Alternaria phoenicis Y. Djellid, A. E. Mahamedi, F. Lamghari & A. Berraf-Tebbal, 2025

Djellid, Youssef, Mahamedi, Alla Eddine, Spetik, Milan, Hakalová, Eliska, Eichmeier, Ales, Gonçalves, Micael Ferreira Mota, Lamghari, Fouad, Al Hmoudi, Maryam Ali Saeed Mohamed & Berraf-Tebbal, Akila, 2025, Alternaria phoenicis sp. nov. and Alternaria ouedrighensis sp. nov. (Pleosporales, Pleosporaceae): Two new species associated with leaf spot and blight diseases of date palm (Phoenix dactylifera L.), MycoKeys 120, pp. 295-315 : 295-315

Alternaria phoenicis Y. Djellid, A. E. Mahamedi, F. Lamghari & A. Berraf-Tebbal sp. nov.

Fig. 3

Type.

Algeria • Ghardaia Province (32°10'18.174"N, 3°34'56.6976"E), on symptomatic leaflet and rachis of Phoenix dactylifera L., 2017, Y Djellid, ( MEND-F-1166 , holotype), ex-type culture CBS 152585 .

Etymology.

Named after the host genus ( Phoenix ) from which the fungus was isolated.

Description.

Colonies on PDA reaching 75 mm diam. after 7 d at 25 ° C, circular, cottony with dense hyphae, off-white to light grey in the center, reverse buff to dark brown in the center. Minimum temperature for growth 5 ° C, optimum 25 ° C, maximum 37 ° C. On Potato dextrose agar (PDA; Fig. 3 ), conidiophores arising directly from lateral of aerial hyphae, straight or curved, geniculate, smooth-walled, with up to 5 – septate, unbranched or with up to two branches, pale brown; Conidia solitary, subcylindrical to obclavate, (18.1 –) 21.4 – 29.1 (– 38.8) × (7.4 –) 9.7 – 12.8 (– 14.8) μm, (av. 25.3 ± 3.9 × 11.2 ± 1.6), non-beaked with a narrow base, light brown, with some darkened middle transverse septa, 3–6 transverse septa, and 0–1 longitudinal or oblique septa per transverse segment; these primary conidia produce secondary conidiophores that consist in a subapical extension from the conidial body. Sexual morph not observed.

Notes.

Phylogenetically, this species grouped within Ulocladioides section but was different from the closest species ( A. malicola , A. preussii and A. cantlous ) in a distinct lineage with 100 % ML / 94 % MP statistical support. Alternaria phoenicis sp. nov. is different from its sister species A. malicola , A. preussii and A. cantlous , based on sequences derived from five loci (Fig. 2 ). After conducting a nucleotide pairwise comparison as recommended by Jeewon and Hyde (2016), the present species can be distinguished from the closet species A. malicola , A. preussii and A. cantlous . Based on GAPDH, RPB 2 and TEF 1 genes, A. phoenicis sp. nov. has 7 bp differences (2 %, no gap) in GAPDH, 1 bp (1 %, no gap) in RPB 2 and 29 bp (7 %, 6 gaps) in TEF 1 when compared to A. malicola . Alternaria preussii presents 5 bp differences (2 %, no gap) in GAPDH and 11 bp (2 %, no gap) in RPB 2. However, A. cantlous shows 1 bp difference (1 %, no gap) in RPB 2 and 29 bp (11 %, 6 gaps) in TEF 1. Morphologically, A. phoenicis (Fig. 3 ) can be distinguished by having narrower conidia (7.4–14.8 µm) compared to the three closely related species: A. cantlous (7.4–14.8 µm), A. preussii (13.0–13.7 µm), and A. malicola (8–16 µm). In terms of length, its conidia are shorter than those of A. cantlous (24–36 µm) but longer when compared to A. preussii (18.3–20.4 µm). However, the conidial length of A. malicola (16–35 µm) is comparable to that of A. phoenicis (18.1–38.8 µm). Regarding the conidial septation, A. phoenicis is characterized by multiple transverse septa (up to 6). In contrast, its closely related species exhibit fewer transverse septa, up to four in A. canlous and up to three in both A. preussii and A. malicola . Additionally, A. phoenicis has the fewest longitudinal septa (0–1), compared to A. preussii (1–2), A. malicola (1–5), and A. canlous (0–2) ( Runa et al. 2009; Wang et al. 2010; Dang et al. 2018).

Figures

Figure 2. Phylogenetic tree based on the maximum likelihood analysis of Alternaria species inferred from combined LSU, ITS, GAPDH, RPB 2 and TEF 1. Maximum likelihood (ML) and maximum parcimony (MP) bootstrap values (≥ 50 %) given at the nodes (ML / MP) are computed at from 1000 replicates. The tree is rooted to Cicatricea salina (CBS 302.84) and Stemphylium herbarum (CBS 191.86). The novel species are highlighted in bold. The monotypic lineages are indicated by black dots.

Figure 3. Morphology of Alternaria phoenicis. Colony on PDA after 7 days at 25 ° C (A); Conidiophores and conidiogenouse cells (B, C); Conidia (D – M). Scale bars: 10 μm.