IUCN SSC Mid-Atlantic Island Invertebrates Specialist Group


BackTrechus montanheirorum Oromi & Borges, 1991

Trechus montanheirorum Oromi & Borges, 1991

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

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

Countries of Occurrence:
Portugal - Azores


Danielczak, A.

Lamelas-Lopez, L.

Facilitators / Compilers/s:

Assessment Rationale:

Trechus montanheirorum is an endemic species from Pico (Azores, Portugal) . It has a very small extent of occurrence (EOO = 12 km²) and reduced area of occupancy (AOO = 12 km²). The species is very rare and only known from three genetically isolated natural subpopulations. The main current threat to this species is cave visitation by tourists and the impact of agriculture activities. We suggest 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 Critically Endangered (CR), mostly due to its small extend of occurrence (EOO) and area of occupancy (AOO), population fragmentation and decline of habitat quality.

Geographic Range:

Trechus montanheirorum is an endemic cave adapted species known from Pico (Azores, Portugal) (Borges et al. 2010), occurring in only three lava tube caves (Furna de Frei Matias, Furna dos Montanheiros and Gruta dos Vimes). The extent of occurrence (EOO) is 12 km² and the maximum estimated area of occupancy (AOO) is 12 km².

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


The species is relatively abundant in at least one of the caves (Furna dos Montanheiros). Based on genetic analysis, the species is formed by three subpopulations very fragmented (Amorim 2015). The area surrounding one of the the caves (Furna dos Montanheiros) is relatively well protected, but the area surrounding the other two caves is more disturbed. Therefore we assume relatively few impacts for the population. However, tourism visitation could be a problem as well agriculture management in two of the caves. 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 three caves of Pico island (Furna de Frei Matias, Furna dos Montanheiros and Gruta dos Vimes). This species has some ability to colonise the entrances of caves, but no specimens were ever collected outside of a cave (Oromí & Borges 1991; Amorim 2015). 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 recreational cave visitation and impact of pasture lands. 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 cave; potential human recreational activities with radical cave visitation; reforestation of the area with exotic trees with unknown impact and geological events (volcanic activity and earthquakes).

Conservation Actions

The species is protected by regional law (RAA 2008). Its habitat is in a regionally protected area (Natural Park of Pico), but only one of the three caves where this species occurs is within a regionally protected area. Further research is needed into its ecology and life history in order to find extant specimens in more caves. It is necessary a monitoring plan for the invertebrate community in the cave habitat in order to contribute to the conservation of this species. We suggest as future measure of conservation the fencing the entrances of the caves where human intrusion and disturbance has been occurring. A habitat management plan is needed and anticipated to be developed during the coming years.