This study documents the first records of the moss family Gigaspermaceae in Saudi Arabia. Two taxa were discovered in the southern and western highlands: Gigaspermum mouretii Corb., recorded from several granite slopes in Al Bahah and Mecca provinces, and Oedipodiella australis (Wager and Dixon) Dixon, found at multiple localities in the Asir Mountains. The material of G. mouretii is unequivocally paroicous and fertile, with sessile sporophytes bearing giant spores, thereby providing clear morphological support for its separation from G. repens. O. australis is sterile, as elsewhere outside South Africa, but readily identified by its characteristic apical gemma cups. Both species inhabit shaded sites on granitic or metamorphic substrates, typically in soil-filled pockets beneath boulders or on small ledges within open montane scrub and Juniperus procera woodland. These microhabitats provide partial shelter from solar radiation within generally xeric, steep slopes. To a certain extent, the new records reshape the biogeographical understanding of the family. G. mouretii extends its circum-Mediterranean pattern into Arabia, bridging the gap between Yemen and the Levant. O. australis, previously considered disjunct between southern Africa and Macaronesia/ southern Europe, now forms part of a broader Afro–Arabian–Mediterranean arc, suggesting long-term persistence in sheltered montane refugia rather than human-mediated introduction. These results show that the Arabian Peninsula occupies a central position between African and Mediterranean regions, and they emphasise how much remains to be discovered in its poorly surveyed mountain ranges.
The moss Bryum arachnoideum Müll.Hal. is reported from the Western Ghats of Kerala as new record for India. A detailed description and photographs are provided based on the fresh collections made during the explorations.
Lichenometry, a dating method that relies on the largest lichen to infer the age of a surface, is widely used due to its simplicity and affordability. However, several of the processes underlying the basic assumptions are assumed to be constant, while in reality they are climate-dependent, particularly those concerning colonisation, mortality, and thallus growth rates. This limits the comparability of lichenometric studies in different climates. Therefore, a better understanding of the environmental influence on lichen growth is required. Urban environments, with many homogeneous dated surfaces, can offer a unique opportunity to study lichen growth. To get a better understanding of urban lichen growth patterns, we investigated the largest Circinaria contorta thalli on sidewalks of varying ages in three temperate cities. Results suggest a sigmoidal growth pattern, reaching a peak radial growth rate of 1.68 mm year–1, similar to other temperate crustose lichens. Variation within and between cities is substantial and only partially explained by shade and sidewalk area. However, a rough estimation of concrete pavement age can be inferred from the largest thallus diameter.
The well-known limestone species Tortella fragilis consists of two species, which are clearly circumscribed by the nuclear molecular marker ITS, and the plastid atpB-rbcL and rps4. The morphological differences between the two are relatively small. Because all specimens cannot be identified with certainty they could be understood as semi-cryptic. The two differ in the orientation of dry leaves and the appearance of papillae on lamina cells in mid-leaf. Dry leaves of T. fragilis s.str. are often screwed or slightly so, and near the shoot apex numerous leaves are sometimes tightly adhering (or parallel) to each other and together slightly screwed, or sometimes more loosely so or somewhat curled, and the lamina cells are densely papillose with papillae that are difficult to distinguish individually and obscure the cell walls. In T. fragmenta, which is described as new, the leaves are at most slightly screwed, curled, also near shoot apex, and not or hardly adhering to each other, and the lamina cells are moderately densely papillose with distinct and sometimes forked papillae that do not obscure the cell walls. Tortella fragilis is widespread in Fennoscandia, whereas T. fragmenta occurs primarily in the mountain range, with scattered occurrences in the lowlands of the boreal zone. Both species occur in calcareous or base-rich sites, with a tendency for T. fragilis to grow in wetter sites than T. fragmenta.
