Lecanora tropica Zahlbr. (1928: 589) 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 : 60-61

Lecanora tropica Zahlbr. (1928: 589) MycoBank no. 389513

Type:— COLOMBIA (“Nova Granata”), GUALIVÁ PROVINCE: Villeta , 1200 m, sine dato, Lindig, A. s.n. [H-Nyl 27567a– lectotype selected by Lumbsch (1994)] .

( Fig. 12C–D )

Thallus corticolous, thick, rimose to rimose areolate, areoles granular to densely verrucose or bullate; surface white to pale gray, yellowish gray or pale brownish gray, roughened, matt, epruinose or with scarce, whitish pruina, lacking soredia; prothallus weakly developed, powdery arachnoid to compact, generally white, but occasionally blackening and forming a line where different thalli meet. Apothecia numerous, often densely aggregated, circular to slightly irregular in outline, often deformed by mutual pressure, 0.4–1.4 mm in diam., adnate to soon sessile and then ±constricted, distinctly lecanorine with persistent, entire, even to barely undulating, smooth, crenate or strongly verruculose, epruinose to sparsely whitish pruinose margin, concolorous with the thallus; disc plane to ±convex, deep mahogany brown, epruinose to sparsely whitish pruinose; hymenium hyaline, not inspersed; epihymenium lacking crystals, with a diffuse reddish brown pigment (arnoldiana -brown: K+ dull brown, HCl+ reddish brown, N−), pigment persistent in K (glabrata - type); proper exciple thin, indistinct, with few crystals insoluble in K; thalline exciple thick, distinctly corticate, with many large crystals insoluble in K and sparse small crystals soluble in K (pulicaris - type); hypothecium hyaline; ascospores 8/ascus, simple, narrowly ellipsoid to broadly ellipsoid, (9.9)–14.4–13.3–(14.9) × (5.0–)5.2–6.8 (–6.9) µm (n = 45). Pycnidia not seen.

Chemistry: Thallus cortex including apothecial margin P+ yellow, C− or C+ yellow to orange, KC− or KC+ yellow to orange, K+ yellow, UV− (all Galapagos specimens are UV−, but specimens with xanthones react C/KC+ yellow to yellow orange); with atranorin [major], ±zeorin [major], ±3- O -methylthiophanic acid [minor], thiophanic acid [major], ±unknown terpene [trace]; [specimen analyzed with TLC: Bungartz, F. 7192 ( CDS 37676)]. Guderley (1999) reports additional ±chloroatranorin, ±chodatin, ±demethylchodatin, and ±other unidentified xanthones.

Ecology and distribution: Pantropical, first reported from the Galapagos by Guderley (1999); a moderately common species in the coastal, dry and lower transition zone of the islands, most common on Bursera graveolens , also on a few other native trees and shrubs .

Notes: This corticolous species appears extremely similar to the saxicolous L. subimmergens . However, thiophanic acid has not been detected in L. subimmergens .

Specimens examined. ECUADOR. GALÁPAGOS: Española, trail from Bahía Manzanillo on the N-coast of the island to the highest point, 1˚22’18.69’’ S, 89˚42’7.40’’W, 125 m alt., dry zone, Cordia lutea shrubland with some Prosopis juliflora shrubs at bottom of a basalt outcrop, trunk of Cordia lutea , on bark, 11-Nov-2010, Yánez-Ayabaca, A. 1688 ( CDS 45571). Floreana, along trail going to Post Office Bay off the dirt road between highlands and Puerto Velasco Ibarra, at Laguna Seca, 1˚15’30.80’’ S, 90˚26’26.60’’W, 206 m alt., dry zone, very open Bursera graveolens forest over SE-exposed lava flow with Prosopis juliflora , on NE-exposed trunk of Bursera graveolens , 14-Jan-2011, Bungartz, F. 9540 ( CDS 46823). 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 trunk of Piscidia carthagenensis , on bark, 22-Apr-2007, Bungartz, F. 6325 ( CDS 34540); 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 branches of Cordia lutea , 22-Apr-2007, Bungartz, F. 6274 ( CDS 34486); along trail from Bahía Sardinas at the NWcoast of the island to Cerro Pan de Azúcar, 0˚42’28’’ S, 89˚21’29’’W, 13 m alt., dry zone, open woodland of Bursera graveolens and Piscidia carthagenensis with dense understory of Scutia spicata , Gossypium darwinii and Waltheria ovata , on trunk of Piscidia carthagenensis , 24-Apr-2007, Bungartz, F. 6482 ( CDS 34699); crest of Cerro Tortuga, ca. 4 km inland from the NW-coast, 0˚44’54’’ S, 89˚23’32’’W, 116 m alt., dry zone, open Piscidia carthagenensis woodland with few Bursera graveolens and dense understory of Croton scouleri , Cordia lutea , and Mentzelia aspera on rocky SE-exposed slope of hill, on trunk of Bursera graveolens , 25-Apr-2007, Bungartz, F. 6520 ( CDS 34738). Santa Cruz, vicinity of Academy Bay, trail to first barranca, dry zone, Bursera , on bark, 15-Feb-1964, Weber, W.A. s.n. (L-40616, COLO 192529); s.n. (L-40423, COLO 188938); along the road from Bellavista to El Garrapatero, ca. 2 km from the coast, at the campsite of the National Park, 0˚41’25’’ S, 90˚13’35’’W, 24 m alt., dry zone, deciduous dry lowland forest, Bursera graveolens , Acacia rorudiana , Opuntia echios , Croton scouleri , on trunk of Bursera graveolens , 14-Feb-2006, Bungartz, F. 3560 ( CDS 27359); Aptroot, A. 63964 ( CDS 30523); on the North side of the island, along the dirt road to the ash quarry Mina Granillo Negro , 0˚34’22’’ S, 90˚19’55’’W, 27 m alt., dry zone, dry deciduous lowland forest ( Bursera graveolens , Heliotropium sp. , Acacia sp. , Zanthoxylum fagara ), Bursera , on bark, 23-Feb-2006, Aptroot, A. 64485 ( CDS 31057). Santa Fé, on top of lava flow at the N-coast of the island, 0˚48’12.4’’ S, 90˚2’34.5’’W, 13 m alt., coastal zone, open scrubland of partly dead shrubs ( Croton scouleri , Cordia lutea ), few shrubby Bursera graveolens , and Opuntia echios var. barringtonensis among lava rocks, on SE-exposed branches of Bursera graveolens , 25-Oct-2007, Bungartz, F. 7192 ( CDS 37676). Santiago, Santiago Bay, on cactus, 15-Feb-1964, Dawson, E.Y. 356 (L-41028, COLO 192940), s.n. (L-40089, COLO 188062); along the trail from the caseta in La Central to La Bomba (at the coast), halfway down to the coast, 0˚12’54’’ S, 90˚43’21’’W, 293 m alt., dry zone, open woodland of Bursera graveolens and Opuntia galapageia with shrubs of Castela galapageia and Clerodendrum molle among basalt boulders and rocks, on twigs of Clerodendrum molle , 25-Mar-2006, Bungartz, F. 4928 ( CDS 29132), 4929 ( CDS 29133); SE of James Bay, 0˚16’45’’ S, 90˚50’0’’W, 40 m alt., dry zone, open Bursera forest on a lava flow, Bursera , on bark, 26-Apr-1971, Pike, L.H. 2577 (0, OSC 99473); E of salt lake at James Bay, 0˚14’25’’ S, 90˚48’50’’W, 170 m alt., transition zone, Bursera - Psidium forest on pahoehoe lava flow, Bursera , on bark, 30-Apr-1971, Pike, L.H. 2706 ( OSC 99470). Isabela, Volcán Alcedo, in the crater near fumaroles, 0˚27’1’’ S, 91˚7’19’’W, 780 m alt., transition zone, mostly Bursera graveolens and dense scrub on uneven lava, Bursera , on bark, 07-Mar-2006, Aptroot, A. 64777 ( CDS 31352); along the trail going up the E-slope, 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 , on trunk of Bursera graveolens , 09-Mar-2006, Bungartz, F. 4372 ( CDS 28456). Volcán Cerro Azul, along the first few meters of the path from the Caseta del Parque to Caleta Iguana, 0˚58’44.20’’ S, 91˚26’46.27’’W, 12 m alt., dry zone, dense scrubland of mostly Clerodendrum molle , some Gossypium darwinii and Croto scouleri, very sparse Bursera graveolens trees, on S-exposed Bursera graveolens trunk, 09-May-2012, Bungartz, F. 10530 ( CDS 52542). Volcán Darwin, southwestern slope, above Tagus Cove, 0˚14’50’’ S, 91˚21’29.89’’W, 67 m alt., dry zone, open Bursera graveolens forest with Waltheria ovata and Macraea laricifolia , few Acacia rorudiana and Cordia lutea , along small lava flow, on W-exposed trunk of Bursera graveolens , 11-Nov- 2007, Bungartz, F. 7380 ( CDS 37867); 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 stem and branches of Croton scouleri , 15-Nov-2007, Bungartz, F. 7675 ( CDS 38178). 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, SW-slope of old lava flow with scattered vegetation ( Bursera graveolens , Opuntia echios , and Waltheria ovata ), on SW-exposed young stem of Bursera graveolens , 10-Sep-2007, Bungartz, F. 6940 ( CDS 36440); 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. 8398 ( CDS 41044), 8425 ( CDS 41071); 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. 10754 ( CDS 40493).

Figures

FIGURE 12. Species in the L. subfusca-group; superficially similar species with deep brown apothecial disc and pulicaris-type exciple (large crystals only). A–B. Lecanora schindleri (Weber, W. A. s.n., L-40337, COLO 188861). A. Thallus continuous to barely rimose with fimbriate whitish prothallus, apothecia adnate to sessile, margin entire, disc deep reddish brown to almost blackish brown, epruinose or with very faint, whitish pruina. B. Apothecial section (in water, DIC), exciple with abundant minute, soluble crystals obscuring few large, insoluble ones (melacarpella-type), epihymenium with reddish brown, insoluble pigment and minute soluble crystals (pulicaris-type). C– D. Lecanora tropica. C. Thallus rimose-areolate, slightly verrucose, delimited by a darkened prothallus line, apothecia adnate to sessile, margin entire to ±crenulate, disc deep reddish brown, epruinose (Bungartz, F. 8425, CDS 41071). D. Apothecial section (in water, DIC): exciple with conspicuous, large, insoluble crystals and few minute, soluble ones (pulicaris-type), epihymenium with insoluble brown pigment, lacking crystals (glabrata-type) (Dawson, E.Y. s.n., L-40089, COLO 188062). E–F. L. subimmergens (Bungartz, F. 7600, CDS 38096). E. Thallus areolate, apothecia adnate to sessile, margin entire, slightly undulate, disc dark reddish to blackish brown, epruinose. F. Apothecial section (in water, DIC): exciple with conspicuous, large, insoluble crystals and few minute, soluble ones (pulicaris-type), epihymenium with insoluble brown pigment, lacking crystals (glabrata-type). Scales: A, C & E = 5 mm; B, D & F = 100 µm.