Ochrolechia kerguelensis Ertz & Kukwa, 2016

Ertz, Damien, Fryday, Alan, Schmitt, Imke, Charrier, Maryvonne, Dudek, Magdalena & Kukwa, Martin, 2016, Ochrolechia kerguelensis sp. nov. from the Southern Hemisphere and O. antarctica reinstated from the synonymy of O. parella, Phytotaxa 280 (2), pp. 129-140 : 133-135

Ochrolechia kerguelensis Ertz & Kukwa sp. nov. MycoBank no 817620

Diagnosis: Characterized by pruinose apothecial discs, usually 4-spored asci, large ascospores of 50–90 × 32–56 μm, and the production of gyrophoric acid only in apothecia and the lack of variolaric acid.

Type:— KERGUELEN ISLANDS. Île Guillou, elev. 130 m, 49°28’34”S, 69°48’36”E, crête rocheuse au sommet de l’île, rocher exposé, 8 January 2014, D. Ertz 18906 (holotype BR!, isotype UGDA!). ( Fig. 2 )

Thallus thin, esorediate, strongly rimose-areolate, with areoles 0.1–0.5 mm in diam., grey to pinkish-brown, epruinose or rarely partly white pruinose, in some specimens areoles covered with free-living trentepohlioid algae; photobiont cells isodiametric 7–16 μm diam. with a thick wall of 1–2 μm, without (in lower part of medulla in thalline margin) or with 1–3 large and several smaller orange guttules (in upper part of thalline margin medulla and thallus); apothecia dispersed, rarely grouped in pairs, sessile, usually not constricted at the base, with open discs or ascomata perithecioid in shape, up to 2 mm in diam.; thalline margin pinkish brown, but always covered by continuous or discontinuous layer of white pruina, smooth or rimose or radially cracked, 0.3–0.5 mm wide, usually slightly protruding above the hymenial disc; excipulum proprium not visible in surface view of mature apothecia, but visible in section, up to c. 40 μm wide; margin cortex well developed, 75–100 μm wide in upper part, extending up to 125 μm at the base; algal layer well developed in excipulum, but algal cells in groups below hypothecium; hymenial disc flat to concave, with scabrose or cracked-rimose surface, slightly darker than the apothecial margin, covered by a thin layer of white, granular pruina; hypothecium hyaline; hymenium not inspersed, hyaline, I+ blue, KI+ blue, with granules dissolving in K into a yellowish solution, 200–270 μm tall; paraphyses numerous, simple at the base, becoming richly branched and anastomosing towards epihymenium, 2 μm in width, not distinctly enlarged at the apex, apex hyaline; asci clavate, with thick wall and thicker apical wall without recognizable structures, I+ blue, KI+ blue, (3–)4–spored, 190–250 × 60–70 μm; ascospores broadly ellipsoidal, sometimes more or less mucronate at one end, hyaline or yellowish when over mature, 50–90 × 32–56 μm; conidiomata not seen.

Chemistry: Gyrophoric and lecanoric acids (with unidentified pigments) in apothecia, thallus without lichen substances detectable by TLC. Thallus cortex and medulla K–, C–, UV–, apothecia UV+ bluish white, apothecial margin medulla C+ red in the upper part, epihymenium and apothecial margin cortex C+ red.

Distribution and habitat: Ochrolechia kerguelensis is known only from the Kerguelen Islands (Grande Terre, Île Guillou, Île Haute and Île Longue) where it inhabits exposed, dry siliceous rocks ( Fig. 2A & B ). The species seems absent from the closest subantarctic archipelagos since no Ochrolechia species was recorded from Heard Island ( Øvstedal & Gremmen 2006, 2008, 2010) or Marion and Prince Edward Islands ( Øvstedal & Gremmen 2001, 2007, 2010, 2014). The species was not observed on Île de la Possession (Crozet archipelago) during a field trip in 2015 by the first author.

Notes: The new species is characterized by pruinose apothecia, usually 4-spored asci, large ascospores and the production of gyrophoric acid only in the apothecia (epihymenium and apothecial margin). Whereas all previously described species of the genus Ochrolechia are known to have a chlorococcoid/trebouxioid photobiont, the new species, surprisingly, has a photobiont with cells containing orange guttules and thus recalling trentepohlioid algae ( Fig. 2G ). However, we could observe the same photobiont type in O. austroamericana (specimen Flakus 16538 & Rodriquez, UGDA). We have examined specimens of other Ochrolechia species from Europe (viz Kukwa 2011), as well as fresh specimens of O. balcanica Verseghy (1962: 85) (Ertz 20328, BR), O. pallescens (Ertz 20338, BR) and O. parella (Ertz 20317, 20345, BR) from Sicily and all contained chlorococcoid/trebouxioid algae, without any visible orange guttules. It must be noted that some microalgae have the ability to accumulate carotenoids under unfavourable conditions, that carotenoid biosynthesis appears to be important for microorganisms to withstand low temperature and that light quality seems to influence carotenogenesis ( Varela et al. 2015 and references cited therein). Molecular methods are needed to investigate the identity of the photobionts in the genus Ochrolechia and the taxonomic value of the presence of carotenoids in photobionts of lichens in general.

Ochrolechia kerguelensis is very similar to O. austroamericana , which also has pruinose apothecia and contains gyrophoric acid. However O. austroamericana has usually 8-spored asci, smaller ascospores measuring 17–35 × 10– 20 μm and produces gyrophoric acid also in the cortex of the thallus ( Messuti & Lumbsch 2000; Kukwa et al. 2013). Ochrolechia kerguelensis can be confused also with O. osorioana Verseghy (1962: 117) , a South American species with pruinose apothecia containing gyrophoric acid, but the asci of O. osorioana are 8-spored, ascospores are smaller (32–51 × 19–27 μm) and gyrophoric acid is present also in thallus cortex ( Messuti & Lumbsch 2000). Ochrolechia austroamericana and O. osorioana are morphologically very similar and the main difference, except the colour of the thallus, is the ascospore size ( Messuti & Lumbsch 2000). In many Ochrolechia species the variation of ascospore length is large, and it is possible that O. osorioana represents only a form of O. austroamericana with long ascospores. However, as we examined only one specimen of the former species (specimen P. Ranta 3108, H), we are refraining from uniting them.

Ochrolechia africana Vainio (1926: 3) , which sometimes grows on rocks, is also similar to O. kerguelensis , but this species has a C negative apothecial margin cortex, C+ red margin medulla and contains methylated hiascic acids and/or lichexanthone ( Brodo 1991, Kukwa et al. 2013).

Due to the pruinose discs the new species resembles O. parella and specimens referred here to O. antarctica but those species produce variolaric acid in the cortex of the thallus and apothecial margin. Moreover, our phylogenetic analysis shows that O. kerguelensis is only distantly related to O. parella ( Fig. 1 ). Ochrolechia parella s. str. might be restricted to the Northern Hemisphere where it is known from Northern Africa, Asia and Europe ( Hanko et al. 1986; Kukwa 2011).

Additional specimens of O. kerguelensis examined (all saxicolous). KERGUELEN ISLANDS. Grande Terre , Péninsule Courbet, broad ridge between Rivière du Sud & Rivière du Château, c. 7 km NW of Port-aux-Français, elev. 250 m, 17 February 1971, G. C. Bratt 71/156 ( MSC) ; ibid., summit of peak on ridge between Rivière du Sud & Rivière du Château, elev. 376 m, 24 March 1971, H. A. Imshaug 49332 ( MSC). Presqu’île Jeanne D’Arc, rock pinnacles on Plateau du Vent, NNE of Mt. du Refuge , elev. 500–600 m, 22 February 1971, G. C. Bratt 71/243 ( MSC) ; ibid., 1 km. N of les Bessons , elev. 620 m, 22 February 1971, G. C. Bratt 71/263 ( MSC) ; ibid., summit of Mt. du Refuge, elev. 614 m, 22 February 1971, R. C. Harris 6712 B ( MSC) ; ibid., summit of Mt. des Lichens , elev. 603 m, 22 February 1971, H. A. Imshaug 48491 ( MSC) ; ibid., terrace above Port-Jeanne d’Arc on E side of Ravin du Charbon, elev. 150 m, 24 February 1971, H. A. Imshaug 48591 ( MSC) ; ibid., rock outcrop in Vallee des Neiges , E of outlet of Lac Bleu, elev. 300 m, 25 February 1971. G. C. Bratt 71/328- A, 336 ( MSC) ; ibid., rock outcrop E of outlet of Lac Bleu in Vallée des Neiges, elev. 300 m, 25 February 1971, G. C. Bratt 71/328 B ( MSC) ; ibid., Vallée des Neiges , elev. ca 130 m, 49°34’S, 69°52’E, 26 January 2014, D. Ertz 19108 ( BR) ; Presqu’île Ronarc’h , small peaks on NW side of le Trièdre, elev. 400–500 m, 17 March 1971, R. C. Harris 7193 ( GZU) ; ibid., cliffs on NE face of le Pouce, elev. 700 m, 16 March 1971, G. C. Bratt 71/624 ( MSC) ; ibid., basalt outcrop on NE slope of le Pouce, elev. 400 m, 16 March 1971, R. C. Harris 7182 ( MSC) ; ibid., small peaks on NW side of le Trièdre, elev. 400–500 m, 17 March 1971, R. C. Harris 7193 ( MSC) ; ibid., summit of Mt. des Fées , elev. 381 m, 19 March 1971, G. C. Bratt 71/718, 71/724 ( MSC) ; ibid., red rock bluff on N ridge of Mt. Wyville Thomson , elev. 550 m, 20 March 1971, G. C. Bratt 71/742 ( MSC). Ile Guillou, elev. 85 m, 49°28’57”S, 69°48’33”E, 9 January 2014, D. Ertz 18928 ( BR). Ile Haute, highest part of Table des Mouflons, elev. 310–320 m, 5 March 1971 & R. C. Harris 6965 ( MSC). Ile Longue, summit of unnamed peak ( SE of Port-Bizet), elev. 223 m, 17 March 1971, H. A. Imshaug 49121 ( MSC) .

Selected specimens of chemotype I of O. antarctica examined. ANTARCTICA. Süd-Georgien, on rock, 22 October 1883, Will ( M 13504, holotype of Pertusaria (sect. Ochrolechia) antarctica ). ARGENTINA. Isla De Los Estados, Bahia Capitan Canepa, Headlands with heath and isolated Nothofagus groves, on E side of outer bay, elev. 30–60 m, 54°51’S, 64°29’W, on rock, 03 November 1971, H. A. Imshaug 52907 & K. E. Ohlsson ( H, MSC). ARGENTINA. Isla Grande (Tierra del Fuego): Sierra de Sorondo, to the E of Monte Olivia, elev. 760 m, 54°43’S, 68°07’W, rock outcrop on shoulder of mountain, 28 November 1971, H. A. Imshaug 55642 & K. E. Ohlsson ( MSC); ibid., Sierra Alvear, on W side of Paso Garibaldi, elev. 460 m, 54°42’S, 76°47’W, krummholz region, 24 November 1971, H. A. Imshaug 54835 & K. E. Ohlsson ( MSC); ibid., Sierra Lucas Bridges, on E side of Paso Garibaldi, elev. 610 m, 54°42’S, 67°45’W, cliffs just above treeline, 27 November 1971, H. A. Imshaug 55469 & K. E. Ohlsson ( MSC); ibid., Bahia Valentin, at summit of mountain behind bay, elev. 500 m, 54°53’S, 65°32’W, krummholz area, 15 October 1971, H. A. Imshaug 50299 & K. E. Ohlsson ( MSC). CHILE. Prov. Magallanes, Patagonian Channels, shoreline at head of fiord E of Mte Roberto, I. Madre de Dios, 50°20’S, 75°21’W, on rock, 29 September 1969, H. A. Imshaug 44109 & K. E. Ohlsson ( BM, MSC); ibid., Strait of Magellan, SE end of I. Nassau, B. San Nicolás, 53°50’S, 71°04’W, 9 October 1969, H. A. Imshaug 45365 & K. E. Ohlsson ( MSC); ibid., shore on W side of Bahía Borja, 53°32’S, 72°30’W, 7 October 1969, H. A. Imshaug 45232, 45334 & K. E. Ohlsson ( MSC); ibid., Isla Desolacion, Bahía Tuesday, along S shore of Caleta San José, 54°51’S, 74°28’W, Hebe scrub, 4 October 1969, H. A. Imshaug 44741 & K. E. Ohlsson ( MSC); Prov. Valdivia, Corral, on rock, Stockert ( W 19020008159, holotype of O. chilensis, BP 19922, isotype). FALKLAND ISLANDS. West Falklands, Hill Cove, stone run at NE base of French Peaks, elev. 200 ft., on rock, 24 January 1968, H. A. Imshaug 41027 & R. C. Harris ( BM, MSC); ibid., Fox Bay, Empetrum -heath NE of Kelp Pt, elev. 30 ft., on rock, 9 February 1968, H. A. Imshaug 42271 & R. C. Harris ( BR); ibid., Fox Bay, along shore N of East Head, UTM 21 F TC 9435, 7 February 1968, H. A. Imshaug 42140 & R. C. Harris ( MSC); East Falkland, N of Stanley, Moody Brook, on rock, 21 January 2009, S. Davey 21-7 ( MSC).

Selected specimens of chemotype II of O. antarctica examined. ANTARCTICA. South Shetland Islands, Île Déception, elev. 300 m, Ie excursion, n°74, sur une roche volcanique, 23 December 1908, Gain ( PC, holotype of Lecanora (sect. Ochrolechia) deceptionis ); King George Island, Admiralty Bay, Brama hill between Baranowski Glacier and Tower Glacier, 62°12’30”S, 58°38” W, elev. 180 m, on rock, 18 January 1980, R. Ochyra 804/80 & 807/80 ( H); Siodło hill in Baranowski Glacier, 62°12’S, 58°27” W, elev. 120 m, on rock, 18 January 1980, R. Ochyra 772/80 ( H). CHILE. Prov. Magallanes, Brunswick Peninsula, Seno Otway, at Bahía Camden, Nothofagus & Drimys forest, rock in tidal pool, 20 December 1967, H. A. Imshaug 39131 & R. C. Harris ( MSC); ibid., Seno Otway, along shore E of Canelos & just W of Ch. La Quema, on rock on beach, 20 December 1967, H. A. Imshaug 39193, 39179 & R. C. Harris ( MSC). FALKLAND ISLANDS. West Falklands, UTM Grid 21 F TC 9342, Fox Bay, along the shore of the lake in SE corner of Stud Paddock, elev. 200 ft, on rock, 10 February 1968, H. A. Imshaug 42294 & R. C. Harris ( B, MSC); ibid., Saunders Island, Rookery Cottage, elev. 50 m, -51.307000° -60.098500°, pebbles in Empetrum heath near cottage, 6 November 2015, A. Fryday 11355 ( MSC); East Falklands, Lafonia, Bleaker Island, on rock, 27 January 2009, S. Davey no 27-3 ( MSC). Argentine Cemetery near Goose Green, on rock, 23 January 2009, S. Davey no 23-4 ( MSC), North Arm, Garden Point, 52°08’06”S, 59°22’24”W, on rock, 4 February 2015, A. Fryday 11048 ( MSC); ibid., Darwin Settlement, coastal cliffs, on S side of Carcass Bay, Darwin Harbour, UTM 21 F UC 6457, 11 January 1968, H. A. Imshaug 40259 & R. C. Harris ( MSC).

Figures

FIGURE 1. Phylogenetic relationships among 33 samples of Ochrolechia (with three Marfloraea species used as outgroup taxa) based on a data set of mtSSU sequences that resulted from a Bayesian analysis using MrBayes. Posterior probabilities are shown above internal branches. Internal branches considered strongly supported are represented by thicker lines. The newly sequenced specimens are in bold. Collecting numbers of the authors or the GenBank accession numbers following the species names act as specimen and sequence identifiers. Species of interest, discussed in the paper, are highlighted in colour. The length of the branch represented by dashed lines was reduced by 50% for editing reason.

FIGURE 2. Ochrolechia kerguelensis. A, typical landscape of islands in Golfe du Morbihan, a habitat of the new species (view from Australia Island); B, macroscopical overview of a thallus of ca. 50 cm in diam. on Île Guillou; C–F, morphology of apothecia and thallus [C: field observation, on Grande Terre-Rivière du Sud; D–E: Ertz 18906; F: Ertz 19108]; G, photobiont (trentepohlioid); H, hymenium with one ascus; I–J, ascospores. Scale bars: D–F = 2 mm, G = 10 μm, H= 50 μm, I–J = 25 μm.