The paper discusses the bryophyte flora of 77 sites in the Mecsek Mountains, mainly in deeper valleys. It includes species that are new to the area’s flora and/or endangered in Hungary, as well as mosses that have become more widespread or locally abundant compared to data from 1968 and 1983. The names of the locations, their geographical centers (centroids), and the grid unit IDs of the Hungarian Flora Mapping Programme (HFMP), where the sites are located, are listed and refer­enced according to their number in the list. Some of the species are national rarities, such as Scleropo­dium touretii, newly recorded in the Mecsek in 2023. Its second known occurrence in Hungary is re­ported in the Enumeration. We detail the occurrences of several species new to South Transdanubia, including Dicranum spurium, Diplophyllum albicans, Hypnum jutlandicum, Isothecium myosuroides, Kindbergia praelonga, Rhynchostegiella curviseta, Riccardia palmata, and Sciuro-hypnum plumosum. Additionally, species newly recorded from the Mecsek Mountains include Fontinalis antipyretica, Lepto­don smithii, Plagiomnium ellipticum, Pseudocampylium radicale, and Tortula brevissima. For two taxa, we present data of importance not only for the Mecsek, but also for the North-Hungarian Mts: Riccardia palmata, new for the Tornai-karszt, and Dicranum spurium, for which we confirm a very old record in the Zemplén Mts. We also note the widespread, sometimes massive occurrence of some aquatic and subaquatic mosses, e.g. Rhynchostegiella teneriffae, Hygrohypnum luridum, which have been recorded only once in the mountains in the last 50 years. The taxonomically uncertain Hygroamblystegium fluvia­tile with similar habitat requirements can now be found widely throughout the mountains. New popu­lations of Palustriella commutata, considered endangered and declining in the country, have been found in the Mecsek. The expansion of (sub-)aquatic species is particularly surprising in the light of recent hydroecological studies indicating that the streams in the Mecsek are drying up. The situation is similar regarding Rhynchostegium rotundifolium, previously thought to be a Tilio-Acerion (slope and ravine forest) species, which is legally protected in Hungary and only had one record from the Mecsek in the last century. This forest species is now found in peri-urban, sub-urban, slightly to moderately disturbed and secondary habitats throughout the mountains. Similar to its preference in Germany, outside of semi-natural habitats it occurs mainly on built structures in forest edges, ruins, abandoned mine sites, often in stands mixed with black locust and contaminated with litter. Microeurhynchium pumilum, which prefers sub-Mediterranean and sub-Atlantic climate, shady and humid habitats, has become one of the most widespread and abundant forest bryophytes in the Mecsek, in contrast to its few records 60 years ago. Half (50%) of the new mosses in the flora of the Mecsek can be connected to the cooler bore­al biome, while 21% is associated with the milder Mediterranean-Atlantic biome. The average of MAT (mean annual daily mean air temperatures averaged over one year) and MAP (accumulated precipita­tion amount over one year) of the 14 new species according to BET (Bryophytes of Europe Traits) indi­cates areas with much lower temperatures (7.7°C) than in Hungary, but with precipitation conditions (749 mm) similar to those in the Mecsek. The vast majority of the new species are extremely rare in Hungary, and are inconsistent with current climate warming trends. In contrast to the mosses with striking increase in records, the detection of new species is likely due to chance, in addition to system­atic research at finer spatial scales, rather than to local expansion of the species. However, in the case of expanding and abundant species, it is still an open question whether their dynamics compared to 40-60 year old references are apparent or real: the result of sampling bias in previous surveys or a conse­quence of climate change. In any case, the abundance of the above mentioned bryophytes in the Mecsek is not consistent with their current Hungarian Red List threat classification, and this cannot be attribut­ed to changes in definitions since 2010. The detected distribution and abundance, as well as the in­crease in the number of new species in the country within a decade, highlights the need for an updated Red List of Hungarian bryophytes.