Leiothecium dictyophorum S.M.Romero & Comerio, sp. nov.

(Fig. 2)

DIAGNOSIS. — Leiothecium dictyophorum S.M.Romero & Comerio, sp. nov.; ex affinitate L. ellipsoidei Samson & Mouch. et L. cristati Y.Marín, Stchigel & Cano, ab utroque ascosporarum ornamento reticulato-foveato sine manifestis cristis distinctum.

Leiothecium dictyophorum S.M. Romero & Comerio sp. nov.; of the affinity of L. ellipsoideum Samson & Mouch. and L. cristatum Y. Marín, Stchigel & Cano, distinct from both by the ascospores’ ornament reticulate-foveate without prominent crests.

TYPE MATERIAL. — Argentina • Catamarca,RN 60 km 1016; 29°30’4”S, 65°37’57”W; 237 m alt.; 22.VIII.2011; S.M. Romero leg.; Holotype: BAFC 53468 (dried culture); BAFCcult 4595 = FMR≈15063, culture ex type; GenBank BenA sequence PP149064, rpb 2 sequence PP149071.

ADDITIONAL SPECIMENS STUDIED. — Argentina • Catamarca; RN 60 km 1102; 28°55’15”S, 66°08’46”W; 338 m alt.; 5.I.2009; BAFCcult 4599 = FMR 16764 • RN 38 km 563; 28°35’5”S, 65°52’27”W; 522 m alt.; 12.I.2009; BAFCcult 4592 = FMR 15065 • RN 60 km 1016; 29°30’4”S, 65°37’57”W; 237 m alt.; 2.I.2010; BAFCcult 4608= FMR 15066 • RN 38 km 563; 28°35’5”S, 65°52’27”W; 522 m alt.; 23.VIII.2011; BAFCcult 4597 = FMR 15067, FMR 16766, BAFCcult 4596 = FMR 16767 .

MYCOBANK. — MB857727.

ETYMOLOGY. — Dictyon (δικτΥΟΝ, net) and phorum (ΦΟΡΟς, bearing) were combined to coin dictyophorum (adj.): net-bearing; regarding the distinctly net-like ornamentation of ascospores.

LATIN DESCRIPTION

Coloniae in agaro malto confecto, 25°C, post 7 dies, 75-79 mm diam., fuscae, albis annulis mycelialibus praeditae; pars aversa fusca. In agaro farina avenae confecto, 25°C, post 7 dies, 60-64 mm diam., fuscae, quasi continuum stratum ascomatum efficientes, mycelium aerium vix effectum.

Hyphae hyalinae, laeves, 3-11 µm diam. Cleistothecia globosa, glabra, atro-brunnea, 40-125 µm diam., inter mycelium aerium disposita vel in substratum semiimmersa; parietes cleistotheciorum persistentes, 5-8 µm lati, texturam angularem praebentes, e cellulis atro-brunneis crassitunicatis 15-25 µm diam.compositi.Asci globosi vel subglobosi,13-15 × 14-18 µm, octospori, evanescentes. Ascosporae unicelulares, ellipsoideae, hyalinae, ornamentum reticulatum-foveatum ostendentes, 5.5-7 × 7-9 µm. Chlamydosporae subglobosae vel ellipsoideae, hyalinae, plerumque terminales umbonataeque, nonnumquam intercalares, etiam endogenae, crassitunicatae, 6-18 × 5-12.5 µm diam.

ENGLISH DESCRIPTION

Colonies on MEA, 25ºC, 7 days, 75-79 mm diam., dark, with aerial white mycelium in concentric circles; reverse dark (Fig. 2A). At 35°C, covering the whole plate before 7 days; reverse dark due to numerous ascomata. At 15°C, 7 days, 0-8 mm diam.; at 40°C, 7 days, 21-31 mm diam. On PDA, 25°C, covering the whole plate at 7 days, dark, with scarce aerial white mycelium, reverse dark. On OA, 25°C, 7 days, 60-64 mm, dark colonies forming an almost continuous layer of ascomata, aerial mycelium scarce (Fig. 2B). At 35°C, spreading all over the plate before 7 days; development in subtle circles, aerial mycelium less floccose than in MEA. On CY20S, 25°C, 7 days, 83 mm diam. On MY50G, 25°C, 7 days, 42 mm diam.

Mycelium composed of hyaline, smooth-walled, hyphae, 3-11 µm wide. Cleistothecial ascomata, globose, glabrous, dark-brown 40-125 µm diam., both intermixed within the white mycelium and semi-submerged in agar (Fig. 2C, D); with a persistent wall, textura angularis, 5-8 µm thick, composed of dark brown thick-walled cells of 15-25 µm diam. (Fig. 2F, G). Asci globose to subglobose, 13-15 × 14-18 µm, eight-spored, evanescent. Ascospores one-celled, ellipsoidal, hyaline, 5.5-7 × 7-9 µm, loosely reticulated (Fig. 2I); SEM shows a reticulated-foveate ornamentation in mature ascospores. Chlamydospores present, subglobose to ellipsoidal, hyaline, usually terminal but sometimes intercalary, endogenously generated present as well, smooth- and thick-walled, 6-18 × 5-12.5 µm.

NOTES

Leiothecium dictyophorum S.M.Romero & Comerio, sp. nov. displayed a distinctive ascospore ornamentation which set it morphologically apart from L. ellipsoideum and L. cristatum, consisting in a reticulate-foveate-net-ascospores without prominent crests (Fig. 2N). Some ascospores of L. dictyophorum S.M.Romero & Comerio, sp. nov. have shown areas where the net was not completely developed, as it is shown at the central region of the ascospore illustrated in the Fig. 2M. Probably, this particular feature, present in several ascospores, reflects some unripeness degree. Leiothecium dictyophorum S.M.Romero & Comerio, sp. nov. ascospores has not exhibited prominent crests as L. ellipsoideum (Fig. 3C, D) and L. cristatum clearly do. The referred difference between ascospores of L. dictyophorum S.M.Romero & Comerio, sp. nov. and L. ellipsoideum is illustrated in Fig. 3.