Systematics of Halosarpheia based on morphological and molecular data

Abstract

The genus Halosarpheia (Halosphaeriales) was established for marine ascomycetes with obpyriform to sub-globose, coriaceous, brown to black ostiolate ascomata with long necks; hamathecia of catenophyses; thin-walled, unitunicate, persistent asci with thick-walled apices; and ellipsoid, one septate, hyaline ascospores equipped with coiled, threadlike apical appendages that unfurl in water. Emphasis on ascospore appendage morphology has led to the inclusion in the genus of morphologically disparate fungi from a variety of marine and freshwater habitats. To better understand the evolutionary relationships of Halosarpheia species, phylogenetic analyses were conducted on 16 Halosarpheia species, 13 other species of Halosphaeriales and representatives of the Microascales, Hypocreales, Sordariales and Xylariales using 18S and 28S rDNA sequence data. All of the Halosarpheia species occurred on the Halosphaeriales clade. The type species of the genus, H. fibrosa, occurred on a well-supported clade with two morphologically similar species, H. trullifera and H. unicellularis. This clade, which phylogenetically was distant from the clades of other Halosarpheia species, represents the genus Halosarpheia sensu stricto. The other Halosarpheia species were distributed among eight other well-supported clades clearly separated from one another based on molecular data. New generic names are established for six of these clades, one new species is described, and one species is transferred to Aniptodera. A table (Table I) comparing the morphology, habitat, substrate and distribution of the genera of aquatic ascomycetes with coiled, threadlike apical appendages treated in this study is provided, along with a key for their identification.

• aquatic
• Ascomycetes
• Halosphaeriales
• phylogenetics
• rDNA

We would like to thank J. L. Crane, P. Fallah, M. Hildago, W. L. Hurley, G. Laursen, J. D. Schoknecht and R. Wulffen for assistance with collecting. Our thanks also go to C. Brown for assistance with isolate measurements, B. and J. Kohlmeyer for provision of cultures and their encouragement and suggestions, and J. David at CABI for checking the Latin names. Appreciation is expressed to ATCC and the University of Portsmouth, UK, for provision of cultures. Financial support of this study by the National Science Foundation (NSF Grant Nos. DEB 92-00885 and DEB 95-08992) and the National Institutes of Health (NIH Grant No. R01 GM-60600) is gratefully acknowledged.