Pronectria loweniae Flakus, Etayo, Rodr. Flakus & Zhurb., sp. nov.

Index Fungorum number: IF 900452; MycoBank number: MB 900752: Facesoffungi number: FoF 14203; Fig. 1

Etymology – T he new species is named in honor to the eminent American mycologist Dr. Rosalind Lowen (New York), who studied the species for the first time together with Swedish lichenologist Dr. Rolf Santesson, for her important contribution to knowledge on lichenicolous Hypocreales.

Lichenicolous. Growing on discs of apothecia and occasionally adjacent parts of the thallus of lichen-forming fungi Solorina bispora, S. saccata and S. spongiosa. Sexual morph: Ascomata perithecia, growing on discs of apothecia and occasionally also adjacent parts of thallus of Solorina species, aggregated in small groups, subglobose to obpyriform, 120–250 μm wide, 110–220 μm tall, often shortly papillate, with distinct ostiole, erumpent and occasionally up to 1/3 exposed, pale yellowish, yellow- to apricot-orange, rarely also medium orange-brown or reddish orange, with projecting hyaline, thin-walled, septate hyphae 5–25 × 3–6 μm (sometimes radially spreading over the host hymenia as paler areas surrounding ostiolar regions). Exciple 20–25 μm wide below, up to 60 μm wide above, of cells 1–17 × 1–3 μm, consists of hyaline inner layer, composed of tangentially elongated, thin-walled cells (strongly inspersed by small orange oil droplets; the droplets sometimes observed additionally inside the asci and the whole ascomatal cavities) and hyaline to pale orange outer layer composed of tangentially elongated to isodiametric thick-walled cells, KOH–, lactic acid–. Interascal filaments scarce, 2–10 μm wide, hyaline, septate, constricted near septa. Periphyses hyaline, simple to branched, sometimes septate, 15–30 × 1–2 μm. Asci unitunicate, subcylindrical to elongate-clavate, truncate at the apex, 8-spored, 60–70×8–10 μm. Ascospores hyaline, elliptic to narrowly elliptic (sometimes almost fusiform), occasionally with slightly wider upper cell, smooth-walled, without evident gelatine coat, with pale orange guttules, 1-septate, usually slightly constricted at the septum (if observed in
water), 10–(x = 13.2 ± 1.8)–18 × 3–(x = 5.1 ± 1.5)–8 μm, l/b ratio 1.5–(x = 2.8 ± 0.7)–5 (n = 230) [in holotype: 11–(x = 14.5 ± 1.6)–17 × 3.5–(x = 5.6 ± 0.6)–6.5 μm, l/b ratio 2.2–(x = 2.6 ± 0.3)–3.7 (n = 53)], diagonally uniseriate to biseriate in the ascus. Asexual morph: Undetermined.

Material examined – France, Arette, La Pierre St. Martin le Braca, hayedo-abetal close to road D-132, 42° 59′ 06″ N, 0° 44′ 38″ W, 1480 m, on terricolous Solorina saccata in limestone crack, 1 August 2018, P. Rodriguez-Flakus 4000, J. Etayo & A. Flakus (KRAM-L 73248, holotype, herb. Etayo, isotype); Canada, Nunavut: Ellesemere Is., Eureka, 80° 06′ N, 85° 38′ W, on S. bispora var. subspongiosa, 30 July 1999, N.V. Matveeva (LE 260160); ibid., Black Top Ridge, 80° 04′ N, 85° 29′ W, 900 m, on S. bispora var. subspongiosa, 30 July 1999, F.J.A. Daniëls (LE 260039); Mongolia, Khubsugul Aimak, Renchinlkhumbe Somon, headwaters of Ar Khordolyn Gol River, NE slope of Khordolyn Sardig Nuru Range, 50° 53′ 32″ N, 99° 56′ 50″ E, 2050 m, on S. saccata, 15 July 2018, M.P. Zhurbenko 1885a (LE 309699a); 16 July 2018, M.P. Zhurbenko 1886 (LE 309700); Norway, Svalbard, Dickson Land, W coast of Billefjorden, 7 km S of Pyramiden, near Nidedalselva river mouth, 78° 37′ N, 16° 20′ E, 2–100 m, on S. bispora, 23 July 2003, M.P. Zhurbenko 03329 (LE 260960); M.P. Zhurbenko 03333 (LE 261160); Russia, Arkhangelsk Region, Franz Josef Land, Hooker Is., Cape Sedov, 80° 20′ N, 52° 52′ E, on S. bispora var. subspongiosa, 2 August 1930, V.P. Savicz 9d (LE 207391); Krasnoyarsk Territory, Kara Sea, Vize Is., 79° 32′ N, 76° 50′ E, on S. bispora var. subspongiosa, 14 August 1930, V. P. Savicz 1607 (LE 207390); Taimyr Peninsula, Byrranga Mts, Zamknutaya River, 74° 37′ N, 98° 33′ E, 150 m, on S. bispora var. subspongiosa, 6 August 1995, M.P. Zhurbenko 95474 (LE 233942); N of LevinsonLessing Lake, 74° 31′ N, 98° 36′ E, 400 m, on S. bispora var. subspongiosa, 20 August1995, M.P. Zhurbenko 95501b (LE 260299b); on S. bispora var. bispora, 22 August 1995, M.P. Zhurbenko 95500 (LE 260260); Republic of Sakha (Yakutia), Lower Lena River, Primorskii Range, Stolb meteostation, 72° 22′ N, 126° 42′ E, 50 m, on S. bispora var. subspongiosa, 4 August 1998, M.P. Zhurbenko 98368 (LE 260100); Samoilovskii (D’ieleekh Aryyta) Island, 72° 22′ N, 126° 29′ E, 10 m, 27 July 1998, M.P. Zhurbenko 98371 (LE 260080); USA, Alaska, Sagwon, 69° 26′ N, 148° 40′ W, 280 m, on S. bispora var. bispora, 7 August 2003, D.A. Walker (LE 260067); Kobuk Valley Wilderness, 67° 07′ N, 159° 03′ W, 40 m, on S. bispora var. bispora, 9 August 2000, M.P. Zhurbenko 00465 (LE 260277); 67° 06′ N, 159° 01′
W, 50 m, on S. spongiosa, 4 August 2000, M.P. Zhurbenko 00179 (LE 260028).

Additional material examined – of P. robergei: Russia, Murmansk Region, Pyukhyakuru River, 66° 47′ N, 30° 00′ E, on Peltigera canina, 12 August 1986, T.A. Dudoreva (LE 233837); ibid. Nenets Autonomous Area, Khar’yaga oilfield, 67° 11′ 07″ N, 56° 29′ 37″ E, 70 m, on P. aphthosa, 25 July 2007, M.P. Zhurbenko 0727 (LE 210498); 67° 11′ 19″ N, 56° 29′ 53″ E, 70 m, on P. aphthosa, 22 July 2007, M.P. Zhurbenko 0728 (LE 210346); Komi Republic, headwaters of Pechora River, 62° 02′ N, 58° 05′ E, 180 m, on P. praetextata, 10 July 1997, M.P. Zhurbenko 97264 (LE 210237); 62° 05′ N, 58° 25′ E, 200 m, on P. leucophlebia, 7 July 1997, M.P. Zhurbenko 97279 (LE 210351); Krasnoyarsk Territory, 40 km NW of Krasnoyarsk, near Pogorelka Village, 56° 25′ N, 93° 00′ E, on P. canina, 20 July 2000, T.N. Otnyukova (LE 210259); Altai Republic, Kuderli Lake, 55° 52′ N, 88° 35′ E, 1700 m, on Peltigera sp., 10 June 1987, N.I. Zolotukhin (LE 207388a); Republic of Buryatia, Khamar-Daban Range, Temnik River, 51° 05′ N, 104° 55′ E, 1200 m, on Peltigera sp., 21 July 1994, G.P. Urbanavichyus (LE 207389); Spain, Navarra, Orbaiceta, Irati forest, coming up from Orbaiceta to Azpegui refuge, Ursario, on Peltigera sp., 43° 02′ 02″ N, 1° 12′ 50″, 1030 m., 13 September 2018, J. Etayo (Etayo 31406).

GenBank numbers – ITS: OR116443; LSU: OR133232.

Notes – Our new collection is characterized by small, pale yellowish-orange (rarely reddish orange), often finely papillate ascomata immersed in hymenia of various species of Solorina (likely without causing visibly damages to the host), exciple strongly inspersed by small, orange oil droplets with thickened in the apical part, and constantly smooth-walled ascospores.

Our phylogenetic analyses based on the concatenated dataset of LSU and ITS (Fig. 2) revealed that our collection clustered with Pronectria species within Bionectriaceae (Hypocreales). Further, it formed a sister clade to Pronectria robergei (growing on lichen in Peltigera) and Protocreopsis freycinetiae that growing on remnants of monocotyledonous plants (Rossman et al. 1999). The subclade formed by these three species, then sistered to a subclade with the saprobic species in genera Lasionectriella and Ochronectria and these phylogenetic placements are very similar to Rossman et al. (1999) and Lechat and Fournier (2016). Our collection clustered with P. robergei in our phylogenetic analyses (Fig. 2).

Figure 1 – Pronectria loweniae (KRAM-L 73248, holotype). a–c Habit of ascomata growing in hymenia of Solorina saccata. d Transversal section of ascoma showing exciple differentiated into inner layer inspersed by orange droplets and thickened apically outer layer (mounted in LPCB). e Thickened apical outer layer of exciple (mounted in LPCB). f Periphyses (mounted in LPCB). g Exciple divided into inner layer inspersed by orange droplets and hyaline outer layer (mounted in LPCB). h Asci (mounted in LPCB). i Interascal filaments (mounted in distilled water). j Ascospores mounted in distilled water (upper row) and LPCB (lower row). Scale bars: a–c=500 µm, d=50 µm, e–j=10 µm

Figure 2 – Phylogenetic reconstruction of the systematic position of Pronectria loweniae within Bionectriaceae inferred from ML analyses of combined nuLSU and nuITS rDNA dataset. Species from the Hypocreaceae (Hypocrea and Hypomyces) were used as outgroup. Bold branches represent either bootstrap values≥70 and/or Bayesian posterior probabilities≥0.95