Table 3.

Morphological comparison of North American members of the Postia caesia complex. Description of P. simulans is based on European and North American material (excluding East Asia).

	Species	Distribution/ host	Upper surface	Pores per mm	Tramal hyphae (measurements include 60 % of variation around median diameter)	Basidiospores (variation of specimen means)	Other
\	arbuti	North America (NW); temperate; Arbutus	smooth	6–8	thick-walled, densely arranged, 2.4–3.1 μm (walls up to 1 μm)	L=4.54-4.58 μm, W=1.13-1.15 μm, Q=3.95-4.05
	caesiosimulans	holarctic; temperate; Fagus, deciduous trees, rarely conifers	smooth	5–7	slightly to distinctly thick-walled, often densely arranged, 2.9–3.8 μm (walls up to 1 μm)	L=4.47-5.14 μm, W=1.14-1.27 μm, Q=3.79-4.05	Q mostly <4; few western conifer specimens W>1.4 μm; context usually thin
	comata	North America (NE); temperate; conifers	pubescent	4–6	thick-walled, 2.8–3.8 μm (walls up to 1 μm)	L=4.34-4.39 μm, W=1.2-1.21 μm, Q=3.59-3.66
	livens	North America; temperate; conifers and deciduous trees	matt to pubescent	4–6	thin- to moderately thick-walled, 2.9–4.0 μm (walls up to 0.5–0.8 μm)	L=4.30-5.25 μm, W=1.2-1.37 μm, Q=3.31-4.17	thick context, often big basidiomes
	populi	holarctic; temperate / boreal; deciduous trees, prefers Populus	smooth	5–7	thick-walled, densely arranged, 2.7–3.3 μm (walls regularly >1 μm)	L=4.58-5.07 μm, W=1.12-1.24 μm, Q=3.86-4.37	undulating cap margin, Q mostly >4
	subviridis	North America (W); temperate; conifers	smooth	6–8	thick-walled, 2.5–3.1 μm (walls up to 1 μm)	L=4.07-4.92 μm, W=1.1-1.16 μm, Q=3.51-4.47
Wide-spored species(W≥1.4 μm)	simulans	holarctic; temperate / boreal; prefers conifers	smooth to pubescent, often blue	5–7	thin- to slightly thick-walled, rarely thick-walled, often collapsing, (2.2)2.8–3.8 μm	L=4.87-5.93 μm, W=1.4-1.55 μm, Q=3.17-4.12