Steinera membranacea Ertz & R.S. Poulsen, 2017

Ertz, Damien, Poulsen, Roar S., Charrier, Maryvonne & Søchting, Ulrik, 2017, Taxonomy and phylogeny of the genus Steinera (Arctomiales, Arctomiaceae) in the subantarctic islands of Crozet and Kerguelen, Phytotaxa 324 (3), pp. 201-238 : 215-219

Steinera membranacea Ertz & R.S. Poulsen spec. nov. ( Fig. 7 )

MycoBank: MB 822681

Diagnosis: A species of Steinera characterized by a subfoliose to placodioid, dark olive-green to brownish black, non-isidiate thallus, (2–)3-septate ascospores that are 22.5–30(–33) × (7.5–)9–12.5 μm.

Type:— KERGUELEN, Presqu’Île Jeanne d’Arc, c. 2 km au SE de Port-Jeanne d’Arc, c. 100 m, 49°34’S, 69°51’E, 26 January 2014, D. Ertz 19126 (holotype BR!, isotypes REN!, PC!).

Etymology: The specific epithet refers to the membranaceous-like appearance of the thallus, ressembling those of dry Enchylium species in the field.

Thallus subfoliose to placodioid, rather tightly attached to the substrate, c. 2–5 cm diam., often fusing together, margin distinctly and ±regularly lobate, central parts sometimes ±squamulose and rather loosely attached to the substrate; marginal lobes 0.5–3 mm wide. Upper surface smooth, dark olive-green to brownish black, not pruinose, without soredia or isidia. Apothecia abundant, discrete or sometimes 2–3 contiguous, 0.8–1.2(–1.5) mm diam., immersed when young, becoming sessile at maturity, with or without a constricted base; disc pale brown to red-brown, plane to strongly convex at maturity; thalline margin inconspicuous or well-developed at maturity, to 0.4 mm wide, concolourous with thallus. Thalline anatomy: thallus 215–280 μm thick; hyphae in upper 1/3–1/4 of thallus running perpendicularly to surface becoming distinctly narrower towards the upper surface, c. 1 μm wide; upper ±algal-free layer consists of a c. 6–14 μm thick, yellowish-brown layer due to the colour of the gelatinous intercellular matrix, which is sometimes overlaid by a necrotic layer, 1–3 μm thick; a true upper cortex is not developed. Photobiont Nostoc ; individual photobiont cells, 3–5 μm diam., heterocytes 4–7 μm diam.; hyphae in medulla c. 3–4 μm wide. Lower surface light-brown to whitish, in the subfoliose distal parts of thallus with a ±irregularly developed cortex layer c. 25–40 μm thick, composed of thick-walled, irregularly shaped, ±isodiametric cells, c. 4–5 μm diam, often with thick short hyaline hyphae, extending downwards to the substrate, c. 12–30 × 4–5 μm. Apothecial anatomy: Excipulum inconspicuous or consisting of an inner proper exciple (remnants of the formative tissue) of few hyphae arranged in parallel, c. 10–15 μm thick, and an outer thalline exciple. Hymenium 125–150(–210) μm high; epihymenium hyaline; paraphyses branched mainly in upper parts of hymenium, 1.5–2.5 μm wide; apical cells shortened, not or slightly swollen, hyaline, up to 4.5 μm wide. Hypothecium 150–200 μm high. Asci 90–130(–165) × 15–25 μm, tholus KI+ deep blue with a darker thin outer layer; ascospores 8 per ascus, (2–)3-septate, hyaline, straight, narrowly ellipsoid to oblong with rounded to rarely ±pointed ends, 22.5–30(–33) × (7.5–)9–12.5 μm. Pycnidia hyaline, immersed in thallus, in section globose to ellipsoid, c. 140–160 μm diam.; conidiogenous cells c. 5–6 x 4.5–5.5 μm; conidia rod-shaped to ellipsoid, 3–4 × 1.5 μm.

Distribution and ecology: So far S. membranacea is only known from Crozet and Kerguelen. It is scattered throughout most investigated areas in Kerguelen, except Peninsule Rallier du Baty where it was not observed. The species is very rare on Crozet and was only collected once near the research station. It is found below 500 m elevation and is most common in lowland areas. It grows on basaltic seepage rock, on pebbles in damp situations and on periodically inundated rocks by lake or stream borders etc. In the La Mortadelle area in the western part of Kerguelen with high annual precipitation, it is occationally found directly on dry, exposed rock as well. It seems to be the most moisture-dependent species in the genus.

Notes: Steinera membranacea resembles members of the genus Enchylium (Ach.) Gray (recently resurrected to accommodate the Collema Tenax-group; Otálora et al. 2014) in the field, but regarding anatomical features of the thallus and the apothecia, it is similar to the other Steinera species, except that the hyphae often become narrower towards the upper surface whereas in other Steinera species these hyphae gets short-celled and densely packed. The species is somewhat similar to Enchylium expansum (Degel.) P.M. Jørg. in Jørgensen & Goward (2015: 42) (Basionym: Collema tenax var. expansum Degel. ), but that species differs in thallus anatomy by having a much looser medulla with more algal gelatin (polysaccharid matrix around the Nostoc colonies that swells when wet) as is typical of species of Enchylium (e.g. Otálora et al. 2014), larger apothecia (up to 3(–4) mm diam.), a more foliose thallus with larger thallus lobes (5–10 mm broad), a minutely striated upper surface of the thallus and 3-septate to submuriform ascospores ( Degelius 1954). Enchylium expansum also has a different ecology, being a species growing on soil together with mosses and small phanerogams ( Degelius 1954) or on mossy, calcareous rocks ( Jørgensen & Goward 2015), whereas S. membranacea grows only on rock, never on mosses. Jørgensen & Goward (2015) recorded Enchylium expansum from Kerguelen, which would be the only known locality in the Southern Hemisphere, but this specimen (Poulsen 490, the collecting number omitted in Jørgensen & Goward 2015) is a misidentification of Steinera membranacea . However, a species of Enchylium occurs in Kerguelen but its identification at the species level still need further studies.

Additional examined specimens: CROZET. Île de La Possession, juste au sud de la base Afred Faure, c. 124 m, 46°26’03”S, 51°51’35”E, dalle rocheuse, 11 December 2013, D. Ertz 18652 p.p. (BR, sub. Placopsis stellata ). KERGUELEN. Péninsule Courbet, Cirque du Chateau, on plateau around upper course of Rivière de la Grande Muraille c. 1–2 km S of la Grande Cascade , 300 m, 49°17’6”S, 70°07’9”E, 15 December 1998, R.S. Poulsen 175 (C); Val Studer, vallon encaissé s’ouvrant dans le versant droit de la Rivière du Sud un peu en aval du Lac Supérieur, 105 m, 49°17’27”S, 70°03’11”E, 16 November 2016, D. Ertz 20999 (BR); ibidem, Grande Cascade , c. 800 m SE of Lac Supérieur, 100 m, 49°17’5”S, 70°03’3”E, 18 December 1998, R.S. Poulsen 370 (C); Mt. du Chateau, c. 1 km WSW of Les Créneaux, 450 m, 49°14’9”S, 70°06’7”E, 20 December 1998, R.S. Poulsen 490 (C); près de la cabane Jacky, versant gauche de la rivière du Sud, c. 170–200 m, 49°18’54”S, 70°07’45”E, 14 January 2014, D. Ertz 18983 (BR). Presqu’Île Ronarc’h, seepage area with small stones between Le Castel and Le Pouce, 200 m, 16 March 1971, R.C. Harris 7171 (MSC). Presqu’Île Jeanne d’Arc, Canyon des Sourcils Noirs, versant gauche du canyon, 55 m, 49°40’55”S, 70°14’18”E, 31 December 2013, D. Ertz 18806 (BR); Port-Jeanne d’Arc, c. 121 m, 49°33’22”S, 69°48’39”E, 23 January 2014, D. Ertz 19060 p.p. (BR, sub Lichina ); ibidem W edge of Ravin du Charbon, 100–200 m, 19 February 1971, G.C. Bratt 71/190 and 71/191 (MSC); Isthme entre la presqu’Île Jeanne d’Arc et la presqu’Île Ronarc’h, c. 8 m, 49°37’59”S, 70°08’03”E, 1 January 2014, D. Ertz 18845 (BR). La Mortadelle, SE part (at the foot) of La Mortadelle, c. 0.5 km W of Lac Ampère, c. 100 m from cabin/shelter, 150 m, 49°25’4”S, 69°10’8”E, 17 January 1999, R.S. Poulsen 585 (C); c. 250 m NW cabin/shelter, 150 m, 49°25’3”S, 69°10’6”E, 20 January 1999, R.S. Poulsen 610 (C). Île Foch, along SE side of Baie Phillips c. 2 km from W end (bottom) of the bay, 10 m, 48°57’0”S, 69°19’6”E, 19 February 1999, R.S. Poulsen 966 (C). Golfe du Morbihan, Île Guillou, 85 m, 49°28’57”S, 69°48’33”E, 9 January 2014, D. Ertz 18927 (BR).

Steinera molybdoplaca (Nyl. ex Cromb.) Zahlbr. ( Fig. 8 , see also Henssen & James 1982, Keuck 1977 who illustrated the holotype) Deutsche Südpolar-Expedition 8: 43 (1906). Basionym: Amphidium molybdoplacum [ ‘ molybdophaeum ’] Nyl. in Crombie, J. Bot. Lond.

13 (New Series vol. 4): 333 (1875); [‘ molydoplacum ’] in Crombie, J. Linn. Soc. (Bot.) 15: 181 (1876). Type:— KERGUELEN .

Swain’s Bay, December 1874, A.E. Eaton (Venus Transit Expedition). (lectotype BM!, isolectotypes BM, H).

Thallus subfoliose to placodioid, closely appressed to the substrate, to 6 cm diam., margin distinctly and ±regularly lobate, central parts becoming areolate ±crustose; marginal lobes broadening to 2 mm towards their ends and there occasionally notched. Upper surface smooth to roughened, sometimes coarsely scabrid, uniformly pale grey or becoming darker grey towards the centre or at the margin, sometimes with an olive tinge, not pruinose, without isidia, in some specimens with soredia at the margins of thallus lobes (sorediate morphs). Areoles derived from secondary rimose cracking between the main fissures, complete or incomplete, coarse, angular, flat to convex. Apothecia scarce, rarely abundant, discrete or sometimes 2(–4) contiguous, developed on the uppermost part of the inner areoles, up to 0.8(–1) mm diam., immersed when young, eventually more or less level with the surface of the thallus, urceolate, without constricted base at maturity; disc dull brown to reddish-brown, concave or plane at maturity; thalline margin not or slightly elevated, markedly scabrid, to c. 0.15 mm wide, concolourous with thallus. Thalline anatomy: thallus c. 210–1000 μm thick; hyphae in upper 1/2–1/3 of thallus running perpendicularly to the surface, becoming short-celled and densely packed towards upper surface; upper ±algal-free layer consists of a c. 5–40 μm thick, hyaline layer of oval, rounded or cuboidal cells 5–10 μm diam., and elongated cells 8–10 × 3–4 μm diam. that is overlaid by a necrotic layer, c. 5–10 μm thick. Photobiont Nostoc ; individual photobiont cells 4–8 μm diam., heterocytes 5–7 μm diam.; hyphae c. 4–5 μm wide. Lower surface pale grey to pale brown, in the distal parts of thallus with a ±irregularly developed cortex layer c. 25 μm thick, composed of ±periclinal hyphae, c. 2–3 μm diam. in cross section of the thallus lobes. Apothecial anatomy: Excipulum -like structure hyaline, pale brownish near the surface, 30–40 μm, composed of small, ±cuboid cells, 5–7 × 5–6 μm, I+ pale orange; with a thalline margin at the outer edge containing clusters of the photobiont. Hymenium 115–245 μm high; epihymenium pale orange to pale brown, 20–30 μm; paraphyses branched-anastomosing mainly in upper parts of hymenium, 2–4 μm wide; apical cells shortened, swollen, with pale brown walls, up to 4–6 μm wide, K+ faintly darker brown. Hypothecium 125–175 μm high. Asci 100–135 × 14–23 μm, tholus including a deeper staining I+, KI+ dark blue ring structure; ascospores (4–7)–8 per ascus, (1–2–)3-septate, straight or slightly curved, narrowly ellipsoid to oblong with rounded ends, (18.5–)19–25 × 7–10(–11) μm, I–, KI–. Pycnidia not seen.

Distribution and ecology: Steinera molybdoplaca is known from Crozet (this paper), Heard Island ( Øvstedal & Gremmen 2006, sub. ‘ Steinera glaucella ’), Kerguelen (type locality and this paper), and probably occurs also on Prince Edward Islands ( Øvstedal & Gremmen 2001, as S. sorediata ). The species is scattered to relatively common throughout most investigated areas. Together with Steinera isidiata and S. pannarioides , it is the most frequently encountered Steinera species on Crozet and Kerguelen and in the La Mortadelle area (Kerguelen) it appears to be one of the most abundant species with Aspiciliopsis macrophthalma (Hook. f. & Taylor) B. de Lesd. Steinera molybdoplaca is found in lowland to high elevation. It grows in a variety of places ranging from dry, exposed rock to periodically inundated seepage rock. Like S. membranacea , it occurs most often in perhumid environments; for example, on seepage rock, on pebbles on damp soil, on rock at lake and stream margins etc.

Notes: Steinera molybdoplaca is morphologically similar to S. lebouvieri , which differs by having a thallus with larger lobes, less appressed to the substrate, never crustose-areolate in central parts, usually having a pinkish tinge and usually with several apothecia per thallus lobe and with slightly smaller apothecia. Henssenia glaucella shares the greyish colour of the thallus but differs by having smaller thalli (up to 3.5 cm diam., but often smaller), apothecia that might become sessile and simple ascospores. Several specimens (viz. 71/181, 102, 858, 6851, 20567, 20821, 20862, 20995) have thallus lobes that are sorediate on the margins, otherwise looking like non-sorediate S. molybdoplaca although the thalli are often smaller. According to our molecular data, including identical ITS sequences ( Fig. 3 ), these specimens are sorediate morphs of S. molybdoplaca . Steinera sorediata described from New Zealand differs by having laminal soralia, (3–)5–7-septate and much longer (45–57 μm) ascospores ( Henssen & James 1982). Specimens of S. sorediata (all sterile) recorded from Prince Edward Islands by Øvstedal & Gremmen (2001) are probably sorediate morphs of S. molybdoplaca . Specimen Ertz 18932 has a lichenicolous fungus occuring on its thallus.

Additional examined specimens: CROZET. Île de La Possession, summit area of Mt. Branca 2 km W of Base Alfred-Faure, 350 m, 46°26’0”S, 51°50’5”E, 10 December 1998, R.S. Poulsen 102 (C); entre la base de recherche Alfred Faure et le vallon du barrage, c. 120 m, 46°26’05”S, 51°51’31”E, 11 December 2013, D. Ertz 18651 (BR); sommet de la rive droite du vallon de la rivière du Camp, 200 m, 46°25’48”S, 51°51’00”E, 10 November 2016, D. Ertz 20942 (BR); près de la Pointe du Bougainville, c. 150 m, 46°26’22”S, 51°50’58”E, rocher dans le lit d’un ruisseau, 21 November 2015, D. Ertz 20567 (BR); Pic du Mascarin, c. 930 m, 46°26’19”S, 51°44’41”E, 6 December 2015, D. Ertz 20821, 20827, 20836 (BR); Mont du Mischief, près du sommet, 798 m, 46°25’03”S, 51°41’33”E, 8 December 2015, D. Ertz 20862 (BR). KERGUELEN. Péninsule Courbet, cabane Jacky, versant droit de la Rivière du Sud, grande chute d’eau dans un petit canyon, c. 90 m, 49°19’3.7”S, 70°06’44”E, 13 January 2014, D. Ertz 18972 (BR); Val Studer, vallon encaissé s’ouvrant dans le versant droit de la Rivière du Sud un peu en aval du Lac Supérieur, 105 m, 49°17’27”S, 70°03’11”E, 16 November 2016, D. Ertz 20995 (BR); ibidem, 285 m, 49°17’40”S, 70°03’15”E, 16 November 2016, D. Ertz 21002 (BR); versant droit de la Rivière du Sud, en amont du vallon du Mica, 150 m, 49°16’07.6”S, 70°03’11.1”E, 17 November 2016, D. Ertz 21017 (BR); Port aux Francais, c. 0.7 km N of base by lake, 25 m, 49°20’8”S, 70°13’5”E, 14 December 1998, R.S. Poulsen 151 (C); Grande Muraille , 150 m, 49°17’0”S, 70°08’5”E, 15 December 1998, R.S. Poulsen 159 p. p. (C, sub Steinera glaucella ); Rivière du Chateau, c. 50 m SE of La Grande Cascade , 200 m, 49°16’9”S, 70°07’8”E, 15 December 1998, R.S. Poulsen 162 (C); Mt. du Chateau, c. 0.5 km WSW of Les Créneaux, 550 m, 49°14’7”S, 70°07’1”E, 20 December 1998, R.S. Poulsen 482 (C). Péninsule Rallier du Baty, Les Deux Frères, canyon at SE-most corner of the mountain, c. 200 m, 49°38’0”S, 69°00’4”E, 5 February 1999, R.S. Poulsen 858 (C). La Mortadelle, NW-most edge of Plaine Ampère, 0.3 km N of Rivière de la Diozaz, c. 1 km S of SE corner of La Mortadelle, 25 m, 49°25’8”S, 69°10’9”E, 25 January 1999, R.S. Poulsen 670 (C); c. 300 m W of Lac Ampère, c. 500 m S of cabin/shelter, 75 m, 49°25’6”S, 69°10’8”E, 29 January 1999, R.S. Poulsen 703 (C); SE part (at the foot) of La Mortadelle, c. 0.5 km W of Lac Ampère, c. 100 m S of cabin/shelter, 150 m, 49°25’4”S, 69°10’8”E, 30 January 1999, R.S. Poulsen 709 (C). Golfe du Morbihan, Île Guillou, c. 14 m, 49°28’57”S, 69°49’06”E, 8 January 2014, D. Ertz 18868 (BR); ibidem, 60 m, 49°29’08”S, 69°48’41”E, 9 January 2014, D. Ertz 18924 (BR); ibidem, 85 m, 49°28’57”S, 69°48’33”E, 9 January 2014, D. Ertz 18932 p.p. (BR, sub. unknown lichenicolous fungi); ibidem, Île Mayes, E end of the island 100–200 m from sea, 30 m, 49°28’2”S, 69°57’1”E, 17 December 1998, R.S. Poulsen 262 (C). Île Foch, c. 200 m NE of summit of Mt. R. Bureau, 610 m, 48°58’5”S, 69°20’4”E, 14 February 1999, R.S. Poulsen 909 (C).

Figures

FIGURE 3. Phylogenetic relationships among 27 Steinera samples (with Gregorella humida as outgroup) based on a dataset of nuLSU, mtSSU, RPB1 and nuITS sequences that resulted from a Bayesian analysis using MrBayes. Posterior probabilities ≥ 0.95 are shown above internal branches, and Maximum Likelihood bootstrap values ≥ 70 obtained from a Garli analysis are shown below internal branches. Internal branches, considered strongly supported by both analyses, are represented by thicker lines. All Steinera samples are newly sequenced. Lineages representing new species of Steinera are highlighted.

FIGURE 7. Steinera membranacea. a Fertile thalli on pebbles in damp situations (Kerguelen, Presqu’Île Jeanne d’Arc). b Thallus and apothecia (Kerguelen, Île Guillou). c–e Thallus and apothecia (Ertz 19126). f Longitudinal section of thallus lobe in lactophenol blue coton (Ertz 19126). g Upper part of ascus in water (Ertz 19126). g Ascospores in water (Ertz 19126). Scale bars: c=1.5 mm, d–e=0.5 mm, f=50 μm, g–h=10 μm. (Photos D. Ertz)

FIGURE 8. Steinera molybdoplaca. a Fertile non-sorediate thallus (Kerguelen, Île Guillou). b Fertile non sorediate thallus (Crozet, Île de La Possession). c–d Thallus and apothecia (lectotype). e Sorediate thallus (Kerguelen, Val Studer). f Ascus in lugol (Ertz 18932). g Ascus in KI (Ertz 18932). h Ascus in water (Ertz 18932). i Ascospores in water (Ertz 18932). Scale bars: c=1.5 mm, d =0.5 mm, f–h=20 μm, i=10 μm. (Photos D. Ertz)