Ascospore dispersal of Ceratocystiopsis ranaculosus, a mycangial fungus of the southern pine beetle

Abstract

Ascospores of the heterothallic fungus Ceratocystiopsis ranaculosus were found in sporothecae of three mite species of the genus Tarsonemus. These mites were phoretic on the coniferous bark beetles Dendroctonus frontalis, D. brevicomis, and Ips acuminatus. Ceratocystiopsis ranaculosus inhabits the mycangium of both Dendroctonus species as conidia in a budding yeast-like form. Ascospores are not known to occur in mycangia of bark beetles, and the means of ascospore dispersal has not previously been reported. It is postulated that ascospores transported by phoretic mites may be responsible for establishing sexually compatible colonies of the fungus in beetle galleries either by themselves or in combination with the mycangial fungus type.

Key Words:

• Ceratocystiopsis
• southern pine beetle