Toothed Bracket Fungus

A few days ago I came across this bracket fungus on the end of a birch log (Betula sp).  I took a sample home with me to look at more closely.

The upper surface was whitish and faintly banded:

Turning it over, I expected the underside to appear either white and smooth, like a Stereum sp, or white and pored, like a Trametes sp, but was surprised to see it was actually orange and toothed, like Steccherinum ochraceum:

I wasn't aware that S. ochraceum could reflex to form brackets like this but apparently it can:

Upper Surface: When present grooved and hairy to velvety; with more or less concentric zones of color and texture; grayish to brownish or whitish; margin white, scalloped.

The spores at x600 (86um image width), are about 3 x 2um:

This is at the lower end of the 3-3.5 x 2-2.5um spore size quoted for S. ochraceum here at Mycobank.

[Note added 2013-01-28: I took a further sample from this fungus today and under the microscope found clamp connections in it.  Chris Yeates and Andreas Gminder at WildAboutBritain agree that it probably is Steccherinum ochraceum.  According to Andreas there are other Steccherinum species with orange teeth but they tend not to form brackets.]

First photo and sample taken in the Wilderness, Whiteknights Park, Reading, UK, on 2013-01-25.