98 AMCS Bulletin 19 / SMES Boletín 7 — 2004

Biospeleology in Macaronesia Pedro Oromí

Dept. of Biology, University of La Laguna, Tenerife, Canary Islands

Geographical and speleological original basements, were uplifted over do not necessarily follow the sur- background the sea level and are now exposed on face topography, and normally open to the surface by the effects of erosion. On outside at cliffs and other steep terrains In the biogeographical sense Maca- other islands like Santa Maria (Azores) due to erosion. Some examples of this ronesia is a subregion of the Western and () some lime- kina of caves are Gruta dos Anjos (Santa Palaearctic which includes southwest stone rocks of marine origin have been Maria), Gruta do Inferno (Selvagem continental , part of the coastal formed and are actually emerged because Grande) or Cueva de la Fajanita (La zone of south Morocco, and the Atlantic of eustatic movements of the sea level. Palma). archipelagos of the Azores, Madeira, These non volcanic rocks are anyway The volcanic pits often derive from Selvagens, Canaries and Cape Verde. very scarce, and have developed such a the emptying of volcanic chimneys when Since the establishment of the term in slight karstification that true caves are the eruption stops and the remaining lava the 19th century by the British botanist not found at all inside them. Therefore, contracts. The spatter cones are hollows P.B. Webb, much has been discussed in the Macaronesian islands the caves with limited dimensions, while other about the validity of Macaronesia as a enough developed as to be considered volcanic pits can exceed 100 m deep, biogeographic unit, about its appropri- of speleological interest occur only in like Algar do Montoso, in São Jorge ate space and boundaries, and about volcanic terrains. (Azores). They are usually bell-shaped, its different meaning for vegetal and Such particular cavities have a gen- though they often show more complex animal organisms. Two continental esis, morphology and a life span very structures with connected cavities and areas and five volcanic archipelagos different than limestone caves. The main multiple vents. The geysers and the vents have generally been identified within types of volcanic caves are lava tubes of gaseous phreatomagmatic eruptions Macaronesia. The islands are of oceanic and volcanic pits, each with their variants can originate remarkable pits, like that of origin with no surface connection with depending on the type of Sima de Tinguatón in Lanzarote. Some other land since they emerged from (see Montoriol, 1973). times the retraction cracks originated the sea bottom. Independently to other The lava tube caves are formed only after cooling trachytic, viscous lavas can biogeographic considerations, in this text in fluid basaltic lavas, never occurring also originate remarkable pits, like the we only pay attention to the strictly vol- in viscous acidic lava flows of trachytic 70 m deep Sima Vicky (Tenerife). canic Macaronesian archipelagos, which nature. They originate after more or less Also lava tubes can be combined with constitute an insular geographic reality permanent lava channels that consolidate volcanic pits in a single but complex very different to that of the continental by cooling of the peripheral layers, and cavity with several levels at different Macaronesian enclaves. From a political are finally roofed when significant speed depths, like it occurs in Sima de Las point of view the Azores, Madeira and differences are established between the Palomas (El Hierro) and Cueva del Selvagens belong to Portugal, the Canary inner and the surface flow. The inner Sobrado (Tenerife). Islands to Spain, and the Cape Verde temperature of the tube allows the lava Speleogenesis and ecological form an independent country, though to keep flowing inside until the emission succession on volcanic terrains with a strong Portuguese character for stops, the liquid empties totally and the obvious historical reasons. system becomes a hollow tube. These Besides their peculiar speleogenesis The Macaronesian archipelagos have caves are therefore usually shallow and when compared to karstic caves, lava common geological features mainly follow parallel to the surface topography tube caves have a geological cycle and derived from their volcanic origin. All at the moment of being formed. Great an ecological succession also very differ- the islands have been built up from the accumulation of further new lavas on that ent (see Howarth, 1996). The formation sea bottom by successive accumula- containing the , and changes on the of a lava tube is very quick, sometimes tion of volcanic materials that finally relief by important erosive effects can just a few days, and immediately starts emerged over the marine surface along alter this parallelism between lava tubes its evolution towards definitive destruc- the Tertiary and Quaternary. Actually the and the actual surface upon them. tion as a cave, which will take place volcanism is still active on the Azores, A particular type of lava tubes are within a period of 100,000 to 500,000 the Canaries and the Cape Verde islands. those originated by the emptying of years depending on the local climate Almost all the rocks forming these archi- a dyke. They usually have a different and erosion (Howarth, 1973). Volca- pelagos are volcanic. However, in some morphology and since their origin are nic pits, however, can last longer time. of the Canary Islands (i.e. La Palma, La located much deeper below surface than The cycle of lava tubes is very short Gomera and Fuerteventura) there are the so called rheogenetic lava tube caves in geological terms, compared to that plutonic rocks that belonged to their (Socorro & Martín, 1992). These dyke of limestone caves (millions of years) AMCS Bulletin 19 / SMES Boletín 7 — 2004 99 which needed at least 100,000 years to some troglobites have been found in the richness of sap-sucking plant-hoppers initiate its formation. On the other hand, deepest passages, while lavicolous spe- (Cixiidae and ) on three of lava tube caves usually have much less cies are the only inhabitants in the rest of the archipelagos, while in Europe and permanent water than limestone caves the cave (Ashmole et al., 1992; Martín, North Africa these groups are unknown (which need it for their formation and 1992). In limestone caves instead, the in the caves. It is also peculiar of these is only absent in fossil, inactive caves), oldest habitats are closer to the surface island cave-dwelling communities the and are in general much shallower so that and ecological succession progresses presence of troglobitic species belong- the roots of surface plants often reach downwards. ing to taxonomical groups absent in and invade the cave. The older is a lava tube, the higher caves of the nearby mainland, and even A recently formed lava tube starts probability to be covered by further lava very rare all over the world. This is with a juvenile phase characterized by its flows, which keep the cave away from the case for landhoppers (Amphipoda: dependence on the outside climate due to surface. In such conditions the roots Talitridae), earwigs (Dermaptera) and the network of cracks of the lava, easily do not reach the cave, and provision of thread-legged bugs (: Redu- connecting the cave to the exterior. As organic matter by percolating water is viidae) which have troglomorphic spe- ecological succession goes on over the more difficult. Consequently, lava tubes cies only in the Canary Islands and in lava, the soil seals the surface, shallower occurring under many lava flows hold a Hawaii. The diversity and abundance passages retain moisture and the cave poor fauna or are even abiotic, as it also of troglobitic cockroaches (Blattaria) in enters in a mature phase with the sub- happens in dyke caves. the Canaries contrasts with the absence sequent climatic isolation (temperature Animal communities of these in caves of the whole and humidity). Thus, there is a simulta- in volcanic caves Palaearctic. neous ecological succession inside and Troglobitic species are unable to sur- outside the cave, which is very impor- When a lava tube has attained maturity, vive outside their hypogean environ- tant to determine the living community its environmental conditions are similar ment, and therefore they cannot colo- inhabiting this environment (Ashmole to that of limestone caves: absence of nize other islands. This implies that all et al., 1992). There is a particular way light, temperature stability, humidity troglobites in Macaronesia are always to accelerate this process when a thick close to saturation. Scarcity of organic endemic to a single island. The pres- layer of small-sized pyroclasts (cinder matter is also severe, with lesser provi- ence of a troglobite in two islands could and lapilli) are deposited upon the re- sion by water than in limestone caves but only be explained when these islands cent lavas, which isolate the cave from frequently compensated by the presence had been connected in relatively recent outside temperatures, keep the moisture of roots (if there are). In the Macaron- past times due to regressions of the sea and allow many plants to grow up and esian islands bat colonies are very few level (for example Pico and Faial in the provide roots to the cave. Many caves inside the caves, therefore the guano is Azores; Fuerteventura and Lanzarote in in recent or very dry areas of the Canary negligible. the Canaries). and the Cape Verde islands have good Volcanic pits are usually richer in food Types of caves and conditions for troglobites thanks to be because they operate as pitfall traps for biological richness covered by ash fields. As time goes by many organisms; on the contrary, in lava the erosion leads the cave to a senile tubes the input of energy through the It is very common to find a troglobitic stage, in which silting of the network of entrance only affects a few metres inside, species in different, distant caves formed cracks and voids in the surrounding lava and hardly progresses into the cave. in separated lava flows within an island. isolates the system, the inner space of Adaptations to cave life are the same This is due to the existence of the so the cave can be even stuffed up by clay for volcanic and limestone troglobites: called Mesovoid Shallow Substratum deposits, and internal collapses finally depigmentation, eye reduction, elonga- (MSS: Juberthie, 1983; Culver, 2001), destroy the cavity. Volcanic pits usually tion of body and appendages, slow me- an extensive network of cracks and voids have a much longer senile stage due tabolism, starving resistance, longer life connecting large areas, which is suitable to their larger volume and their verti- span, inability to live outside the cave, to be occupied by many troglobites. cal shape and more solid architecture. k reproductive strategies (more limited There is a particular type of MSS in Thus volcanic pits last much longer than but successful offspring), etc. Higher volcanic islands made up by the lava lava tube caves, reaching a few million tolerance to temperature changes has clinker covered by a thin soil (Oromí years and being the only caves in the been observed in island troglobites with et al., 1986), which has provided a rich oldest terrains of the islands (Oromí et respect to temperate continental species, adapted fauna in places without caves al., 1985). both in the nature and in laboratory ex- on the Canary and the Azores islands In the lava tube caves ecological suc- periences (Izquierdo, 1997); this could (Medina & Oromí, 1990 and 1991; cession typically progresses upwards be related to the shallower lava tubes to Borges, 1993). (Howarth, 1996) in such way that deep which they are adapted, and maybe also Actually troglobites occupy the ex- levels reach maturity before the upper to the less marked seasonal differences tensive network of spaces in the appro- levels, which need better soil cover on in oceanic islands. priate underground, either good caves, the surface to maintain ideal conditions In these volcanic hypogean commu- crevices or MSS. In general they often for troglobites. For example Cueva de nities the root-feeding species are par- prefer small tubes and cracks than proper Todoque (La Palma, Canary Is.) formed ticularly abundant with respect to other “caves” that are for us just windows in the lavas of San Juan eruption (1949) trophic categories. It is remarkable the to reach the hypogean habitat. But in 100 AMCS Bulletin 19 / SMES Boletín 7 — 2004

Table I. Types of caves and animal richness. from Europe and North America (Van- del, 1964; Barr, 1968), since glaciations didn’t affect these islands of the mid Atlantic. Maybe their relict condition was due to secondary climatic changes derived from glaciations (drought, forest withdrawal). Azores Islands This is the western and northernmost archipelago, being located on the Midat- lantic ridge. This implies interesting geo- general the abundance of cavities is a to colonize oceanic islands, being their logic consequences, with predominance good indicator to the richness of well potential hypogean niches occupied by of Hawaiian type volcanism and there- adapted fauna in an area, especially lava other groups that commonly don’t do it fore basaltic rocks, very suitable for the tube caves which are found in basaltic in the mainland. formation of lava tubes. Its geographical terrain, the best for a good network of All Macaronesian troglobites have situation divides the archipelago in two spaces. evolved locally, in such way that all spe- groups of islands, one at west (Flores and Besides the stage of ecological suc- cies are endemic to a single island with Corvo) and the other at east (rest of the cession and the geographic situation of a the exceptions above mentioned. This islands) of this ridge, in such way that cave, the animal communities occurring implies allopatric speciation and many the former shift westwards together with in it also depends on its morphology independent colonisations of the under- the ocean floor, and the second group and depth. Mature lava tubes are more ground. However, some genera include move eastwards towards Europe. The isolated from the surface than volcanic various related troglobitic species in one age of each island varies depending on pits concerning direct input through the island (3 spp. in Pico, 5 Cixius the distance to the ridge, the youngest entrance. Thus the pits can hold a richer spp. in La Palma, 11 Loboptera spp. and being those of the central group (Faial, fauna with many epigean species, while 8 Dysdera spp. in Tenerife, etc.) In some Pico and São Jorge) and the oldest one in the tubes the community is poorer but of these cases two or more congeneric Santa Maria. The greatest abundance with much higher proportion of troglo- species are found together, but they have on lava tube caves is in general in the bites. The dyke caves are usually very different epigean sister species, which youngest islands, though older islands poor because of their location very deep also implies independent invasions of can be also rich in such caves whenever underground, where neither roots nor the underground. Moreover, many of recent volcanism (in geological terms) percolating water with organic matter the epigean sister species are actually have took place and have modern ter- arrive easily. Most of the dyke caves occurring on the surface in the same area rains, like for instance São Miguel. On we have studied had a scarce fauna and to their corresponding hypogean sister the contrary, modern islands like Flores always close to the entrance. Other pits species, what means that the latter have (2.16 Ma) but lacking recent eruptions, like big crevices are also poor because evolved by parapatric speciation. This are poor in such caves. All the Azores they are usually formed in acidic la- is a common situation in Macaronesian islands are rather rich in lava tube caves vas, which are more impermeable and islands and agrees with the adaptive shift except Corvo, Flores and Santa Maria, unconnected to the Mesovoid shallow hypothesis for the origin of troglobites and at least some troglobitic species are substratum (MSS), an important reser- (Rouch & Danielopol, 1987; Howarth, so far known from all the rest except voir of the hypogean fauna in volcanic 1987). However, there are also troglo- Graciosa (see Table II). terrains without lava tubes. The erosion bites with no epigean relatives at all on The studies on cave biology had been caves generally formed close to the sea their island and even on the whole archi- very sporadic before the 1980’s, and only shore are very often also dyke caves, and pelago. This is the case for the thread- a few freshwater species occurring in lack an adapted hypogean fauna. legged bugs Collartida anophthalma pools at the bottom of pits were known. Main features of the terrestrial (from El Hierro) and Collartida tanausu The knowledge on the terrestrial fauna cave fauna in Macaronesia (from La Palma), several species of the started in 1987, when an expedition by pseudoscorpion genus Tyrannochthonius researchers from Edinburgh Univer- Island faunas are always peculiar be- and the genus Meenoplus. sity (UK) and La Laguna University cause of their disharmony, with many Some of the species belong to endemic (Canary Islands) financed by National absent animal groups that are found genera, like the harvestman Maiorerus Geographic Society and with the valu- in the continent. This is also the same randoi from Fuerteventura, the ground able collaboration of Os Montanheiros concerning to cave , in such way Spelaeovulcania canariensis members (Angra do Heroísmo) stud- that these lacking species are partially from Tenerife and Pseudoplatyderus ied the cave fauna from Terceira, Pico, replaced by other species preadapted amblyops from La Gomera, with no re- and São Jorge, and discovered the first to hypogean life, very often belong- lated species elsewhere in the world. It is cave-dwelling species (see Oromí et al., ing to unusual taxonomic groups in the difficult to say that these species evolved 1990). The same team visited again the continental cave faunas. This is due to according to the classical climatic relict archipelago in 1989, also joining the first the inability for some of these groups hypothesis proposed for the troglobites Azorean biospeleologist (Paulo Borges) AMCS Bulletin 19 / SMES Boletín 7 — 2004 101

Table II. Islands of the Azorean archipelago. Ages in million years (after França et al., it was at the sea level (now the cave is 2004). Presence or absence of volcanic caves with apparent conditions to hold troglo- higher up). It was recently visited by bitic fauna. Presence or absence of troglobites. a biologist from La Laguna who was looking for cave fauna. The conditions are not good for trogobites, and just a troglophilic spider was collected (Sper- mopohorides selvagensis Wunderlich) (Arechavaleta et al., 2001). Canary Islands for the study of caves in São Miguel, Madeira Islands where they also were helped by the This is the larger archipelago and the local caver Teófilo Braga (Amigos dos The archipelago of Madeira is located closest to the mainland (110 km from Açores). They also visited Pico, São at latitude of 33ºN and is formed by Fuerteventura to the Sahara coast), being Jorge, Faial and Graciosa, and found two main islands, Madeira and Porto situated between 27° and 29° N. Their new troglobitic species in all except Santo, and the Desertas islets. Porto ages rank from 21 Ma (Fuerteventura) to Graciosa (Oromí et al., 1990; Oromí & Santo is an old island (15 Ma), without less than 1 Ma (El Hierro), in such way Borges, 1991; Mahnert, 1990; Merrett & lava tube caves and troglobitic fauna that the age decreases from east to west Ashmole, 1989). Since then the biospe- known so far. Madeira is younger (5.5 (see Table III). The origin of the Canaries leologist team created in Universidade Ma) but with scarce recent volcanism, is not related to the mid-Atlantic ridge dos Açores at Terceira, has continued the and therefore with few caves. How- like the Azores but to a hotspot model research on cave fauna from the different ever, the island had often been visited with the peculiarity that the older islands islands, and now they have an advanced by entomologists which sporadically still continue with volcanic activity (Car- knowledge on the Azorean hypogean entered the caves and discovered a few racedo et al., 1998). This has allowed fauna, both from caves and from the troglobitic species of woodlice (Vandel, the presence of modern lavas on all the MSS. The BALA Project carried out in 1960), spiders (Wunderlich, 1992) and islands except La Gomera where no 1998-2001 and directed by Prof. Paulo beetles (Erber, 1990; Serrano & Borges, eruptions have occurred along the last 3 Borges provided a remarkable improve 1995). In 2000 the GIET team from the Ma (Cantagrel et al., 1984). The islands on the knowledge of the Azorean fauna University of La Laguna organized a with more volcanic caves are Lanzarote, (Borges et al., 2005a, 2005b). research expedition to Madeira and vis- Tenerife, La Palma and El Hierro. The Actually 20 species of troglobites ited Grutas do Cavalum (Machico) and lava tube caves in Lanzarote are large have been found on the archipelago, Grutas de São Vicente, but it has been and abundant, but the aridity of the cli- belonging to eight different orders of after 2002 when Dora Aguín and Elvio mate and the scarce soil covering the (Borges & Oromí, 1994 and Nunes, from Universidade da Madeira, lavas prevents the existence of the neces- in press). All of them are endemic to a who carried about for the first time an sary humidity for the existence of a true single island, except a few which are accurate study of Machico caves, and troglobitic fauna. The islands containing found both in Pico and Faial, This is discovered several unknown troglobites more troglobites are Tenerife, La Palma difficult to explain unless a land con- (Nunes et al., 2003). and El Hierro. In Fuerteventura they are nection existed between the two islands The cave-dwelling fauna from Ma- also rare because of the dry climate, but in the past allowing troglobites to move deira is not very rich in species, which there are two species. In Gran Canaria to each other, separated by less than have a little marked degree of troglomor- there are few caves, but recent research 50 m depths (see Eason & Ashmole, phism (Serrano & Borges, in press). This points to the presence of an adapted 1992); however, this hypothesis is con- is the only archipelago in Macaronesia fauna. A similar situation occurs on La troversial since the western part of Pico where no cave-adapted Gomera, where there are no caves at all is extremely recent, probably younger have ever been found. Not a single genus but a few hypogean species inhabit the than the descent of sea level during the of arthropods includes various troglobitic MSS in the humid forest. last glaciation (João C. Nunes, pers. species, which probable indicates that The studies on the underground fauna comm.). The hypogean species from its limited underground environment has in the Canaries early started in 1892 the Azores have a moderated degree not promoted the radiative evolution in when the crab Munidopsis polymorpha of troglomorphism, with an obvious this habitat. was described from the anchialine cave reduction of eyes but never reaching Selvagens Islands Jameos del Agua (Lanzarote), together the eyeless condition, and never with a with some other adapted species (Koel- very marked lengthening of appendages. This very small and isolated archipelago bel, 1892). The animal community of this The most remarkable case of splitting is between Madeira and the Canaries, at cave and the neighbouring Túnel de la is found in the genus Trechus which 30° N. It originated some 24 Ma but it Atlántida has been intensively studied includes seven different cave-dwelling after remained under the sea level for a along the last century, and as much as 25 species in the archipelago (see Oromí long time, when new eruptions emerged species adapted to this particular habitat & Borges, 1991; Borges & Oromí, 1991 again the islands between 12 and 8 Ma. are so far known (Oromí & Izquierdo, and in press; Borges et al., 2004). They are low islands (less than 150 m) 1994, in press). It is remarkable the and only Selvagem Grande has one cave, existence of Speleonectes ondinae, the formed in a dyke by marine erosion when only Remipede crustacean known from 102 AMCS Bulletin 19 / SMES Boletín 7 — 2004 the oriental part of the Atlantic. Table III. The islands of the Canary archipelago set from west to east according to their The first terrestrial troglobite to be geographic position. Ages in million years. Presence of caves apparently suitable to hold described was Collartida anophthalma, terrestrial adapted fauna. Number of troglobitic species. discovered in the early 80’s by catalan cavers in El Hierro (Español & Ribes, 1983). At this time was created the Grupo de Investigaciones Espeleológicas de Tenerife (GIET) from the University of La Laguna (Tenerife), which has been regularly studying the hypogean fauna on the cave fauna from the Canary Is- exceptions. with a remarkable success (Oromí & lands and its conservation. Various genera having undergone Izquierdo, 1994, in press). In the Museo The hypogean fauna from the Canar- radiative evolution on the Canaries are de Ciencias Naturales de Tenerife also ies is the richest in Macaronesia, 132 of also represented in the underground the late J.J. Hernández Pacheco was ac- terrestrial troglobitic and 57 aquatic sty- fauna, like the spiders Dysdera (9 spp.) tive on cave research up to his death in gobiont (either freshwater or anchialine) and Spermophora (5 spp.). In other gen- 1993 (Hernández Pacheco et al., 1995), species having been found so far. This is era such as the cockroaches Loboptera and in La Palma island members of the also the fauna with the most advanced (Blattaria), the planthoppers Meenoplus G.E. Benisahare club also studied degree of troglomorphism among these (Hemiptera) and the beetles Domene many caves with discoveries of many Atlantic islands, including some species and Wolltinerfia (Coleoptera) this ra- interesting hypogean species (García & such as the thread-legged bug Collartida diation has originated only troglobitic Oromí, 1996; Machado, 1998). anophthalma (Hemiptera, Reduviidae) species(see Table IV). There are also The organization in 1992 of the 10th and the rove- Domene vulcani- hypogean species with no relatives on the Int. Symposium of Biospeleology in ca (Coleoptera, Staphylinidae) easily surface, neither belonging to the same Tenerife by the GIET team, and the 7th comparable to the most troglomorphic nor to close genera, for which they can Int. Symposium on Vulcanospeleology in species from the Palaearctic. The most be considered as relict species whose 1994 in La Palma by Junonia and GIET adapted fauna to the underground occurs epigean ancestors disappeared from the groups, show the intense activity and the in the modern terrains of Tenerife, while islands after originating the actual hy- relevance of their studies. Between 1999 the hypogean species from the western pogean forms. In this sense they are re- and 2001 this team from La Laguna car- islands (La Palma and El Hierro) are markable the cases of Tyrannochthonius ried out a research LIFE-Nature project usually more ambimorphic with some and Lagynochthonius (Pseudoscorpiones

Table IV. polyspecific genera with troglobites in the Canary Islands. The islands where each species occurs are indicated (H: El Hierro; P: La Palma; G: La Gomera; T: Tenerife; F: Fuerteventura). AMCS Bulletin 19 / SMES Boletín 7 — 2004 103

Chthoniidae), Maiorerus (Opiliones of an adapted fauna on this archipelago. Ciencias, 12 (3-4) (2000): 83-99. Laniatores), Collartida (Hemiptera Troglobites were found only in caves ASHMOLE, N.P., P. OROMÍ, M.J. Reduviidae) or Spelaeovulcania and above 2000 m from the sea level, be- ASHMOLE & J.L. MARTIN. 1992. Canarobius (Coleoptera Carabidae). ing remarkable for their adaptations the Primary faunal succession in volcanic One of the most interesting features of planthopper Nysia subfogo (Hemiptera, terrain: lava and cave studies in the the Canary hypogean fauna is the pres- Meenoplidae), a Cryptopidae centipede Canary Islands. Biological Journal ence of unexpected groups in such fau- and two still undescribed spiders (Hoch Linnean Society, 46: 207-234. nas of the neighbouring mainland. The et al., 1999). BARR, T.C. 1968. Cave ecology and the cave-adapted cockroaches are unknown The aridity of Cape Verde prevents evolution of troglobites. Evolutionary in the whole Palaearctic, while landhop- most of its caves to be inhabited by tro- Biology, 2: 35-102. pers (Amphipoda Talitridae), earwigs globites, since the inner environment is BORGES, P.A.V., C. AGUIAR, J. AMA- (Dermaptera) and thread-legged bugs highly influenced by the climate outside. RAL, I.R. AMORIM, G. ANDRÉ, (Hemiptera Reduviidae) have troglobitic Only in Fogo the Chã das Caldeiras caves A. ARRAIOL, A. BAZ, F. DINIS, species only in the Canary Islands and covered by a thick layer of cinders are H. ENGHOFF, C. GASPAR, F. IL- in Hawaii. isolated and keep humidity enough for HARCO, V. MAHNERT, C. MELO, Cape Verde Islands the development of true cave-dwelling F. PEREIRA, J.A. QUARTAU, S. species. More visits and research are RIBEIRO, J. RIBES, A.R.M. SER- The Cape Verde Islands are the south- needed to better know this adapted fauna, RANO, A.B. SOUSA, , R.Z. STRAS- ernmost in Macaronesia, being located which is probably richer than the few SEN, L. VIEIRA, V. VIEIRA, A. some 500 km west of Dakar, in Senegal. species so far discovered. VITORINO, & J. WUNDERLICH. They form a double arch of islands, the The hypogean fauna from Macaron- 2005a. Ranking protected areas in windward islands (Ilhas de Barlavento) esia is abundant in spite of being recently the Azores using standardized sam- and the leeward islands (Ilhas de So- studied, it is varied and has a special pling of soil epigean arthropods. tavento) with ages decreasing from east interest for the peculiarities due to the Biodiversity and Conservation, 14: to west. The easternmost islands (Sal, insular condition. All troglobitic species 2029-2060. Boavista and Maio) are low and rather are endemic to reduced areas, since they BORGES, P.A.V., R. CUNHA, R. GA- flat, with an arid climate and very few are almost always exclusive to a single BRIEL, A. F. MARTINS, L. SILVA, caves due to erosion in such old terrains. island. They are the result of local pro- & V. VIEIRA, (eds.). 2005b. A list of Santo Antão, São Vicente, São Nicolau, cesses of speciation, with the appearance the terrestrial fauna (Mollusca and and Santiago are mountainous but with of troglomorphic characters in groups Arthropoda) and flora (Bryophyta, hardly any recent volcanism for which often unexpected in other parts of the Pteridophyta and Spermatophyta) lava tubes are also scarce: only a few world. But they are often threatened from the Azores. Direcção Regional unexplored caves in Santo Antão and the species as well, since the fragility of do Ambiente and Universidade dos clay-silted Gruta do Lázaro in Santiago their environment is remarkable. Many Açores, Horta, Angra do Heroísmo are known. But in Fogo island there is an caves on the Azores are silting up due to and Ponta Delgada, 318 pp. active recent volcanism (last eruption in transformation of forest in pastureland, BORGES, P.A.V. 1993. First records for 1995) with abundant basaltic lavas which the few caves in Madeira are absolutely the Mesocavernous Shallow Stratum have originated abundant caves, though spoiled for tourist use without any sen- (MSS) from the Azores. Mémoires never as large as those from the Azores sibility by the owners (case of Grutas Biospéologie, 20: 49-54. and the Canary Islands. The relatively de São Vicente) or very damaged by BORGES, P.A.V. & P. OROMÍ. 1991. recent lava tube caves related to the uncontrolled visits and vandalism (case Cave-dwelling ground beetles of the main volcano (both in Chã das Caldeiras of Grutas do Cavalum); and many caves Azores (Col., Carabidae). Mémoires and on the eastern slopes of the island) on the Canary Islands are more and more Biospéologie, 18: 185-191. are better preserved than those in older severely polluted by sewage (case of BORGES, P.A.V. & P. OROMÍ. 1994. terrains of the rest of the island. Cueva del Viento and other lava tubes in The Azores. In C. Juberthie & V. Decu Knowledge and popularization of Icod de los Vinos), stupidly transformed (Eds.) Encyclopaedia Biospeologica, caves has been scarce in Cape Verde. as show-caves in spite of the presence vol. I. Soc. Biospéologie, Moulis and Besides some popular believes (the so of protected species (case of Cueva del Bucarest, 605-610. called “grutas de Lázaro” on Santiago, Llano in Fuerteventura and the endan- BORGES, P.A.V. & P. OROMÍ. In press. where supposedly this Robin Hood like gered Maiorerus randoi), or spoiled by The Azores. In C. Juberthie & V. Decu bandit hid his treasures) and a few refer- uncontrolled visits. The troglobitic fauna (Eds.) Encyclopaedia Biospeologica, ences in modern tourist guides (Schleich has a low resistance to environmental vol. I. Soc. Biospéologie, Moulis and & Schleich, 1995), very little is pub- changes and they can easily disappear Bucarest, in press. lished about this subject. The serious from the caves. BORGES, P. A. V., A. R. M. 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