MAIISG

Assessment Rationale:

Liacarus angustatus is an endemic species of the Azores (Portugal), known from the islands of Faial, Pico, Terceira, S. Miguel and Sta. Maria. From the available data, it could have an extent of occurrence (EOO) of 22,992 km2 , but a limited area of occupancy (AOO = 64 km2 ), but these are likely underestimates, as this species probably has a wider distribution through the soil component of the islands. It can be assumed that this species is affected by human activities and invasive plant species that alter the natural structure and composition of the soil, as such it could be said to occur at only a small number of locations. Future climatic changes and increased risk of droughts will also affect this species. The present situation of this species needs to be assessed and further research is needed into its population, distribution, threats, ecology and life history. However, the EOO and AOO of the species are relatively small, on the global scale, and if there were more data available it is possible that the species could qualify as threatened under criterion B. Therefore, the species is assessed as Near Threatened. Conservation of natural habitats and invasive species control could potentially aid this species' conservation. 

Geographic Range:

Liacarus angustatus is an Azorean-endemic oribatid mite species known from Faial, Pico, Terceira, S. Miguel and Sta. Maria islands (Azores, Portugal) (Borges et al. 2010). It has been recorded from several natural and disturbed areas and also in the lava tube of Furna dos Montanheiros in Pico. It is present in four Natural Forest Reserves; Caldeira do Faial (Faial), Biscoito da Ferraria and Caldeira Sta. Bárbara e Mistérios Negros (Terceira), Graminhais (S. Miguel) and Pico Alto (Sta. Maria). From the available data, the Extent of Occurrence (EOO) could be ca. 22,992 km² and the Area of Occupancy (AOO) could be 64 km².

Population:

No current population size estimates exist for this species. This species occurs on several islands and as an oribatid mite, it is likely common and widespread in the soil habitat. Current Population Trend:  Unknown

Habitat and Ecology

The ecology and traits of this species are unknown. Oribatid mites are associated with organic matter in most terrestrial ecosystems, being found throughout the soil profile, in surface litter, on grasses, shrubs or in the bark and leaves of trees, among other habitats. Oribatida are also one of the most numerically dominant arthropod groups in the organic horizons of most soils (Behan-Pelletier 1999). This species has been found in a range of natural and disturbed habitats and in the vicinity of urban areas. Additionally, Liacarus angustatus was also collected from a lava tube, but according to Morell and Subias (1991), oribatid mites are soil species and should not be considered as strictly cave species. This species is likely an eutroglophile (epigean species able to maintain a permanent subterranean population) (Borges et al., 2012). Systems:  Terrestrial

Major Threat(s):

A lack of information regarding the present range of this species precludes an accurate assessment of potential threats. Nevertheless, it can be assumed that this species will be affected by future habitat declines as a consequence of climate change (Ferreira et al. 2016) and increased droughts. This species has been found in areas of native vegetation but also in disturbed areas, and it can be assumed that factors degrading habitat quality, in the form of changes in the soil structure and composition, namely land use changes, agricultural practices, urbanisation, pesticides and nutrient loads or invasive plants might also affect this species.

Conservation Actions

The species is not protected by regional law, but part of its habitat is in regionally protected areas (Natural Parks of Faial, Pico, Terceira, S. Miguel and Sta. Maria). Besides climate change and increased risk of droughts, land-use changes and invasive species are likely the main current and future threats faced. As such, conservation of native habitats and invasive species control could potentially aid this species' conservation. Further research is needed into its population, distribution, threats, ecology and life history, and it is necessary to develop a monitoring plan for the invertebrate community in order to contribute to the conservation of this species.