Alternaria hungarica B. Toth, J. Varga, M. Csosz, E. G. Simmons & R. A. Samson

Bessadat, Nabahat, Bataillé-Simoneau, Nelly, Colou, Justine, Hamon, Bruno, Mabrouk, Kihal & Simoneau, Philippe, 2025, New members of Alternaria (Pleosporales, Pleosporaceae) collected from Apiaceae in Algeria, MycoKeys 113, pp. 169-192 : 169-192

Alternaria hungarica B. Toth, J. Varga, M. Csosz, E. G. Simmons & R. A. Samson

Fig. 3

Specimen examined.

Algeria • Mostaganem City, Kheir Eddine , from leaves of cultivated Daucus carota . 01 December, 2020, N. Bessadat, Living culture NB 968 ; ibid. Algeria, Ain Témouchent province, Bouzedjar , from leaves of wild Daucus carota . 02 February, 2020, N. Bessadat, Living culture NB 803 .

Description.

Colonies on PCA velvety, approximately 70 mm in diameter, with three discrete concentric rings of growth after 7 days. Aerial axes abundant and reaching a size length of 113–387 µm, with 5 to 10 lateral conidiogenous branches and tips in light-exposed zones of young parts of the colony (Fig. 3 A ). These branches most frequently on the upper portions of aerial conidiogenous elements, forming an arachnoid layer of branching hyphae. Primary conidiophores formed outside the center of the colony, simple, rarely branched, produced at the substrate surface, conspicuous, straight, or geniculate, up to 30–110 (– 352) × 3.8–5 µm, often developing through geniculate extensions. Each conidiophore bearing 1–3 conidia, sometimes with additional short chains of 2–3 conidia through secondary conidiophores formed mainly from distal terminal conidial cells (Fig. 3 B ). Secondary conidiophores short, 20–52 (– 105) × 3–5 µm, with one or two conidiogenous sites. A high percentage of conidia of any age remaining solitary. The sporulation patterns in small clumps on elongate-branched sporulating hyphae forming a brown layer at the center of the colony. Conidia medium brown to brown, short ellipsoid, ovoid, muriform, mainly beakless or with a rounded apex (Fig. 3 B ). Dominant size range: 22–37 (– 40) µm long × 13–20 μm width with 2–4 (– 5) transverse septa and 0–2 (– 3) longitudinal septa in each of the transverse segments. In the center of the colony, a high percentage of dark pigmented conidia mature of smaller size, 17.5–25 × 12–17.5 µm, initiating chain development. All maturing conidia distinctly constricted at their transverse septa, developing thick and dark-brown pigmented outer walls and sometimes with a punctate surface.

Culture characteristics at 25 ° C in 7 d — Colonies on PDA cottony compact, greyish green (30 E 5 / 30 E 7) with irregular margins, attaining 67.5 ± 0.6 mm diam. (Fig. 3 C ); reverse olive (3 E 4). On PCA, velvety, olive brown (4 E 4), 69.4 ± 0.5 mm diam. (Fig. 3 D ); reverse grayish same color. On MEA, cottony, olive (1 E 3) with a grayish surface, irregular margins, 65.1 ± 0.6 mm diam. (Fig. 3 E ); reverse olive brown (4 D 3). On OA, cottony, grey to dull green (29 D 4) with a grayish surface, 63.8 ± 1.0 mm diam. (Fig. 3 F ); reverse olive brown (4 E 3). Sporulation of studied isolates occurs in all tested media after 7 days of incubation. It was abundant on PCA and PDA but moderate on MEA and OA.

Notes.

NB 803 and NB 898 formed a well-supported clade with A. hungarica (ex-type, CBS 123925 ) phylogenetically close to A. cumini (ex-type, CBS 121329 ). Between these three strains and A. cumini (ex-type, CBS 121329 ), there were 2 / 464 differences in ITS, 9 / 529 in gpd, 10 / 833 in rpb 2, and 2 / 199 in tef 1. Morphological features of two isolates from carrot leaves (wild and cultivated) are similar to A. hungarica and did not contradict descriptions of Toth et al. (2011). The conidial and sporulation characteristics resemble those of CBS 123925 but with some variations in cultural characteristics (colony color and texture on PDA). Isolates NB 803 and NB 898 form a less dense mycelium but are darker than CBS 123925 . Cultural characters, sporulation pattern, and conidia shape of this species are different from A. cumini (17.5–40 × 12–20 vs. 50–90 × 13–23 μm, respectively). The latter species produce short and erect conidiophores of 18–60 × 5–7 μm ( Nishikawa and Nakashima 2020), while A. hungarica form long geniculate conidiophores (30–352 × 3.8–5 µm). A high percentage of conidia are in clumps or short chains in A. hungarica , while A. cumini produces conidia in simple chains. Both species produce dark yellow (4 C 8) pigmentation on PDA after 7 days, which is lacking in A. eureka .

Figures

Figure 3. Morphology of Alternaria hungarica (strain: NB 803). Sporulation patterns on PCA for 14 days at 22 ° C (A); Conidiophores and conidia on PCA for 7 days at 22 ° C (B); Colony phenotypes on PDA (C), PCA (D), MEA (E), and OA (F) for 7 days at 25 ° C. Scale bar: 25 µm (A, B); 10 mm (C – F).