Verticillium klebahnii

Verticillium klebahnii

MycoBank: MB563554

Etymology: Named after Heinrich Klebahn (1859–1942), in recognition of significant contributions to Verticillium taxonomy.

Latin diagnosis.

Verticillio tricorpus morphologia simile, sed characteribus sequentiarum nucleidearum distinguendum. Actin positione 82 (C), 92 (T), 256 (C); Elongation factor 1-alpha positione 160 (C), 186 (T), 191 (A), 195 (T), 196 (G), 203 (A), 215 (A), 220 (A), 264 (C), 312 (C), 352 (G), 355 (C), 363 (G), 384 (C); Tryptophan synthase positione 167 (T).

Description.

Colonies on PDA after two weeks 4–6.5 cm diam, white at first, later yellow, reverse orange to yellow, then darkening due to the formation of brown-pigmented hyphae, chlamydospores and microsclerotia (Figures 8a, 8b). Aerial mycelium generally abundant, floccose, hyphae smooth-walled, 1–3.5 µm wide. Conidiophores erect or slanted (Figure 8c), generally determinate, branched or unbranched, formed disjointedly throughout the colonies, hyaline, verruculose surface ornamentation present at times, 130–700 µm in length, 3–5 µm wide, narrowing towards the apex to 2–3 µm, transversely septate, septa spaced more narrowly towards the apex. Conidiogenous cells are phialides, arranged in (1–) 2–7 (–8) whorls along conidiophores (Figure 8c). Whorls spaced 30–65 µm apart, closer towards the apex, consisting of (1–) 2–5 (–7) phialides (Figure 8c), arising below transverse septum. Apical whorls consisting of one apical and one to several lateral phialides (Figure 8c). Phialides subulate, tapering from 1.5–2.5 µm at the base to 1–1.5 µm at the tip, terminal phialides 30–60 µm long, lateral phialides 18–45 µm long (Figure 8c). Conidia hyaline, smooth-walled, cylindrical with rounded apices to oval (Figure 8d), tapering at times, (3.5–) 5.0 µm±0.5 µm (–10.0)×(1.5–) 2.5 µm±0.5 µm (–4.5) (l/w = (1.0–) 1.9±0.2 (–2.4), n = 73), accumulating at the tip of the phialides (Figure 8c). Resting mycelium, chlamydospores and microsclerotia present. Resting mycelium consisting of brown-pigmented hyphae, up to 8 µm wide (Figure 8e), chlamydospores solitary or in chains, up to 13 µm wide (Figure 8f), microsclerotia rounded or variously shaped, up to 80 µm diam and consisting of rounded to elongate cells, up to 9 µm wide (Figure 8g). Yellow-pigmented hyphal cells present, up to 7.5 µm wide, containing globules of yellow pigment, at times pigment accumulating as crystals outside the cell, up to 14 µm diam (Figure 8h).

Types.

Holotype: Dried culture of V. klebahnii strain PD401 (USA: CA; lettuce) deposited at UC (UC 1953897), an ex-holotype culture at CBS (CBS 130344) and NRRL (NRRL 54789).

Specimens examined.

The description was based on V. klebahnii strains PD347, PD401, PD407 and PD458 (USA: CA; lettuce), PD657, PD658 and PD659 (USA: WA; lettuce) (Table S1).

Distribution and host range.

Currently only known from the USA (CA, WA) from lettuce.

Commentary.

Verticillium klebahnii is morphologically indistinguishable from V. isaacii and V. tricorpus. Verticillium isaacii and V. klebahnii were described as new species because no synonyms of the morphologically similar V. tricorpus were available (www.indexfungorum.org, accessed on September 30, 2011).