Cladosporium omanense Halo, Maharachch., Al-Yahyai & Al-Sadi, 2019

Halo, Boshra A., Maharachchikumbura, Sajeewa S. N., Al-Yahyai, Rashid A. & Al-Sadi, Abdullah M., 2019, Cladosporium omanense, a new endophytic species from Zygophyllum coccineum in Oman, Phytotaxa 388 (1), pp. 145-154 : 149-151

Cladosporium omanense Halo, Maharachch., Al-Yahyai & Al-Sadi , sp. nov. ( Figs. 2-4 )

MycoBank: MB 828709

Facesoffungi number: FoF 05383

Etymology: Named after the country where the fungus was collected, Oman

Mycelium superficial, partly immersed, dimorphic, ranging from narrow to much wider hyphae. Narrow hyphae septate, branched, sometimes ornamented with longitudinal layouts, hyaline or subhyaline and light brown beige, septa pale, often hyphae enveloped in polysaccharide-like material, short cross links were observed between hyphae, 7.0 – 21.0 × 1.3–3.0 μm (x = 13.6 μm × 1.7 μm). Wider hyphae branched, pluriseptate, sometimes swollen and constricted at the septa, subhyaline and brown beige, septa and walls pale, sometimes hyphae enveloped in polysaccharide-like materials, 7.5–26.5 × 3.3–7.3 μm (x = 17.0 μm × 4.5 μm), thick-walled, 0.5–1.4 μm wide (x = 0.8). Conidiophores dimorphic, often micronematous 5–100 × 1.0–3 μm (x = 40.4 μm × 2.2 μm) or macronematous 12.5–214 × 3–3.8 μm (x = 57.5 μm × 3.3 μm), erect, flexuous or straight, cylindrical or subcylindrical, geniculate, septate, not constricted at septa, non-nodulose, simple or branched, smooth or rarely rough-walled with longitudinal layouts, thin-walled, light brown beige, septa and walls dark. Conidiogenous cells integrated, terminal or intercalary, aseptate, rarely septate, rarely proliferation sympodial, filiform or cylindrical-oblong, non-nodulose, sometimes geniculate, often smooth or rarely ornamented with longitudinal layouts, 5.0–56 ×1.1–3.1μm (x = 27.4 μm × 2.2 μm), bearing 1–3 conidiogenous loci, of 0.6–1.8 μm diam, conspicuous, slightly protuberant, subdenticulate, darkened-refractive. Ramoconidia formed by macronematous and micronematous conidiophores, subcylindrical to cylindrical-oblong, 11.5–31 × 1.7–3.3 μm (x = 22.1 μm × 2.6 μm), 0–1-septate, apex with 2−3-hila at the apex, 0.8–1.5 μm diam, light brown beige, base truncate or slightly convex, often thickened and darkened-refractive, smooth, sometimes ornamented with loosely irregularly reticulate structures, occasionally has slightly protuberant shrivelling surface ornamentation. Secondary ramoconidia ellipsoid, subcylindrical, 7.5–18 × 1.9–3.3 μm (x = 11.1 μm × 2.5 μm), 0–1-septate, not constricted at septa, hila pronounced denticulate, 0.5–1.5 μm diam, brown beige or light brown beige, base truncate or slightly convex, thickened, darkened-refractive, walls slightly thickened or thin, often has slightly protuberant shrivelling surface ornamentation. Conidia catenate, usually in branched chains, straight to slightly curved, up to 7 conidia in the unbranched terminal part of the chain, intercalary conidia ovoid to ellipsoid, fusiform, 2.5–5.7 × 1.9–3.5 μm, (x = 4.1 μm × 2.7 μm), 0–1-septate, walls slightly to conspicuously thickened, apex with 1–3- distal protuberant hila, moderate thickened to thickened, slightly darkened, base truncate or slightly convex, brown beige, small terminal conidia globose, subglobose to obovoid, 1.9–3.6 × 1.6–3.1 μm (x = 2.8 μm × 2.4 μm), aseptate, walls often thickened, base truncate or convex, rounded apex, brown beige, both conidia roughened and with conspicuously protuberant shrivelling surface ornamentation.

Culture characteristics:— Colonies on MEA reaching 26–32 mm diam after 7 d at 25 ˚C, deep into the agar, irregular, often folded, sometimes crateriform or planar, sulcate, velvety, glabrous to feathery and fluffy, iron-grey or greyish brown, dark greyish brown and black reverse, margins slightly undulate or curled, sulcate, glabrous and velvety, colourless to pale white, aerial mycelium sparse, loose or rarely diffuse, sometimes abundant mainly in the centre, fluffy, white or silver, growth raised of abundant mycelium, sporulation profuse, soluble pigments absent, exudates small clear droplets mainly at centre. Colonies on CYA reaching 25–35 mm diam after 7 d at 25 ˚C, deep into the agar, iron-grey or greyish brown, iron-grey reverse, irregular or regular, often folded and sulcate or raised, sometimes symmetrical, velvety, fluffy and fasciculate with feathery bundles, margins entire or slightly undulate, sometimes sulcate, velvety, colourless, pale white and pastel yellow, aerial mycelium abundant, diffuse or sometimes covered the area between margin and centre while sparse at centre and margin, fluffy, white or silver, sporulation profuse, soluble pigments absent, exudates small or big, clear or dark green droplets mainly at centre. Colonies on PDA reaching 25–30 mm diam after 7 d at 25 ˚C, deep into the agar, greyish brown to iron-grey, dark iron-grey reverse, often regular, sometimes irregular, umbonate or raised, often slightly folded, sometimes sulcate, velvety and fluffy, margins entire or slightly undulate, sometimes sulcate, fluffy and velvety, colour gradual first pastel yellow or white then brown or black finally pale white, aerial mycelium sparse, loose increasing density towards margin, rarely diffuse, fluffy, white and silver, sporulation profuse, soluble pigments absent, exudates small clear droplets mainly at centre on 7 d, clear, dark green and black droplets mainly at centre on 14 d. Colonies on YES reaching 29–44 mm diam after 7 d at 25 ˚C, growing very deeply into the agar, iron-grey, dark iron-grey reverse, regular, folded, planar to raised, sulcate, velvety, fluffy, floccose and fasciculate with feathery bundles, margins entire and curled, sulcate, feathery, glabrous and velvety, pastel yellow, black and pale white, aerial mycelium abundant, diffuse, increasing density in the centre, fluffy, white and pale white, growth slightly raised due to abundant mycelium, sporulation profuse, soluble pigments absent, exudates absent on 7 d, clear and black droplets mainly at centre on 14 d.

Material examined:— SULTANATE OF OMAN, Al Gaba, Adam, Ad Dakhilyah, from healthy leaves of Zygophyllum coccineum ( Zygophyllaceae ), 10 August 2016, B. A. Halo 31 R (SQU H-103, holotype), ex-type culture SQUCC 13165; ibid., roots of Zygophyllum coccineum ( Zygophyllaceae ), 20 September 2016, B. A. Halo 24 R, culture SQUCC 13174; ibid., stem of Zygophyllum coccineum ( Zygophyllaceae ), 05 January 2017, B. A. Halo 29 R, culture SQUCC 13156.

Figures

FIGURE 2. Micromorphological characters of the Cladosporium omanense (SQUCC 13165). a. Micronematous conidiophores and conidial chains with terminal and intercalary conidiogenous cells. b. Macronematous conidiophores and conidial chains. c. Branched micronematous conidiophores and conidial chains with geniculate conidiophores, ramoconidai, secondary ramoconidia, intercalary conidia and small terminal conidia. d. Branched micronematous conidiophore with geniculate intercalary conidiogenous cell. e. Longitudinal layouts ornamentation of conidiophore and conidial chain. f. Wider hyphae g. Narrow hyphae enveloped in polysaccharide-like material. Scale bars: a–b, d, f = 25 μm, g = 10 μm. Scale bar of b applies to b–c. Scale bar of d applies to d–e.

FIGURE 3. Structure and surface ornamentation of Cladosporium omanense under scanning electron microscope. a. Conidial chains b–c. Conidiogenous cells d. Truncate base of ramoconidia. E. Conidium. Scale bars: a = 10 μm b–e = 5 μm.

FIGURE 4. Colony characters of Cladosporium omanense. a. CYA. b. YES. c. PDA. d. MEA.