## 4 Discussion
### Temperature and Osmotic Tolerance as Indicators of Environmental Preferences  
The thermal trials yielded important information on the optimum temperature of the studied strains, their growth range, and also on their growth rate. The majority of the strains grew within the range 5-30 \({}^{\circ}\)C, 39% of them instead within 0-35 \({}^{\circ}\)C, and only one, _E. oligosperma_ CCFEE 6327, at 37 \({}^{\circ}\)C. With respect to their growth rate, the studied strains can be clustered into three groups: fast-; mid-fast-; and slow-growing black fungi. The majority of the slow-growing fungi (e.g., _V. calcicola_ CCFEE 5770, _C. uncultatum_ CCFEE 5737, and _Knutfa_ species) have been recorded from stone surfaces only; the others, namely the fast-growing (_A. pullulans_ CCFEE 5736, and _Sacotheiaceae_. CCFEE 5778) and the mid-fast- growing species (e.g., _E. bontarie_ and _E. oligosperma_, Unknown CCFEE 5945, _Verr. dirime_ CCFEE 5707, and _N. capensis_ CCFEE 6200), can be considered at least in part to be occasional. _A. pullulans_ is considered, indeed, a generalist that can inhabit different habitats without substantial specialization at the genomic level [54], and _E. oligosperma_ is a well-known opportunistic isolated from a number of household environments such as tap water and diesel car tanks [41; 55; 56]. This confirms the two survival strategies in fungi from extreme environments: they can be either widespread generalists, thriving in both extreme and moderate conditions, or specialists more or less confined to extremes [57; 58; 59].  
Growth rate can even be drastically affected when salt is addicted to culture medium. All the tested strains were able to grow at 3.5% of NaCl. This trait increases their fitness for the site, being close to the sea with saltiness periodically deposited and washed away from surfaces with rains. Anyway, different degrees of tolerance were recorded, and strains tested grouped with respect to their response to increasing salt concentration and to their limits. The lowest tolerance has been recorded for _C. uncinatum_ CCFEE 5737 and the unknown CCFEE 5945. The majority of the strains have their limits between 7 (6/18) and 10% (5/18), respectively. Five, instead, can grow up to 20%. While _A. pullulans_ showed a broad-range tolerance to salt, _Verr. dirinae_ CCFEE 5707, _N. bulbillosa_ CCFEE 5704, _Sal. thailandicus_ CCFEE 5723, and _Neoph. triangularis_ CCFEE 5703 proved to be halophilic. The halophilic trait for a part of them was already reported [60, 61], however, it was not for _N. bulbillosa_ CCFEE 5704 and _Verr. dirinae_ CCFEE 5707, which ability was suggested by indirect evidences only. For example, _N. bulbillosa_ was isolated from limestone formations in Cala Saint Vincen\(\mathcal{G}\) in Mallorca Island, so possibly subjected to some extent to saltiness [62]. Otherwise, _Verr. dirinae_ is worth a mention as even if described as a parasite of the lichen _Dirina massiliensis_[63], it has been isolated from other substrates/salted niches such as wood and marine macroalgae [64, 65]. Moreover, the presence of some BF has been suggested to be in relation with the biodeterioration degree of tombstones [66].