Diet and body condition of cave‐dwelling dwarf crocodiles (Osteolaemus tetraspis,Cope 1861) in Gabon

We present the first ever observations of dwarf crocodiles (Osteolaemus tetraspis) selectively utilizing a cave ecosystem. We analysed crocodile diet to preliminarily assess the degree of ecological isolation of cave‐dwelling crocodiles from their forest‐dwelling conspecifics despite their physical proximity. We additionally conducted the first study of body condition of dwarf crocodiles and compared cave‐dwelling individuals to surface‐dwelling individuals from a variety of alternative habitats and sites as a means to better understand the implications of a semihypogean life on this species. Crocodiles captured in the caves appeared to forage exclusively in the caves and ate mostly cave crickets and bats, whereas crocodiles captured in the surrounding forest habitat consumed primarily freshwater crustaceans and insects and were not found to consume cave‐dwelling prey. Juvenile cave crocodiles had significantly higher body condition compared to juvenile forest crocodiles, which did not vary amongst forest locations. The difference in body condition between adult cave and forest crocodiles was not statistically significant despite also being higher; we suspect this is an artefact of the low sample size rather than a real nondifference. Forest adult crocodiles generally had significantly higher body condition than juveniles, but did not vary by site or habitat. This lack of variation suggests that habitat type is not the most important factor influencing dwarf crocodile body condition. Our results provide a unique insight into facultative cave use by a principally surface‐dwelling species and reinforce the necessity for further research into this unique system to better understand the evolutionary‐scale implications of cave habitat use by dwarf crocodiles.     

Evolution of cave living in Hawaiian Schrankia (Lepidoptera: Noctuidae) with description of a remarkable new cave species

Although temperate cave‐adapted fauna may evolve as a result of climatic change, tropical cave dwellers probably colonize caves through adaptive shifts to exploit new resources. The founding populations may have traits that make colonization of underground spaces even more likely. To investigate the process of cave adaptation and the number of times that flightlessness has evolved in a group of reportedly flightless Hawaiian cave moths, we tested the flight ability of 54 Schrankia individuals from seven caves on two islands. Several caves on one island were sampled because separate caves could have been colonized by underground connections after flightlessness had already evolved. A phylogeny based on approximately 1500 bp of mtDNA and nDNA showed that Schrankia howarthi sp. nov. invaded caves on two islands, Maui and Hawaii. Cave‐adapted adults are not consistently flightless but instead are polymorphic for flight ability. Although the new species appears well suited to underground living, some individuals were found living above ground as well. These individuals, which are capable of flight, suggest that this normally cave‐limited species is able to colonize other, geographically separated caves via above‐ground dispersal. This is the first example of an apparently cave‐adapted species that occurs in caves on two separate Hawaiian islands. A revision of the other Hawaiian Schrankia is presented, revealing that Schrankia simplex, Schrankia oxygramma, Schrankia sarothrura, and Schrankia arrhecta are all junior synonyms of Schrankia altivolans. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 156 , 114–139.     

Spatial segregation among age classes in cave salamanders: habitat selection or social interactions?

Within species, individuals with different sexes, morphs and age classes often show spatial segregation. Both habitat selection and social processes have been proposed to explain intraspecific spatial segregation, but their relative importance is difficult to assess. We investigated spatial segregation between age classes in the cave salamander Hydromantes (Speleomantes) strinatii, and used a hypothetico-deductive approach to evaluate whether social or ecological processes explain segregation pattern. We recorded the location and age class of salamanders along multiple caves; we measured multiple microhabitat features of different sectors of caves that may determine salamander distribution. We assessed age-class segregation, and used generalized mixed models and an information-theoretic framework, to test if segregation is explained by social processes or by differences in habitat selection. We found significant age-class segregation, juveniles living in more external cave sectors than adults. Multiple environmental features varied along caves. Juveniles and adults showed contrasting habitat selection patterns: juveniles were associated with sectors having high invertebrate abundance, while adults were associated with scarce invertebrates and low temperature. When the effect of environmental features was taken into account, the relationship between juveniles and adults was non negative. This suggests that different habitat preferences, related to distinct risk-taking strategies of age classes, can explain the spatial segregation. Juveniles require more food and select more external sectors, even if they may be risky. Conversely, adults may trade off food availability in favour of safe areas with stable micro-climate.     

The distribution of cave twilight‐zone spiders depends on microclimatic features and trophic supply

Caves are not closed systems. Trophic dynamics in these habitats are driven by resource availability, and species that move between cave and outdoor environments may play a major role in resource availability. Spiders are among the most abundant invertebrates in caves; however, very few studies have tested factors hypothesized to affect the distribution of spiders among caves, and it is not known whether the trophic features of caves play a role in determining the occurrence, abundance, or breeding success of spiders. We assessed the distribution of the cave‐dwelling orb‐weaver spider Meta menardi in Italy, in a Mediterranean and in a Pre‐alpine area during summer and winter. We analyzed the relationships between spider distribution and multiple cave features, describing both the abiotic and the biotic environment. Using visual encounter surveys, the detection probability of this species was high, indicating that this technique provides reliable information on spider distribution. In Mediterranean caves, spider presence was more likely in cold and wet caves with abundant dipterans. In Pre‐alpine caves, spider presence was more likely in deep caves with abundant dipterans. Dipteran abundance was the variable best explaining spider distribution when pooling all sampled caves. This study shows that adults of M. menardi do not occur randomly among caves, but select caves with specific features. Prey availability and abiotic features are major determinants of habitat suitability for cave spiders. The strong relationship between spider distribution and prey availability suggests that the distribution of these spiders might be an indicator of the resources available in the twilight zones of caves.     

Local genetic structure in the critically endangered,cave‐associated perennial herb Primulina tabacum (Gesneriaceae)

The local spatial genetic structures of cave‐associated plants are seldom studied. Given that these plants are mainly confined to small areas in and around the entrances of caves, we hypothesized that they might lack genetic structures at local scales. To test this hypothesis, we sampled two large populations (named D and T) of a critically endangered perennial herb, Primulina tabacum, which is endemic to karst caves in southern China. We analysed nine microsatellite loci and sequenced four chloroplast DNA (cpDNA) intergenic spacer regions to study the genetic diversity and structure within and between both populations. Both populations have distinct genetic characteristics. Samples from two subpopulations in population D showed considerable genetic divergence. This is not consistent with the hypothesis that P. tabacum has a weak genetic structure at a local scale. However, 94% of the individuals in population T shared the same multilocus genotype, which indicates little genetic structure within this population. The contributions of seed flow, pollen flow and (sub)population history to the genetic diversity and structure in each and both populations are discussed. Our study is the first to investigate local genetic diversity and structure in a cave‐associated plant, and provides valuable information for the sustainable conservation of such species. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 747–756.     

Big family,warm home,and lots of friends: Pteronotus large colonies affect species richness and occupation inside caves

Roosts are essential for the survival of most animals. Due to homothermic requirements, mammals are particularly dependent on roost quality and availability. Bats select their roosts in a species-specific way, likely related to species´ different physiological and adaptive needs. Unlike species whose individuals roost solitarily, roost selection is critical for bats forming large colonies due to the requirements for maintaining thousands of individuals in a single shelter. This is the case of Pteronotus (Mormoopidae), whose colonies reach hundreds of thousands of bats. Using captures, bioacoustics, and automated censuses, we evaluated how cave size, ceiling characteristics, environmental stability, temperature, and humidity influence the formation of exceptionally large colonies, species richness and composition in caves in north-eastern Brazil. We expected that colonies would be positively related to cave size and stability, internal cave selection would be species-specific, but larger and more environmentally stable caves would have higher richness. Pteronotus colonies were positively related to cave size, stability, and ceiling characteristics, and their presence strongly influenced cave temperature variation. Species richness was positively correlated to a cave stability index. Species other than Pteronotus preferred different climatic and ceiling characteristics. We detected an indirect influence of the large colonies of Pteronotus on the species richness and occupation inside caves. On the other hand, such caves favor species coexistence, as they offer a range of microenvironments, reducing niche overlap in their interior. Pteronotus gymnonotus and Pteronotus personatus are both key- and umbrella-species for cave ecosystems, stressing the need for specific conservation strategies in Brazil. Abstract in Portuguese is available with online material.     

Troglomorphic Sculpins of the Cottus Carolinae Species Group in Perry County, Missouri: Distribution, External Morphology, and Conservation Status

The existence of cavernicolous sculpin (here allocated to Cottus carolinae, banded sculpin, and referred to as grotto sculpin), in the karst regions of Perry County, Missouri, first came to our attention in 1991. Examination of 35 caves in Missouri, 96 in Illinois, 17 in Tennessee, two in Indiana, and 11 in Arkansas revealed that banded sculpin are common in cave habitats; however, grotto sculpin are limited to two karst areas of Perry County, Missouri, where they are known from only six cave systems. These caves and their streams are extensive and apparently provide a unique habitat compared to other karst systems; this may be a critical factor in the present restricted distribution of the grotto sculpin. Grotto sculpin occupy pools and riffles of cave streams, and occur over a variety of substrates, from sediment to breakdown. Density estimates in Mystery and Running Bull caves were 0.29 and 0.63 individuals m^-2, respectively. Grotto sculpin have small eyes (1–6% SL vs. 6–10% SL in epigean samples), significantly reduced pigmentation (including nearly complete loss of dorsal saddles), a reduction in pelvic fin ray number (from 4+4 elements to often 4+3 , or 3+3), and enlarged cephalic lateralis pores (e.g., mandibular pores of cavernicolous samples are 2–3 times those of epigean stream samples). Multivariate analyses of body shape revealed statistically significant separation of epigean and hypogean samples, with eye size highly variable, but smallest in the Running Bull Cave population. We interpret these results as representative of losses associated with long-term cave habitation. Caves of Perry County provide ample habitat for grotto sculpin, but because the caves are located downgradient of the city of Perryville and an intensively farmed landscape, point and non-point source pollution threaten their continued existence. Escape of farm-pond fishes through the extensive sinkhole network in Perry County has increased potential predation pressure on grotto sculpin by channel catfish, Ictalurus punctatus, and other species normally excluded from cave environments.     

中华菊头蝠的栖息生态特征及种群保护

中华菊头蝠(Rhinolophus sinicus)主要分布于我国境内,属于典型的洞栖食虫性蝙蝠,具有重要的研究意义与保护价值。近年,在湘西州境内的16个溶洞中对其栖息生态特征进行了观察,共记录到其个体12942只次,数据分析结果显示：该蝠是该区域溶洞中的居留型优势蝠种,具有集群冬眠的习性。每年的9月中下旬开始逐步聚群冬眠,翌年的3月底开始苏醒,其夏季的繁育场所非常隐蔽,通常位于人无法进入的洞段或人迹罕至的洞穴。总体上,其栖点主要集中于距洞口150—200 m(91.60%)的洞段,离地高度6—10 m(91.75%),多以“双足悬挂”的栖姿将身体悬空倒挂于洞道的顶壁。其体温与栖点温度之间不存在显著性差异(P>0.05),但具有明显的线性正相关关系(R~2=0.8886)。其栖点安全性春夏季高,秋冬季中等偏低。中华菊头蝠作为该区域洞栖性蝙蝠的优势种,在维持洞穴生态系统的稳定中发挥着至关重要的作用,加强对洞穴生态系统中蝙蝠伞护性的研究有助于洞穴生态保护教育及对蝙蝠种群的保护实践。     

Roosting ecology and variation in adaptive and innate immune system function in the Brazilian free-tailed bat (<Emphasis Type="Italic">Tadarida brasiliensis</Emphasis>)

Bats have recently been implicated as reservoirs of important emerging diseases. However, few studies have examined immune responses in bats, and even fewer have evaluated these responses in an ecological context. We examined aspects of both innate and adaptive immune response in adult female Brazilian free-tailed bats (Tadarida brasiliensis) at four maternity roosts (two natural caves and two human-made bridges) in south-central Texas. Immune measurements included in vitro bactericidal ability of whole blood and in vivo T cell mediated response to mitogenic challenge. Bactericidal activity in T. brasiliensis varied with roosting ecology, but appears to be sensitive to colony-level effects. Blood from females living at one cave had significantly lower bactericidal ability than blood from females at three other sites. T cell mediated response in this species was associated with variation in roost ecology, with females from two caves having greater responses than females from two bridges. T cell mediated response and bactericidal activity were negatively correlated with one another within individuals that were tested for both. Variation in immunological response of T. brasiliensis is important for understanding the influence of the environment on the frequency and distribution of immunologically competent individuals and for understanding disease-host dynamics in this and other colonial species.     

Phylogeny and historical biogeography of the cave-adapted shrimp genus Typhlatya (Atyidae) in the Caribbean Sea and western Atlantic

Aim To infer phylogenetic relationships among five species of the cave‐adapted shrimp genus Typhlatya in order to test competing hypotheses of dispersal and colonization of the disjunct cave localities occupied by these five species. Location Typhlatya species are found in caves and anchialine ponds across the northern margin of the Caribbean Sea, along the Mediterranean and Adriatic coasts and on oceanic islands in the Atlantic and eastern Pacific oceans. This study focuses on five species, one from Bermuda, one from the Caicos Islands and three from the Yucatan Peninsula of Mexico. Methods Partial sequences (c. 1400 bp) from the mitochondrial cytochrome b, 16S rDNA and COI genes were obtained from representative samples of the five species. Phylogenetic inference was carried out with maximum parsimony and maximum likelihood analyses. Parsimony networks were constructed for the Bermudian species Typhlatya iliffei and one Yucatan species Typhlatya mitchelli, to determine the degree of connectivity among populations inhabiting different cave systems. Results All three land masses were recovered as monophyletic. The two insular marine species from Bermuda and the Caicos Islands formed a clade, while the three continental freshwater species from the Yucatan Peninsula formed another. Within both Bermuda and the Yucatan, shared haplotypes were found in different cave systems, suggesting recent or ongoing gene flow among populations in both locales. Main conclusions The two insular marine Typhlatya species originated from an ancestral marine population, possibly already cave‐adapted, that is suggested to have colonized the Caicos Islands and subsequently dispersed to Bermuda via the Gulf Stream. Divergence estimates suggest that colonization occurred before the formation of present‐day anchialine cave habitat, which did not form on either island until the late Pliocene to early Pleistocene. Divergence estimates also indicate that the Yucatan freshwater species split before the formation of freshwater cave habitat in the Yucatan. These species could have inhabited crevicular marine habitats before the late Pliocene/early Pleistocene in the Yucatan or elsewhere in the Caribbean, and subsequently migrated to freshwater caves once they formed.     

Population ecology ofGoniosoma spelaeum, a cavernicolous harvestman from south-eastern Brazil (Arachnida: Opiliones: Gonyleptidae)

Goniosoma spelaeum (Mello-Leitão) is a widespread trogloxene harvestman in caves of the Ribeira Valley in São Paulo State. It inhabits walls and ceilings near cave entrances. Populations inhabiting six selected caves of the region were analysed during this study. Mark-recapture techniques were used to estimate population sizes. Populations vary from tens to hundreds of individuals in each cave, and vary throughout the year. Barra Bonita cave had the largest population and was used to identify other ecological features of the species. These harvestmen show a high degree of philopartry, and recapture rate was high. They remain motionless inside the caves during the day, leaving them after dark to forage, and return just after dawn. They always feed outside the caves and do not carry food into the caves. Soft-bodied insects were the main food observed in the field. In the laboratory, they accepted plant and animal items and industrial foods. Their main predators are the spider Ctenus fasciatus , the heteropteran Zelurus travassosi , and the marsupial Philander opossum , and their main parasites are dipteran larvae (probably Phoridae).     

Is foraging innovation lost following colonization of a less variable environment? A case study in surface‐ vs. cave‐dwelling Asellus aquaticus

Behavioral innovation is a key process for successful colonization of new habitat types. However, it is costly due to the necessary cognitive and neural demands and typically connected to ecological generalism. Therefore, loss of behavioral innovativeness is predicted following colonization of new, simple, and invariable environments. We tested this prediction by studying foraging innovativeness in the freshwater isopod Asellus aquaticus. We sampled its populations along the route of colonizing a thermokarstic water‐filled cave (simple, stable habitat with only bacterial mats as food) from surface habitats (variable environment, wide variety of food). The studied cave population separated from the surface populations at least 60,000 years ago. Animals were tested both with familiar and novel food types (cave food: bacterial mats; surface food: decaying leaves). Irrespective of food type, cave individuals were more likely to feed than surface individuals. Further, animals from all populations fed longer on leaves than on bacteria, even though leaves were novel for the cave animals. Our results support that cave A. aquaticus did not lose the ability to use the ancestral (surface) food type after adapting to a simple, stable, and highly specialized habitat.     

Origins and Relationship of Cave Populations of the Blind Mexican Tetra, Astyanax Fasciatus, in the Sierra De El Abra

The blind morph of Astyanax fasciatus (Pisces: Characidae) has been more thoroughly studied than any other cave inhabiting organism. Most studies of A. fasciatus have used individuals from different caves of the Sierra de El Abra, Mexico, and have assumed that each population independently evolved to live in the cave environment. We analyzed the relationships among several cave populations that delineate the Sierra de El Abra using RAPD markers. The results indicate that all cave populations are more closely related to one another than they are to the surface populations. This suggests that present day cave populations derived from a common ancestral stock, most likely due to a single colonization event, or alternatively, that strong gene flow among cave populations has occurred, raising precaution against considering each cave population as independent.     

Fine-scale genetic population structure in a mobile marine mammal: inshore bottlenose dolphins in Moreton Bay, Australia

Highly mobile marine species in areas with no obvious geographic barriers are expected to show low levels of genetic differentiation. However, small‐scale variation in habitat may lead to resource polymorphisms and drive local differentiation by adaptive divergence. Using nuclear microsatellite genotyping at 20 loci, and mitochondrial control region sequencing, we investigated fine‐scale population structuring of inshore bottlenose dolphins (Tursiops aduncus) inhabiting a range of habitats in and around Moreton Bay, Australia. Bayesian structure analysis identified two genetic clusters within Moreton Bay, with evidence of admixture between them (F_ST = 0.05, P = 0.001). There was only weak isolation by distance but one cluster of dolphins was more likely to be found in shallow southern areas and the other in the deeper waters of the central northern bay. In further analysis removing admixed individuals, southern dolphins appeared genetically restricted with lower levels of variation (AR = 3.252, π = 0.003) and high mean relatedness (r = 0.239) between individuals. In contrast, northern dolphins were more diverse (AR = 4.850, π = 0.009) and were mixing with a group of dolphins outside the bay (microsatellite‐based STRUCTURE analysis), which appears to have historically been distinct from the bay dolphins (mtDNA Φ_ST = 0.272, P < 0.001). This study demonstrates the ability of genetic techniques to expose fine‐scale patterns of population structure and explore their origins and mechanisms. A complex variety of inter‐related factors including local habitat variation, differential resource use, social behaviour and learning, and anthropogenic disturbances are likely to have played a role in driving fine‐scale population structure among bottlenose dolphins in Moreton Bay.     

Climate change may drive cave spiders to extinction

Subterranean ecosystems present ideal opportunities to study mechanisms underlying responses to changes in climate because species within them are often adapted to a largely constant temperature. We have characterized the thermal conditions of caves in the western Alps, and related these hypogean climate data to the occurrence of Troglohyphantes spiders (Araneae, Linyphiidae). Our data indicated that present distributions reflect Pleistocene glaciation events and also pointed to specific responses as a consequence of changes in temperature. Constant temperatures recorded inside caves provide an approximation of the mean annual temperature outside, thus we extended the results to a regional scale. We used ecological niche modeling to predict habitat suitability both in the Pleistocene and under future global warming scenarios. These analyses pointed toward a future decline in habitat suitability for subterranean spiders and the potential extinction of the most restricted endemic species. When compared with other species that live in confined habitats such as islands and mountains, we expect cave species to be as much, if not more, vulnerable to climate change.     

Small‐scale genetic structuring in a tropical cave snail and admixture with its above‐ground sister species†

We analyse the phylogeographical structure in the cave snail Georissa filiasaulae Haase & Schilthuizen, 2007 (Gastropoda: Hydrocenidae) and its above‐ground sister species G. saulae (van Benthem‐Jutting, 1966) at limestone outcrops in Sabah, Malaysian Borneo. Morphometric and 16S mitochondrial DNA data for some 220 individuals reveal strong morphological differentiation, despite ongoing unidirectional gene flow from the epigean into the hypogean environment, strong, small‐scale genetic structuring within the cave and underground dispersal between caves that were previously thought to be isolated. We discuss these results – which constitute the first phylogeographical analysis of a terrestrial cave snail – in the light of speciation in cave organisms and across ecotones in general. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 727–740.     

The largest European lion Panthera leo spelaea (Goldfuss 1810) population from the Zoolithen Cave,Germany: specialised cave bear predators of Europe

Remains of 13 individuals with 3/1 male/female ratio of the extinct Upper Pleistocene lion Panthera leo spelaea (Goldfuss, 1810) from the Zoolithen Cave near Burggeilenreuth (Bavaria, Germany) include the holotype skull and all paratype material. The highest mortality rate for the Zoolithen Cave lions is in their reproductive adult ages. Bite marks on lion bones or skulls are results of hyena activities, or rare cannibalism of lions under stress situations. Lions were possibly also killed in battles with cave bears during predation on hibernating bears in winter times. This cave bear hunt specialisation in caves overlaps with the ecological behaviour of cave bear feeding by Ice Age-spotted hyenas. Both largest Ice Age predators, lions and hyenas, had to specialise on feeding herbivorous cave bears in boreal forest mountainous cave rich regions, where the mammoth steppe megafauna prey was absent. This cave bear hunt by felids, and scavenging by hyenas and other large carnivores such as leopards and wolves explains why cave bears hibernated deep in to the European caves, for protection reasons against predators. Within such lion–cave bear and even lion–hyena conflicts in the caves lions must have been killed sometimes, explaining mainly the skeleton occurrences in different European caves.     

Habitat Use,Roost Selection and Conservation of Bats in Tsingy De Bemaraha National Park,Madagascar

Although the land mammals of Madagascar have been the subject of many studies, the island’s bats have yet to feature prominently on the research or conservation agenda. In this study we used mist nets, acoustic sampling and cave surveys to assess habitat use, seasonality and roost selection. Four microchiropteran species (Triaenops rufus, T. furculus, Miniopterus manavi and Myotis goudoti) appeared to be strongly associated with the forest interior based on trapping, but analysis of time-expanded echolocation recordings revealed that T. rufus and M.␣manavi were frequently recorded in forest edges and clearings. Bat activity was significantly lower inside the forest than at the interface between agricultural land and forest. The caves visited most often by tourists were low in bat abundance and species richness. Anjohikinakina Cave, which was visited infrequently by people, was used by five species and contained between 54% (winter) and 99% (summer) of bats counted in 16 caves and is a site of national importance for bat conservation. Hipposideros commersoni was only netted in our study area during October and may be a migrant to the site or present but inactive during the austral winter. The forest surrounding the caves is therefore important because it provides cover for emerging bats and a potential source of invertebrate prey whilst the forest edge is important to foraging bats.     

The Occurrence of Fungi in the Recently Discovered Jarkowicka Cave in the Karkonosze Mts. (Poland)

Our study is one of the very few cases of speleomycological research in recently discovered caves. The aim of this research was to assess the population size of fungal colonies and their species composition in the Jarkowicka cave, discovered in 2012. The air samples were taken from one location outside the cave and from two locations inside of it. Mycological evaluation of the rocks inside the cave was performed usingswab sampling procedure. In the Jarkowicka cave we found 22 species of fungi, including 13 isolated from air at the entrance and from the walls, and 8 species from air inside the cave. Cladosporium spp. were the fungi most frequently isolated from internal atmosphere of the Jarkowicka cave, and from the external air. On the other hand, the fungi most frequently isolated from the rocks were Mucor spp. We found several species not yet described as cave inhabitants: Hypocrea pachybasioides, Cladosporium uredinicola, and Embellisia abundans. Our study may provide a basis for comparison to other similar studies conducted in frequently visited caves by tourists.     

Cyanidium chilense (Cyanidiophyceae,Rhodophyta) from tuff rocks of the archeological site of Cuma,Italy

Phlegrean Fields is a large volcanic area situated southwest of Naples (Italy), including both cave and thermoacidic habitats. These extreme environments host the genus Cyanidium; the species C. chilense represents a common phototrophic microorganism living in anthropogenic caves. With a view to provide a comprehensive characterization for a correct taxonomic classification, morpho‐ultrastructural investigations of C. chilense from Sybil's cave (Phlegren Fields) was herein carried out and compared with the thermoacidophilic C. caldarium. The biofilm was also analyzed to define the role of C. chilense in the establishment of a biofilm within cave environments. Despite the peculiar ecological and molecular divergences, C. chilense and C. caldarium shared all the main diacritic features, suggesting morphological convergence within the genus; cytological identity was found among C. chilense strains geographically distant and adapted to different substrates, such as the porous yellow tuff of Sybil cave, and calcyte, magnesite and basaltic rocks from other caves. C. chilense is generally dominant in all biofilms, developing monospecific islets, developing both superficially or between fungal hyphae and coccoid cyanobacteria. Extracellular polymeric substances (EPS) were recorded in C. chilense biofilms from Sybil cave, confirming the role of EPS in facilitating cells adhesion to the surface, creating a cohesive network of interconnecting biofilm cells.