Steinera pannarioides 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 : 220-222

Steinera pannarioides Ertz & R.S. Poulsen spec. nov. ( Fig. 9 )

MycoBank: MB 822682

Diagnosis: A species of Steinera characterized by a subfoliose to placodioid, dark-brown to grey-brown non-isidiate thallus with marginal lobes (0.5–)1–2(–3) mm wide, apothecia becoming sessile to substipitate at maturity, (1–)3-septate ascospores that are 20–25(–27) × (6–)7.5–9 μm.

Type:— KERGUELEN. Presqu’île Jeanne d’Arc, près de Port-Jeanne d’Arc, c. 20 m, 49°33’03”S, 69°48’28”E, cavité humide sur un plateau rocheux près de la mer, 25 January 2014, D. Ertz 19096 (holotype BR!, isotype PC!).

Etymology: The specific epithet refers to the Pannaria -like appearance of the species in the field due mainly to the substipitate apothecia and subfoliose thallus.

Thallus subfoliose to placodioid, rather loosely attached to the substrate, 3–5(–6) cm diam., often fusing together, central parts ±subcrustose, sometimes cracked-areolate, with areoles c. 1–2(–3) mm diam.; marginal lobes (0.5–)1– 2(–3) mm wide. Upper surface smooth in distal parts, often ±scabrid in central parts, dark-brown to grey-brown, sometimes dark brown-flecked, not pruinose, without soredia or isidia. Apothecia abundant, mostly restricted to the central areas of the thallus, discrete, 0.7–1.5(–2.0) mm diam., immersed when young, becoming sessile to substipitate at maturity; disc red-brown to almost black, plane to slightly convex at maturity; thalline margin well-developed but narrow at maturity, to 0.22 mm wide, concolourous with thallus. Thalline anatomy: thallus c. 200–300 μm thick near the margin, becoming thicker in the center up to c. 650 μm thick; hyphae in upper 1/2–1/3 of thallus running perpendicularly to surface getting short-celled and densely packed towards upper surface; upper ±algal-free layer consists of a c. 7–12 μm thick, brown layer of ±isodiametric to slightly elongated cells c. 4–8 × 4–5 μm diam. that is overlaid by a necrotic layer, 3–8 μm thick. Photobiont Nostoc ; individual photobiont cells 3.5–6 μm diam., heterocytes 5–8 μm diam.; hyphae in medulla c. 2–4(–5) μm wide. Lower surface light-brown to whitish, in the foliose distal parts of thallus with a ±irregularly developed cortex layer c. 25–50 μm thick, composed of thick-walled, irregularly shaped, ±isodiametric cells, c. 5 μm diam. Apothecial anatomy: Excipulum compound, consisting of an inner proper exciple of short-celled hyphae arranged in parallel, hyaline becoming brownish near the surface, 25–50 μm thick, and an outer thalline exciple up to 200 μm thick. Hymenium 90–130(–160) μm high; epihymenium brown; paraphyses branched-anastomosing mainly in upper parts of hymenium, 2–2.5 μm wide; apical cells shortened and swollen, with brown walls, up to 5(–6) μm wide. Hypothecium 140–190 μm high. Asci 70–115 × 15–23 μm, tholus apparently including a deeper staining KI+ dark blue ring structure; ascospores (6–)8 per ascus, (1–)3-septate, straight, narrowly ellipsoid to oblong with rounded to pointed ends, 20–25(–27) × (6–)7.5–9 μm. Pycnidia globose to ellipsoid, c. 260–440 × 200–360 μm; conidiogenous cells short-celled, mainly producing conidia laterally, c. 3–5 × 3–4 μm diam.; conidia rod-shaped, 3–4 × 1–1.5 μm.

Distribution and ecology: Steinera pannarioides is so far only known from Crozet and Kerguelen. It is locally common on Crozet and Kerguelen but generally scattered throughout the investigated areas. In the eastern parts of Kerguelen, it is largely restricted to alpine areas. This species is strictly saxicolous mostly occurring in habitats with relatively high humidity either near streams, on seepage rocks, or, in the western more humid parts of Kerguelen, also on exposed, dry rock.

Notes: S. pannarioides is a very distinct species that does not look like any other species of the genus. It is characterized by a combination of the following characters: thallus saxicolous, subfoliose, light- to dark-brown, producing sessile to substipitate apothecia and four-celled ascospores. The species has been distributed from MSC to other herbaria under the unpublished name S. brattii , in sched. A lichenicolous Arthonia species is present on specimens Ertz 18901, 19050 and will be described in a separate work dealing with lichenicolous fungi.

Additional examined specimens: CROZET. Île de la Possession , partie amont de la rivière de la Crique de la Chaloupe (nord-ouest de la base Alfred Faure), le long du transit vers la Baie Américaine, c. 125 m, 46°24’40”S, 51°49’58”E, 26 November 2015, D. Ertz 20687 ( BR) ; Pic du Mascarin , c. 930 m, 46°26’19”S, 51°44’41”E, 6 December 2015, D. Ertz 20829 ( BR) ; Pointe Basse , rivière juste en amont de l’arbec, c. 80 m, 46°21’56”S, 51°42’40”E, 30 November 2015, D. Ertz 20710 ( BR). KERGUELEN. Péninsule Courbet, cabane Jacky, versant gauche de la Rivière du Sud, c. 170 m, 49°18’54”S, 70°07’45”E, 14 January 2014, D. Ertz 18982 ( BR) ; versant droit de la rivière du Sud, vallon du Mica , 150 m, 49°16’07.6”S, 70°03’11.1”E, 17 November 2016, D. Ertz 21013 ( BR) ; entre la base de Port-aux-Français et la Rivière du Château , c. 40 m, 49°20’11”S, 70°13’18”E, 18 December 2015, D. Ertz 20892 ( BR) ; SW corner of plateau between Rivière du Sud and Rivière du Chateau, 325 m, 49°18’3”S, 70°07’2”E, 15 December 1998, R. S. Poulsen 190 (C) ; Mt. Crozier , just below and <150 m from summit, 950 m, 49°17’7”S, 69°59’1”E, 18 December 1998, R. S. Poulsen 318 (C), 330 (C, H) ; Mt. du Chateau , c. 0.5 km NE of Les Créneaux, 640 m, 49°14’6”S, 70°08’0”E, 20 December 1998, R. S. Poulsen 469 (C) ; c. 1 km WSW of Les Créneaux , 500 m, 49°14’9”S, 70°06’7”E, 20 December 1998, R.S. Poulsen 485 (C) ; Col between Mt. du Milieu & Mt. Werth , 630 m, 7 March 1971, H.A. Imshaug 48943 (C). Presqu’Île Jeanne d’Arc, Port-Jeanne d’Arc, vallon à l’ouest de la cabane, c. 40 m, 49°33’S, 69°48’E, 22 January 2014, D. Ertz 19049 ( BR) ; ibidem, D. Ertz 19050 p.p. ( BR, sub. Arthonia ) ; ibidem, N shore of Lac Bleu, 172 m, 25 February 1971, R. C. Harris 6810 (C). Golfe du Morbihan, Île Australia, 100 m, 49°28’25”S, 69°52’41”E, 21 December 2013, D. Ertz 18719 ( BR) ; Île Guillou , crête rocheuse au sommet de l’île, 130 m, 49°28’34”S, 69°48’36”E, 8 January 2014, D. Ertz 18901 p.p. ( BR, sub. Arthonia ). Île Longue, feldmark in valley on central plateau SE of Port- Bizet, 120 m, 20 March 1971, H.A. Imshaug 49247 ( MSC). La Mortadelle, SE part (at the foot) of La Mortadelle, c. 0.5 km W of Lac Ampère, c. 25 m from cabin/shelter, 150 m, 49°25’4”S, 69°10’8”E, 17 January 1999, R. S. Poulsen 565, 567 (C) ; ibidem, c. 100 m from cabin/shelter, R.S. Poulsen 570 (C) ; near SE foot of La Mortadelle , c. 0.5 km W of Lac Ampère, c. 400 m SSW of cabin/shelter, 150 m, 49°25’6”S, 69°10’7”E, 21 January 1999, R. S. Poulsen 621 (C) ; ibidem, c. 300 m SW of cabin/shelter, 150 m, 49°25’5”S, 69°10’7”E, 22 January 1999, R.S. Poulsen 629 (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 701 (C). Île Foch, c. 1 km NNE of summit of Mt. R. Bureau, c. 400 m, 48°58’1”S, 69°20’4”E, 14 February 1999, R. S. Poulsen 922 (C, H) ; 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 964 (C). Presqu’Île Bouquet de la Grye, Port Couvreux, c. 400 m SE of old farm house, 50 m, 49°17’3”S, 69°42’1”E, 28 February 1999, R. S. Poulsen 1067 (C, H) .

Figures

FIGURE 9. Steinera pannarioides. a Thallus and apothecia (Kerguelen, Presqu’Île Jeanne d’Arc). b Thallus and apothecia (Crozet, Île de La Possession). c–d Thallus and apothecia (Ertz 20687). e Photobiont (Ertz 18982). f Epihymenium in water (Ertz 18982). g Ascus in water (Ertz 19096). h Ascospores in water and one in KI (right one) (Ertz 19096). i Conidia in water (Ertz 18719). Scale bars: c=1.5 mm, d=0.5 mm, e–f=10 μm, g=20 μm, h–i=10 μm. (Photos D. Ertz)