To study position specificity in the insect-parasitic fungal genus Coreomyces (Laboulbeniaceae, Laboulbeniales),
we sampled corixid hosts (Corixidae, Heteroptera) in southern Scandinavia. We detected Coreomyces thalli in five different
positions on the hosts. Thalli from the various positions grouped in four distinct clusters in the resulting gene trees, distinctly
so in the ITS and LSU of the nuclear ribosomal DNA, less so in the SSU of the nuclear ribosomal DNA and the mitochondrial
ribosomal DNA. Thalli from the left side of abdomen grouped in a single cluster, and so did thalli from the ventral right side.
Thalli in the mid-ventral position turned out to be a mix of three clades, while thalli growing dorsally grouped with thalli from
the left and right abdominal clades. The mid-ventral and dorsal positions were found in male hosts only. The position on the left
hemelytron was shared by members from two sister clades. Statistical analyses demonstrate a significant positive correlation
between clade and position on the host, but also a weak correlation between host sex and clade membership. These results
indicate that sex-of-host specificity may be a non-existent extreme in a continuum, where instead weak preferences for one
host sex may turn out to be frequent.
2018. Vol. 1, p. 217-228