World distribution: The species is distributed from southern Scandinavia to North Africa, and from Great Britain to the Ural (James & Rose 1974b, Esslinger 1977). The British and Scandinavian distribution resembles that of M. elegantula. Melanelia laciniatula is rare in Sweden except in Skåne (Ingelög et al. 1993, map), and is spreading in Denmark (Alstrup & Søchting 1989)
Ecology: Results. The species was reported from Quercus sp. (1) and Tilia sp. (1), in parks or on roadside trees within or near cities. In one locality (1472) it was found together with Physconia grisea. Discussion. The ecological requirements of Melanelia laciniatula are very similar to those of M. elegantula and the two species are often associated (James & Rose 1974a, 1974b). Melanelia laciniatula is more strongly confined to the boles of broadleaved trees, especially Ulmus glabra and Acer pseudoplatanus, as well as Quercus spp. and Fraxinus excelsior (James & Rose 1974b, Thell 1989). It is most frequently found on roadside trees, especially near villages and small towns, and is tolerant of moderate eutrophication (James & Rose 1974b, Thell 1989) as well as SO2 pollution (up to 65 µg/m3, Purvis & James 1992c). Melanelia laciniatula is often mentioned under the phytosociological alliance 'Xanthorion', but it appears to require a somewhat lower pH, and, like M. elegantula, grows in habitats where the genera Phaeophyscia, Physcia, Physconia, and Xanthoria are of minor importance (Almborn 1948, Barkman 1958, James & Rose 1974b, James et al. 1977). According to James & Rose (1974b) acidification of bark surfaces of such trees as Ulmus, Fraxinus, and Acer increases the substrate availability for M. laciniatula. It is also reported from worked timber in the British Isles (Brightman & Seaward 1977)
Threats: Results. Recorded threat was road construction (1). Discussion. The species is, as M. elegantula, moderately resistant to SO2, and is in the process of spreading rapidly in many lowland areas of the British Isles (James & Rose 1974b). It is more common in Sweden than M. elegantula (Thell 1989), and since it favours well-lit trees near towns, it should hardly be threatened
Status: Two old localities were visited, and a small populations of 3-4 cm2 were found on two old trunks of Tilia sp. in a park in one locality (1472). The other locality (2438) was destroyed by a road expansion, and the species was considered to be extinct. No new localities have been recorded since 1969. There are no protected localities
Specimens in other herbaria, litterature, etc.