Absidia edaphica, Hurdeal & Gentekaki & Lee & Jeewon & Hyde & Tibpromma & Mortimer & Xu, 2021

Hurdeal, Vedprakash G., Gentekaki, Eleni, Lee, Hyang B., Jeewon, Rajesh, Hyde, Kevin D., Tibpromma, Saowaluck, Mortimer, Peter E. & Xu, Jianchu, 2021, Mucoralean fungi in Thailand: novel species of Absidia from tropical forest soil, Cryptogamie, Mycologie 20 (4), pp. 39-61 : 46-47

Absidia edaphica V.GHurdeal., E.Gentekaki., H.B.Lee & K.D.Hyde, sp. nov.

MYCOBANK NUMBER. — MB 836158.

FACES OFF FUNGI NUMBER. — FoF 07990.

HOLOTYPE. — MFLU 20-0416.

ETYMOLOGY. — Referring to the substrate/host (soil) from which the species was first isolated.

MATERIAL EXAMINED. — Thailand. Chiang Mai Province, Mae Taeng District, Pa Pae sub district, Pha Deng village, isolated from soil, 11.VIII.2019, Bhavesh Raghoonundon, T19-0986 (holo-, MFLU [MFLU 20-0416]), ex-type living culture MFLUCC 20-0088, MFLUCC 20-0087.

CULTURE CHARACTERISTICS. — Colony exhibits high growth rate in YMA, PDA, and MEA ( Figs 6 ; 7 ). Within two days, the colony attains a diameter of 55 mm (n = 10) at room temperature in PDA. Day-old cultures are white in all media changing to pale brown upon maturation ( Fig. 7 ). Colours are changed from the center of the plate and progressing outwards. Initially, a pale brown colour is apparent only in PDA and YMA, as compared to MEA and CMA, where cultures are white or with a very light brown tint. Colony covers most of the surface of the agar plate within 4 days on PDA, MEA and YMA (when fungal plug is placed in the middle of the agar plate). Reverse of colony white and irregularly zonate. In YMA, the colony reverse gradually turns from white to pale yellow to pale brown. Specific to YMA, a distinct white zone is observed around the colony with the zone being significantly larger at 20°C ( Fig. 7 ). More concentric rings are observed in the colony reverse at 20°C than in 30°C in PDA. Colony is raised, undulate and can grow at 4, 20, 25 and 30°C. Growth at 30°C appears within the first 24 hours. No growth is observed at 37°C and 42°C, even after 7 days.

DESCRIPTION

Associated with soil.

Asexual morph

The measurements were taken from cultures grown in MEA.

Sporangiophore. Arised from the stolon singly or in whorls (1-6), are hyaline to pale brown, 2.5-5.4 Μm wide and show occasional branching, erect. Septum consistently present below the apophysis, 2-4 Μm long approximately 20-33.5 Μm (x = 25.5 Μm, n = 40), in length from the apophysate line.

Sporangium. Mature sporangia appear more quickly in PDA and YMA media, followed by MEA and CMA, are 30.5-35.5 × 24-27 Μm (x = 33.5 × 25.5 Μm, n = 30), globose to slightly elliptical. Immature sporangia beginning hyaline and later on turn to pale brown.

Columella. 5-9.5 × 6.5-20 Μm (x = 7 × 12 Μm, n = 40), globose, hyaline with apical projection and collarette as in all Absidia species ( Fig. 4 A-E, G, H).

Spores. Sporangiospores 3.5-5.5 × 2-3.5 Μm (x = 4.5 × 2.5 Μm, n = 30), numerous, short cylindrical to oblong, slightly curved at both end, hyaline, smooth-walled. Azygospores and zygospores not observed. Chlamydospores absent.

Rhizoids. Pale brown, aseptate and taper at the ends ( Fig. 4F ).

Sexual morph

Undetermined.

NOTES

Absidia edaphica V.GHurdeal., E.Gentekaki., H.B.Lee & K.D.Hyde, sp. nov. differs from A. koreana phylogenetically and morphologically. Absidia edaphica V.GHurdeal., E.Gentekaki., H.B.Lee & K.D.Hyde, sp. nov. produces larger sporangia and columellae with the colony attaining a diameter 55 mm in PDA within two days but A. koreana reaches 39.5-41 mm by the fourth day at 25°C. Compared to A. soli V.GHurdeal., E.Gentekaki., H.B.Lee & K.D.Hyde, sp. nov., the sporangia and columella are smaller. The length from the apophysate line to the septum is shorter than A. soli V.GHurdeal., E.Gentekaki., H.B.Lee & K.D.Hyde sp. nov. (20-33.5 Μm). Phylogenetic analysis provides strong statistical support to establish two different species ( Figs 1; 3). This finding is also supported by GCPSR analyses where no significant recombination could be detected. The genetic distance between A. edaphica V.GHurdeal., E.Gentekaki., H.B.Lee & K.D.Hyde, sp. nov. and A. koreana in the ITS regions is 25.1%, LSU 6.3% and SSU 2.1%. Compared to A. soli V.GHurdeal., E.Gentekaki., H.B.Lee & K.D.Hyde, sp. nov., genetic distance in the ITS regions was of 11.2%, LSU 4.7%, SSU region 0.2%/0.2% and in the ACT-1 gene region 4.3% ( Table 4).

Figures

FIG. 6. — Mycelial growth of Absidia edaphica V.GHurdeal., E.Gentekaki., H.B.Lee & K.D.Hyde, sp. nov. and Absidia soli V.GHurdeal., E.Gentekaki., H.B.Lee & K.D.Hyde, sp. nov. in different media at 25°C.

FIG. 7. —Mycelial growth of A.edaphica V.GHurdeal.,E.Gentekaki.,H.B.Lee & K.D.Hyde, sp.nov.(MFLUCC 20-0088,ex-type) and A. soli V.GHurdeal.,E.Gentekaki., H.B.Lee & K.D.Hyde, sp. nov. (MFLUCC 20-0086, ex-type) in various media at room temperature (around 26°C to 27°C) after two days: A-D, colonies on MEA; E-H, colonies on PDA; I-L, colonies on CMA; M-P, colonies on YMA. The first two rows represent colonies of of A. edaphica sp. nov. and the bottom two rows A. soli sp. nov (obverse (first and third rows) and reverse (second and fourth rows).

FIG. 4. — Absidia edaphica V.GHurdeal.,E.Gentekaki., H.B.Lee & K.D.Hyde,sp.nov. (MFLU 20-0416, holotype) (Cultures grown at room temperature for 3-5 days): A-E, different stages of sporangia development (C-E, sporangium stained with Lacto-phenol cotton blue reagent); F, rhizoids; G, columella with collarette, apical projection and septum below the apophysis; H, single sporangiophore originating from the stolon; I, sporangiospores in CMA; J, sporangiospores produced in MEA. Scale bars: A-F, H, 20 μm; G, 10 μm; I-J, 5 μm.