Henssenia werthii Ertz, R. S. Poulsen & Sochting. An 2017, comb. nov.
Creators: name: Ertz, Damien
name: Poulsen, Roar S.
name: Charrier, Maryvonne
name: Søchting, Ulrik
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Fungi
Ascomycota
Lecanoromycetes
Peltigerales
Koerberiaceae
Henssenia
Henssenia werthii

description: Henssenia werthii (Zahlbr.) Ertz, R.S. Poulsen & Søchting comb. nov. (Fig. 13)   
MycoBank: MB 822686  
 Basionym: Steinera werthii Zahlbr., Deutsche Südpolar-Expedition 8: 43 (1906). Type:— KERGUELEN. ‘An Steinen im Rundhöckerterrain am Stationssee (WERTH)’ - no original material was traced in B, H, M, W and WU.   
 Neotype here selected:— KERGUELEN, versant droit de la vallée de la Rivière du Sud, Ravin du Mica, 150 m, 49°16’07.6”S, 70°03’11.1”E, 17 November 2016, D. Ertz 21009 (BR!).   
 Description from our material (but see also description in Zahlbruckner 1906): Thallus placodioid, 0.5–1 cm diam., but sometimes contiguous and covering areas of 2–3 cm diam., margin distinctly and ±regularly lobate, central parts crustose-areolate; marginal lobes 0.2–0.8(–1) mm wide; areoles of central parts flat, c. 0.2–1 mm diam. Upper surface smooth in distal parts, slightly roughened in central parts, pale olivaceous brown, longitudinally ±white striped near the margin and white-flecked in central parts, not pruinose, without soredia or isidia. Apothecia discrete or sometimes 2–4 contiguous, up to 0.7(–1) mm diam., immersed when young, bursting through the cortex, remaining immersed with hymenial disc level with the thallus, sometimes half-immersed or rarely superficial and then with a narrow thalline margin; disc dark brown or reddish-brown to almost black, sometimes pale brown, plane to slightly convex at maturity. Thalline anatomy: thallus lobes c. 100–180 μm thick, becoming thicker in the center up to c. 450 μm; upper ±algal-free layer consists of a c. 10–20 μm thick, hyaline layer of ±isodiametric cells, (2–)3–9 μm diam.; hyaline necrotic layer on the upper surface c. 1–4 μm thick. Photobiont cells 6–11 μm diam., or often slightly wider than long c. 3–10 × 7–16 μm, heterocytes of similar size; hyphae below algal layer more loosely arranged, mainly ±horizontally aligned; hyphae in medulla c. 2–5 μm wide. Lower surface with a poorly differentiated cortical layer. Apothecial anatomy: Proper exciple laterally of hyphae arranged in parallel, 15–20 μm, with elongated cells of c. 3–8 × 2–3(–5) μm becoming isodiametric, thick-walled, c. 3–5 μm diam. near the surface; basally indistinguishable from the hypothecium. Hymenium 80–125 μm high; epihymenium dark brown (gelatinous matrix; paraphyses tips difficult to separate), c. 10–15 μm; paraphyses 2.5–4(–5) μm wide; apical cells slightly swollen, 4–6 μm wide, K–. Hypothecium inversely cone-shaped, extending down to the substratum, very thick, 70–125 μm high, consisting of densely short-celled hyphae above, becoming paraplectenchymatous with cells 2–5 μm diam. below. Asci 50–65 × 10–11 μm; ascospores 8 per ascus, simple, with a thin and more or less median plasma-bridge, but without a true transverse septum, straight, ellipsoid to narrowly ellipsoid with rounded ends, 10–14(–15) × 4–5(–5.5) μm, without a distinct gelatinous sheath, KI–. Pycnidia not seen.   
 Distribution and ecology: This species is only known from Crozet (this paper) and Kerguelen. Dodge & Rudolph (1955, p. 132) recorded the species from Heard Island, but this is likely to be a confusion with another species of Henssenia. The species is found mainly in lowland areas, in exposed situations on basaltic rock. It is easily overlooked due to its small size.   
 Notes: Henssen & James (1982) did not treat this species because no original material could be located. This still holds true, and it is believed that the material was destroyed in Berlin in 1943. During our fieldwork in Kerguelen, we have found material of a Steinera species that corresponds in many important characters (e.g. small size ‘usque 10 mm. latas) to the illustrations and description in Zahlbruckner (1906). Despite some differences that could be erroneous in Zahlbruckner (1906) (e.g. the thallus is shown to be subsquamulose in the center, not areolate, the spore are said to be 8–10 × 5–7 μm; the striation on the thallus lobes might have been overlooked), a neotype is therefore chosen and the name reintroduced. H. subglaucella is close to H. werthii but differs by slightly larger, not white-flecked thalli, apothecia that become slightly sessile, and slightly shorter ascospores.   
 Examined specimens: CROZET. Île de La Possession, Pic du Mascarin, c. 930 m, 46°26’19”S, 51°44’41”E, 6 December 2015, D. Ertz 20833 (BR). KERGUELEN. Peninsule 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 18977 (BR); ibidem, versant droit de la rivière du Sud, dans un petit vallon, c. 83 m, 49°17’47.5”S, 70°04’40.6”E, 17 November 2016, D. Ertz 21027 (BR); ibidem, 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 20893 (BR). ‘ Val Studer’, Canyon Mica, 49°16.7’S, 70°03.0’E, 19 December 1998, U. SØchting 9488 (C). Golfe du Morbihan, Île Guillou, 85 m, 49°28’57”S, 69°48’33”E, 9 January 2014, D. Ertz 18930 (BR). La Mortadelle, 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 620 (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 917 (C); 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 961 (C).
description: Published as part of 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, pp. 201-238 in Phytotaxa 324 (3) on pages 229-230, DOI: 10.11646/phytotaxa.324.3.1, http://zenodo.org/record/13698300