Tubeufia inaequalis Y.Z. Lu, J.C. Kang & K.D. Hyde
Index Fungorum number: IF 554904; Facesoffungi number: FoF 04759
Etymology: “inaequalis” referring to irregular conidiogenous cells of this fungus.
Holotype: HKAS 97440
Saprobic on decaying wood in a freshwater stream. Sexual morph Undetermined. Asexual morph Hyphomycetous, helicosporous. Colonies on the substratum superficial, effuse, gregarious, white to pale brown. Mycelium composed of partly immersed, partly superficial, hyaline to pale brown, septate, abundantly branched hyphae, with masses of crowded, glistening conidia. Conidiophores macronematous, mononematous, flexuous, cylindrical, branched, septate, 33–86 μm long, 4–5.5 μm wide, hyaline to pale brown, smooth-walled. Conidiogenous cells holoblastic, mono- to polyblastic, integrated, sympodial, intercalary or terminal, irregular cylindrical, sympodial, repeatedly geniculate, truncate at apex after conidial secession, 8–17 μm long, 4–5 μm wide, hyaline to pale brown, smooth-walled. Conidia solitary, acropleurogenous, helicoid, rounded at tip, 45–60 μm diam. and conidial filament 5.5–9 μm wide (x̄ = 51 × 7 μm, n = 50), 350–480 μm long, coiled 2–3½ times, becoming loosely coiled in water, indistinctly multi-septate, guttulate, hyaline, smooth-walled. (Lu et al. 2018)
Culture characteristics: Conidia germinating on water agar and germ tubes produced from conidia within 12 h. Colonies growing on PDA, circular, obviously umbonate, with rough surface, veined and wrinkle, edge entire, reaching 15 mm in 2 weeks at 28 °C, pale brown to brown in PDA medium. Mycelium superficial and partially immersed, branched, septate, hyaline to pale brown, smooth.
Material examined: CHINA, Guangxi Province, Fangchenggang City, on submerged decaying wood in a freshwater stream, 14 May 2016, Yong-Zhong Lu, PF09–1 (HKAS 97440, holotype; GZAAS 16–0097, isotype), ex-type living culture, MFLUCC 17–0053 = GZCC 16–0085; Ibid., PF01–4 (GZAAS 16–0091, paratype), living culture, GZCC 16–0079; Ibid., PF15–2 (GZAAS 16–0099, paratype), living culture, GZCC 16–0087; THAILAND, Trat, Amphoe Ko Chang, Yuttha Navi Ko Chang Memorial, on submerged decaying wood in a freshwater stream, 27 April 2017, Yong-Zhong Lu, TW01–3 (MFLU 17–1129 = HKAS 100801, paratype), living culture, MFLUCC 17–1989; Ibid., TW07 (MFLU 17–1138 = HKAS 100809, paratype), living culture, MFLUCC 17–1998.
Notes: Our multi-gene phylogenetic result shows that there are five new isolates that cluster together with Helicomyces roseus (BCC 8808), which was identified by Tsui et al. (2006). Boonmee et al. (2014) renamed this strain as Tubeufia roseus in their phylogenetic tree but did not formally synonymize it. We compared the sequence data of BCC 8808 with our five newly obtained isolates and there are no differences in their ITS and LSU sequences between BCC 8808 and MFLUCC 17–1998 (No protein gene data are provided for BCC 8808). Hence, they should be the same species. Besides, we noted that in our five newly obtained isolates, three of them collected from southern China were phylogenetically apart from the other two collected from Thailand. Following the recommendations of Jeewon and Hyde (2016) for delimitation of new species, we looked into pairwise dissimilarities of DNA sequences and noted that there are indeed differences in the ribosomal ITS sequences that may explain a close phylogenetic relatedness between them and their slight phylogenetic divergence from the other isolates. There are four noticeable nucleotide differences among the 550 nucleotides analyzed between isolates (MFLUCC 17–0053, GZCC 16–0079 and GZCC 16–0087) and the other two (MFLUCC 17–1989 and MFLUCC 17–1998). Major differences are as follows: nucleotide T instead of C at position 35 and 92; nucleotide T inserted at position 103; nucleotide C lost at position 486. We also compared their LSU, RPB2 and TEF1α sequence data but there are no differences between them. Furthermore, we could not observe any morphological features separating these five isolates. Accordingly, we identify these five isolates and reappraised Helicomyces roseus (BCC 8808) as T. inaequalis.
Freshwater distribution: China (Lu et al. 2018), Thailand (Lu et al. 2018)