Rhexoacrodictys fimicola (M.B. Ellis & Gunnell) W.A. Baker & Morgan-Jones, in Baker, Partridge & Morgan-Jones, Mycotaxon 82: 103 (2002)

Bao, Dan-Feng, Bhat, Darbhe J., Boonmee, Saranyaphat, Hyde, Kevin D., Luo, Zong-Long & Nalumpang, Sarunya, 2022, Lignicolous freshwater ascomycetes from Thailand: Introducing Dematipyriforma muriformis sp. nov., one new combination and two new records in Pleurotheciaceae, MycoKeys 93, pp. 57-79 : 57

Rhexoacrodictys fimicola (M.B. Ellis & Gunnell) W.A. Baker & Morgan-Jones, in Baker, Partridge & Morgan-Jones, Mycotaxon 82: 103 (2002)

Fig. 3

Holotype.

Maya, Perak, on elephant dung, September 1958, A.H.S, Onions, IMI 76413.

Description.

Saprobic on submerged decaying wood. Sexual morph: Undetermined. Asexual morph: Colonies on the substratum superficial, effuse, hairy or velvety, black. Mycelium mostly immersed, composed of branched, septate, smooth, pale brown hyphae. Conidiophores (17.5-)20-44.5 (-65.5) × 2.5-4.0 μm (x - = 32.2 × 3.4 μm, n = 20), macronematous, mononematous, erect, straight or slightly flexuous, thick-walled, smooth, orange-brown or brown, 3-7-septate. Conidiogenous cells monoblastic, integrated, terminal. Conidia 16.5-24 × 11-15 μm (x - = 20.3 × 13 μm, n = 30), solitary, dry, acrogenous, broadly oval to subglobose, muriform, transversely and longitudinally septate, with transverse septa typically spanning the whole conidial width, with longitudinal septa typically incomplete, short; dark-blackish brown to black, smooth, narrowly truncate at the base.

Cultural characteristics.

Conidia germinating on PDA within 24 h. Germ tubes produced from the basal cell. Colonies on PDA reaching 3 cm diameter in 30 days at 20-25 °C, pale brown, with dense, tight mycelia on the surface, sparse at the margin, reverse dark brown, with smooth margin. Conidiophores reduced to conidiogenous cells. Conidiogenous cells holoblastic, monoblastic, integrated, hyaline to pale brown, smooth. Conidia broad oval to subglobose, muriform, strongly constricted at all the septa, hyaline when young, brown to grayish-brown when aged, smooth-walled.

Material examined.

Thailand, Bangkok Province, Bang Kapi District , on decaying wood submerged in a freshwater stream, 3 October 2017, Z.L. Luo, Bsite 4-3-2 (MFLU 21-0147 = KUN-HKAS 122859), living culture, MFLUCC 18-0340 .

Notes.

In the phylogenetic analysis, our new isolate MFLUCC 18-0340 clustered with three strains of Rhexoacrodictys fimicola (HMAS 42882, HMAS 43690 and HMAS 47737) with strong support (100% ML/ 1.00 PP). The nucleotide BLASTn search of ITS showed that our new strain (MFLUCC 18-0340) has 99.7%, 99.3% and 99.1% similarities with strain HMAS 43690, HMAS 47737 and HMAS 42882 of Rhexoacrodictys fimicola , respectively. Morphologically, our new collection is similar to R. fimicola in having macronematous, mononematous, indeterminate conidiophores, integrated, terminal, monoblastic, pale brown conidiogenous cells and broadly oval to subglobose, transversely and longitudinally septate, smooth, brown to black conidia, with the size of conidia and conidiophores are overlapping ( Ellis 1961; Baker et al. 2002). Based on both phylogeny and morphology, we identified our species as R. fimicola .

Rhexoacrodictys fimicola was originally introduced by Ellis (1961) as Acrodictys fimicola . Baker et al. (2002) transferred A. fimicola to Rhexoacrodictys based on morphological characteristics. Rhexoacrodictys fimicola has been reported on Bambusa vulgaris and elephant dung from Africa and Malaysia respectively. Our collection, on the other hand, was collected from freshwater habitats and represents the first time it was reported from Thailand.

Figures

Figure 3. Rhexoacrodictys fimicola (MFLU 21 - 0147, new record) a-c colonies on wood d-j conidiophores with conidia k-m conidi n germinating conidium o-r re-produced asexual morph of Rhexoacrodictys fimicola s-t culture on PDA from surface and reverse. Scale bars: 20 μm (d-j, o-r); 10 μm (k-n).