Dimorphiseta acuta J.M. Liang, G.S. Li & L. Cai

Liang, Junmin, Li, Guangshuo, Zhou, Shiyue, Zhao, Meiqi & Cai, Lei, 2019, Myrothecium-like new species from turfgrasses and associated rhizosphere, MycoKeys 51, pp. 29-53 : 29

Dimorphiseta acuta J.M. Liang, G.S. Li & L. Cai sp. nov. Fig. 2

Type.

China, Beijing, isolated from rhizosphere soils of Poa pratensis , 26 Aug 2017, J.M. Liang, holotype HMAS 247957, dried culture on PDA, ex-holotype culture CGMCC3.19208 = LC12122.

Description.

Colonies on PDA, CMA and OA approx. 7-8 cm diam. after 7 d at room temperature (approx. 25 °C), mycelium white and abundant, with conidiophores forming on the aerial mycelium, carrying slimy olivaceous green to black conidial masses, reverse on PDA buff. Conidiomata sporodochial, stromatic, superficial, cupulate to discoid, scattered, rarely gregarious, irregular in outline, 50-300 μm diam., 60-150 μm deep, consisting of bundles of parallel, longitudinal, closely compacted hyphae, terminating in whorls of 3-5 conidiogenous cells, covered by an olivaceous green to black slimy mass of conidia without marginal hyphae. Stroma poorly developed, hyaline, of a textura angularis. Setae arising from the conidial mass, thick-walled, subhyaline, smooth, 5-15-septate, tapering to sharp apices, 120-370 μm long, 10-13 μm wide at the broadest part, 2-4 μm wide at the apex. Conidiophores macronematous, irregularly, unbranched, smooth to lightly verrucose, arising from the basal stroma. Conidiogenous cells phialidic, subcylindrical, hyaline, smooth, 10-20 μm long, 2-3 μm wide. Conidia aseptate, smooth, hyaline, ellipsoidal, rounded at the base, pointed at the apex with a funnel-shaped appendage, 7-12 × 2-3 μm (av. 10 ± 0.7 × 3 ± 1.3 μm, n = 50).

Distribution.

China.

Etymology.

Name refers to the setae with tapered and sharp apices.

Additional isolates examined.

China, Beijing, from leaves of Digitaria sanguinalis , 21 Aug 2017, J.M. Liang, LC12123; China, Beijing, from leaves of Poa pratensis , 21 Aug 2017, J.M. Liang, LC12124; China, Beijing, from rhizosphere soils of P. pratensis , 21 Aug 2017, J.M. Liang & G.S. Li, LC12125, 21 Jul 2017, J.M. Liang, LC12126, 25 Jul 2017, J.M. Liang, LC12127.

Notes.

The multi-locus phylogenetic analyses indicated that D. acuta formed a sister clade to D. terrestris , but differs from the latter in the type and size of setae. Dimorphiseta terrestris produces both types of setae, the thin-walled and circinate type (Type I) and the thick-walled sharp-edged type (Type II), whereas D. acuta only produces the type I setae. In addition, the setae of D. acuta are much longer and wider than that in D. terrestris (120-370 μm × 10-13 μm vs. 70-95 × 3-4 μm) ( Lombard et al. 2016). Morphologically, D. acuta should also be compared with M. miconiae and M. xigazense , which also produce sharp-edged setae. Myrothecium miconiae , however, differs from D. acuta in producing 1-septate conidia ( Alves et al. 2010), while M. xigazense differs in producing conidia that are truncate at both ends ( Wu et al. 2014).