Intumescentia ceratinae 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): 13 (2023)

Index Fungorum Number: IF 844853, MycoBank Number: MB 844853, Facesoffungi Number: FoF 15853

Etymology – Named after its host lichen species, Usnea ceratina.

Holotype – China, Yunnan Province: Tiesuo Township, 26°32′71” N, 100°57′3” E, ca.2115 m elev., isolated from Usnea ceratina, 17 January 2021, H.L. Si, CX80A2 (HMAS 352147, Holotype), ex-type Culture CGMCC3.23630.

GenBank Accession Numbers – ITS: OP342838, LSU: OP345117, SSU: OP345112, ACT: OP354480, CAL: OP354486, RPB2: OP354474, TEF1: OP354468.

Description – Hyphae are asperulous, brown in color, septate, multi-guttulate, branched, compartments are variable in size, measuring 1.54–5.03 μm (x̄ = 3.40 μm, n = 50), usually with globose, sub-globose, or irregular hyphal swelling that is apical or intercalary in position; lateral branching usually arises from swollen compartments. Conidial cells catenulate, with three to four in a chain, they are lateral or terminal in position, and caducous, measuring 7.16–75.41 × 2.09–4.93 μm (x̄ = 31.61 × 3.5 μm, n = 50); each conidium is thick-walled, columnar in shape, dark brown in color, measuring 5.12–11.59 × 1.35–3.9 μm (= 7.49 × 3.29 μm, n = 50), and multi-guttulate. Sexual structures were not observed.

Colony morphology and growth – Colony on PDA after 30 days at 25 °C is blackish brown in color (top and reverse), compact, superficial, slightly raised in the center and villose, with margins that are finely serrated and irregularly lobed. Optimal growth temperature is 25 °C (0.4 mm/day). Growth was observed at 5 °C (0.06 mm/day), whereas no growth was detected at 35 °C.

Notes – Intumescentia ceratinae has both unique and overlapping morphological characteristics with other Intumescentia species described in this study. The colony morphology, hyphal morphology, and conidia measurements distinguish this species from others, whereas the dimensions of the hyphal compartments, the shape of the hyphal swellings, and the optimal growth temperature of I. ceratinae are comparable to those of other Intumescentia species. In the phylogenetic analyses, I. ceratinae appeared as basal to other species in this family. However, this relationship did not receive significant branch support. Nonetheless, we placed this species in the genus Intumescentia. In the future, when more species from this genus are recovered, the taxonomic placement of this fungus can be re-evaluated.

Figure 1 – Colony morphology of Intumescentia ceratinae sp. nov. (CGMCC3.23630) on PDA medium after 30 days at 25 °C, (i) top, (j) reverse, (k) asperulous hypha with intercalary swelling, (l) hypha with variable compartment sizes, (m,n) lateral conidial initials, (o) chain of conidia with thick walls, (p) 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.