Lecanora caesiorubella Ach. (1810: 366) MycoBank

Bungartz, Frank, Elix, John A. & Printzen, Christian, 2020, Lecanoroid lichens in the Galapagos Islands: the genera Lecanora, Protoparmeliopsis, and Vainionora (Lecanoraceae, Lecanoromycetes), Phytotaxa 431 (1), pp. 1-85 : 20-22

Lecanora caesiorubella Ach. (1810: 366) MycoBank no. 356369

Type:— NORTH AMERICA, exact locality unknown, original label data: “habitat in cortice arborum Americae septentrionalis ”, sine dato, Swartz, O.P. s.n. [ UPS-ACH 644 – syntype; no lectotype designated by Brodo (1966) or Lumbsch et al. (1997)] .

( Fig. 6A–B )

Thallus corticolous, moderately thickened, continuous to rimose-areolate to verruculose areolate; surface whitish gray to grayish green (becoming beige with prolonged storage in the herbarium), smooth, epruinose, lacking soredia; prothallus whitish, arachnoid or forming a compact, whitish line, occasionally indistinct. Apothecia sparse to numerous, circular or slightly undulate in outline, 0.8–3 mm in diam., sessile, distinctly lecanorine with a smooth, epruinose, persistent, prominent thalline margin concolorous with the thallus; disc plane to weakly convex, pale yellowish beige to pinkish or pale carneous, densely whitish pruinose; hymenium hyaline, not inspersed, epihymenium with a diffuse, dull brown pigment (elachista -brown: dissolving in K, HCl± dull greenish, N−) and few to abundant minute crystals, mostly dissolving in K (residue of fine, rounded, reddish granules persistent, 0.5–1 µm); proper exciple thin, indistinct, with few minute crystals; thalline exciple thick, of thin-walled, radiating hyphae with numerous, but inconspicuous photobiont cells obscured from abundant small crystals dissolving in K, ecorticate or indistinctly corticate (outer cells darker brown); hypothecium hyaline; ascospores 8/ascus, simple, broadly ellipsoid or subglobose, (5.0−)7.7−10.5(−11.9) × (4.0−)5.5−7.2(−7.9) µm (n = 45). Pycnidia not seen.

Chemistry: Thallus cortex including apothecial margin P+ orange-red, C−, KC−, K+ yellow, UV− (pale yellow); with atranorin [major], protocetraric acid [major], ±lichesterinic acid [minor]; [specimens analyzed with TLC: Bungartz, F. 4466 ( CDS 28552), 6225 ( CDS 28552), 6254 ( CDS 34466), 6316 ( CDS 34531), 6348 ( CDS 34563), 7441 ( CDS 37928), 7845 ( CDS 38354); Simbaña, W. 537 ( CDS 32373); Weber, W.A. s.n. (L-62866, COLO 294655)].

Ecology and distribution: Pantropical (North and South America, Africa, Asia, Australia and Oceania); a very common corticolous species in the Galapagos, from the coastal through the dry into the transition zone, typically in open, sunny and exposed habitats, frequent on small trees and shrubs like Bursera , Croton , Psidium , and Piscidia , occasionally also on cacti ( Jasminocereus ).

Notes: Imshaug & Brodo (1966) distinguished five subspecies of L. caesiorubella , by chemical and distributional differences. Lumbsch et al. (1997) accepted L. caesiorubella ssp. lathamii Imshaug & Brodo at species level as L. subpallida Zahlbr. , but found more complex patterns of chemical variation, which they regarded inconsistent with the subspecies concepts of Imshaug & Brodo (1966). None of the authors selected a lectotype. Since the species in its broad circumscription is widespread and the designation of a lectotype could have far-reaching consequences for the naming of chemotypes and subspecies we prefer not to designate a lectotype here either.

All Galapagos specimens contain atranorin and protocetraric acid but no virensic acid. These collections would therefore belong to L. caesiorubella ssp. glaucomodes in the sense of Brodo et al. (2019) or chemotype II sensu Lumbsch et al. (1997). The occurrence of the aliphatic lichesterinic acid in some of the collections from Galapagos suggests that these specimens constitute a hitherto unrecognized chemotype. However, Brodo et al. (2019) recently reported the occurrence of roccellic and nephrosteranic acids (aliphatic acids as well) in L. caesiorubella ssp. glaucomodes and ssp. saximontana . In light of the unresolved taxonomy and apparently complex chemistry of the group as well as lack of molecular data we prefer to keep the specimens under L. caesiorubella “ s.l. ” for the time being.

In the archipelago L. caesiorubella can be confused with superficially very similar specimens of Ochrolechia . Both have white thalli and similar apothecia, although the apothecia of the Ochrolechia species are generally much larger. Specimens can readily be distinguished chemically since thalli of L. caesiorubella react P+ orange-red (protocetraric acid) whereas the Ochrolechia species in the Galapagos are P−.

Specimens examined. ECUADOR. GALÁPAGOS: Española, along S-coast of the island, SE of Punta Suárez, ca. 500 m inland from coast, 1˚22’56.60’’ S, 89˚43’8.40’’W, 133 m alt., dry zone, lava cliff with Cordia lutea , Ipomoea habeliana , and few trees of Bursera graveolens , on SW-exposed trunk of Bursera graveolens , 10-Nov-2010, Bungartz, F. 8940 ( CDS 45758), Bungartz, F. 8959 ( CDS 45777). Fernandina, W-side, 335 m alt., transition zone, Chiococca alba , on bark, 15-Feb-1964, Cavagnaro, D. s.n. (L-40439, COLO 193187). Floreana, along trail from Black Beach to Cruz farm, Bursera , on bark, 25-Apr-1976, Weber, W.A. s.n. ( CDS 10857), (L-62955, COLO 294567), ( QCA); Ladera N del Cerro Ventanas, 1˚16’12’’ S, 90˚25’49’’W, 400 m alt., zona húmeda, tallo de Bursera graveolens , sobre corteza, 27-Mar-2006, Simbaña, W. 557 ( CDS 32393); at the base of Cerro Comunista, 1˚17’22.89’’ S, 90˚28’22.39’’W, 158 m alt., dry zone, dense low forest of Croton scouleri , Waltheria ovata and Castela galapageia with occasional trees of Acacia rorudiana and Bursera graveolens , on branches and twigs of Acacia rorudiana , 16-Jan-2011, Bungartz, F. 9710 ( CDS 47027), 9713 C ( CDS 49514); inside the crater of Cerro Laguna at E-side of island, on W-exposed slope, 1˚16’11.80’’ S, 90˚23’17’’W, 245 m alt., transition zone, dense forest of Prosopis juliflora , Clerodendrum molle , very few Bursera graveolens and some Jasminocereus thouarsii in the upper part among lava outcrops and boulders; Ramalina usnea /anceps hanging in curtains from Clerodendrum twigs, on twigs of Bursera graveolens , 20-Jan-2011, Bungartz, F. 9945 ( CDS 47314); ca. 500 m S of La Lobería, ca. 200 m inland from coast, 1˚17’12.69’’ S, 90˚29’36’’W, 20 m alt., dry zone, very open Bursera forest with Waltheria ovata , few Scalesia affinis and some grasses on lava flow, dead branch of Bursera graveolens , on bark, 16-Jan-2011, Yánez-Ayabaca, A. 1990 ( CDS 48340); lower S-slope of Cerro Ventanas, 1˚16’36.10’’ S, 90˚25’41.10’’W, 295 m alt., transition zone, open shrubland of Macraea laricifolia and some lower Waltheria ovata shrubs in between, fallen branch, on bark, 18-Jan-2011, Yánez-Ayabaca, A. 2025 ( CDS 48375), 2019 ( CDS 48369). Pinta, along the trail up to the summit from the S-coast, 0˚33’22’’N, 90˚44’34’’W, 88 m alt., dry zone, open woodland of Bursera graveolens and few Opuntia galapageia with an understory of Croton scouleri , Castela galapageia , Waltheria ovata , Lantana peduncularis among Pahoehoe lava, on trunk of Bursera graveolens , 28-Feb-2007, Bungartz, F. 6018 ( CDS 33697); 0˚34’3’’N, 90˚44’56’’W, 233 m alt., transition zone, open woodland with Bursera graveolens , Zanthoxylum fagara , Pisonia floribunda , Croton scouleri , and few Opuntia galapageia among old lava flows; in between Alternanthera filifolia and grasses, on trunk of Bursera graveolens (ca. 15 cm in diam.), 28-Feb-2007, Bungartz, F. 5976 ( CDS 33654); along the trail up to the summit, ca. 1 km inland from the S-coast, 0˚33’8’’N, 90˚44’29’’W, 54 m alt., dry zone, open vegetation of Bursera graveolens , Croton scouleri , Castela galapageia , and Opuntia galapageia among lava blocks, on upper side of branches of Bursera graveolens , 25-Feb-2007, Bungartz, F. 5656 ( CDS 33291); near volcano in the south-central part, 150 m alt., dry zone, in open forest, Bursera , on bark, 08-Jul-1976, Sipman, H.J.M. s.n. (L-63593, COLO 297843). Pinzón, from the NE-coast to the highest summit, 200 m alt., dry zone, vertical face of boulder, on rock, 02-Jul-1976, Sipman, H.J.M. s.n. (L-63566, COLO 297870). Rábida, E-side of the island, dry zone, Bursera forest and lava talus slope, 01-May-1976, Weber, W.A. s.n. (L-62866, COLO 294655). San Cristóbal, along the trail from Galapagera at the NW-coast of the island to Media Luna, 0˚42’41’’ S, 89˚18’15’’W, 33 m alt., dry zone, open woodland of Piscidia carthagenensis , Bursera graveolens , and Gossypium darwinii shrubs, on branches of Bursera graveolens , 22-Apr-2007, Bungartz, F. 6316 ( CDS 34531); near Rosa Blanca, at the SE-coast of the island, 0˚49’31’’ S, 89˚21’4’’W, 1 m alt., coastal zone, lava plateau with small shrubs of Croton scouleri , few Opuntia megasperma and Rhizophora mangle towards the waterfront, on twigs of Rhizophora mangle , 23-Apr-2007, Bungartz, F. 6348 ( CDS 34563); Cerro Colorado summit, around the viewpoint, 0˚54’54.89’’ S, 89˚26’1.5’’W, 159 m alt., dry zone, dry zone vegetation with Croton scouleri , Cordia lutea and Macraea laricifolia , slope 15° SWW (on the ridge), on bark, 24-Aug-2008, Herrera-Campos, M.A. GAL-475 ( CDS 43366); northwestern foothills of Media Luna, inland from the NW-coast, 0˚43’41’’ S, 89˚18’44’’W, 75 m alt., dry zone, open woodland of Cordia lutea and Bursera graveolens , on twigs of Bursera graveolens , 22-Apr-2007, Bungartz, F. 6225 ( CDS 34437); SW foothills of Media Luna, inland from the NW-coast of the island along the trail from Galapagera to Media Luna; bottom of small crater to the NW of Media Luna, 0˚43’53’’ S, 89˚18’57’’W, 124 m alt., dry zone, upper dry zone; woodland of Piscidia carthagenensis , Cordia lutea , Zanthoxylum fagara , Croton scouleri and few Bursera graveolens , on trunk of Bursera graveolens (ca. 10 cm in diam.), 22-Apr-2007, Bungartz, F. 6254 ( CDS 34466). Santa Cruz, on the North side of the island, along the dirt road to the ash quarry Mina Granillo Rojo , 0˚36’56’’ S, 90˚22’3’’W, 570 m alt., transition zone, lower transition zone; dry semi-deciduous forest with Bursera graveolens and Zanthoxylum fagara , on branches of Bursera graveolens , 23-Feb-2006, Bungartz, F. 3921 ( CDS 27803), 3882 ( CDS 27764), Aptroot, A. 64592 ( CDS 31165); E-side of island, trail from parking lot to El Garrapatero beach, N-side of trail, 0˚41’26.69’’ S, 90˚13’19.10’’W, 6 m alt., dry zone, open deciduous forest of Bursera graveolens , Cordia lutea , Opuntia echios with Castela galapageia and Alternanthera echinocephala and others in the understory, Bursera graveolens , on bark, 16- Jun-2010, Spielmann, A.A. 8218 ( CDS 45344), 8224 ( CDS 45345); vicinity of Academy Bay, along new trail, dry zone, cactus forest, trees, Piscidia , on bark, 15-Feb-1964, Weber, W.A. s.n. (L-40295, COLO 192783). Santa Fé, large Bursera tree, on bark, 15-Feb-1964, Koford, C.B. s.n. (L-40590, COLO 192503). Santiago, 5 km al NO de Bahía Sullivan, desde el Cerro Inn, 0˚15’36’’ S, 90˚36’56’’W, 100 m alt., zona seca, tallo de Bursera graveolens , sobre corteza, 16-Jul-2005, Simbaña, W. 537 ( CDS 32373); ca. 5 km inland from the E-coast, ± at the same latitude as Bahía Sullivan, 0˚16’52’’ S, 90˚37’17’’W, 175 m alt., dry zone, rubble of older lava with very scarce vegetation of few Bursera graveolens trees, Macraea laricifolia , and Mentzelia aspera , on dead wood of standing tree ( Bursera graveolens ), 16-Jul-2006, Bungartz, F. 5044 ( CDS 29257); along the trail from the caseta in La Central to La Bomba, halfway down to the coast, 0˚12’54’’ S, 90˚43’21’’W, 293 m alt., dry zone, dry zone; open woodland of Bursera graveolens and Opuntia galapageia with shrubs of Castela galapageia among basalt boulders and rocks, on wood, 25-Mar-2006, Aptroot, A. 65627 ( CDS 32217); along the trail from Bucanero to Jaboncillos, ca. 5 km SE of Bucanero, 0˚11’19’’ S, 90˚47’48’’W, 562 m alt., transition zone, open woodland of large Bursera graveolens and smaller Psidium galapageium trees with Blainvillea dichotoma , Mentzelia aspera and Senna obtusifolia in between, Psidium , on bark, 22-Mar-2006, Aptroot, A. 65421 ( CDS 32007); E of salt lake at James Bay, 0˚14’25’’ S, 90˚49’40’’W, 70 m alt., dry zone, open Bursera forest on pahoehoe lava flow, Bursera , on bark, 30-Apr-1971, Pike, L.H. 2673 ( OSC 99708). Isabela, Volcán Alcedo, along the trail going up the E-slope, 0˚23’42’’ S, 91˚1’40’’W, 237 m alt., dry zone, scattered small Bursera graveolens trees, Opuntia insularis , and Cordia lutea , open scrub of Waltheria ovata , Scutia spicata var. pauciflora , and Castela galapageia , on trunk of Bursera graveolens , 10-Mar-2006, Bungartz, F. 4466 ( CDS 28552); at the NW-side of the trail, 0˚24’5’’ S, 91˚2’36’’W, 420 m alt., dry zone, open Bursera graveolens stand with an occasional Pisonia floribunda and Zanthoxylum fagara and shrubs of Macraea laricifolia and Waltheria ovata , trunk of Bursera graveolens (ca. 25 cm in diam.), SE-exposed, on bark, 09-Mar-2006, Bungartz, F. 4350 ( CDS 28434); basalt rubble field to the SE-side of the trail and the barranco, 0˚24’6’’ S, 91˚2’53’’W, 530 m alt., dry zone, basalt rubble field with scattered vegetation ( Bursera graveolens , Zanthoxylum fagara , Pisonia floribunda , Senna pistaciifolia ), Bursera , on bark, 10-Mar-2006, Aptroot, A. 64909 A ( CDS 31487); in the crater, 0˚27’9’’ S, 91˚6’41’’W, 780 m alt., transition zone, mostly Bursera graveolens and dense scrub on uneven lava, Bursera , on bark, 07-Mar-2006, Aptroot, A. 64764 ( CDS 31339). Volcán Darwin, southwestern slope, above Tagus Cove, 0˚13’59’’ S, 91˚20’8’’W, 597 m alt., dry zone, open Bursera graveolens forest with Croton scouleri and Macraea laricifolia shrubs, few Chiococca alba and Scalesia microcephala , among lava boulders and outcrops, Bursera graveolens , on bark, 16-Nov-2007, Ertz, D. 11980 ( CDS 37339), 11990 ( CDS 37349), 11974 ( CDS 37333), 12010 ( CDS 37369); Bungartz, F. 7817 ( CDS 38326), Bungartz, F. 7845 ( CDS 38354); 0˚13’57.89’’ S, 91˚20’5.096’’W, 613 m alt., transition zone, SW-exposed lava flow of weathered AA-lava with scarce vegetation ( Macraea laricifolia , Croton scouleri , Dodonaea viscosa , Scalesia microcephala , Cordia revoluta and Opuntia insularis ), on branches of Croton scouleri , 12-Nov-2007, Bungartz, F. 7401 ( CDS 37888), 7394 ( CDS 37881), 7398 A ( CDS 37885); 0˚13’43.27’’ S, 91˚19’47.27’’W, 724 m alt., transition zone, SW-exposed lava flow of weathered AA-lava with scarce vegetation ( Macraea laricifolia , Dodonaea viscosa , Croton scouleri , Cordia revoluta and Jasminocereus thouarsii ), Jasminocereus thouarsii , on cactus, 12-Nov-2007, Ertz, D. 11815 ( CDS 37174); Bungartz, F. 7441 ( CDS 37928); 0˚13’27.60’’ S, 91˚19’21.19’’W, 860 m alt., transition zone, open scrubland of Dodonaea viscosa , Croton scouleri , Macraea laricifolia , Scalesia microcephala , few Opuntia insularis and dry grasses in the understory, on S-exposed stem of Croton scouleri , 15-Nov-2007, Bungartz, F. 7677 ( CDS 38180); 0˚13’11.4’’ S, 91˚19’14.1’’W, 955 m alt., transition zone, open scrubland of mainly Dodonaea viscosa shrubs, with some Macraea laricifolia , Cordia revoluta , Scalesia microcephala and dry grasses in the understory, on branches and twigs of Dodonaea viscosa , 14-Nov-2007, Bungartz, F. 7638 ( CDS 38140). Volcán Sierra Negra, along dirt road from Puerto Villamil to crater of Sierra Negra, 0˚55’12.4’’ S, 90˚59’38.20’’W, 30 m alt., dry zone, top of old lava flow with scattered vegetation ( Bursera graveolens , Opuntia echios , and Waltheria ovata ), on branches and trunk of Bursera graveolens , 10-Sep-2007, Bungartz, F. 6983 ( CDS 36487); Muro de las Lagrimas W of Puerto Villamil, small hill above the wall, 0˚57’54.77’’ S, 91˚0’47.10’’W, 81 m alt., dry zone, dry zone vegetation with Bursera graveolens and Opuntia echios , slope 45° N, Bursera graveolens , on bark, 17-Aug-2008, Herrera-Campos, M.A. 10759 ( CDS 40498), 10766 ( CDS 40505); area around the Muro de las Lagrimas, ca. 5 km W of Puerto Villamil, 0˚57’54.27’’ S, 91˚0’48.77’’W, 81 m alt., dry zone, open Bursera graveolens forest on NNE-exposed slope with Opuntia echios , Scalesia affinis and Lantana peduncularis , on trunk of Bursera graveolens , 17-Aug-2008, Bungartz, F. 8392, 8393 ( CDS 41039), Herrera-Campos, M.A. 10767 ( CDS 40506), Truong, C. 1295 ( CDS 39606).

Figures

FIGURE 6. Species in the L. pallida-group. A–B. Lecanora caesiorubella. A. Rimose-areolate thallus with fimbriate white prothallus (Bungartz, F. 4466, CDS 28552). B. Thick exciple of thin-walled radiating hyphae, evenly pale brown throughout, inspersed by minute crystals (Aptroot, A. 64592, CDS 31165). C–G. Morphological variation of Lecanora cerebriformis. C–D. Specimen with continuous to barely rimose, not distinctly cerebriform thallus (Bungartz, F. 10260, CDS 47679). C. Thallus flat, only where apothecia form in the center the thallus becomes barely convoluted. D. Thick exciple of thin-walled radiating hyphae, evenly pale brown throughout, inspersed by minute crystals. E–G. Strongly cerebriform specimens. E. Thallus (Bungartz, F. 5215, CDS 29428). F. Lecanora-type asci (Bungartz, F. 6633, CDS 34853–holotype; in Lugol’s iodine, DIC). G. Thick exciple of thin-walled radiating hyphae, evenly pale brown throughout, inspersed by minute crystals (Bungartz, F. 6633, CDS 34853–holotype). Scales: A, C & E = 5 mm; B, D & G = 100 µm; F = 10 µm.