Species conservation profiles of cave-dwelling arthropods from Azores, Portugal

Abstract Background Azorean volcanic cave biodiversity is under considerable pressure due to ongoing threats of pollution, land use change, touristic activities or climate change. In this contribution, we present the IUCN Red List profiles of 15 cave-adapted arthropod species, endemic to the Azorean archipelago, including species belonging to the speciose genus Trechus (Carabidae), which is represented in Azores by seven species. The objective of this paper is to assess all endemic Azorean cave-adapted species and advise on possible future research and conservation actions critical for the long-term survival of the most endangered species. New information Most species have a restricted distribution (i.e. occur in one or two caves), very small extent of occurrence (EOO) and a small area of occupancy (AOO). A continuing decline in the number of mature individuals is inferred from the ongoing cave habitat degradation. The two troglobitic species of the homopteran genus Cixius are in great danger of extinction due to major land-use changes in epigean habitats above their known localities. We suggest, as future measures of conservation, the regular monitoring of the species (every five years), the creation of additional protected caves, the limitation of several aggressive activities around the caves (e.g. decreasing pasture intensification) and in some cases the creation of fences in the entrance of the most important caves.


Introduction
Three archipelagos of Macaronesia (Azores, Madeira, Canaries) have unique arthropod cave biological diversity (Oromí and Izquierdo 1994, Reboleira et al. 2011. The dynamic volcanic activity and isolation were important drivers of species richness, as well as endemism in these archipelagos (Borges and Hortal 2009). A major fraction of these species are obligate cave-adapted species, i.e. troglobionts and tend to have very restricted distributions . A total of 272 cavities were recently listed in a database of the Azorean caves (Pereira et al. 2015), but for only 42 (37 lavatubes and 5 volcanic pits), there is adequate knowledge on their fauna ).
The currently known diversity of Azorean troglobiont arthropods is composed of 17 described species and subspecies and four additional undescribed species Oromí 1994, Borges et al. 2012), all endemic to the archipelago. However, for some species (e.g. some of the Collembola species and the crustacean Amphipod Macarorchestia martini; see Wildish 2014 that mentions it as potentially trogloxene or driftwood specialist), the troglobiont status needs to be confirmed with additional research on its biology. Eight arthropod orders are represented, including the arachnids Pseudoscorpiones (two species) and Araneae (two species), the crustacean Amphipoda (one species) and Isopoda (one undescribed species), the centipede Lithobiomorpha (one subspecies), Collembola (two species, one of them undescribed) and, finally, insects, with Hemiptera (two described and two undescribed species) and Coleoptera (eight species) (Borges and Oromí 1994).
After a previous assessment of the cave spider Turinyphia cavernicola , in this contribution we present the IUCN Red List profiles of 15 additional cave-adapted arthropod species endemic to the Azores, leaving out the centipede subspecies Lithobius obscurus azoreae. The Hemiptera (two species) and Coleoptera (eight species) assessments have already been included in the IUCN Red List of Threatened Species and have a Red List Category assigned: CR (five species), EN (two species) and VU (three species) (see also https://www.iucnredlist.org and http://www.maiisg.com/).

Methods
To create the IUCN Red List profiles, we followed the standard procedures as in , Borges et al. (2017) and Borges et al. (2018): i) the original species descriptions were investigated to learn about the habitats and ecology of the species; ii) all the most recent literature was also investigated to obtain information about synonyms and critical information for the taxonomic notes; iii) for the calculation of AOO and EOO, we consulted the Azorean Biodiversity Portal and downloaded CSV files with the distribution of each species; iv) images of the species were also obtained from the repository available in the A zorean Biodiversity Portal, the most important source of information for Azores biodiversity (see Borges et al. 2010a).
Prior to the calculation of area of occupancy (AOO) and extent of occurrence (EOO), the 500 m x 500 m cells obtained from Azorean Biodiversity Portal were filtered to consider only the cells with high level of precision as defined by: 1 -very precise location, usually point UTM data; 2 -literature location not exceeding 25 km . The centroid for each cell was calculated to obtain the distribution points for each species. The calculation of AOO and EOO was performed using the Geospatial Conservation Assessment Tool (GeoCAT) and using an approximation to the standard IUCN 2 km × 2 km cells (4 km ). Final maps with species distributions were produced using the IUCN standards with Google Earth (kmz files).

No
The genus Pseudoblothrus is exclusively cave-dwelling (Mahnert 1990). Pseudoblothrus oromii is a cavernicolous (i.e. a troglobitic species) predator and/or saprophagous species. The main current threats to this species are the loss of habitat quality due to the impact of agriculture activities, agricultural and domestic pollution and recreational cave visitation. However, there are several future potential threats: climate changes in many habitats in Azores (see Ferreira et al. 2016) that can change the conditions inside the cave; change in the road infrastructure around the cave; potential human recreational activities with disturbance caused by radical cave visitation.
Needed -1.1. Land/water protection -Site/area protection -2.1. Land/water management -Site/area management -2.3. Land/water management -Habitat & natural process restoration -5.1.3. Law & policy -Legislation -Sub-national level -4.1. Education & awareness -Formal education Although the species is protected by regional law (RAA 2012), the cave where it occurs is, however, not protected. Land-use changes are one of the main current and future threats and conservation measures should be extended beyond the cave. As future measure of conservation, the limiting of visits to the cave could be considered. A habitat management plan is needed and anticipated to be developed during the coming years.

International
The species is not utilised.

Less important
Insufficient information available. No decrease in AOO has been registered, but it is inferred from decline due to the vulnerability of its habitat, associated with the degradation of volcanic caves and anthropogenic impact in the surrounding area (see details above).

Yes Unknown
Locations 8 This species occurs in eight volcanic caves in Pico (Furna da Baliza, Furna do Frei Matias and Furna Nova) and Terceira (Gruta das Agulhas, Gruta do Coelho, Gruta da Malha, Gruta dos Principiantes and Gruta de Santa Maria) islands that are under several threats, namely: agricultural activities and livestock raising, agricultural and domestic pollution and recreational cave visitation. Additionally, invasive plant species, altering the habitat at the entrance of the caves, might also impact the overall habitat quality in the caves.

Decline (inferred)
Those 8 volcanic caves in Pico and Terceira islands are located in an area heavily impacted by agricultural activities and livestock raising, agricultural and domestic pollution, as well as by recreational cave visitation. Additionally, invasive plant species, altering the habitat at the entrance of the caves, might also impact the overall Population Unknown Decline (inferred) Due to ongoing impacts on the caves, the impact of human activities decreases the quality of cave environment.
-(c) a decline in area of occupancy, extent of occurrence and/or quality of habitat No Yes Unknown This species is apparently quite common, occurring in eight volcanic caves. However, the threats described below are believed to be leading to a decrease in population numbers.

Decline (inferred)
The areas surrounding the caves ar heavily impacted by human disturbance.

Yes
The species occurs in eight lava tubes, some in protected areas (Natural parks of Pico and Terceira), others are surrounded by highly disturbed or urbanised areas and two being coastal caves.

Decline (observed)
Major Importance There is limited information regarding this species ecology and life-history. The genus Pseudoblothrus is exclusively cave-dwelling (Mahnert 1990). Specimens were found near the entrance of the caves, under rotting wood and other organic litter. It is a cavernicolous (i.e. a troglobitic species) predator and/or saprophagous species. Its eyes are more developed than those of P. oromii (Mahnert 1990 The main current threats to this species are the loss of habitat quality due to the impact of agricultural activities and livestock raising, agricultural and domestic pollution and recreational cave visitation. Additionally, invasive plant species, altering the habitat at the entrance of the caves, might also impact the overall habitat quality in the caves. However, there are several future potential threats: climatic changes will impact many habitats in Azores (see Ferreira et al. 2016) and this can change the conditions inside the cave; change in the road infrastructure around the cave; potential human recreational activities with disturbance caused by radical cave visitation. The species is protected by regional law (RAA 2012), as are some of the caves where it occurs (Natural Parks of Pico and Terceira). Land-use changes are one of the main current and future threats and conservation and restoration measures should be extended beyond the caves. As a future measure forconservation, the restriction of visits to the caves could be considered. A habitat management plan is needed and is anticipated to be developed during the coming years. It is necessary to establish a monitoring plan for the invertebrate community in the habitat in order to contribute to the conservation of this species.  two islands may imply that we are in the presence of two cryptic species. Therefore, there is the urgent need of a taxonomic revision of this taxon.

275
Decline (inferred) The species is a specialised troglobite living in constant humidity conditions. Many caves in Faial and Pico Islands are being impacted by pollution due to intensive cattle production, with changes in ecological conditions of caves in the last 50 years, namely, the change of the N and P abiotic cycles and changes in the water pH (Hathaway et al. 2014). In Faial and Pico Islands, there are 19 well-surveyed caves and we found subpopulations in only seven. The trend of decline is partly based on the assumption that this species can occur in all these caves and that the absence is due not only to biological reasons (type of cave; age of the lava flow), but mainly to anthropogenic disturbance on caves during the last 50 years. Indeed, there is a strong predominance of intensive pastures and maize in areas theoretically unsuitable for this purpose in many Azorean islands, with the expansion between 2001 and 2011 of pasture intensification to areas more suitable to forest (Reis and Dentinho 2015). Most of the caves were in the past covered by dense humid native forest and forest clearance promoted changes in humidity and resource availability in the cave environment.

6
Six out of the seven volcanic caves (Gruta da Agostinha, Furna dos Montanheiros, Gruta das Canárias, Gruta do Henrique Maciel, Gruta do Mistério da Silveira I, Gruta do Soldão) (Pereira et al. 2015) are being affected by different threats, mainly touristic pressure, wine and cattle production with consequent deforestation and nutrient input into caves.

Decline (inferred)
After a detailed survey of 19 caves in Faial and Pico islands that include most of the range of the species, the species was only found at seven, which is a small number of caves for a predictably larger range (up to 5 times larger) just 50 years ago.

Decline (inferred)
Each cave where the species occurs is affected by different threats, mainly touristic pressure, wine and cattle production with consequent deforestation and nutrient input into caves.
-(c) a decline in area of occupancy, extent of occurrence and/or quality of habitat Seven subpopulations of this species can be found across two islands, but most of them are very small and located in disturbed lava tubes. The single large subpopulation is located in Gruta da Agostinha, which is under future threat due to increasing possibility of land-use changes for wine production.

7
Decline (observed) Most of the subpopulations are living in volcanic caves surrounded by agricultural activities and/or domestic pollution and we suspect that the species has disappeared from other caves in the region.

Yes
The species is a troglobite specialist, occurring only in humid lava tubes and volcanic pits. In the cave with the larger subpopulation (Gruta da Agostinha), the species occurs in all sections of the cave.

Decline (inferred)
The intensive cattle production in the islands of Faial and Pico has increased considerably in the last twenty years and creates high disturbance and pollution in the cave systems. Touristic pressure and land-use changes to wine production might also be a threat, through reduction in habitat quality. The main current threat to this species is the impact of agricultural activities, namely the expansion of wine production and domestic pollution. However, there are several future potential threats: climatic changes will impact many habitats in the Azores (see Ferreira et al. 2016) and this can change the conditions inside the caves; urban development in coastal areas, changes in the road infrastructure around the caves; logging of Pittosporum undulatum exotic forests over the caves; potential human recreational activities with disturbance caused by radical cave visitation. The species is not protected by regional law. Some of the caves are included in the Natural Park of Faial and Pico. Since land-use changes (for Pittosporum undulatum removal, urban development, wine production) is the main current and future threat, it might be important to safeguard the species survival in the future and conservation should be extended beyond the current area, possibly allowing the recovery of other caves to original conditions where the species might be reintroduced. The addition of fences around the caves will be an important mitigation measure.

International
The species is not utilised. Further research is needed into its ecology and life history in order to find extant specimens in additional caves. An area-based management plan is necessary for the most disturbed caves including invertebrate monitoring to contribute to a potential species recovery plan. The extent of occurrence (EOO) is 4 km² and the maximum estimated area of occupancy (AOO) is 4 km².

5
Macarorchestia martini is possibly an endemic cave-adapted species known from a single island, Terceira (Azores, Portugal) (Borges et al. 2010b) and occurs in a single cave, the coastal lava tube of Gruta das Agulhas. Additional surveys are needed to confirm the troglobiont status of this species (see e.g. Wildish 2014).

Number of individuals:
The species is occurring in a single cave, the coastal lava tube of Gruta das Agulhas, Terceira (Azores, Portugal). No decrease in EOO has been registered but it is inferred from decline due to the vulnerability of its habitat, associated with the degradation of volcanic caves and anthropogenic impact in the surrounding area (e.g. agriculture pollution).

Decline (inferred)
This species occurs only in a cave of Terceira island (Gruta das Agulhas) and it is not known if it ever occurred outside it. No decrease in AOO was observed, but it is inferred from decline in habitat quality associated with the degradation of volcanic caves and anthropogenic impact in the surrounding area (e.g. agriculture pollution).

1
The species is only known on a single island, Terceira (Azores, Portugal) (Borges et al. 2010b) and occurs in a single cave, the coastal lava tube of Gruta das Agulhas, that is heavily impacted by human disturbance. The aboveground area is disturbed by urbanisation and agricultural fields.

Stable
The species is only present in one single cave. Stable despite the impending threats.

Decline (inferred)
The area surrounding the cave is heavily impacted by human disturbance and decreases the quality of the cave environment.
-(c) a decline in area of occupancy, extent of occurrence and/or quality of habitat No Yes Unknown Unknown The species is rare and only known from a single subpopulation in Terceira island. The area surrounding the cave is heavily impacted by human disturbance.

Stable
Only one subpopulation historically known.
The species occurs naturally in a single cave.

Yes
Specimens were found at some distance from the entrance of Gruta das Agulhas (a 250 m long lava tube on the seashore, opening some 5 m above the sea level), but where dim light was still available, in high humidity but without permanent water.

Decline (inferred)
The area surrounding the cave is heavily impacted by human disturbance; the aboveground area is disturbed by urbanisation and agricultural fields (pollution by herbicides and pesticides). The easy access to the cave leads to uncontrolled cave visitation with potential impacts on the quality of the ecosystem. Debris is frequently seen in the cave. The main current threats to this species are the loss of habitat quality at the cave entrance due to the impact of agriculture activities, agricultural and domestic pollution and recreational cave visitation. However, there are several future potential threats: climatic changes (see Ferreira et al. 2016) are expected to cause habitat changes in lower elevations in the Azores, that can change the conditions inside the cave, particularly at the cave entrance where the species occurs; change in the road infrastructure around the cave; expanding urban development in the coastal area. The current increase in tourism in the Azores is promoting the increase in cave visitation and Although the species is protected by regional law (RAA 2012), the cave where it occurs is, however, not protected. Land-use changes are one of the main current and future threats and conservation measures should be extended beyond the cave. As a future measure of conservation, the restriction of visits to the cave could be considered. A habitat management plan is needed and is anticipated to be developed during the coming years.

International
The species is not utilised.

Less important
Insufficient information available.

. Monitoring -Habitat trends
Further research is needed into its ecology and life history in order to provide a species conservation plan and a management plan that would improve the survival chances of this species for the future. A species conservation plan and a management plan would improve its survival chances for the future. Additional surveys are needed to confirm the troglobiont status of this species (see e.g. Wildish 2014).

Geographic range
Biogeographic realm:

Observed
The extent of occurrence (EOO) is ca. 2828 km² and the maximum estimated area of occupancy (AOO) is 52 km².
Pseudosinella ashmoleorum is an endemic cave-dwelling springtail species known from Faial, Pico and Terceira islands (Azores, Portugal) (Borges et al. 2010b), known from several caves and lava tubes in Faial (Furna Ruim); in Pico (Gruta da Agostinha, Gruta do Henrique Maciel, Gruta do Soldão); and in Terceira (Algar do Carvão, Gruta das Agulhas, Gruta dos Balcões, Gruta da Caldeira, Gruta do Coelho, Gruta do Chocolate, Gruta da Madre de Deus). The species was also found in the MSS ("Milieu Souterrain Superficiel" or "Mesocavernous Shallow Stratum") (Borges 1993) in the area of Pico Rachado (Terceira island), far from its known distribution in lava caves. The species occurs in several caves and lava tubes in Faial (Furna Ruim); in Pico (Gruta da Agostinha, Gruta do Henrique Maciel, Gruta do Soldão); in Terceira (Algar do Carvão, Gruta das Agulhas, Gruta dos Balcões, Gruta do Caldeira, Gruta do Coelho, Gruta do Chocolate, Gruta da Madre de Deus) that are under the impact of several important threats, namely: climatic changes in several important habitats in Azores (see Ferreira et al. 2016) that can change the conditions inside the caves; change in the road and urban infrastructure around the caves; potential human recreational activities with disturbance caused by radical cave visitation; reforestation of the areas with exotic trees with unknown impact. The species is known to be present in 11 caves in 3 different islands that are under the impact of several important threats. The possible additional locations were lost more than 10 years ago, meaning the current trend in number of locations is probably stable despite the impending threats.

Decline (inferred)
The decline in number of individuals is inferred from the decline of habitat quality in many caves. Indeed, the high level of agriculture pollution is dramatically changing the cave ecosystems.
-(c) a decline in area of occupancy, extent of occurrence and/or quality of habitat No Yes Unknown No current population size estimates exist for this species, but it seems to be relatively widespread through several caves and in the MSS of three islands. The areas surrounding the caves are heavily impacted by human disturbance, including nitrates pollution.

Decline (inferred)
The decline in number of subpopulations is inferred from the decline of habitat quality in many caves.

No
There is limited information regarding this species ecology and life history. It occurs in eleven volcanic caves, some in protected areas (Natural Parks of Pico and Terceira) and some surrounded by disturbed habitats and also in the MSS (mesocavernous shallow stratum) habitats (Borges 1993). Nevertheless, this species has only small possible adaptations to a troglobiont life-style, being likely an eutroglophile (i.e. epigean species able to maintain a permanent subterranean population).

Decline (inferred)
The quality of the habitat in most of the caves is decreasing due to the impact of several important threats, namely: agriculture pollution; change in the road and urban infrastructure around the caves; potential human recreational activities with disturbance caused by radical cave visitation; reforestation of the areas with exotic trees with unknown impact. Pseudosinella ashmoleorum was found in the dark and humid part of caves, with abundant mud or roots from the ceiling (Gama 1988), suggesting the species to be saprophagous. The main current threats to this species are the loss of habitat quality due to human activities like agriculture pollution, urbanisation and construction and recreational cave visitation. However, there are several future potential threats: climatic changes will impact many habitats in the Azores (see Ferreira et al. 2016) and this can change the conditions inside the caves, but also changes in the nearby infrastructure, changes in land use, potential human recreational activities with disturbance caused by radical cave visitation.

Law & policy -Compliance and enforcement -Sub-national level -Education & awareness -Awareness & communications
The species is not protected by regional law. Part of its habitat is in regionally protected areas (Natural Parks of Pico and Terceira). Land-use change is one of the main current and future threats and conservation and restoration measures should be extended beyond the caves. As a future measure of conservation, the restriction of visits to the caves could be considered. A habitat management plan is needed and is anticipated to be developed during the coming years.

International
The species is not utilised.

Less important
Insufficient information available.

. Monitoring -Habitat trends
Additional research is needed in order to determine the levels of population size, as well as its ecology and life history. It is also necessary to establish a monitoring plan for the invertebrate community in the habitat in order to contribute to the conservation of this species. Cixius cavazoricus is a single island endemic cave planthopper species restricted to Faial Island (Azores, Portugal) (Borges et al. 2010b). The species only occurs in two small caves (Gruta das Anelares and Gruta do Cabeço do Canto) (Pereira et al. 2015) and recent fieldwork failed to find it in one of the caves.

Extent of occurrence
No decrease in EOO has been registered but it is inferred from decline in the habitat quality. No decrease in AOO has been registered but it is inferred from decline in the habitat quality.

Yes Unknown
Locations 2 Two locations, Gruta das Anelares and Gruta do Cabeço do Canto, are threatened by above-cave deforestation which will reduce the amount of roots suitable as food resources. Increasing nitrogen levels derived from the use of pesticides in neighbouring agricultural land are also a threat since they change the necessary cover by native trees and shrubs above ground. The current trend in number of locations is probably stable despite the impending threats.

Unknown
Decline (estimated) The current threats are believed to cause a decrease in the species population numbers at unknown rates.
-(c) a decline in area of occupancy, extent of occurrence and/or quality of habitat No Yes Unknown Cixius cavazoricus is an obligate cave species known to occur in two lava tubes in Faial Island (Azores, Portugal). The species is extremely rare since only a few specimens have been found despite the sampling efforts. The species was not found during a fieldwork survey in 2010 and only a single specimen was found in one of the caves in May 2014.

Decline (estimated)
Only two subpopulations historically known. The species was not found during a fieldwork survey in 2010 and only a single specimen was found in one of the caves in May 2014.

Habitat
Terrestrial Yes This is a troglobitic species that only occurs in two lava tubes in Faial Island (Azores, Portugal) (Hoch 1991). Habitat quality is decreasing due to above-cave deforestation which reduces the food resources. Increasing nitrogen levels derived from the use of pesticides in neighbouring agricultural land are also a threat since they change the necessary cover by native trees and shrubs above ground.
Major Importance The species is restricted to the deep dark cave zone (Hoch 1991), presents low dispersal ability and it is known to feed on roots of the abovecave vegetation. Cixius cavazoricus is highly threatened by above-cave deforestation which reduces the food resources. Increasing pesticides in neighbouring agricultural land are also a threat. However, there are also several future potential threats: climatic changes will impact many habitats in the Azores (see Ferreira et al. 2016) and this can change the conditions inside the caves; change in the road infrastructure around the caves; potential human recreational activities with disturbance caused by radical cave visitation.

. Education & awareness -Awareness & communications
The species is protected by regional law (RAA 2012) and one of the caves is in the Natural Park of Faial. Monitoring is needed to assess population trends and confirm if the species is no longer present in one of its locations. Measures should be taken to prevent deforestation in the areas above the caves where this species occurs to prevent reduction of food resources for this species. A habitat management plan is needed and is anticipated to be developed during the coming years. Further research is needed into its ecology and life history in order to find extant specimens in additional caves. A species conservation plan and a management plan would improve the survival chances of this species for the future.  Species conservation profiles of cave-dwelling arthropods from Azores, ...

Map of records (Google Earth):
Basis of EOO and AOO: Basis ( No decrease in AOO has been registered but it is inferred from decline in the habitat quality, including deforestation above the lava tubes, decreasing the amount of roots available, increased nitrogen concentration from the use of pesticides in nearby pastures and increased dryness inside the caves. Six locations, Furna dos Montanheiros, Gruta das Canárias, Gruta da Agostinha, Gruta do Mistério da Silveira I, Gruta do Soldão and Gruta das Torres, are threatened by above-cave deforestation which will reduce the amount of roots suitable as food resources. Increasing pesticide levels, derived from neighbouring agricultural land, are also a threat.

Stable
The current trend in number of locations is probably stable despite the impending threats.

Population
Unknown Decline (inferred) The current threats are believed to cause a decrease in the species population numbers at unknown rates.
-(c) a decline in area of occupancy, extent of occurrence and/or quality of habitat

Unknown
The species only occurs in six lava tubes (caves) in Pico Island (Azores) and is particularly rare in terms of abundance in all caves.

Decline (inferred)
Only six subpopulations historically known and some are in danger of extinction. The recent trend in removing exotic and native trees and shrubs for wine fields can be a major threat. Threat type:

Habitat
Terrestrial Yes This is a troglobitic species with low dispersal ability (Hoch 1991), that occurs in lava tubes with aboveground cover by trees and shrubs. In Furna dos Montanheiros and Gruta das Torres that are located at higher elevations, the dominant vegetation is native, however in the caves located at lower elevations, the vegetation is dominated by the invasive tree Pittosporum undulatum.

Decline (observed)
Threats to this species include deforestation above the lava tubes, decreasing the amount of roots available, increased pesticides in nearby pastures and increased dryness inside the caves.
Major Importance -7.1. Caves and Subterranean Habitats (non-aquatic) -Caves This species is threatened by above-cave deforestation which will reduce the amount of roots suitable as food resources. The recent trend in removing exotic and native trees and shrubs for wine fields can be a major threat. Increasing pesticides in neighbouring agricultural land are also a threat. However, there are also several future potential threats: climatic changes will impact many habitats in the Azores (see Ferreira et al. 2016) and this can change the conditions inside the caves; change in the road infrastructure around the caves; potential human recreational activities with disturbance caused by radical cave visitation. This species is not protected by law in the Azores, but part of its distribution is included in protected areas namely in a protected landscape area (Furna dos Montanheiros inside de Pico Natural Park) and a natural monument (Gruta das Torres). Degraded habitats should be restored and a strategy needs to be developed to address the future threat by climate change that may change the vegetation cover of caves. A habitat management plan with associated education outreach initiatives is needed and anticipated to be developed during the coming years. It is necessary to establish a monitoring plan for the invertebrate community in the habitat in order to contribute to the conservation of this species. This species occurs only in single cave in S. Miguel island (Gruta de Água de Pau). The value of AOO given is an overestimation given that the AOO value is based on cave spatial occupancy, but the species in question might be restricted to a smaller area within the lava tube.

Unknown
Locations 1 This species occurs only in single cave of S. Miguel island (Gruta de Água de Pau), that is under several threats, namely: i) residential and commercial development in coastal areas; ii) cave visitation by tourists and coastal recreational activities; iii) agriculture activities with cattle pollution; iv) creation of roads or coastal tracks; v) domestic water management.

Stable
Only naturally present in a single location. Several caves in this island have been sampled for cave fauna ) and this species has never been found at any other cave, meaning the current trend in number of locations is probably stable despite the impending threats.

Decline (inferred)
The species is very rare and only known from a single population. A continuing decline in the number of mature individuals is inferred from the ongoing cave habitat degradation due to pasture cattle pollution and pollution resulting from fertiliser use.
-(c) a decline in area of occupancy, extent of occurrence and/or quality of habitat Occurs naturally in a single cave under current and potential future threats, that include tourist visitation, cattle pollution and climate change. This is believed to be leading to a decrease in population numbers.

Stable
Only one subpopulation historically known.

Yes
This species occurs in a volcanic cave (a lava tube only 15 m above the sea level and covered by some 70 m of overburden) in the S. Miguel island (Gruta de Água de Pau) (Oromí and Borges 1991). The cave is small (323 m).

Decline (inferred)
The habitat is under several current and future threats (visitation, cattle pollution and Climate Change) (see more details below).
Major Importance

Conservation actions:
This is a troglobiont species with considerable eye reduction, depigmentation and appendage elongation (Oromí and Borges 1991). The known specimens were captured under stones in humid sections of the cave. The main threats to this species are: i) residential and commercial development in coastal areas; ii) cave visitation by tourists and coastal recreational activities, promoting disturbance; iii) agriculture activities with cattle pollution; iv) creation of roads or coastal tracks; v) domestic water management; and vi) future climatic changes are expected to have impacts on coastal habitats (Ferreira et al. 2016).

Conservation
In Place

In Place
The species is protected by regional law (RAA 2012). Its habitat is in a regionally protected area (Natural Park of S. Miguel). We suggest, as a future measure of conservation, the creation of a fence in the entrance to the cave.

. Monitoring -Habitat trends
Additional research is needed in order to determine the levels of population size as well as its ecology and life history. It is also necessary to establish a monitoring plan for the invertebrate community in the habitat in order to contribute to the conservation of this species.

Habitat importance:
The single location is the full known historical range. Several caves in this island have been sampled for cave fauna ) and this species has never been found at any other cave, possibly due to its being isolated in Algar do Morro Pelado volcanic region, meaning the current trend in number of locations is probably stable despite the impending future threats.

Stable
The species is very rare and only known from a single subpopulation. The number of individuals caught when the species was discovered was small when compared with other Trechus Azorean species more abundant in traps (e.g. T. terceiranus and T picoensis). The cave where the species occurs is located in a protected area and of difficult access and we assume there is no current impact for the population.

Stable
Only one subpopulation historically known.

Yes
This species occurs in a volcanic pit (Algar do Morro Pelado, S. Jorge island) of great dimensions (140 m deep) located at 1000 m asl. The surrounding area consists of natural grassland (Borges et al. 2007).

Stable
The habitat is pristine and well preserved. No threats are currently available, since the volcanic pit is located in an inaccessible area and the area is protected. However, there are several future potential threats: climatic changes will impact many habitats in Azores (see Ferreira et al. 2016) and this can change the conditions inside the volcanic pit; 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, earthquakes and landslides).

Conservation
In Place -1.1. Land/water protection -Site/area protection -2.1. Land/water management -Site/area management The species is protected by regional law (RAA 2012). Its habitat is in a regionally protected area (Natural Park of S. Jorge, within the regionally protected area of Pico da Esperança e Planalto Central). It is necessary to establish a monitoring plan for the invertebrate community in the habitat in order to contribute to the conservation of this species. A habitat management plan is needed and is anticipated to be developed during the coming years.

International
The species is not utilised.

Less important
Insufficient information available. Additional research is needed in order to determine the levels of population size as well as its ecology and life history. A monitoring plan is also necessary for the invertebrate community in the habitat in order to contribute to the conservation of this species.

Species information
Cave ground-beetle (English) ; Carocho cavernícola (Portuguese) Trechus jorgensis is an endemic cave-adapted species known from a single island, S. Jorge (Azores, Portugal) (Borges et al. 2010b) and occurs in a single cave, the volcanic pit of Algar das Bocas do Fogo (Oromí and Borges 1991).

Decline (inferred)
This species occurs only in a cave of S. Jorge island (Algar das Bocas do Fogo). The species is threatened due to the loss of habitat quality, since the volcanic pit has been used as a dump site. In addition, there is ongoing destruction of the surrounding habitat due to the spread of invasive plants.

Stable
The single location is the full known historical range.

Decline (inferred)
The species is very rare and only known from a single subpopulation. In all the sampling occasions, only a small number of specimens were collected. The area surrounding the cave is heavily impacted by human activities and used as a dump area. This species occurs in a 50 m deep volcanic pit (Algar das Bocas do Fogo, S. Jorge island), whose internal vault is in penumbra (not complete darkness). The surrounding area consists of exotic plantations of Pittosporum undulatum (Oromí and Borges 1991).

Decline (observed)
The habitat is under severe destruction by being located in a dump area. The main current threats to this species are the loss of habitat quality, as the volcanic pit has been used as a dump site, as well as the destruction of the surrounding habitat by invasive plants. However, there are several future potential threats: climatic changes will impact many habitats in Azores (see Ferreira et al. 2016) and this can change the conditions inside the volcanic pit; change in the road and urban infrastructure around the cave.

. Education & awareness -Formal education
Although the species is protected by regional law (RAA 2012), the cave where it occurs is, however, not protected. It is necessary to establish a monitoring plan for the invertebrate community in the habitat in order to contribute to the conservation of this species. We suggest as future measures for conservation: a scoping mission to determine thecurrent status of the cave habitat throughout the full extent of the cave; restoring habitat by cleaning the trash from the cave; the creation of a fence surrounding the top of the pit. A habitat management plan is needed and is anticipated to be developed during the coming years.

International
The species is not utilised.

Less important
Insufficient information available.

. Monitoring -Habitat trends
Additional research is needed in order to determine the levels of population size as well as its ecology and life history. A monitoring plan is also necessary for the invertebrate community in the habitat in order to contribute to the conservation of this species.

Stable
The current trend in number of locations is probably stable despite the impending threats.

Decline (inferred)
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 but infer some decrease in density of individuals in at least two of the caves. However, tourism recreational activities could be a problem as well as agriculture management in two of the caves.
-(c) a decline in area of occupancy, extent of occurrence and/or quality of habitat The species is relatively abundant in at least one of the caves (Furna dos Montanheiros). The area surrounding one of the caves (Furna dos Montanheiros) is relatively well protected, but the area surrounding the other two caves is more disturbed.

Decline (inferred)
In at least two of the subpopulations, the threats are sufficient for placing the subpopulations at a risk of extinction (Furna do Frei Matias and Gruta dos Vimes).

Yes
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 to the caves, but no specimens were ever collected outside a cave (Oromí and Borges 1991, Amorim 2005.

Decline (observed)
There is already some impact from touristic visitation in at least one of the caves (Furna Frei Matias).
Major Importance

Conservation action type:
No This is a cavernicolous (i.e. a troglobitic species) predator and/or saprophagous species. The main current threats to this species are the loss of habitat quality, due to recreational cave visitation and the impact of pasture lands. In one of the caves (Furna de Frei Matias), the species is threatened by uncontrolled visits and, in the other two, by dairy cattle pollution. However, there are several future potential threats: climatic changes will impact many habitats in the Azores (see Ferreira et al. 2016) and this can change the conditions inside all three caves; change in the road infrastructure around the cave (particularly important to Furna dos Montanheiros that crosses a main road); potential human recreational activities with disturbance caused by radical cave visitation (particularly important to Furna de Frei Matias and Furna dos Montanheiros); reforestation of the area with exotic trees with unknown impact (important for all three caves).

Conservation
In Place -1.1. Land/water protection -Site/area protection -2.1. Land/water management -Site/area management

. Education & awareness -Formal education
The species is protected by regional law (RAA 2012). 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. It is necessary to establish a monitoring plan for the invertebrate community in the cave habitat in order to contribute to the conservation of this species. We suggest, as a future measure of conservation, the fencing of the entrances to the caves where human intrusion and disturbance have been occurring. A habitat management plan is needed and is anticipated to be developed during the coming years.

International
The species is not utilised.

. Monitoring -Habitat trends
Additional research is needed in order to determine the levels of population size as well as its ecology and life history. It is also necessary to establish a monitoring plan for the invertebrate community in the habitat in order to contribute to the conservation of this species.

Observed
The extent of occurrence (EOO) is 4 km and the maximum estimated area of occupancy (AOO) is 4 km .

Decline (inferred)
This species occurs only in a cave of Faial island (Gruta do Parque do Capelo). No decrease in EOO has been registered, but it is inferred from decline in the habitat quality. This species occurs only in a cave of Faial island (Gruta do Parque do Capelo) that is threatened by the loss of habitat quality, due to recreational cave visitation and to the impact of the management of the Nature Reserve & Recreational Park, where the cave is located.

Stable
The single location is the full known historical range.

Decline (estimated)
The area surrounding the cave is heavily impacted by human disturbance. The cave entrance is located in a forest recreational park with several kind of activities and it is frequent to see some uncontrolled cave visitation.
-(c) a decline in area of occupancy, extent of occurrence and/or quality of habitat No Yes Unknown

Unknown
The species is very rare and only known from a single subpopulation in Faial island.

Stable
Only one subpopulation historically known.

Yes
The species is very rare and only known from a single subpopulation in Faial island. The area surrounding the cave is heavily impacted by human disturbance.

Decline (observed)
There is already some impact from construction and human activity in the Forest Park, where it is located. Unfortunately, some uncontrolled cave visitation is frequently seen. In addition, there was a recent reorganisation of the park with some trees removed and new buildings and trails created with unknown impacts on the cave. Reserve & Recreational Park, where the cave is located. Unfortunately, some uncontrolled cave visitation is frequently seen. In addition, there was a recent reorganisation of the park with some trees removed and new buildings and trails created with unknown impacts on the cave. However, there are several future potential threats: climatic changes will impact many habitats in the Azores (see Ferreira et al. 2016) and this can change the conditions inside the cave; change in the road infraestructure around the cave; potential human recreational activities with disturbance caused by radical cave visitation.

Conservation
In Place The species is protected by regional law (RAA 2012). Its habitat is in a regionally protected area (Natural Park of Faial). It is necessary to establish a monitoring plan for the invertebrate community in the habitat in order to contribute to the conservation of this species. We suggest, as a future measure of conservation, fencing the entrances to the caves where human intrusion and disturbance have been occurring. A habitat management plan is needed and is anticipated to be developed during the coming years.

International
The species is not utilised.

Less important
Insufficient information available.

. Monitoring -Habitat trends
Additional research is needed in order to determine the levels of population size, as well as its ecology and life history. It is also necessary to establish a monitoring plan for the invertebrate community in the habitat in order to contribute to the conservation of this species.

Geographic range
Biogeographic realm:

Observed
The extent of occurrence (EOO) is 8 km and the maximum estimated area of occupancy (AOO) is 8 km .

Extent of occurrence
The species occurs only in two lava-tube caves (Furna das Cabras II -200 m length; and Gruta da Ribeira do Fundo -200 m length) on the island of Pico (Azores, Portugal). The value of EOO is an overestimation given that the EOO value is based on cave size and not on the actual area occupied by the species which might be smaller. No decrease in EOO has been registered but it is inferred from decline in the habitat quality. The species occurs only in two lava-tube caves (Furna das Cabras II and Gruta da Ribeira do Fundo) on the island of Pico (Azores, Portugal). The value of AOO given is an overestimation given that the AOO value is based on cave size, but the species in question might be restricted to a smaller area within the lava tube. No decrease in AOO has been registered, but it is inferred from decline in the habitat quality. The species occurs only in two lava-tube caves (Furna das Cabras II and Gruta da Ribeira do Fundo) on the island of Pico (Azores, Portugal) and which are currently under serious threat.

Stable
The current trend in number of locations is probably stable despite the impending threats.

Decline (inferred)
Species abundance may have decreased in one of the caves (Gruta da Ribeira do Fundo) as it has been used as a dump site up till recently; and the population in the other cave where this species occurs (Furna das Cabras II) may be negatively impacted since the area surrounding the cave is suitable for forest exploitation.
-(c) a decline in area of occupancy, extent of occurrence and/or quality of habitat This species is mainly threatened by human activities, especially garbage dumping and livestock farming affecting his habitat (Gruta da Ribeira do Fundo). However, there are several future potential threats: climatic changes will impact many habitats in the Azores (see Ferreira et al. 2016) and this can change the conditions inside the caves; change in the road infrastructure around the cave (Gruta das Cabras II); potential human recreational activities with disturbance caused by radical cave visitation; forest logging (Gruta das Cabras II).

Conservation
In Place The species is protected by regional law (RAA 2012). As a future measure forconservation, it is suggested to fence the entrance of the caves where the species occurs. A habitat management plan is needed and is anticipated to be developed during the coming years.

International
The species is not utilised.

Less important
Insufficient information available. Additional research is needed in order to determine the levels of population size as well as its ecology and life history. It is also necessary to establish a monitoring plan for the invertebrate community in the habitat in order to contribute to the conservation of this species.

770
Trechus picoensis is a cave-adapted endemic species known from Pico (Azores, Portugal) (Borges et al. 2010b It has a relatively small extent of occurrence (EOO = 285 km²) and the area surrounding some of the caves is heavily impacted by human activities, namely agriculture/livestock farming and unregulated visitation to some of the caves.

Decline (inferred)
Degradation of the habitat is observed due to human activities: agriculture/livestock farming and unregulated visitation to some of the caves.

Decline (inferred)
The decreasing abundance of some subpopulations is inferred from the decrease in habitat quality and pollution derived from dairy cattle exploitation.
-(c) a decline in area of occupancy, extent of occurrence and/or quality of habitat No Yes Unknown

Unknown
The species is particularly abundant in some of the caves in Pico island.

Decline (inferred)
Some of the subpopulations are under intense threat due to pollution derived from dairy cattle exploitation. This species occurs in several volcanic caves (lava-tubes) of Pico island. It shows a strong morphological adaptation to cave life (Machado 1988, Amorim 2005.

Decline (inferred)
The area surrounding some of the caves is heavily impacted by human activities: livestock farming/agriculture, timber production (Cryptomeria japonica) and by human intrusion and disturbance. The main current threats to this species are the loss of habitat quality due to human activities: agriculture/livestock farming, forest logging and unregulated visitation to some of the caves. However, there are several future potential threats: climatic changes will impact many habitats in the Azores (see Ferreira et al. 2016) and this can change the conditions inside the caves; change in the road infrastructure around the caves; potential human recreational activities with disturbance caused by radical cave visitation.

In Place
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 to the caves, most impacted by unregulated human visitation, should be fenced. A habitat management plan is needed and is anticipated to be developed during the coming years. Additional research is needed in order to determine the levels of population size, as well as its ecology and life history. It is also necessary to establish a monitoring plan for the invertebrate community in the habitat in order to contribute to the conservation of this species. Trechus terceiranus is a widespread cave-adapted endemic species from Terceira (Azores, Portugal) (Borges et al. 2010b), known from several caves (Algar do Carvão, Gruta da Achada, Gruta dos Balcões, Gruta do Caldeira, Gruta do Coelho, Gruta da Malha, Gruta do Natal, Gruta dos Principiantes, Gruta do Chocolate and Gruta de Santa Maria). The species was also found in the MSS ("Milieu Souterrain Superficiel" or "Mesovoid Shallow Substratum") (Borges 1993) in the area of Pico Rachado, far from the location of known caves.

Stable
It has an extent of occurrence (EOO) of 48 km² and the species is known from ten isolated subpopulations, but also occurs in "Milieu Souterrain Superficiel" or "Mesovoid Shallow Substratum" (MSS). The species occurs in ten volcanic pits and/or lava-tubes (Algar do Carvão, Gruta da Achada, Gruta dos Balcões, Gruta do Caldeira, Gruta do Coelho, Gruta da Malha, Gruta do Natal, Gruta dos Principiantes, Gruta do Chocolate and Gruta de Santa Maria), that are under several potential threats.

Stable
The species is known from ten isolated abundant subpopulations, but the area surrounding some of the caves is not protected and we assume some possible future impacts for those isolated subpopulations. It is a widespread cave-adapted endemic species from Terceira (Azores, Portugal).

Unknown
The species is particularly abundant in Terceira island.

Stable
The species is known from ten isolated abundant subpopulations, but the area surrounding some of the caves is not protected and we assume some possible future impacts for those isolated subpopulations. This species occurs in several volcanic formations (lava tubes and volcanic pits) of Terceira island. This species is distributed by all hypogean environments of Terceira both in the cave and MSS -mesocavernous shallow stratum habitats (Borges 1993, Amorim 2005.

Decline (observed)
The area surrounding some of the caves is heavily impacted by human activities and, in the Algar do Carvão Show-Cave, there is an ongoing impact from tourism visitation.
Major Importance -7.1. Caves and Subterranean Habitats (non-aquatic) -Caves Trechus terceiranus is a cavernicolous (i.e. a troglobitic species) predator and/or saprophagous species. Based on monthly data collected from the Algar do Carvão show cave during ten years, we can confirm that this species is active all months of the year, but with a high density between May and September. The main current threat to this species is cave visitation by tourists and the impact of agriculture activities. However, there are several future potential threats: climatic changes will impact many habitats in the Azores (see Ferreira et al. 2016) and this can change the conditions inside the caves; change in the road infrastructure around the caves; potential human recreational activities with disturbance caused by radical cave visitation.

Conservation
In Place -1. Land/water protection -2. Land/water management The species is not protected by regional law. Part of its habitat is in a regionally protected area (Natural Park of Terceira). 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 is anticipated to be developed during the coming years.

International
The species is not utilised.

Less important
Insufficient information available. Further research is needed into its ecology and life history in order to find extant specimens. It is necessary to establish a monitoring plan for the invertebrate community in the habitat in order to contribute to the conservation of this species.

Discussion
In this study, we have studied 15 Azorean endemic arthropods with some level of cave adaptation, grouping the historical data and giving new information about its distribution, habitat, threats and proposals for its conservation. Only three out of the 15 studied species are known from more than one island and the remaining are restricted to single islands. The three more widespread species are one Collembola, one pseudoscorpion and a spider and all of them may need some level of taxomic revision using molecular tools.
However, most of the Azorean cave arthropod species have a very restricted distribution, occupying a unique island and most of the times few caves and therefore they have a very small extent of occurrence (EOO) and area of occupancy (AOO). The lack of new records makes us consider the possibility that one of the species is extinct (Cixius cavazoricus). In fact, the two troglobitic species of the homopteran genus Cixius are under intense disturbance due to major land-use changes in epigean habitats above their known localities. In addition, many others species are in a critical conservation situation and actions should be taken with some urgency, namely the implementation of area-based management plans for the specifc caves.  evaluated the status of Azorean lava-tubes and volcanic pits concerning species diversity and rarity, concluding that, to preserve all troglobiont arthropods endemic to the Azores, it is crucial to protect several caves per island. Since then, there has been an effort to create a new law for the protection of the most important Azorean caves and is expected to be published in 2019-2020. However, many caves in Terceira, Faial and Pico Islands are being impacted by pollution due to the intensive cattle production, with the cha,ges in ecological conditions of caves in the last 50 years, namely the change in the nitrogen and phosphorous abiotic cycles and changes in the water pH (see Hathaway et al. 2014). Therefore, there is some urgency to perform new standardised surveys in the most important caves from the Azores to understand the current status of populations of the 15 species.
Formal education and awareness is needed to allow future investments in cave protection that will create conflicts with farmers. The use of images from extreme macro can be a strategy to inform the public about the ecological an aesthetic value of Azorean endemic cave arthropods as was demonstrated by the recent urban outreach initiative at Angra do Heroísmo in Terceira Island (see Amorim et al. 2016) (Fig. 12).
For the development of this paper the work of IRA, LLL and RN was partly  Trechus terceiranus extreme macro photo used for an urban outreach initiative (Credit: Javier Torrent, Azorean Biodiversity Group, cE3c).