EPOW - Ecology Picture of the Week

The Little-Known Fungivorous Ironclad

Small Ironclad Beetle (Phellopsis porcata), Family Zopheridae
Cascade Mountains, Washington, USA

Explanation:  Deep in the mixed conifer forests of the Cascade Mountains of southern Washington State, USA, resides this little-known, seldom-seen, and most interesting beetle.  This is a small ironclad beetle, so-named for its rough exoskeleton and, well, its relatively small size.  

The main photos above show the dorsum (the "back") and the ventrum (the "belly") of a specimen I caught in a pitfall trap during a study of  invertebrates in the high Cascades.  
  

The diagnostic, 3-segmented club
of an ironclad beetle (60x magnification).

  
Ironclad beetles are inconspicuous, as they appear like a piece of bark.  Indeed, their body is rather flattened, as they hide under bark slabs or on conks and mushrooms of fungi.  They feed on the fungi -- are fungivorous -- and perhaps might serve as a dispersal agent of fungal spores, although as far as I can tell this is unstudied.  Adults apparently feed on the surface of the fungi, whereas the larvae borrow in.  

They likely are not rare, but little is known about their biology and ecology.  But they do seem associated, perhaps primarily, with old-growth forests (Foley and Ivie 2008; pers. obs.).  
  

Species of genus Phellopsis have 11 antennae segments.
This species has a body size of 10-16 mm, as shown here. 

Information:
     Foley, I.A., and M.A. Ivie.  2008.  A revision of the genus Phellopsis LaConte (Coleoptera: Zopheridae).  Zootaxa 1689:1-28.