Ophiocordyceps myrmicarum, a new species infecting invasive Myrmica rubra in Maine

• Myrmica rubra is an invasive ant species in Maine, USA.
• Synnemata of a new Ophiocordyceps species described here grew on cadavers of M. rubra.
• The Ophiocordyceps species is morphologically and phylogenetically distinct.
• Ophiocordyceps myrmicarum is a new species and pathogen of M. rubra in Maine, USA.

Myrmica rubra L. (Formicidae: Hymenoptera), an invasive ant species in Maine, has been problematic in coastal communities over the past 15 years and the subject of studies on its ecology, effects, and management. In recent years we observed a fungus growing from moribund M. rubra (in vitro) and have isolated multiple cultures of this previously unreported fungus over 2 y. We analyzed morphology and DNA molecular sequences of this fungus and identified it as a member of the genus Hirsutella Pat. (Ophiocordycipitaceae; Hypocreales), the use of which is suppressed in favor of a monophyletic Ophiocordyceps clade. Molecular and morphological characters support the description of this fungus as a new species, O. myrmicarum, which is the first species in this genus to be isolated from North American M. rubra.

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