ECOLOGY AND DESCRIPTION OF A NEW SPECIES OF OPHIOGNOMONIA ENDOPHYTIC IN THE LEAVES OF QUERCUS-EMORYI

In a study to examine plant-insect-fungal endophyte interactions, we s urveyed the fungal endophyte populations in over 4600 leaves of an eve rgreen oak over three growing seasons. Three of the most frequently is olated endophytes were undescribed species. We describe one of these e ndophytes as a new taxon, Ophiognomonia cryptica, and present details of its ecology in leaves studied from 1993-1995. Ophiognomonia cryptic a was not isolated from leaves during the 6 months following bud burst (May-Nov) but rapidly increases in isolation frequency from December until leaf abscission in April. The first appearance of O. cryptica co incides with a drop in temperature and increase in cumulative precipit ation. Infection levels (infections/cm(2)) were negatively correlated with leaf area on 6 of 7 dates. How ever, infection frequencies (total number of infections per leaf) were negatively correlated with leaf a rea on only 3 of 8 sampling dates and not correlated on the other 5. W e found no within-leaf pattern of infection, exterior sun leaves were more heavily infected relative to interior shaded leaves, and infectio n levels varied among trees. We discuss the ecology of this endophyte in relation to the theory of island biogeography. In addition, we disc uss our results with respect to the prediction that each plant species may harbor 2-4 endophytes species specific to that plant species and its implications to fungal biodiversity.