Peniophora salaccae N. Suwannar., S. Boukaew, & J. Kumla, 2024

Kumla, Sawai Boukaew Jaturong & Suwannarach, Nakarin, 2024, Peniophora salaccae sp. nov. (Russulales, Basidiomycota), a snake fruit (Salacca zalacca) pathogen from southern Thailand, Phytotaxa 662 (2), pp. 137-149 : 145-146

Peniophora salaccae N. Suwannar., S. Boukaew, & J. Kumla , sp. nov. Figure 2

MycoBank number: 854281

Diagnosis:—Distinguishable from other Peniophora species by subtriangular basidiospores and from P. trigonosperma by its larger basidiospores and shorter lamprocystidia.

Etymology:— ‘ salaccae ’ refers to the generic name of the host plant, Salacca .

Holotype:— THAILAND, Phatthalung Province, Thung Nari Subdistrict, Pa Bon District , 7°20'63"N 100°12'47"E, elevation 5 m., on rotten snake fruits, 21 May 2022, S. Boukaew, CMUB 40058 .

Gene sequences (from holotype):—PP892925 (ITS) and PP899634 (nrLSU).

Description:— Basidiomes annual, effused, adnate or slightly detached from substrate with age, membranaceous to coriaceous, up to 65 mm long, 40 mm wide, 150–350 μm thick in section. Hymenophore smooth, orange-gray (5B3) to brownish orange (5C3–5C6), not cracked or with scattered crevices when dry, turning reddish brown in KOH; margin thinning out, indistinct, concolorous or darker than hymenophore surface. Yellowish grey (4B2) to grey (5B1) spore mass in high humidity conditions.

Basidiospores subtriangular in face view, pyriform in profile, hyaline, inamyloid, (n/m/p = 250/5/2) 5.5–6.8 × 5.0–6.0 × 5.7–7.2 μm (the last measurement is the width corresponding to the base of the triangle), average 5.85 ± 0.44 × 5.25 ± 0.25 × 6.16 ± 0.40 μm. Basidia subclavate to subcylindrical, hyaline, thin-walled, sometimes contraction in the middle, 21.2–34.5 × 3.8–4.3 μm, 4-spored; sterigmata up to 4.8 μm long. Gloeocystidia subclavate to subcylindrical, hyaline, slightly thick-walled, smooth, often with contents, with a basal simple septum, 20.3–50.5 × 3.5–5.5 μm. Lamprocystidia numerous, subulate, usually bifurcate, with one or two secondary septa, yellowish brown, distinctly thick-walled, slightly encrusted with fine crystals in the apex, 17.6–25.8 × 3.0–4.5 μm. Hyphal system monomitic; generative hyphae simple-septate, 2.0–4.0 μm wide.

Ecology and distribution:—On fruit rot lesion of snake fruits ( Salacca zalacca ). Known only from the type locality in southern Thailand.

Additional specimen examined:— THAILAND, Phatthalung Province, Thung Nari Subdistrict, Pa Bon District, 7°18'89"N 100°16'85"E, elevation 5.2 m, on rotten snake fruits, 16 August 2023, S. Boukaew, SDBR-SKRU002, gene sequences PP892926 (ITS) and PP899635 (nrLSU).

Note:—The subtriangular of basidiospores in P. salaccae was similar to P. trigonosperma . However, the larger size of basidiospores (5.5–6.8 × 5.0–6.0 × 5.7–7.2 μm) in P. salaccae differs from P. trigonosperma . (4.0–6.0 × 3.0–3.5 × 4.25–5.5 μm) ( Boidin & Lanquetin 1983). Additionally, lamprocystidia (17.6–25.8 × 3.0–4.5 μm) in P. salaccae had shorter than P. trigonosperma (28.0–42.0 × 4.0–7.0 μm). A phylogenetic analysis of the combined ITS and nrLSU sequences confirmed that P. salaccae formed a monophyletic clade and a sister taxon to P. trigonosperma and P. vietnamensis . A pairwise nucleotide comparison of ITS data indicated that P. salaccae differed from the type species of P. trigonosperma CBS 402.83 and P. vietnamensis He 5252 by 2.05% (13/634 bp including gap) and 5.78% (36/634 bp including gap), respectively. The oblong cylindrical basidiospores of P. vietnamensis clearly separate it from P. salaccae ( Xu et al. 2023) .

Pathogenicity test

The initial symptoms were observed on inoculated snake fruits five days after inoculation. Initially, small light brown to brown spots appeared on the fruits. The lesions then enlarged rapidly and developed into brown to dark brown spots covered with yellowish-white fungal mycelia. After one week of incubation, a section revealed that the internal lesion area appeared to be rotting and was surrounded by water-soaked tissue ( Figure 3 ). The inoculated snake fruits exhibited severe infections in the wounded treatment and moderate infections in the non-wounded treatment. However, no rot disease symptoms were observed in the inoculation treatments involving sterile distilled water (control treatment). After two weeks of incubation, the fruits became completely soft and rotten. These disease symptoms were similar to those observed in the field. Fungi on rotten snake fruit were identified as P. salaccae .

Figures

FIGURE 2. Peniophora salaccae (CMUB 40058, holotype).A and B. Basidiomes; C. Basidiospores; D. Basidia; E. Gloeocystidia and F. Lamprocystidia. Scale bars: A and B = 25 mm; C–F = 5 μm.

FIGURE 3. Pathogenicity test of snake fruits using spore suspension of Peniophora salaccae from specimens CMUB 40058 and SDBR- SKRU002. Sections of wounded (A) and non-wounded fruits (B) after one week of incubation. T0 = control treatment, T1 = spore suspension from specimen CMUB 40058, and T2 = spore suspension from specimen SDBR-SKRU002. Scale bar = 30 mm.