Species conservation profiles of cave-adapted terrestrial isopods from Portugal

Abstract Background Terrestrial isopods (Oniscidea) are the most diverse group of troglobionts in caves of continental Portugal. They occur in all karst regions of Portugal, play a major role in decomposition of organic matter in caves and may act as umbrella species for the conservation of all other cave-adapted invertebrates. New information We present the IUCN Red List profiles for the cave-adapted terrestrial isopods from continental Portugal, based on recent distribution data from caves.


Introduction
Cave-adapted fauna have a high and global conservationist interest (Mammola et al. 2019). Cave-adapted communities have typically high endemicity patterns and are composed of a small number of species with small populations; hence, specific conservation measures should be defined and established regionally (Reboleira et al. 2011, Reboleira et al. 2013a, Reboleira and Eusébio 2021. Terrestrial isopods (Oniscidea) evolved to be the only truly terrestrial crustaceans (Hornung 2011). They play a vital role on decomposition of organic matter in the soil (Hassall et al. 1987), contributing to the biogeochemical cycles on Earth (Ravn et al. 2020). Therefore, terrestrial isopods can be used as bioindicators of soil ecosystem health (van Gestel et al. 2018).
In subterranean ecosystems, terrestrial isopods can be seen as sentinel organisms, as they are detritivorous, basal to the cave food webs, source of food for many predators, are generally associated with stable and undisturbed parts of caves and are the most diversified group (Campos-Filho et al. 2014, Reboleira et al. 2015. Portugal is a hotspot of subterranean biodiversity and, amongst all cave-adapted species, terrestrial isopods are the most diverse, represented in mainland by 15 troglobiont species (Reboleira 2012, Reboleira et al. 2015, Vandel 1946. Trichoniscidae is the most diverse cave-adapted isopod family, with 12 troglobiotic species, followed by Armadillidiidae, with two species and Styloniscidae and Porcellionidae, with one species each (Reboleira et al. 2015).
Cave-adapted species of mainland Portugal lack specific protective legislation and Red List profiling (Reboleira and Eusébio 2021). In this paper, we created IUCN Red List profiles for 15 species of cave-adapted isopods from continental Portugal.

Material and Methods
Over the last 15 years, the caves of continental Portugal have been extensively sampled by direct search and baited pitfall traps. The specimens were sorted and identified to species level through dissection, microscopy, comparison with collection specimens and bibliography (Vandel 1946, Reboleira et al. 2015. Extent of occurence (EOO) and area of occupancy (AOO) were calculated using the Geospatial Conservation Assessment Tool (GeoCAT) with an approximation to the standard IUCN 2 km × 2 km cells (4 km ). The maps were generated in the open source software QGIS 3.14.16, with the layer of the natural protected areas of Portugal (ICNF 2020).
Threats were identified in situ, complemented by a literature survey and spatial analysis software. The type of habitat classification, threats and conservation actions were assigned, based on the IUCN Red List database. lake (Grilo et al. 2016). The cave is currently closed by the Municipality and the surrounding area is fully urbanised (Reboleira et al. 2015).

Ecology and traits (narrative)
Trichoniscoides broteroi is a blind and depigmented troglobiont species and a single cave endemic (Reboleira et al. 2015). It shares habitat with another cave-adapted terrestrial isopod, the species Porcellio cavernicolus (Vandel 1946).

Justification for threats
The entrance to the cave is located within a fully urbanised area, more specifically in the middle of a roundabout (Grilo et al. 2016, Reboleira et al. 2015. This cave is located 1.3 km from the Mondego River and 2 km from the city centre of Coimbra.

Justification for conservation actions
This cave was previously excavated for archaeological studies where bone fragments, chipped stone material, ceramic fragments, quartzite blades and bone pins were found ( Grilo et al. 2016). It is also the only location for Trichoniscoides broteroi (Reboleira et al. 2015). Despite its archaeological and ecological importance and the severe threats it faces, this cave is not adequately protected for biodiversity; therefore, conservation of this habitat is crucial. Measures should also be taken to prevent infiltration of wastewaters and urban residues into the subterranean habitat. Trichoniscoides meridionalis occurs in ten caves ( Reboleira et al. 2015, Reboleira andEnghoff 2018).

Population Information (Narrative)
A total of 43 specimens have been collected: six in Moinhos Velhos cave, five in Algar do Vale do Pena, five in Algar do Burro, one in Algar do Zé de Braga, fifteen in Algar do Ladoeiro, ten in Almonda and one in Papagaio Caves (Reboleira et al. 2015).

Habitat (narrative)
The caves are located at an altitude ranging from 95 to 485 m a.s.l. (Reboleira et al. 2015). Amonda Cave represents the easternmost locality for the species' distribution, while Algar do Vale da Pena is the westernmost. Almonda is the largest cave in Portugal, with more than 10 km of mapped galleries (Thomas 1991).

Ecology and traits (narrative)
Trichoniscoides meridionalis is a blind, depigmented troglobiont that is adapted to life in the underground (Vandel 1946, Reboleira et al. 2015. This species can be found both close to the entrance and at the deepest parts of caves, usually associated with decomposing organic matter (Reboleira 2007, Reboleira et al. 2009, Reboleira et al. 2015.

Justification for threats
Almonda Cave is located 50 m from a factory that extracts water from a subterranean river and 420 m from a village, which has many agricultural fields. Algar do Ladoeiro's Cave entrance is 840 m from the closest urbanisation. The Moinhos Velhos Cave is the largest show cave of Portugal with around 140,000 visitors per year. Alcobertas Cave has also been subject to structural alterations with the intention to transform it into a show cave during the last century and it is exploited for tourism by a local association (Reboleira et al. 2009). The subterranean stream in Moinhos Velhos Cave has high input of sewage from the surface and is located below the village of Mira d'Aire; therefore, this cave is extremely contaminated by surface pollutants (Reboleira 2007), its entrance is located in the village centre and, since the 1960s, has had much infrastructure built for touristic exploitation, with a 300 m long show cave section (Reboleira et al. 2015). Alcobertas Cave has been intensively exploited for touristic activities since the 70s, where a second entrance has been opened, drastically changing the climatic conditions (Reboleira 2007, Reboleira et al. 2009). This cave is located 640 m from a field of energy windmills, 1 km from a quarry, 850 m from agricultural lands and 690 m from the nearest village. Algar do Vale da Pena is located in an abandoned quarry, 700 m from the closest village. Papagaio Cave is located 120 m from a quarry and 1 km from a major highway, A1. Algar do Burro is located 500 m from a quarry, 560 m from the A1 highway and 600 m from the closest village. Lapa da Chã de Cima is located 500 m from a quarry. Algar do Zé de Braga is located below intensive agricultural olive production, which is threatened by the use of pesticides at the surface, known to percolate into the underground and cause pernicious effects on subterranean biota (Castaño-Sánchez et al. 2020, Reboleira et al. 2013a).

Justification for conservation actions
Almonda Cave is classified, since 1993, as a Property of Public Interest (IIP) and protected due to its archaeological heritage (Hoffmann et al. 2013). The archaeological arguments are, however, inappropriate for cave-adapted fauna protection, so it is urgent to set protective measures directed at the cave fauna. Of the ten caves, only six are protected under legislation by the "Rede Natura 2000" (Directive 1992, ICNB 2000. Measures need to be established to protect the habitats and locations that are affected by human activities,

Basis of EOO and AOO:
wastewater infiltration and pollution and to implement protection on the locations neglected under the current legislation.

Region for assessment:
-Europe

Geographic range
Biogeographic realm:

Basis (narrative)
Both the extent of occurrence (EOO) and area of occupancy (AOO) are 4 km .

Range description
Trichoniscoides ouremensis is only recorded from Lapa da Salgada Cave, located in the Fátima Plateau, in the eastern part of the Estremenho karst massif (Vandel 1946, Reboleira et al. 2015.

Justification for number of locations
Trichoniscoides ouremensis is recorded from a single cave (Reboleira et al. 2015).

Justification for trend
Lapa da Salgada Cave is the only known location for this species; therefore, the trend in number of locations is stable.

Number of individuals:
Trend: Causes ceased?:

Habitat (narrative)
Lapa da Salgada Cave is composed of a main underground gallery and the floor is mostly covered by flowstone and clay, with a few bat guano deposits.

Ecology and traits (narrative)
Trichoniscoides ouremensis is classified as a troglobiont species, being blind and depigmented. It is a single cave endemic (Vandel 1946, Reboleira et al. 2015.

Justification for threats
The cave entrance is located 270 m from a road in which trucks transport goods from warehouses 600 m away. The cave is also located 1 km away from the closest town.

Justification for conservation actions
Measures need to be put in place in order to protect the habitat and species from the disturbances caused by truck movements and proximity to the urban areas.

Map of records (Google Earth):
Basis of EOO and AOO:

Region for assessment:
-Europe

Geographic range
Biogeographic realm:

Basis (narrative)
Both the extent of occurrence (EOO) and area of occupancy (AOO) are 4 km .

Range description
Trichoniscoides serrai is only recorded from Santo Adrião Cave, located in the palaeokarst of Vimioso in north-eastern Portugal (Cruz 1993, Reboleira et al. 2015.

Justification for number of locations
Trichoniscoides serrai occurs in a single cave (Cruz 1993, Reboleira et al. 2015).

Justification for trend
Santo Adrião Cave is the only known location for this species; therefore, the trend in number of locations is stable.

Justification for threats
The cave entrance is in the border of an active quarry, very close to a road (Moreira and Moreira 2006).

Taxonomic notes
Trichoniscoides sicoensis is blind and depigmented and it can be distinguished from all species of the genus because the male pereopod 7 merus has a lobe on the mid-sternal margin, the male pleopod 1 exopod has a broadly rounded outer margin and two unequal setae, the endopod has a fusiform distal article with a distinct circular suture in the middle and the male pleopod 2 endopod has a thickset distal article bearing two short triangular lobes and two setae at the apex (Reboleira et al. 2015).

Region for assessment:
-Europe Trend:

Geographic range
Biogeographic realm:

Basis (narrative)
The extent of occurrence (EOO) is 129.2 km² and the maximum estimated area of occupancy (AOO) is 20 km².

Range description
Trichoniscoides sicoensis is recorded from six caves located in the Sicó karst area: Cerâmica, Santa Maria da Estrela, Soprador do Carvalho, Algarinho, Arrifana and São Simão (Reboleira et al. 2015). The largest population was found in the type locality Cerâmica Cave, where a higher number of specimens has been collected, followed by Santa Maria da Estrela Cave and then Soprador do Carvalho, Algarinho, Arrifana and São Simão Caves (Reboleira et al. 2015).

Habitat (narrative)
Trichoniscoides sicoensis inhabits the deepest and isolated parts of caves of the Sicó karst area, found up to a maximum altitude of 380 m a.s.l. The easternmost locality is Soprador do Carvalho Cave and the westernmost is Santa Maria da Estrela Cave, its distribution being limited at the north by the Arrifana Cave and at the south by the Cerâmica Cave. Cerâmica Cave opens at 355 m a.s.l., it has a horizontal development of 120 m, a depth of 21 m (Nóbrega et al. 1984) and is the richest cave in biodiversity in central Portugal (Reboleira 2012, Reboleira et al. 2015. Santa Maria da Estrela Cave is the habitat recorded at highest altitude, 380 m a.s.l., with a horizontal development of 200 m and harbours frequently a large bat colony (Nóbrega et al. 1984). Soprador do Carvalho Cave is the largest cave, where T. sicoensis is distributed and it is part of the Dueça Speleological System, which has 7 km of underground galleries (Neves et al. 2005).

Ecology and traits (narrative)
Trichoniscoides sicoensis is classified as a troglobiont species, blind and depigmented. It is endemic to the Sicó karst area (Reboleira et al. 2015). Most of the specimens are found walking on the substrate near roots, but they can exhibit an amphibious behaviour and have also been collected under a stone submerged in the subterranean stream of Soprador do Carvalho Cave (Reboleira et al. 2015).

Threats
Ongoing Threats: Conservation action type: . The subterranean stream that passes inside this cave has observable urban wastewater run-off as it flows below the urbanised areas of the region (Reboleira et al. 2011). Algarinho Cave entrance is located 170 m from Soprador do Carvalho; therefore, they are both exposed to the same threats. However, the terminus of Algarinho is below a quarry and limestone slurry infiltrates from the surface into the cave, which is known to have pernicious effects on subterranean species (Piccini et al. 2019). Arrifana Cave is located 190 m from a road, 370 m from the nearest village and 900 m from a quarry. São Simão Cave entrance is surrounded by agricultural fields and is located 47 m from a road, 100 m from the closest house and 300 m from a transportation company, from where cargo trucks operate. The quarry near Algarinho cave has been reported by Grupo Protecção Sicó, a local ONG from Pombal Municipality, as the source of infiltration of large amounts of fine particles of quarry dust in the cave, which puts groundwater quality in danger (Piccini et al. 2019). Prevention of infiltration of wastewaters from villages into the nearby caves is necessary and the effects of the quarries and agriculture in these cave ecosystems need to be minimised.

Region for assessment:
-Europe

Geographic range
Biogeographic realm: Known habitat extent

Basis (narrative)
Both the extent of occurrence (EOO) and area of occupancy (AOO) are 4 km . 122

Range description
Trichoniscoides subterraneus is only recorded from Alta do Cabeço dos Mosqueiros Cave, located in Carvalhal de Aljubarrota, the western part of the Estremenho karst massif ( Vandel 1946).

Habitat (narrative)
This cave is currently part of the Geocaching network; therefore, it is subject to human disturbance without regulation.

Size:
Generation length (yr): Dependency of single sp?: Threat type: Threats: Conservation action type:

Justification for threats
This cave is frequently visited by geocachers looking for the geocache installed inside the cave.

Justification for conservation actions
Measures to limit the number of visits to the cave should be implemented in order to ensure the integrity of the habitat and the survival of this species.

Map of records (Google Earth):
Basis of EOO and AOO:

Taxonomic notes
Metatrichoniscoides salirensis can be distinguished from all species of the genus because the pleopod 1 exopod of the male has two long distal setae of subequal length and its pleopod 2 endopod has a thickset distal article, ending in a thinner sinuous part with a beak-like small lobe medially directed (Reboleira et al. 2015).

Region for assessment:
-Europe

Geographic range
Biogeographic realm:

Basis (narrative)
Both the extent of occurrence (EOO) and area of occupancy (AOO) are 4 km² 60

Range description
Metatrichoniscoides salirensis is only known from Salir Cave, a single isolated cave located in the western border of Caldas da Rainha Typhonic Valley (Reboleira et al. 2015).

Justification for number of locations
Metatrichoniscoides salirensis is only recorded from one cave (Reboleira et al. 2015).

Population Information (Narrative)
A total of seven specimens have been collected in the type locality (Reboleira et al. 2015).

Unknown
Unknown Unknown

Terrestrial
Yes

Habitat (narrative)
Salir Cave was discovered in the 1960s by the labour force of a quarry. It is located near the sea, at an altitude of 60 m a.s.l. The substrate is mostly composed of flowstone, clay and marine sand that can be found in the deepest parts of the cave (Reboleira et al. 2015).

Ecology and traits (narrative)
Metatrichoniscoides salirensis is classified as a troglobiont species, blind and depigmented and is hitherto the only troglobiont species known from this cave and from this karst area (Reboleira et al. 2015). The mean temperature of the cave is 17.3°C, measured in 2010 at the sediment level.

Justification for threats
The cave entrance is located in a former quarry, at 400 m from the closest house and 1 km from the village centre. Salir Cave has an easy access and mostly horizontal development, which attracts casual visitors. It has suffered recurrent episodes of vandalism, which include paintings inside the first chamber and breakage of many lithological formations. This cave is currently listed in the Geocaching network and subject to human disturbance without regulation.

Justification for conservation actions
The cave should be a protected site, as it is the only locality known for this species; therefore, a site of maximum priority for biodiversity conservation. The entrance should be

Basis of EOO and AOO:
closed and the access regulated in order to prevent the recurrent vandalism and human disturbance to the ecosystem.

Taxonomic notes
Antennae have five flagellar articles, the male pleopod 1 exopod is triangular, as wide as long and the male pleopod 2 endopod distal article has a basal and a distal hook-like process (Reboleira et al. 2015).

Region for assessment:
-Europe

Geographic range
Biogeographic realm:

Basis (narrative)
Both the extent of occurrence (EOO) and area of occupancy (AOO) are 4 km².

Range description
Troglonethes olissipoensis is only recorded from Alvide Cave, located in Cascais Municipality in the Lisbon metropolitan area (Reboleira et al. 2015).

Population Information (Narrative)
A total of 25 specimens have been collected in the type locality (Reboleira et al. 2015).

Terrestrial
Yes

Habitat (narrative)
The entrance to Alvide Cave is through a house currently serving as headquarters of Denível Association. Part of the cave's ceiling has concrete that serves as the base of a residential building. This cave is in the margin of a small canyon and it is composed of three levels of horizontal galleries connected by pits, it has a horizontal development of 708 m and total depth of 28 m.

Ecology and traits (narrative)
Troglonethes olissipoensis is a troglobiont species, being blind and depigmented. It is endemic and the only cave-adapted species known from this cave (Reboleira et al. 2015).
The average temperature of the cave is 18.3ºC at soil level and the specimens of T. olissipoensis were collected in the deepest parts of the cave (Reboleira et al. 2015).

Justification for conservation actions
Measures should be taken to minimise the pernicious effects due to the cave's close proximity to the urbanisation on the habitat.

Taxonomic notes
Antennae have three flagellar articles, the male pereopod 7 carpus is enlarged in the basal part, the male pleopod 1 exopod is triangular and as wide as long and the male pleopod 2 endopod has the distal article with an apical hook-like process (Reboleira et al. 2015).

Region for assessment:
-Europe

Geographic range
Biogeographic realm:

Basis (narrative)
Both the extent of occurrence (EOO) and area of occupancy (AOO) are 4 km².

Range description
Troglonethes arrabidaensis is only recorded from Frade Cave, located in the Arrábida karst massif (Reboleira et al. 2015).

Justification for number of locations
Troglonethes arrabidaensis occurs in a single cave (Reboleira et al. 2015).

Justification for trend
Frade Cave is the only known location for this species; therefore, the trend in number of locations is stable.

Population Information (Narrative)
A total of 17 specimens have been collected in Frade Cave (Reboleira et al. 2015).

Subpopulations
Unknown Unknown Unknown

Terrestrial
Yes

Habitat (narrative)
Frade Cave is located near the seashore, with several anchialine lakes inside, which are influenced by the sea tides with a slight delay period (Reboleira et al. 2015). The cave temperature is 21.5°C.

Ecology and traits (narrative)
Troglonethes arrabidaensis is classified as a troglobiont, depigmented, blind and with an elongated body (Reboleira et al. 2015). It is an endemic and the only cave-adapted species known from this cave so far.

Justification for threats
The cave entrance is located 600 m from a very touristic beach, mainly accessed by boat; therefore, fuel residues brought in by the tidal movement might be a concerning pollutant inside the cave. Contamination of groundwater should be evaluated.

Justification for conservation actions
Even though this cave is protected under legislation by the "Rede Natura 2000" (Directive 1992, ICNB 2000, this single-cave endemic terrestrial isopod lacks specific protection. Measures should be taken to limit human disturbance in the nearby areas.

Taxonomic notes
The male pereopod 7 has a long and stout seta on the distal corner of the ischium and a triangular male pleopod 1 exopod (Reboleira et al. 2015). The specimens from the Sicó karst caves lack eyes, while those from Bolhos have a single black ocellus (Reboleira et al. 2015).

Region for assessment:
-Europe

Ecology and traits (narrative)
Miktoniscus longispina is a troglobiont, with a depigmented and elongated body. All specimens, except for the ones collected in Bolhos Cave, are blind.

Justification for conservation actions
The caves located in the Sicó karst area are protected under the "Rede Natura 2000" (Directive 1992, ICNB 2000. Bolhos Cave is not protected under legislation, urging adequate protection. Measures should be taken to prevent infiltration from agricultural lands, livestock farms and villages and to prevent the pernicious effects resulting from the nearby quarries and windmills.

Taxonomic notes
The male pereopod 7 carpus has a distal lobe on the sternal margin. This new species is easily distinguishable from the other two Moserius species due to the peculiar shape of the male pleopod 1 exopod, with a truncate and sinuous, rather than triangular, distal point (Reboleira et al. 2015).

Region for assessment:
-Europe

Geographic range
Biogeographic realm:

Basis (narrative)
Both the extent of occurrence (EOO) and area of occupancy (AOO) are 4 km . 95

Range description
Moserius inexpectatus is only recorded from Almonda Cave, also known as Olho do Moinho da Fonte, located in the easternmost subunit of the Estremenho karst massif (Reboleira et al. 2015).

Justification for number of locations
Moserius inexpectatus is endemic to a single cave (Reboleira et al. 2015). Habitat importance:

Justification for trend
Almonda Cave is the only location from where this species is known; therefore, the trend in number of locations is stable.

Unknown
Unknown Unknown Unknown Unknown Unknown

Population Information (Narrative)
Only one specimen was collected from the type locality (Reboleira et al. 2015).

Subpopulations
Unknown Unknown Unknown

Habitat
Terrestrial Yes

Habitat (narrative)
Almonda Cave, the type locality for this species, is the largest cave in Portugal (Thomas 1991).

Ecology and traits (narrative)
Moserius inexpectatus is a troglobiont blind and depigmented isopod. This is the third species described from the genus Moserius, previously known from Slovenia and Italy (Reboleira et al. 2015).

Justification for threats
Almonda Cave is located 50 m from a factory that extracts and uses water from a subterranean stream and 420 m from a village, which has many agricultural fields.

Justification for conservation actions
In 1993, Almonda Cave was classified as a Property of Public Interest (IIP) and protected due to its archaeological heritage (Hoffmann et al. 2013). The archaeological arguments are, however, inappropriate for cave-adapted fauna protection, so it is urgent to set protective measures directed at the cave fauna. Measures also need to be established to protect the habitats and locations that are affected by human activities, wastewater infiltration and pollution.

Taxonomic notes
The male pereopod 7 ischium has a rounded hyaline basal lobe, the triangular male pleopod 1 exopod is as long as the endopod and the male pleopod 2 endopod has a complex apical part (Reboleira et al. 2015).

Region for assessment:
-Europe

Geographic range
Biogeographic realm:

-Palearctic
Countries: Known habitat extent

Basis (narrative)
The extent of occurrence (EOO) is 5,893.93 km and the area of occupancy (AOO) is 16 km .

Range description
Cordioniscus lusitanicus is recorded from five caves, located in two isolated karst areas: Algar de Santo António from the Estremoz-Cano karst massif and Ibne Ammar, Algarão do Remexido, Vale Telheiro and Senhora Caves from the Algarve karst massif (Reboleira et al. 2015).

Justification for trend
The four caves, located in the Algarve karst massif, are at 200 km distance from the cave in the Estremoz-Cano karst massif.

Population Information (Narrative)
A total of 26 specimens have been collected: nine from Algar de Santo António, six from Ibne Ammar, six from Algarão do Remexido and four from Senhora (Reboleira et al. 2015) and one from Vale Telheiro. Unknown

Habitat (narrative)
Cordioniscus lusitanicus was collected in two karst areas, Estremoz-Cano and Algarve, located more than 200 km apart, which are isolated from each other by the dry and flat areas of the Alentejo Province. In Algar de Santo António, the specimens were collected in deep layers of soil at the bottom of an entrance pit of the cave (Reboleira et al. 2015).

Ecology and traits (narrative)
Cordioniscus lusitanicus is classified as a troglobiont and endogean species. It is blind, depigmented and has an elongated body (Reboleira et al. 2015).

Justification for conservation actions
Of the five caves, only Ibne Ammar Cave is protected under legislation by the "Rede Natura 2000" (Directive 1992, ICNB 2000 and this troglobiont isopod species is not considered for the protection measures.
Population trends need to be monitored in order to better understand the species abundance patterns and life cycle and the species evolution in two isolated massifs.
Measures to prevent infiltration of wastewaters and agricultural and industrial contamination need to be taken to ensure the proper conservation of the natural landscape, vital to the nutrient flow to the subterranean ecosystems. More than 63 specimens have been collected: 28 from Gruta d'el Rey, 16 from Santa Maria da Estrela, seven from Soprador do Carvalho, three from Cerâmica, four from Abrigo Tomar I and five from Furjaca. The specimens, collected from Algarinho Cave, are simply described as "many" (Reboleira et al. 2015).

Unknown
Unknown Unknown

Terrestrial
Yes

Habitat (narrative)
Porcellio cavernicolus inhabits the most superficial parts of caves and it occurs on roots that hang from the ceiling. Specimens are easily distinguishable due to their whitish colouration (Reboleira et al. 2015).

Justification for threats
Gruta d'el Rey is located in the middle of an urbanised area, 1 km from a quarry and 1.2 km from highway A14. Santa Maria da Estrela Cave is located 86 m from a touristic site called Monstro das Bolachas, 230 m from the Nossa Senhora da Estrela viewpoint, 250 m from the closest house, 80 m from the closest road, 220 m from agricultural fields and 2.6 km from two quarries. Soprador do Carvalho is surrounded by agricultural lands and is located 67 m from the closest house and 1.4 km from a quarry. This cave is also affected by touristic activities, as people who visit the cave walk all over the habitat (Ribera and Reboleira 2019). The subterranean stream that passes inside this cave has observable urban wastewater run-off as it flows below the urbanised areas of the region (Reboleira et al. 2011). Algarinho Cave entrance is located 170 m from the entrance of Soprador do Carvalho Cave; therefore, they are both exposed to similar threats. Cerâmica Cave is

Conservation action type:
Conservation actions:

Figure(s) or Photo(s):
surrounded by agricultural fields and Eucalyptus intensive plantations. It is located 270 m from a road, 550 m from an animal farm, 1.6 km from the closest village and 3.6 km from a quarry. Abrigo Tomar I Cave is located in a quite pristine location and it is a local protected area by the ONG Quercus. Furjaca Cave is located in an abandoned quarry which, after closure, was used as a trash dumping site. Map of records (Google Earth):

Basis of EOO and AOO:
Min Elevation/Depth (m):

Geographic range
Biogeographic realm:

Basis (narrative)
The extent of occurrence (EOO) is 356.4 km and the area of occupancy (AOO) is 16 km .

Habitat (narrative)
Trogleluma machadoi is endemic to karst caves in the southernmost province of Portugal, the Algarve.

Decline (inferred)
Major Importance Conservation action type:

Ecology and traits (narrative)
Trogleluma machadoi is a blind and depigmented species, classified as a troglobiont. Specimens are found in the most deep and well isolated parts of of caves, they have the integument covered with clay, while some others were found walking on cave walls and completely clean of clay, probably recently moulted (Reboleira et al. 2015, Vandel 1946. The temperature of the caves in the distribution localities ranges from 17 to 20.5°C, measured at the sediment level. The species is distributed from 10 m a.s.l., at Ibne Ammar Cave, up to a maximum altitude recorded of 239 m a.s.l. Trogleluma machadoi shares habitat with some iconic cave-adapted species from the Algarve, such as: the giant pseudoscorpion Titanobochica magna ( Reboleira et al. 2010b), the relictual pseudoscorpion Lusoblothrus aenigmaticus (Reboleira et al. 2012b), the dysderid spider Harpactea stalitoides (Ribera 1993), the millipedes Acipes bifilum and A. machadoi and Boreviulisoma barrocalense (Enghoff and Reboleira 2013, Reboleira and Enghoff 2013), the dipluran Litocampa mendesi , the giant silverfish Squamatinia algharbica (Reboleira et al. 2012a) and the beetle Speonemadus algarvensis (Reboleira et al. 2017).

Justification for threats
Ibne Ammar Cave is located right in the flooding zone of the Arade River, 380 m from the national road IC4 and 1.4 km from the nearest town. Algarão do Remexido is located under agricultural lands, 370 m from the closest house and 1.7 km from the closest village. Senhora Cave is located 168 m from the closest house and 900 m from an industrial complex. Abismo Novo Cave is located 100 m from the closest house and 500 m from the village centre and is also located 1 km from Senhora Cave. Algarão do Paulino is located near a road, 90 m from the closest house and 800 m from the closest village. Vale Telheiro Cave is located 50 m from a road and 150 m from the closest house.

Justification for conservation actions
Of the five locations, only three are protected under legislation by the "Rede Natura 2000" (Directive 1992, ICNB 2000. Measures should be taken to prevent infiltration of wastewaters from villages into the nearby caves and to minimise the effects of anthropogenic threats on the habitats and species.

Discussion
Cave-adapted terrestrial isopods are key species for cave ecosystem conservation: i) they are the most diverse group of cave-adapted species in continental Portugal, ii) they have several single cave endemics that are under threat and require specific protection measures, iii) they are basal in the trophic chains in caves and serve as a food source for several other zoological groups; iv) they play a vital role on the decomposition of organic matter in caves; and v) they are very sensitive to contaminants and climate change (Campos-Filho et al. 2014, van Gestel et al. 2018, Reboleira et al. 2015.
Almost all cave-adapted terrestrial isopod species face direct anthropogenic threats, such as point or diffuse pollution, direct habitat destruction by mining and quarry activities or excess cave visitation (Reboleira et al. 2011, Reboleira 2012, Reboleira et al. 2013a, Reboleira et al. 2015. With this research, we offer information about 15 cave-adapted isopods of continental Portugal, their distribution, habitats, species ecology, current threats and conservation measures needed. This information is fundamental to raise awareness on the threats that subterranean ecosystems and fauna face and to establish conservation measures to prevent their decline and possible extinction. In the Iberian Peninsula, cave-adapted terrestrial isopods are also found in shallow subterranean habitats, such as the mesovoid shallow substrate (MSS) (Cifuentes and Barranco 2020). So far, previous biological investigations in the MSS in Portugal have only retrieved troglophile species of Oniscidea (Reboleira et al. 2015). Therefore, there is high potential for future findings of cave-adapted Oniscidea distributed also in the MSS, as recentely happened for other arthropod groups (Eusébio et al. 2021).
It is a priority to establish concrete protection strategies for cave-adapted species in continental Portugal. We need to improve the knowledge about population size and dynamics, real extent of subterranean distribution, improve our knowledge on the functional ecology, understand species life cycle and evaluate their sensitivity to disturbance. This contribution may be used as a support for decision-making for territory management and to define conservation measures for cave endemic species. Caveadapted terrestrial isopods have the potential to be used as umbrella species for the conservation of other cave-adapted species sharing the same subterranean habitats.