Ascomycota, genera » incertae sedis

Myriellina

Myriellina Höhn., Sber. Akad. Wiss. Wien, Math.-naturw. Kl., Abt. 1 124: 100 (1915)

Facesoffungi number: FoF 07455

Ascomycota, genera incertae sedis

Habit on leaves of Cydonia vulgaris (Rosaceae), Imperata cylindrica (Poaceae). Sexual morph: undetermined. Asexual morph: Conidiomata brown, acervular, solitary, subepidermal, immersed to erumpent, linear in outline, subglobose in section view, unilocular, glabrous. Ostiole indistinct, dehiscence by irregular rupture of the apical wall. Conidiomatal wall composed of thin-walled, pale brown cells of textura angularis extending into the hypodermis. Conidiophores arising from the inner cell layers of basal stroma, hyaline, cylindrical, simple or branched, septate, smooth-walled. Conidiogenous cells hyaline, enteroblastic, phialidic, cylindrical to lageniform or irregular, integrated or discrete, determinate, smooth-walled. Conidia hyaline, cylindrical to fusiform, tapered towards apex, truncate at the base, 1–5-septate (mostly 3-septate), smooth-walled.

Type species: Myriellina cydoniae (Desm.) Höhn., Sber. Akad. Wiss. Wien, Math.-naturw. Kl., Abt. 1 124: 100 (1915)

Notes: Sutton (1980) re-described Myriellina and provided a detailed description for the genus. Sankaran and Sutton (1991) described the second species M. imperatae B. Sutton & Sankaran from Imperata cylindrica (Poaceae) in Australia. Myriellina imperatae differs from M. cydoniae by its larger conidia; (15.5–)22–40.5 × 1.5–2 µm in M. imperatae, and 9–17 × 2.5–3 µm in M. cydoniae (Sutton 1980, Sankaran and Sutton 1991). Both Myriellina species are associated with leaf lesions (Sutton 1980; Sankaran and Sutton 1991).

Myriellina is similar to Cheilaria in having acervular conidiomata and fusiform, septate conidia. The differences between those two genera are basal stroma and conidial septation. Cheilaria has basal stroma composed of rather thick-walled, dark brown to pale brown cells of textura angularis to textura epidermoidea, and 0–3-septate (usually 2-septate) conidia. Myriellina has basal stroma composed of thin-walled, pale brown cells of textura angularis, and 1–5-septate (usually 3-septate) conidia. However, conidial septation is not a sufficient character for generic delineation (Minnis et al. 2012). Thus, Cheilaria and Myriellina might be taxonomically congeneric. The differences of basal stroma between these two genera can be used to delineate taxa at the species level. There is no molecular data available for Cheilaria or Myriellina. Therefore, fresh collections are needed to verify our hypothesis.

Distribution: Australia, Italy (Sutton 1980; Sankaran and Sutton 1991).

 

Myriellina cydoniae (redrawn from Sutton 1980) a Conidia. b Vertical section of conidioma. c Conidiophores, conidiogenous cells and developing conidia.

 

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