Schizolysis of dolipore–parenthesome septa in an arthroconidial fungus associated with Dendroctonus ponderosae and in similar anamorphic fungi

Abstract

An arthroconidial anamorphic fungus occurred in pupal chambers of the mountain pine beetle (Dendroctonus ponderosae) in lodgepole pine. No teleomorph was found and no suitable form genus was available for its disposition. However, in cultural characteristics it closely resembled the group 1 arthroconidial fungi, defined by other researchers as probable basidiomycete anamorphs. Septa of the pupal-chamber fungus and several of the group 1 isolates were of the dolipore–parenthesome type. Conidial separation was by septum schizolysis. Cell separation was initiated by disintegration of the dolipore wall, followed by progressive shrinkage of the fused dolipore wall. The parenthesomes retracted towards the dolipore wall and the triangular areas of the cross wall dissolved. The cross wall then split centripetally along the median electron-light layer to complete cell separation. The pupal-chamber fungus was also compared with Phlebia radiata (group 2) and with groups 3 and 4 strains of other researchers. Mauginiella scaettae was confirmed to have simple septa; thus this genus fails to accommodate arthroconidial basidiomycete anamorphs. Key words: basidiomycete anamorphs, dolipore–parenthesome septa, septum schizolysis, arthroconidiogenesis, Phlebia radiata, Mauginiella scaettae.