

Cave ground beetle (English)/ Carocho cavernicola (Portuguese)

  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Class: Insecta
  • Order: Coleoptera
  • Family: Carabidae
EN Endangered
IUCN Red List Status:

Countries of Occurrence:
Portugal - Azores


Danielczak, A.

Lamelas-Lopez, L.

Facilitators / Compilers/s:

Assessment Rationale:

Trechus picoensis is an endemic cave adapted species from a single island, Pico (Azores, Portugal). It has a relatively small extent of occurrence (EOO = 285 km²) and  reduced area of occupancy (AOO = 40 km²).  The species is known from nine isolated subpopulations. The area surrounding some of the caves is heavily impacted by human activities. A habitat management plan is needed and anticipated to be developed during the coming years. We suggest also as future measures 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. The species is assessed as Endangered (EN).

Geographic Range:

Trechus picoensis is a cave adapted endemic species known from Pico (Azores, Portugal) (Borges et al. 2010), occurring in several lava tubes (Furna da Baliza, Furna de Frei Matias, Furna das Cabras II, Furna dos Montanheiros, Furna Nova I, Gruta do Gabriel, Gruta do Henrique Maciel, Gruta da Ribeira do Fundo and Gruta das Torres). The extent of occurrence (EOO) is 285 km² and the maximum estimated area of occupancy (AOO) is 40 km².

Portugal - Azores
Extent of Occurrence (EOO):
285 (km2)
Area of Occupancy (AOO):
40 (km2)
Elevation Lower Limit:
10 (m)
Elevation Upper Limit:
770 (m)
Biogeographic Realms:
Endemic Azores


The species is particularly abundant in some of the caves in Pico island. The area surrounding two of the caves is protected and we assume some impacts for some of the other subpopulations. This species is assessed here as severely fragmented as at least 50% of its population can be found in subpopulations/in habitat patches that are 1) smaller than would be required to support a viable population, and 2) separated from other habitat patches by a large distance. In fact, the species occurs in caves that are isolated in a sea of pastures and Cryptomeria japonica plantations.

Habitat and Ecology

This species occurs in several volcanic caves (lava tubes) of Pico island. This species show a strong morphological adaptation to cave life (Machado 1988; Oromí et al. 1990; Amorim 2005). It is a cavernicolous (i.e. a troglobitic species) predator and/or saprophagous species.

Major Threat(s):

The main current threats to this species are the loss of habitat quality due to human activities: agriculture/livestock farming and unregulated visitation to some of the caves. However, there are several future potential threats: climatic changes (see Ferreira et al.2016) that can change the conditions inside the caves; change in the road infrastructure around the caves; potential human recreational activities with radical cave visitation and geological events (volcanic activity and earthquakes).

Conservation Actions

The species is not protected by regional law. Some of the caves are in a regionally protected area (Natural Park of Pico). Degraded habitats should be restored, a strategy needs to be developed to address the future threat by climate change that may change the vegetation cover above the caves, and the entrance of the caves most impacted by unregulated human visitation should be fenced. A habitat management plan is needed and anticipated to be developed during the coming years.