Chaetopsina aquatica Bakhit & Abdel-Aziz, 2021

Bakhit, Mahmoud S. & Abdel-Aziz, Ahmed E., 2021, Chaetopsina aquatica sp. nov. (Hypocreales, Nectriaceae) from the River Nile, Egypt, Phytotaxa 511 (3), pp. 289-295 : 292-293

Chaetopsina aquatica Bakhit & Abdel-Aziz , sp. nov. ( Figure 2 )

MycoBank no.: MB839354

Etymology. Name referring the aquatic habitat, of which the species was collected.

GenBank numbers: ITS: MW633072 ; LSU: MW633073

Saprobic on decaying submerged stem of Phragmites australis . Sexual morph: Undetermined. Asexual morph on natural substrate: Mycelium partly superficial, composed of septate, irregularly branched, 2–2.5 µm wide, smooth, subhyaline to pale red-brown hyphae. Conidiophores solitary or clustered, macronematous, 2–4 septate, unbranched, reddish orange to reddish brown, erect, straight, gradually paler towards the apex, becoming yellow in lactophenol, thick-walled with wall 1.5–2 μm thick, smooth, 88–145 μm long (x = 116 µm, n = 19), with a bulbose base 12–16 μm wide, subulate, 7–11.3 μm wide just above the bulbose base, tapering slightly to 5–7.5 μm wide at the apex, bearing a single, terminal, 38–86 μm wide, colorless to pale yellow slimy head of conidia. Fertile region orange to reddish brown, comprising loosely and regularly arranged penicillate, smooth-walled, 1–2 septate branches bearing conidiogenous cells. Conidiogenous cells cylindrical to ampulliform, 10–20.2 μm long x 2.5–4.1 μm wide (x = 15.4 x 3.2 µm, n = 19), aseptate, hyaline to pale reddish brown, smooth, thin-walled, blastic, phialidic, discrete. Conidia 20–35.2 long × 5–8.5 μm wide (x = 27.1 × 6.5 μm, n = 35), aseptate, smooth, hyaline, solitary, multiguttulate, cylindro-fusoid to obovoid, sometimes slightly curved. Conidial secession schizolytic.

Cultural characteristics: Colonies on MEA reaching 18–23 mm diam., after 2 weeks at 24 °C, raised, smooth, irregular, colony from above: white converted to orangish red after 4 weeks of incubation, from below pale reddish brown; aerial mycelium floccose, composed of hyaline to reddish orange, 2.5–3 μm wide, septate, branched hyphae, sometimes aggregated to form mycelial cords. Conidia production were observed after 5 days while conidiophores after 4 weeks. Conidiophores similar in morphology and dimension to those recorded on natural wood. Conidiogenous cells often arising from vegetative hyphae, 10–26 × 2–3.5 μm (x = 16.8 x 3.0 µm, n = 14), with periclinal thickening at the tip, collarette sometimes flared, producing cylindrical to cylindro-fusoid conidia, 27.5–41.5 × 5–7 (x = 34.9 × 5.5 μm, n = 42) otherwise as found in nature. Colonies on PDA reaching 12–16 mm diam., and on OA 9–14 mm diam. after 2 weeks at 24 °C, surface white and reverse caramel, with sparse aerial mycelium.

Material examined: — EGYPT. Sohag, River Nile (26°32’44.3”N 31°42’25.5”E), decaying submerged stem of Phragmites australis (Poaceae) , 20 November 2018, M. S. Bakhit, holotype SUMCC H- 18001 (Sohag University microbial culture collection, Egypt). Culture ex-holotype: SUMCC 18002.

Known Distribution: Sohag Governorate, Egypt.

Comments: — Chaetopsina aquatica is reported on decaying stems of Phragmites australis and decaying rachis of Phoenix dactylifera . The species was commonly recorded during winter season. Sexual morph of Chaetopsina aquatica was not observed in both natural wood and after three months of incubation of the fungus on matchsticks in Petri plates.

Figures

FIGURE 2. Chaetopsina aquatica (SUMCC H-18001, holotype). a Conidiophores on substrate. b–d Conidiophores bearing conidia. e Conidiophore with slimy head of conidia. f, g Conidiogenous cells with a flared collarette (arrowed) and stages in conidia production. h, j Conidia. i Conidiogenous cells with periclinal thickening (arrowed) k Germinating conidium. l, m Conidia. n, o Upper and reverse view of the 2 weeks old colony on MEA respectively. a–c, e, h, l from natural wood. d, f, g, i–k, m from culture. Scale bars: a = 100 μm, b–e = 20 μm, f–m = 10 μm.