Lasiodiplodia exigua

Lasiodiplodia exigua Linald., Deidda & A.J.L. Phillips, in Linaldeddu, Deidda, Scanu, Franceschini, Serra, Berraf-Tebbal, Zouaoui, Boutiti, Jama & Phillips, Fungal Diversity 71: 207 (2014)

MycoBank: MB 808355

Etymology: in reference to the small conidia

Sexual state: Not seen. Asexual state: Conidiomata pycnidial formed on poplar twigs in culture within 3–4 weeks, solitary and covered by mycelium, dark brown to black. Paraphyses hyaline, cylindrical, mostly septate, ends rounded, 80.1 ± 19 × 2.9 ± 0.5 μm (mean ± S.D., n = 20). Conidiogenous cells 15.6 ± 3.2 × 4.2 ± 1 μm (mean ± S.D., n = 20), hyaline, smooth, cylindrical, sometimes slightly swollen at the base, holoblastic forming conidia at their tips. Conidia ellipsoid to ovoid, apex and base rounded, thick-walled, initially hyaline and aseptate, becoming one septate and then dark brown with age, with longitudinal stria- tions (19.6–)21.8(−24.3) × (10.8–)12.3(−13.3) μm, 95 % confidence limits = 21.5–22.1 × 12.1–12.4 μm (mean ± S.D. = 21.8±1.1×12.3±0.5 μm, l/w ratio=1.8±0.1).

Cultural characteristics: Colonies initially white to light- brown with fluffy, aerial mycelium, becoming olivaceous- grey on the surface after 3–4 days; reverse side of the colonies dark-brown.

Cardinal temperatures for growth: Minimum <10 °C, max- imum <40 °C and optimum 25–30 °C, covering the medium surface (90 mm) before 7 days in the dark.

Habitat: Twigs and branches of Retama raetam and Pistacia vera.

Known geographic distribution: Tunisia and Arizona (USA).

Specimens examined: TUNISIA, Nabeul, isolated from a branch canker of Retama raetam, 27 June 2012, Benedetto T. Linaldeddu, HOLOTYPE LISE 96302, a dried culture sporu- lating on Quercus ilex twigs, culture ex-holotype CBS 137785 = BL104. Other isolates examined are listed in Table 2.

Notes: Phylogenetically L. exigua is closely related to Lasiodiplodia mahajangana Begoude, Jol. Roux & Slippers, but can easily be distinguished on average conidial dimen- sions and l/w ratio. Moreover, average size of the septate paraphyses of L. exigua are 80.1 × 2.9 μm, whereas aseptate paraphyses of L. mahajangana are 43 × 3 μm.