Wallemiales » Basidiomycota genera incertae sedis » Arcispora

Arcispora bisagittaria

Arcispora bisagittaria Marvanová & Bärl. 1998, in Marvanová & Bärlocher, Mycologia, 90(3), 531-536 (1998).

Etymology:  The epithet bisagittaria (Lat.) means 'equipped with two arrows' and refers to the two parallel conidial branches.

Diagnosis: Colonies on malt extract agar (Oxoid, 2%) at 15 Celsius slow-growing, reaching ca. 10 mm diam after 30 da, restricted, mealy, beige, in some isolates darker in the center or brownish throughout, center raised. Odor pungent, resembling that of the cultivated mushroom. Surface mycelium sparse, adpressed, hyphae septate, 0.8-1.2 µm wide, primary septa clamped, clamps 35-87 µm apart, secondary septa frequent, clampless. Advancing hyphae scanty, mostly curved, tangled, branches often perpendicular to the parent hypha. Substrate mycelium with globose to irregular, thin-walled inflated cells 5-17 X 4-15 IJ.m, in groups or short chains (FIG. 2K), clamps present on some septa. Sporulation from pieces of agar culture submerged in standing water occurred within a few days. Conidiophores single, simple or rarely sparsely branched, flexuous, mostly apical, integrated with hyphae, or rarely lateral and then up to 35 X 1-1.5 µm. Conidiogenous cells apical, integrated, proliferating sympodially from the loops of the clamps, usually bearing a chain of clamp remnants (FIG. 1B-E, G-J; FIG. 3C, arrow), as a result of progressing conidiation. Conidia consisting of axis and typically two branches, all elements lying in one plane (FIG. 2A, B, D-J, L). Axis nearly straight or slightly sigmoid, 21-28 X 2-2.5 µm, distal portion usually slightly curved to the ventral side, proximal portion mostly straight, with one submedian clamped septum (rarely 2-3 along the length of the axis, FIG. 2B, E, I,J); apex rounded, base truncate, often with a small peg on the ventral side, which is a remnant of the clamp of the delimiting septum, and with a percurrent extension up to 20 X 1-1.5 µm appearing after secession. Branches lateral, closely sequential, basipetal, situated near the middle of the axis, perpendicular to the axis and more or less parallel, sometimes with ends slightly crossing each other, the distal (upper) originating from the axis, 8-13 (-18) X 2-2.5 µm, the proximal one from the loop of the axial clamp, 7-10 X 2-2.5 µm; both separated from the parent element by a septum and bearing a clamp on the outer side near their base; the free ends of the conidium are typically provided with discrete or more or less integrated extensions appearing before secession, up to 12 (-18) X 1-2 µm. Secession schizolytic, leaving the loop of the clamp at the apex of the conidiogenous cell, where it, in its turn, gives rise to a new conidium. Germination mostly from the extensions. Conidial ontogeny as compiled from conidia seen in various stages of development is as follows: a subclavate, often gently curved conidial initial is delimited from the conidiogenous cell by a septum with the clamp at the ventral side of the future conidium (FIG. 1B; FIG. 3A, lower arrow). The distal branch starts to develop in the median or submedian part of the initial (FIG. 1C; FIG. 3A, upper arrow), and more or less simultaneously a clamp appears closely below it (FIG. 1D). The proximal branch grows from the loop of the clamp and develops more slowly than the distal one (FIG. 1E-J). Before maturation is complete, a clamped septum appears near the base of each of the branches (FIG. 11, J). Thin apical extensions develop in situ at all free ends of the conidium (FIG. 11); after secession a similar extension appears also at the base.

Index Fungorum Number: IF443608

FIG. 1. Arcispora bisagittaria. Conidial development. A-C. Early stages. D-G. Basipetal development of conidial branches. H-J. Second conidium growing from the loop of the clamp at the base of the first conidium. Note the clamp remnants at the conidiophore apices in B-E and in G-J. A, B, E, J from CCM F-40594; C, D, F-I from CCM F-40694. Scale bar = 25 µm.


Figure 2. Arcispora bisagittaria. A, D, F, G, H. Typical conidia. B, E, I, J, L. Conidial axis with more than one septum. C. Single-branched conidium. K. Inflated cells. A-G, K from CCM F-40594. H-I, J from CCM F-40694. Scale bar = 25 µm.