Intumescentia pseudolivetorum H.L. Si, R.L. Chang, T. Bose & Y.C. Wang, in Si, Wang, Liu, Li, Bose & Chang, Journal of Fungi 9(4, no. 423): 12 (2023)

Index Fungorum Number: IF 844859, MycoBank Number: MB 844859, Facesoffungi Number: FoF 15845

Etymology – Named after its host lichen species, Cetrelia pseudolivetorum.

Holotype – China, Yunnan Province: Tiesuo Township, 26°32′71” N, 100°57′3” E, ca. 2115 m elev., isolated from Cetrelia pseudolivetorum, 17 January 2021, H.L. Si, CX115A1a (HMAS 352172), ex-type Culture CGMCC3.23635.

GenBank Accession Number – ITS: OP345109, LSU: OP345119, SSU: OP345148, ACT: OP354479, CAL: OP354485, RPB2: OP354473, TEF1: OP354467.

Description – Hyphae are smooth, brown in color, septate, and the septa are slightly constricted, multi-guttulate, with columnar compartments that are variable in size, measuring 2.14–4.37 μm (x̄ = 2.95 μm, n = 50), usually with sub-globose, pyriform, or irregular hyphal swelling that is apical or intercalary in position. Conidial cells are thick walled, catenulate, with two to eight in a chain, apical in position, and caducous, measuring 13.46–45.41 × 4.21–11.12 μm (x̄ = 24.5 × 5.99 μm, n = 11); the individual conidia are highly variable in shape, they can be bi- or tri-celled, septa transverse, fusoid to columnar in shape, brown in color, apical or lateral in position, measuring 2.94–15.7 × 3.03–7.07 μm (x̄ = 6.65 × 4.4 μm, n = 50), and multi-guttulate. No sexual structure was observed.

Colony morphology and growth – Colony on PDA after 30 days at 25 °C is blackish brown in color (top and reverse), compact, superficial, tomentose, the margins are entire and irregularly lobed. Optimal growth temperature is 25 °C (0.27 mm/day). Growth was observed at 5 °C (0.06 mm/day), whereas no growth was detected at 35 °C.

Notes – Intumescentia pseudolivetorum emerged as the sister species to the clade that includes I. tinctorum and I. vitii (Figure 1). This species can be differentiated from other Intumescentia species based on the hyphal dimensions, position, shape, and measurement of the conidia (Table 1).

Figure 1 – Colony morphology of Intumescentia pseudolivetorum sp. nov. (CGMCC3.23635) on PDA medium after 30 days at 25 °C, (a) top, (b) reverse, (c) hyphae with thick-walled apical conidia, (d) hyphae with lateral branching with basal constriction, (e) 2, 3, and 7-celled conidia, (f) chain of conidia with both columnar and fusoid conidia, (g) apical conidia, (h) a single fusoid conidium. Bars = 5μm. Morphological structures listed above are indicated with arrows.

Table 1 – Comparison of the morphological characters and growth rate of Intumescentia species recovered in this study.