Basidiopycnides albertensis
Basidiopycnides albertensis J. Reid, Eyjólfsd. & Georg Hausner 2008, in Hausner et al., Mycotaxon 103: 285 (2008).
Etymology: From the provincial name, Alberta.
Diagnosis: Colonies on MEYE white to very pale brown (10YR8/2 to 8/3) with even margins in alternating light and dark at 20 oC, margins white (10YR8/2) to translucent. Dark grown colony margins often irregular due to faster growing hyphae developing short, lateral dendroid branches around the margins, but these are less pronounced in alternating light. White (10YR8/2) beneath areas of denser mycelium, but colourless elsewhere. Odour lacking or indistinct. Attaining 16-32 mm diam in 12 days or 26-80 mm in 21days in darkness, and 13-17 mm in 12 days in alternating light and dark, all at 20 oC. Hyphae hyaline, smooth-walled, 1.5-3.6 μm wide, cells binucleate, aerial hyphae collapsing in older cultures. Clamps and chlamydospores lacking. Conidiophores erect, initially arising from single hyphal elements, phalacrogenous, mononematous, semi-macronematous or macronemetous, the latter often coalescent laterally and then resembling top-shaped conidiomata with glistening apices (Figure 1,2).
Macronematous conidiophores 220-400 μm long, with each branch narrowed at its point of emergence from immediately below a septum in the originating hypha, curving upward sharply and widening to normal size; the vast majority have a basal septum above the curve, and all are terminated by percurrently proliferating annellophores (Figure 2,3,4); producing slimy conidial masses; medium-embedded hyphae may produce crescent-shaped conidial masses. Conidiogenous cells holoblastic, terminal, integrated, percurrent, forming conspicuous annellophores 25-150 X 2.5-3.5 (-4.0) μm; these are at first parallel-sided but taper gradually towards the apex, and are occasionally either slightly constricted or form slightly swollen nodular annellations at their base. Annellations occur at intervals of 0.5-7.0 μm, with the longer intervals formed first. Conidia (Figs. 3,6) unicellular, hyaline, binucleate, smooth-walled, oblong to occasionally short clavate, with an obtuse apex and truncate base that may be slightly narrowed, but with a short but definite frill, 6.5-16(-18.5) (sd=11.45 ± 2.78) X 2.5-4.0(-4.5) (sd=3.45 ±0.65) μm, narrowed bases 2.5 ± 0.8 μm, produced singly, but aggregating in slimy masses in culture, germinating by germ tubes or directly produced annellophores.
Individual dark grown isolates varied slightly in growth rates and colony morphologies, but in alternating light and dark growth they were very similar. And in all cases secondary conidium production greatly increased the size of the slimy conidial masses on the surface of a colony. Importantly, the nature of the conidiomata formed in twig cultures was the same as on agar plates, e.g., size variation, branching pattern, conidium size, etc. Occasionally conidia remain attached at the conidiogenous locus; this caused bending in the annellation zone (Figure 3). However, this is different from the situation where seceded conidia sometimes remain adherent after secession; presumably because of the presence of mucilaginous material on either walls of the conidia or conidiogenous cell. When viewed with phase contrast optics, both conidium initials and most conidia have a halo surrounding them (Figure 5); that may be a mucilaginous sheath.
Index Fungorum Number: IF510903
Figure 1. Conidiomata of Basidiopycnides albertensis (strain: UAMH 10784 = WIN(M) 720) in various stages of development, growing on an autoclaved pine twig in agar. Bar = 10 mm.
Figure 2. Line drawings of Basidiopycnides albertensis (strain: UAMH 10786 = WIN(M) 1397). A. Habit sketch of individual conidiophores aggregations; not to scale. B. Conidial size variation. Some conidia have guttules and / or sheaths. Bar = 20 μm. C. An annellation zone from which a conidium was displaced in a sympodular manner. D. Basal branching of a complex conidiophore. E. Two mononematous conidiophores (annellophores), one highly guttulate. When a conidium is formed initially, it is often subtended by a slight constriction in the originating conidiogenous cells (ca). Bar for C, D, and E = 20 μm. F. Young conidioma with branched conidiophores arising from a single element; conidium with mucilaginous sheath (ms); annellation (a); branch constriction (bc). Bar = 20 μm.
Figure 3. An incident-light fluorescent micrograph of a DAPI-stained slide culture (strain: UAMH10784 = WIN(M) 720]. A. Binucleate hyphal cells; septa (s) and nuclei (n). Swellings on the annellophore base (sa). Laterally displaced seceded conidia (ac) still adhering to a proliferated annellophore. Repetitively produced annellations (ra). Bar = 20 μm. B. Two bipolar germinating conidia (bg). Bar = 20 μm. In both A and B, the conidia are regularly binucleate and, on germinating, successive conidiogenous sites are often narrower.
Figure 4. Phase contrast micrographs of conidiomata (strain UAMH 10786 = WIN(M) 1397). A. An apparent aggregation of at least three conidiomata arising from at least three separate hyphal elements (see base). Note the constricted branch bases (arrows), and the very regular intervals between successive annellations, Bar = 20 μm. B. The base of a conidioma arising from a parent hyphal element shown in two different focal planes. The constricted bases of branching elements can be clearly seen, even in successive branches (arrows). Note on the right the “three level branching pattern of the conidiophore” sensu Jacobs et al. (2003, Fig 12); on the left the conidioma is derived from a single branch arising from a vegetative hyphal element, Bar = 10 μm.
Figure 5. Phase contrast micrographs of conidia (strain UAMH 10786 = WIN(M)1397). A. Oblong conidia with truncated basal frill [compare with Jacobs et al. 2003, Fig 10], Bar = 10 μm. B. Conidia.The presumed sheath is indicated by arrows. Bar = 10 μm.
Reference:
Hausner, G., & Reid, J., & Eyjolfsclottir, G. G., & Iranpour, M., & Loewen, P. C. (2008). Basidiopycnides albertensis gen. et sp. nov., a new anamorphic fungus with phylogenetic affinities in the Atractiellales (Basidiomycota). Mycotaxon, 103, 279-298.
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