Monochaetia schimae Z. X. Zhang, J. W. Xia & X. G. Zhang, 2022

Zhang, Zhaoxue, Liu, Rongyu, Liu, Shubin, Mu, Taichang, Zhang, Xiuguo & Xia, Jiwen, 2022, Morphological and phylogenetic analyses reveal two new species of Sporocadaceae from Hainan, China, MycoKeys 88, pp. 171-192 : 171

Monochaetia schimae Z. X. Zhang, J. W. Xia & X. G. Zhang sp. nov.

Fig. 2

Type.

China, Hainan Province: East Harbour National Nature Reserve , on diseased leaves of Schima superba , 23 May 2021, Z.X. Zhang (holotype HSAUP212201; ex-type living culture SAUCC212201) .

Etymology.

Name refers to the genus of the host plant Schima superba .

Description.

Leaf spots irregular, pale brown in centre, brown to tan at margin. Sexual morph not observed. Asexual morph on PDA: Conidiomata solitary, scattered, black, raising above surface of culture medium, subglobose, exuding black conidial droplets from central ostioles after 10 days in light at 25 °C. Conidiophores cylindrical, hyaline, smooth-walled. Conidiogenous cells 9.0-16.5 × 1.2-2.2 μm, phialidic, ampulliform, discrete, hyaline, smooth, thin-walled. Conidia 18-24 × 4.5-6.0 μm, mean ± SD = 20.5 ± 1.1 × 5.5 ± 0.4 μm, fusiform, tapering at both ends, 4-septate; apical cell 2.0-4.0 μm long, conical, hyaline and smooth-walled; three median cells doliiform, 12.5-15.5 μm long, mean ± SD = 14.2 ± 0.7 μm, olivaceous, rough-walled, upper second cell 3.8-5.3 μm long, upper third cell 3.4-5.0 μm long, upper fourth cell 4.4-5.4 μm long; basal cell 2.2-4.5 μm long, conical, hyaline and smooth-walled; apical appendage 7.0-12.5 μm long (mean = 9.2 μm), single, unbranched, central, tubular, filiform; basal appendage 2.5-5.0 μm long, single, unbranched tubular, filiform.

Culture characteristics.

Colonies on PDA 39.0-45.0 mm in diameter after 15 days at 25 °C in darkness, growth rate 2.5-3.0 mm/day, irregularly circular, raised, dense surface with lobate edge, zonate in different sectors, light brown at the margin, brown at the centre; reverse brown at the margin, dark brown at the centre.

Additional specimen examined.

China, Hainan Province: East Harbour National Nature Reserve, 23 May 2021, Z.X. Zhang. On diseased leaves of Schima superba , paratype HSAUP212202, living culture SAUCC212202; on diseased leaves of Schima superba , paratype HSAUP212203, living culture SAUCC212203.

Notes.

Monochaetia schimae is introduced based on the multi-locus phylogenetic analysis, with three isolates clustering separately in a well-supported clade (BI/ML = 0.99/96). Monochaetia schimae is phylogenetically close to M. castaneae from leaves of Castanea mollissima , M. ilicis from leaves of Ilex sp., and M. junipericola from twigs of Juniperus communis . However, Monochaetia schimae differs from M. castaneae by 148 nucleotides (11/463 in ITS, 89/743 in tub2 and 48/403 in tef1), from M. ilicis by 94 nucleotides (18/526 in ITS, 32/698 in tub2 and 44/456 in tef1), and from M. junipericola by 91 nucleotides (10/524 in ITS, 40/411 in tub2 and 41/304 in tef1). Furthermore, they are distinguished by hosts and conidial sizes (18.0-24.0 × 4.5-6.0 μm in M. schimae vs. 18.8-27.3 × 4.7-6.6 μm in M. castaneae vs. 20.0-27.0 × 5.0-8.0 μm in M. ilicis vs. 22.0-28.0 × 5.0-7.0 μm in M. junipericola ). In morphology, Monochaetia castaneae differs from M. schimae by the colour of colonies (cinnamon vs. brown), Monochaetia ilicis differs from M. schimae by the colour of median cells (brown vs. olivaceous), and M. junipericola differs from M. schimae by longer conidiogenous cells (10.0-30.0 μm vs. 9.0-16.5 μm) ( de Silva et al. 2017; Crous et al. 2018; Jiang et al. 2021b).

Figures

Figure 2. Monochaetia schimae (SAUCC 212201, ex-type) a diseased leaf of Schima superba b surface of colony after 15 days on PDA c reverse of colony after 15 days on PDA d conidiomata e, f conidiogenous cells with conidia g-j conidia. Scale bars: 10 μm (e-j).