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Calathus carvalhoi is endemic to Terceira (Azores, Portugal). It has a very small extent of occurrence (EOO = 4-8 km²) and area of occupancy (AOO = 4-8 km²). There is a continuing decline in the EOO, AOO, extent and quality of habitat as well as the number of mature individuals as a result of the invasions of non-native plants. The species occurs only at one location (Terra Brava), since it is possibly considered extinct in Terra Chã. Therefore, we suggest as future measures of conservation: (1) regular monitoring of the species; and (2) control of invasive species namely Hedychium gardnerianum. Based upon the small geographic range of the species with only one location and continuing decline of its habitat area and quality, it is assessed as Critically Endangered.
Calathus carvalhoi is a single island endemic species restricted to Terceira (Azores, Portugal) (Borges et al. 2010), known from Natural Forest Reserve of Terra Brava. The species is possibly considered extinct in Terra-Cha. The extent of occurrence (EOO) is 4-8 km² and the maximum estimated area of occupancy (AOO) is also 4-8 km².
The species is very rare and only known from a single subpopulation. A continuing decline in the number of mature individuals is inferred from the ongoing recent habitat degradation due to invasions of alien plants.
The species occurs in a native forests of the Azores (Terceira Island) dominated by Ilex perado ssp. azorica, Laurus azorica and Juniperus brevifolia, with an altitudinal range between 634 and 710 m. It is a night activity predator that lives under barks of native trees and in the soil
In the past, the species has probably strongly declined due to deforestation. The species is considered extinct in Terra-Chã due to major historical land-use changes with clearing of original habitat. The most important ongoing threat to this species is the spread of invasive plants (Hedychium gardnerianum) that are changing the habitat structure. Based on Ferreira et al. (2016) the habitat will decline as a consequence of climate change (increasing number of droughts, and habitat shift and alteration), which may drive this species to extinction, because it is depending on humid forests. Since the Azores are located on the mid-Atlantic ridge, they are also prone to the effects of volcanoes and earthquakes with deleterious effects on the existing population.
The species is protected by regional law (RAA 2012). Its habitat is in a regionally protected area (Natural Park of Terceira). The Terceira Natural Park administration is currently starting control measures of the invasive plants. Further spread of invasive plants needs to be stopped in order to avoid any future declines of the species. Degraded habitats should be restored and a strategy needs to be developed to address the future threat by climate change. A habitat management plan is needed and anticipated to be developed during the coming years. Since this species is restricted to the relict native Azorean forests, it is suggested that some awareness measures should be put in practice. Research is needed into its ecology and life history in order to learn about its current population size, distribution and trends. A general monitoring scheme for the invertebrate community in the habitat is in place, but the extant subpopulation of this particular species and its habitat in Terra Brava needs to be monitored in more detail. It is also necessary an area-based management plan for the species in Terra Brava. Monitoring every ten years using the BALA protocol will inform about habitat quality (Gaspar et al. 2011). Based on Borges et al. (2016) and Borges et al. (2017) the species is very rare and there is the need to invest in direct nocturnal surveys to evaluate the rarity status of the species