Diploceras leptospermi (R.G. Bagn. & Sheridan) Nag Raj 1993
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Descriptions
Diploceras leptospermi (R.G. Bagn. & Sheridan) Nag Raj 1993
Diploceras leptospermi (R.G. Bagn. & Sheridan) Nag Raj 1993
Foliicolous. Conidiomata stromatic, acervular, amphigenous, scattered to gregarious, subepidermal in origin, innate-erumpent, oval to rounded or irregular in outline, 170-300 µm wide, 80-130 µm deep, unilocular, glabrous, dark brown to black, dehiscing by an irregular rupture of the overlying host tissue, often with the conidia extruded in long dark brown cirrhi; basal stroma 10-20 µm thick, of textura angularis, cells pale brown, smooth. Conidiophores arising from the upper cells of the basal stroma, reduced to Condiogenous cells, rarely 1-septate and branched, almost colourless, invested in mucus. Conidiogenous cells lageniform to subcylindrical, almost colourless, smooth, 7-13 X 2-3 [mean = 9.2 X 2.5] µm, with up to 5 annellations. Conidia acerose, mostly 4-septate, occasionally 3- to 5-septate, periclinal wall in the median part thicker than the transverse septa, wall smooth and slightly constricted at the septa, 44-73 X 3-4 [mean = 62 X 3.5] µm, bearing appendages; basal cell obconic with a truncate base bearing minute marginal frills and a dark attachment scar, colourless in the basal part, almost colourless above, 7-9.5 [mean = 8] µm long; 3 (or 2, or 4) median cells cylindrical, almost colourless, together (20-)24-47 [mean = 35] µm long (second cell from base 9-15 [mean = 13.2] µm, central cell 7-14 [mean = 11.4] µm, fourth cell from base 8-16 [mean = 13] µm long); apical cell conic, almost colourless in the basal part, colourless above, 12-28 [mean = 19] µm long (including appendage), abruptly attenuated at the apex into a single, unbranched, tubular appendage 2-9 µm long; basal appendage tubular, single, unbranched, attenuated, flexuous, excentric, 5-11 [mean = 8] µm long; mean conidium length/width ratio = 17.5:1.
Presumed holomorph: Discostromopsis leptospermi Swart, Trans. Br. mycol. Soc. 73: 218, 1979. Bagnall & Sheridan (1972) and Swart (1979) reported the fungus on L. juniperinum from Australia.