Absidia thailandica Htet & Gomes de Farias

Htet, Yee Mon, Erandi Yasanthika, W. A., Hurdeal, Vedprakash G. & Farias, Antonio Roberto Gomes De, 2024, Absidia thailandica sp. nov., an addition to the diversity of soil fungi from Thailand, Phytotaxa 646 (2), pp. 157-168 : 161

Absidia thailandica Htet & Gomes de Farias , sp. nov. Figure 2 .

Index Fungorum number: IF901385, Faces of Fungi number: FoF 15186

Etymology: The term “thailandica ” in the epithet denotes its association with Thailand, indicating that the fungus was first isolated in this country.

Holotype: MFLU 24-0033

Description: Sporangiophores arise from stolons, usually unbranched, single or 2–4 in whorls, up to 200 in length and 1.5–5.5 μm in width, with a single septum below the sporangium, distance between septa and apophysate 8–25 μm (x̅ = 14.85 μm, n = 20). Sporangia globose to ellipsoidal, mature sporangia dark grey, 8–40 × 7–40 μm (x̅ = 23.94 × 20.44, n = 10). Columellae hemispherical, hyaline to light brown, smooth, 6–14 ×5.5–12.5 μm, with a single projection at the apex and collar present. Sporangiospores ovoidal to ellipsoidal, 3–4.5 × 2–4 μm. Chlamydospores and zygospores not observed. Rhizoids present.

Culture characteristics: Colonies exhibit a high growth rate in PDA. The colony attains 55 mm in diameter at 28 °C in PDA within three days. Flat, woolly to cottony. Initially white, turning into light grey and grey-brown when the colony matures. Reverse initially cream and become grey-brown and irregularly zonate. Short or long, unbranched or weakly branched, tapering rhizoids are present.

Maximum growth temperature: 33 °C.

Materials examined: THAILAND, Chiang Mai Province, Chiang Dao district, 19.76680223N, 98.89228192E, altitude: 3,727 m, isolated from soil, 22 March 2022, Yee M. Htet, A8-9 ( MFLU 24-0033 ), living culture MFLUCC MFLUCC 23–0073 .

Notes: In BLASTn search, the closest match for ITS, LSU sequence of our species ( Absidia thailandica MFLUCC 23-0073) was A. ovalispora (CGMCC 3.16018) with 90.64% (MW264071) similarity, and A. brunnea (CGMCC 3.16055) with 97.22% (MZ350133) similarity, respectively. In our phylogenetic analysis, Absidia thailandica (MFLUCC 23-0073) is sister to the clade comprising A. ovalispora and A. soli (ML=70%), A. brunnea (CGMCC 3.16055), and A. soli (MFLU 20-0414 and MFLU 20-0413) ( Figure 1 ). Moreover, a genetic comparison of the ITS sequences between A. thailandica and A. ovalispora (CGMCC 3.16019) reveals a nucleotide difference of 9.48% (56/591, 23 gaps), between A. thailandica and A. soli (MFLUCC 20-0089) reveals a nucleotide difference of 7. 11% (31/ 436, 12 gaps), and A. thailandica and A. brunnea (CGMCC 3.16055), a difference of 6.88% (30/436, 11 gaps). Compared to A. ovalispora , A. thailandica does not have swollen parts on the sporangiophores and produces smaller sporangia and columella ( Zhao et al. 2021), A. thailandica sp. nov. produces larger sporangiospores, smaller sporangia and columella than A. soli ( Hurdeal et al. 2021) .

Figures

FIGURE 1. Maximum likelihood (ML) phylogenetic tree of Absidia based on ITS and LSU rDNA sequences, with Cunninghamella blakesleeana and C. elegans as outgroups. The new species is in bold. Maximum likelihood (ML) bootstrap values (≥70%) / Bayesian inference (BI) posterior probabilities (≥0.95) of each clade are indicated along branches. “T” after the strain number indicates the type. The scale bar indicates the estimated number of substitutions per site.

FIGURE 2. Morphology of Absidia thailandica sp. nov. MFLUCC 23-0073 (a,b) Colony on PDA at 28 °C after 4 days, (a) obverse, (b) reverse, (c) rhizoids, (d) columella with apical projections, (e) branched sporangiophore, (f) young sporangium, (g) mature sporangium, (h) unbranched sporangiophore with a terminal sporangium, (i,j) sporangiospores. Scale bars: c,f,g,h = 30 μm; d,e,i,j = 10 μm.