MB#404560

Basionym. Lecanora zwackhiana Kremp. Flora 37: 145 (1854).

Type. [GERMANY.] Oberbayern, Schlossberg in Marquartstein, s.d. A. Krempelhuber s.n. (M ‑ lectotype, Mayrhofer & Poelt 1979).

Rinodina violascens H. Magn. Lich. Central Asia I: 154 (1940).

Type. [CHINA.] KANSU. Tuan‑shan‑k'ou, about 15km SSE of Chia‑yu‑kuan at about 1475m, 10/10/1930, B. Bohlin 24b (S ‑ holotype!).

Description. Thallus thick, brown, more rarely ochraceous or dark grey, areolate; areoles lobate at periphery, to 1.20‑1.60 mm wide; surface verrucose, matt or shining; margin usually indeterminate; prothallus sometimes present on hard substrates, pale, fimbriate; vegetative propagules present; soredia often developing on upturned areole margins of thalli mostly lacking apothecia, ca. 20-25 µm diam.  Apothecia absent when sorediate, or broadly attached, frequent, often contiguous, to (0.35-)0.50-1.10 mm in diam.; disc black, persistently plane, sometimes becoming fissured; thalline margin concolourous with thallus, ca. 0.10 mm wide, entire and persistent; excipular ring absent. Apothecial Anatomy. Thalline exciple 90-160 wide; cortex 10-20 µm wide; epinecral layer 5-10 µm deep; crystals absent from cortex and medulla; cortical cells to 4.5-6.5 µm wide, pigmented or not; algal cells to 10.5-13.0 µm long; proper exciple hyaline, 10-20 µm wide, expanding to 40-50 µm at periphery; hypothecium hyaline, 120-190 µm deep, including stipe; hymenium 120-140 µm high, not inspersed; paraphyses 2.0-2.5 µm wide, not conglutinate, with apices to 3.5-4.5 µm wide, lightly pigmented, immersed in blue pigment, forming a blue-grey epihymenium, K+, N+ rose or violet; asci 50-90 x 16-20 µm. Ascospores (4-)8/ascus, developmental type A, Bicincta-type, (15.5-)18.5-20.5(-23.5) x (9.5-)11.0-12.5(-14.0) µm, average l/b ratio 1.5-1.9, pigmentation sometimes commencing at single cell stage, broad canal only visible in minority of immature spores, lumina mostly rounded, lateral wall expanded at septum when young, more so in KOH, spores later becoming constricted, septum strongly pigmented at maturity, cells lacking pigmented bands; torus absent; walls not ornamented. Pycnidia not seen.

Chemistry. Spot tests all negative; secondary metabolites not detected.

Substrate and Ecology. Recorded from limestone, sandstone and shale, at elevations of 760-3170 m, often associated with intermittent water seepage. The species has been collected with R. castanomela.

Distribution. This species has a Colorado Plateau centre of distribution in North America with outliers as far north as South Dakota and Montana, and south to southern California. Also known from southern Europe and China.

Notes. The species is distinguished by its thick, usually brownish thallus with lobate margins, blue-grey epihymenium in fertile material and marginal soredia in specimens lacking apothecia. North American material, which lacks an inspersed hymenium, would be referred to R. violascens H. Magn. by Mayrhofer (1984a), who further distinguishes R. zwackhiana and R. violascens on the basis of their Dubyana‑ and Buellia‑type spores, respectively. Spore structure is extremely variable, depending on developmental stage, and in this author’s opinion the two species are not separable by spore type. Mayrhofer illustrates the spores of R. violascens with swelling at the septum and separation of wall layers in both the septal and apical regions. Sheard (1982) illustrates similar spore features for R. zwackhiana, with the exception that separation of wall layers at the apices has not been observed. The spores may best be interpreted as belonging to the Bicincta-type but lacking the usually characteristic pigmented bands around each cell. Some other species with Bicincta-type spores, such as R. castanomela and R. straussii, show very poor development of these bands and their presence therefore probably should not be regarded as definitive for the spore type.

Rinodina zwackhiana mostly has separate sexual and vegetative forms (Anderson 1962) although a minority of specimens were shown to have both apothecia and soredia by Sheard (1982). There is a large variation in thallus pigmentation ranging from a light ochraceous colour to dark brown, the latter being associated with degree of exposure. No association was found between degree of thallus pigmentation and type of reproduction.

Specimens examined. U.S.A. ARIZONA. Coconino Co., Grand Canyon Nat. Forest, T.H. Nash 35499 (ASU); Navajo Co., Petrified Forest, 1963, G.W. Douglas (COLO). CALIFORNIA. San Bernadino Co., Bear Mountains, K. Knudsen 1607 (UCR). COLORADO. Boulder Co., Boulder, R.A. Anderson 20191, 30073 ; 8 mi N Boulder, S. Shushan 17928; Steamboat Mountain, W.A. Weber 25963; Grand Co., Grand Lake, R.A. Anderson 3280 (all COLO); Jefferson Co., Mount Vernon Canyon, J.W. Sheard  4699b (SASK); Larimer Co., Deer Mountain, R.A. Anderson 3570; 22 mi N Fort Collins, R.A. Anderson 20002; 3 mi W Loveland, R. Fahrenbruch 24572; Owl Canyon, W.A. Weber 28877; S lateral moraine, Big Thomson River, R.A. Anderson 3795; Trail Ridge, R.A. Anderson 4495; Mesa Co., 3 mi S Fruita, S. Shushan 4947; Montrose Co., Buckeye Reservoir, W.A. Weber 31332 (all COLO); San Juan Co., Spruce Tree Canyon, T.H. Nash 17972 (ASU); Summit Co., Dillon Reservoir, 1977, J. Poelt, R.A. Anderson  (GZU); Keystone, J.W. Sheard 4691 (SASK); Yuma Co., 6 mi E Wray, S. Shushan 32959 (COLO). MONTANA. Glacier Co., Glacier Nat. Park, B. McCune 17879 (personal herb.). NEVADA. Clark Co., 60 mi NW Las Vegas, J.L. Collins 235A (COLO). NEW MEXICO. San Juan Co., Chaco Canyon Nat. Mon., T.H. Nash 16136, 16200 (both ASU). SOUTH DAKOTA. Jackson Co., Cedar Pass, R.A. Anderson 20888 (COLO); Lawrence Co., WNW Timon Campground, R.A. Anderson 9517 (ASU). UTAH. Uintah Co., Dinosaur Nat. Mon., R.A. Anderson 29405 (COLO); Washington Co., Zion Nat. Park, T.H. Nash 15551 (ASU).

Selected References. Anderson (1962), Mayrhofer & Poelt (1979), Sheard (1982 Figs. 2-12), Sheard (2004), Mayrhofer (1984a and Abb. 104 as R. violascens).

 

Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Thallus: crustose, thick, areolate, areoles convex and lobate at periphery of thallus, up to 1.2-1.6 mm wide surface: brown, more rarely ochraceous or dark gray, dull or shiny, light colored thalli usually fertile; margin: usually indeterminate; prothallus: sometimes visible on hard substrates, pale, fimbriate soredia: often developing on upturned areole margins in darker thalli lacking apothecia Apothecia: absent when sorediate, or adnate, frequent and often contiguous, up to (0.35-)0.5-1.1 mm in diam. disc: black, persistently plane, sometimes becoming fissured thalline margin: concolorous with thallus, c. 0.1 mm wide, entire and persistent; excipular ring: absent thalline exciple: 90-160 µm wide laterally; cortex: 10-20 µm wide; epinecral layer: 5-10 µm thick; cortical cells: up to 4.5-6.5 µm wide, pigmented or not; algal cells: up to 10.5-13 µm in diam. proper exciple: hyaline, 10-20 µm wide, expanding to 40-50 µm at periphery hymenium: 120-140 µm tall; paraphyses: 2-2.5 µm, not conglutinate, wide with apices up to 3.5-4.5 µm wide, lightly pigmented, immersed in blue pigment, forming a blue-gray epihymenium, K+, N+ rose or violet; hypothecium: hyaline, 120-190 µm thick, including stipe asci: clavate, 50-90 x 16-20 µm, 8-spored ascospores: brown, 1-septate, broadly ellipsoid, developmental type A, Bicincta-type, (15.5-)18.5-20.5(23.5) x (9.5-)11-12.5(-14) µm, pigmentation sometimes commencing at single cell stage, broad canal only visible in minority of immature spores, lumina mostly rounded, lateral wall expanded at septum when young, more so in K, spores later becoming waisted, septum strongly pigmented at maturity, cells lacking pigmented bands; torus: absent; walls: not ornamented Pycnidia: not seen Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: on limestone, sandstone and shale, at elevations of 760-3170 m, often associated with intermittent water seepage, often collected with R. castanomela World distribution: southern Europe and central Asia, and southwestern North America, especially on the Colorado Plateau Sonoran distribution: Arizona, Coconino and Navajo Counties. Notes: North American material lacks an inspersed hymenium and would be referred to R. violascens H. Magn. by Mayrhofer (1984), who further distinguishes R. zwackhiana and R. violascens on the basis of their Dubyana- and Buellia-type spores, respectively. Spore structure is extremely variable, depending on developmental stage, and in the opinion of this author the two species are not separable by spore type. Mayrhofer (loc. cit.) shows the spores of R. violascens with swelling at the septum and separation of wall layers in both the septal and apical regions. Sheard (1982) illustrates similar spore features for R. zwackhiana, with the exception that separate wall layers at the apices have not been observed. The spores are best interpreted as belonging to the Bicincta-type but lacking the usually characteristic pigmented bands around each cell. Other species with Bicincta-type spores, such as R. castanomela and R. constrictula, show very poor development of these bands and their presence therefore should not be regarded as definitive for the spore type.