Search on : Taxa descriptions

 


   
Literature:
 
Page number:312 
Description type:Culture description 
Description:Macroscopic characters: growth moderately rapid, covering Petri dishes in 2-3 weeks. Mycelial mat transparent white at first, later remaining snow white with rather loose mycelium; in some cultures the inoculum becomes cream coloured with a few light yellowish zones appressed to the agar, irregularly distributed. Texture farinaceous during the first week at the inoculum, the rest subfelty, later the whole surface becoming farinaceous and the mycelium much denser (Fig. 102); in other cultures there is an alternation of dense, fan-shaped areas, with much less dense mycelium (Fig. 103), or zones that show alternation of dense and thin mycelium. Reverse: only altered in correspondence with zones of coloured mycelium, which becomes brown. Margin regular, smooth,with mycelium appressed to agar. Odour: slightly fungic to somewhat sweetish. Oxidase reaction: with tannic acid = ++++ with or without growth; with gallic acid = +++ or ++++ with or without growth; with gum guaiac = +.
Microscopic features: marginal mycelium: composed during the 1st week only of generatives, staining or not with phloxine, clamped, thinwalled with septa restricted to clamps, sparsely or not branched (Figs. 88-90), 2-6 µm diam. From the 1st to the 3rd weeks the following appear: i) "stag-horn" generatives, staining with phloxine, whose ends begin to branch out in numerous and very thin ramifications, mostly dichotomic, that become intertwined and form a dense reticulum (Fig. 92), 2-4 µm diam;ii) chlamydospores both intercalary and terminal, abundant, the first originating from generatives, the latter from the ends of stained generatives; thick-walled, golden, with dense contents, ellipsoid, spheri ical or ovoid, dextrinoid, 9-22 x 7-18 µm (Figs. 96-101); iii) fibrous hyphae that are clampless, aseptate, thick-walled, hyaline or pale, not staining, heavily branched, in some cases forming the bulk of the mycelium, 1-4 µm diam (Fig. 77-78); from the 3rd to 4th weeks, there appear "cuticular cells", hyaline, originating from globose ramifications of generatives, of very irregular shape and size, 10-30 µm each, much appressed and forming a pseudoparenchyma that may become very compact (Fig. 93). Inoculum: same features as the marginal mycelium. Yellowish zones: formed by the same elements as the rest of the mat but the "cuticular cells" have a thickened golden wall (Figs.75-76); in a few cases sclerotized clamped hyphae appear, with thick, golden walls, but are not abundant. Submerged mycelium composed of tortuous generative hyphae with thin walls, that may stain or not, and have short but numerous projections, 1-5 µm diam. (Fig. 91). Also chlamydospores similar to those of the margin and a few "cuticular cells" may be found.
Observations: Culture BAFC n°2354 was the only one that fruited in the Petri dishes after the 5th week, in the form of an elevated mound in which a great density of fibrous hyphae concentrated; on them the pores were formed with fertile hymenium composed of globose basidia and basidiospores of the "smooth" type, 8-11 x 5-6 µm.
There exists a difference that allows the separation of the strains in two obvious groups, while the remaining features are similar in all cases, namely, the presence or absence of "cuticular" cells. Strains BAFC n°2372, 277, 113 and 1009 always formed these cells. The rest did not. The basidiomes corresponding to these cultures did not exhibit any differences.
The cultural characteristics of the strains studied coincide with those given by Nobles (1948), excepting the "cuticular cells; which may or may not be present, and the reverse that darkens but does not appear to become discoloured, as mentioned by her. Concerning this aspect, Stalpers (1978) states that it discolours locally and becomes locally coloured, with which observation we agree. Cultures from the CBS and NY identified as G. resinaceum were studied and they also did not show "cuticular cells".
 
Taxon name: