Dothideomycetes families incertae sedis » Pseudorobillardaceae » Pseudorobillarda

Pseudorobillarda sojae

Pseudorobillarda sojae Uecker & Kulik

Synonymy: Stauronematopsis sojae (Uecker & Kulik) Abbas, B. Sutton & Ghaffar, Pakist. J. Bot. 34: 123 (2002)

Index Fungorum number: IF 130133

Holotype: BPI 71933


Asexual morph: Conidiomata pycnidial, immersed, scattered, with globose basal part, 240–300 µm diam., 200–220 µm high, unilocular, glabrous, dark brown to black, ostiolate, beaked; ostiole oval, 60 µm diam.; wall 25–50 µm thick of textura angularis, dark brown, darkest in the ostiolar region, colourless near the base; conidiogenous cells lining the cavity of the conidiomata, invested in mucus. Conidiogenous cells ampulliform to subcylindrical, colourless, smooth, 4–7 × 3–4 µm. Conidia unicellular, ellipsoidal to fusiform, with both ends rounded, hyaline. smooth, guttulate, 13.5–17.5–20 × 3.0–4.3–5.5 µm (n = 150), bearing at the apical end 4–6 attenuated, flexuous, extra-cellular, 14–18.3–24 µm long (n = 150) appendages arising from splitting of the conidial sheath; mean length/width ratio = 4.2 (n = 150). Sexual morph: undetermined. (Description from Plaingam et al. 2005)


Material examined: THAILAND. Prachin Buri, submerged pod of Delonix regia. 5 Jul. 1999, S. Somrithipol (BBH 7301 = SFC 528); Chachoengsao. Bang Pakong. grass internode, 15 Jul. 2000, S. Somrithipol (BBH 7302 = SFC 783); Kasetsart Univ., Bangkok. leaf of Carica papaya, 6 Aug. 2000. S. Sornrithipol (BBH 7304 = SFC 881)


Notes: Collections BBH 7301, BBH 7302 and BBH 7304 possess morphological characteristics that fit those of P. sojae. Uecker and Kulik (1986) mention that the appendages of P. sojae are morphologically and chemically different from the cellular appendages of Robillarda as they are formed within a sheath, never contain nuclei or cytoplasm, and are dissolved by strong hydrochloric acid solutions. Nag Raj (1993) examined the holotype of P. sojae and classified its appendages as ‘type E’, extracellular, formed inside the conidium sheath. Abbas et al. (2002), on the other hand, examined the isotype of P. sojae by using electron microscopy and a staining technique. And recombined it as Stauronematopsis sojae (Uecker & M.M. Kulik) Abbas, B. Sutton & Ghaffar, because of the cellular nature of the conidial appendages and the lack of paraphyses. An ultrastructural study of collection BBH 7301 by Plaingam (2002) revealed that the appendages of this fungus are non-cellular. Transmission electron micrographs of a longitudinal section of the conidium and appendage show that the appendage arises from the outer cell wall layer of the conidium as an outgrowth (Plaingam 2002). Referral of the collections BBH 7301, BBH 7302 and BBH 7304 to Stauronematopsis would be premature. We therefore assign these collections to P. sojae until further research is undertaken to resolve their taxonomic status. (Notes from Plaingam et al. 2005)


Freshwater distribution: Thailand (Plaingam et al. 2005)




Fig. 1. Line drawings of Pseudorobillarda sojae (from SFC 528). 13. Mature conidia. 14. Conidiogenous cells with developing conidia. 15. Vertical section of a conidioma. Scale bars: 13, 14 = 10 µm, 15 = 50 µm. (from Plaingam et al. 2005)




Abbas SQ, Sutton BC, Ghaffar A (2002) Stauronematopsis Abbas, Sutton and Ghaffar gen. nov., an addition to Coelomycetes. Pak J Bot 34:117–124

Nag Raj TR (1993) Coelomycetous anamorphs with appendage-bearing conidia., Waterloo, Ontario, Canada: Mycologue Publications

Plaingam N (2002). Ultrastructure and biodiveristy of tropical coelomycetes. Ph.D. Thesis, Kong Mongkut’s University of Technology Thonburi, Bangkok

Plaingam N, Somrithipol S, Jones EBG (2005) Pseudorobillarda siamensis sp. nov. and notes on P. sojae and P. texana from Thailand. Nova Hedwigia 80:335–348

Uecker FA, Kulik MM (1986) Pseudorobillarda sojae , a new pycnidial coelomycete from soybean stems. Mycologia 78:449–453.


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