Hyperepiphyllous, perianthicolous Hypocreales—highly specialized ascomycetes of the phyllosphere

Abstract

Five species of perithecial ascomycetes obligately infect the developing sporophytes of epiphyllous hepatics (Marchantiophyta, Porellales, Lejeuneaceae and Radulales, Radulaceae) while they are still enclosed by the calyptra and the perianth. These ascomycetes belong to the Hypocreales, which are especially well represented among the hyperepiphyllous fungi. The small and mostly brightly colored ascomata arise within the perianths and perforate its walls to discharge the ascospores. Conidiomata may be present as well. Colonization of the perianths prevents normal sporophyte development, sometimes causing deformities, while the foliose gametophyte remains unaltered. The fungus simultaneously can behave biotrophically toward the gametophyte and necrotrophically toward the sporophyte. Host fertility may be considerably reduced. Anthonectria mammispora is described as a new unispecific genus and Ticonectria testudinea as a new species. Ticonectria testudinea and presumably other species attack the region of the gametophyte-sporophyte junction including the transfer cells. The perianth-inhabiting fungi occupy one of the most distinct and nutrient-rich microniches in bryophytes. They are sex- and organ-specific and seem to be restricted to certain hosts but are not poor in characters as are many bryophilous fungi. These species increase the complexity of the phyllosphere.

• Anthonectria mammispora
• bryophilous
• hepaticolous
• leaf-perforating
• microniche
• Ti-conectria testudinea
• tropical

I am indebted to Dr Andrea Bernecker (Ulm) who generously let me study her rich collections of Radula flaccida from Guyana and Costa Rica partly deposited in USJ. Dr Tamás Pócs (Eger) put African specimens of R. flaccida at my disposal. I also thank Drs Ludwig Beenken (Zürich) and Robert Gradstein (Göttingen) for some references. The manuscript was improved by critical remarks of two anonymous reviewers. My own material was collected mainly during an excursion of the Bavarian Botanical Society to Costa Rica in Mar 2008.