Diagnosis. Differing from Sticta fuliginosa in the arbuscular to penicillate isidia arising predominantly from the lobe margins, and from Sticta beauvoisii in the presence of abundant papillae on the cells of the cyphellary basal membrane.
Type: U.S.A. Alaska: Alexander Archipelago, Tongass National Forest, Coronation Island, Egg Harbor, Nation Point, beach fringe forest edge, on rocky headland at the point of entry into harbour, exposed to Chatham Straits NE aspect, NAD 27: 55°55.372' N, 134°19.596' W, elev. <3m, twigs of Picea sitchensis, 2003-08-12, K. Dillman 2003-911 (CONN 00225971, holotype [GenBank: MH017854, ITS]).
Description. Primary photobiont cyanobacterial (Nostoc). Stipe absent. Thallus irregular in outline, up to 1.5–2.0 cm diam., uni-lobed to at length becoming polyphyllous, brittle, rather fragile. Lobes rounded in outline to more often short-elongate, ascending except often weakly downturned toward the tips, imbricate; secondary lobes often involute; margins sometimes bearing expanded dorsiventral outgrowths of the isidia (and then appearing lacerate), not thickened; lobe internodes 1–4 mm long, 2–7 mm broad. Upper surface plane, grey or medium to dark brown when fresh, not much changing in herbarium, matt to somewhat shiny; margin concolorous; surface without papillae, pruina and cortical hairs, but occasionally with sparse maculae toward lobe tips. Cilia absent. Apothecia not observed. Isidia present, abundant, principally marginal, often continuous along margin, at times also laminal, and then branching upward, at length becoming arbuscular from a well-developed stalk; isidial ‘branches’ spreading and vertically oriented, up to 0.5 (0.6) mm long and 0.1–0.2 mm broad, darker than the thallus, greyish to more often dark brown, shiny, round in section, except basal portions of stalk often somewhat dorsiventral. Medulla rather compact, white, K–, C–, KC–, P–. Lower surface even, cream to brown-colored. Lower tomentum dense, sparse toward margin, thin, pubescent, soft, cream to brown-colored. Rhizines absent. Cyphellae sparse, 41–60 per cm2, scattered throughout, rounded to irregular, urceolate with a wide pore, erumpent to occasionally plane, white to pale cream, without tomentum; pore 0.1–0.5 (–1.0) mm diam.; basal membrane smooth, sometimes pruinose, white, K–, C–, KC–, P–.
Upper cortex paraplectenchymatous, 25–55 μm thick, homogeneous, consisting of 2–4 cell layers with cells 8–14 μm diam., their walls 1–3 μm thick and their lumina rounded to isodiametric, 6–12 μm diam. Photobiont layer 35–65 μm thick, its cells 9–12 μm diam. Medulla 110–240 μm thick, its hyphae 3.5 μm broad, without crystals. Lower cortex paraplectenchymatous, 25–45 μm thick, with 3–4 cell layers; cells 7–13 μm diam., their walls 1–3 μm thick. Hairs of lower primary tomentum 60–150 μm long, in fascicles of 6–12, unbranched, cylindrical hyphae with intertwined apices; occasionally moniliform when close to margins, appearing like a rosary of isodiametric cells. Cyphellae cavity 60–135 μm deep; cells of basal membrane most or less isodiametric, 6–8 μm wide, with papillae.
Chemistry. No substances were detected by TLC.
Etymology. This taxon is named in honor of our friend and colleague Tor Tønsberg on the occasion of his 70th birthday and in recognition of his outstanding, vigorous contribution to lichenology.
Ecology and distribution.Sticta torii is so far known as growing on the outermost branches of Alnus rubra, Malus fusca and Picea sitchensis in beach fringe localities more or less exposed to storms and the open ocean. It appears to be restricted to hypermaritime areas in which subfreezing temperatures are infrequent in winter. The Alaskan locality has been ice-free for approximately 16,000 years BP (Lesnek et al. 2017). Co-occurring epiphytic lichens at the British Columbia site include Arctomia borbonica, Cavernularia hultenii, Collema furfuraceum, Erioderma sorediatum, Fuscopannaria laceratula, F. leucostictoides, Lobaria anomala, Lobaria anthraspis, Nephroma laevigatum, Pannaria malmei, Pseudocyphellaria “mallota”, P. hawaiiensis, Sticta limbata and Usnea longissima. The two paratype specimens from BC were collected at the same locality in different years on dwarfed Picea sitchensis branches in a sheltered north-facing site just above high-tide line on a small rocky islet. Islets provide roosting sites for passerine birds – warblers, kinglets, sparrows, etc. – passing through in migration (Ian Cruickshank, pers. comm.) and may partly account for the occurrence there of a species not noted elsewhere in the area despite intensive searching.
Conservation. Based on available data, S. torii is exceedingly rare, apparently more so even than the federally endangered Heterodermia sitchensis Goward & Noble (COSEWIC 2006), another foliose lichen growing on Picea sitchensis in hypermaritime regions (Goward 1984). Whereas that species is currently known from eleven localities, S. torii is so far known from only five localities along a latitudinal range of c. 1300 km. Taken together, these observations qualify S. torii as endangered [EN: B1ab(iii)] under IUCN criteria (Scheidegger & Goward 2002; Dahlberg and Mueller 2011; IUCN 2012).
It is worth noting that hypermaritime portions of southeastern Alaska and British Columbia have received considerable search effort for lichens (Geiser et al. 1998; COSEWIC 2010, Dillman et al. 2012, Spribille et al. in prep.). Thus, the endangerment status of S. torii is unlikely to be a mere artefact of insufficient documentation.
Comments. Recent phylogenetic studies on the genus Sticta have revealed unexpected taxonomic diversity (e.g., Moncada et al. 2014). In northwestern North America, the formal description of the new species S. torii leaves several further, morphologically similar species in the genus still undescribed. In a recent phylogenetic study on European members of the S. fuliginosa morphodeme (sensu Moncada et al. 2014), Magain and Sérusiaux (2015) included British Columbia material that had tentatively been assigned to S. sylvatica, but which appears to belong to an undescribed species that includes further unpublished accessions from North and South America and Macaronesia, plus one published accession from China (Lohtander et al. 2002; AY124095). Magain and Sérusiaux (2015) also called attention to a BC specimen of S. “fuliginosa” incorporated in the phylogeny of Cornejo et al. (2009; ITS accession DQ419943), which represents an additional, distinct lineage.