Assessment Rationale:

Humerobates pomboi is an endemic species of the Azores (Portugal), known from the islands of Flores, Graciosa, Terceira and S. Miguel. From the available data, it has a relatively small extent of occurrence (EOO = 14,670 km2 ), and a limited area of occupancy (AOO = 60 km2 ), which 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, and future climatic changes and increased risk of droughts will also affect this species. The present situation of this species needs to be further 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:

Humerobates pomboi is an Azorean-endemic oribatid mite species known from Flores, Graciosa, Terceira and S. Miguel islands (Azores, Portugal) (Borges et al. 2010), known mainly from several natural areas. It is present in six Natural Forest Reserves; Caldeiras Funda e Rasa and Morro Alto e Pico da Sé (Flores), Biscoito da Ferraria and Caldeira Sta. Bárbara e Mistérios Negros (Terceira) and Graminhais and Pico da Vara (S. Miguel). From the available data, the extent of occurrence (EOO) could be ca. 14,670 km² and the area of occupancy (AOO) could be 60 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 is present mainly in areas of native vegetation, but also in disturbed habitats. Some specimens of Humerobates pomboi were collected from under Cryptomeria japonica trees. Systems: Terrestrial.

Major Threat(s):

A lack of information regarding the present range of this species precludes an 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 was found in areas of native vegetation but also in disturbed areas, and it can be assumed that factors degrade habitat quality, in the form of changes in the soil structure and composition, namely land use changes, agricultural practices, 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 Flores, Graciosa, Terceira and S. Miguel). 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.