Common, unsightly and until now undescribed: Fumiglobus pieridicola sp. nov., a sooty mold infesting Pieris japonica from western North America

Abstract

Sooty molds (Capnodiaceae) are saprotrophs on the surfaces of leaves, and they take their nutrients from honeydew exuded by sap-sucking insects. We describe and illustrate the sooty mold Fumiglobus pieridicola sp. nov., which, to the dismay of gardeners, forms a thick black mycelial coating on the leaves and twigs of ornamental Japanese andromeda (Pieris japonica) in western North America. As a mitosporic species with a pycnidium that lacks an elongated neck and has at most a rudimentary stalk, the species belongs in the genus Fumiglobus. Although locally common, we found no specimens identified under Fumiglobus or its synonyms in regional herbaria and no record of any similar fungus in host indices. Our species differs from others in Fumiglobus in having smaller pycnidia and conidia and in having intercalary as well as apical pycnidia. We determined partial 18S and 28S ribosomal gene sequences for F. pieridicola, the first for any Fumiglobus species. Sequence analysis provides strong bootstrap support for including Fumiglobus within Capnodiaceae. We also determined 18S and 28S sequences for the type species of the mitosporic genus Conidiocarpus, also in Capnodiaceae. We confirm that Conidiocarpus is the anamorph of Phragmocapnias. Following the rules of nomenclatural priority, we propose the new combinations Conidiocarpus asiaticus, Conidiocarpus betle, Conidiocarpus callitris, Conidiocarpus fuliginodes, Conidiocarpus heliconiae, Conidiocarpus imperspicuus and Conidiocarpus siamensis. We hope that describing the mystery fungus from our region and providing sequences for its molecular identification will lead to new studies on its biology and distribution.

• Capnodiaceae
• Conidiocarpus
• Ericaceae
• Fumiglobus
• Pieris
• scale insects

Acknowledgments

Dr G. Reza Balali, Department of Biology, Isfahan University, Iran, provided the Conidiocarpus caucasicus specimen. Dr Gillian W. Watson, California Department of Food & Agriculture, Sacramento, identified the scale insect on Pieris japonica. Dr Arthur de Cock, CBS-KNAW Fungal Biodiversity Centre, Utrecht, the Netherlands, and Dr John L. Strother, University Herbarium, University of California, Berkeley, provided helpful advice on orthography of names for Fumiglobus and Conidiocarpus species. Thanks to UC and DAVFP for providing us with the herbarium specimens. Thanks Dr S.A. Khoderparast for translation from Persian to English and to Lola Millerman (née Bakhareva) for translations from Russian to English. Prof Sean W. Graham and Prof Quentin C.B. Cronk, Department of Botany, University of British Columbia, Vancouver, provided useful feedback during this study. The UBC Beaty Museum kindly let us use their stereomicroscope for photography of the scale insects. A Discovery Grant from the Natural Sciences and Engineering Research Council of Canada to M.L. Berbee supported this research.

Notes

2 Available at http://www.botany.duke.edu/fungi/mycolab

3 Primer sequences available at http://www.lutzonilab.net/primers/page244.shtml