Rhachomyces hyperommae W. Rossi & M. Leonardi, sp. nov.

Index Fungorum number: IF 559509; MycoBank number: MB 559509; Facesoffungi number: FoF 13386; Fig. 1

Etymology – Named after the host insect genus.

Holotype – CAMB WR2331a

Axis of the receptacle composed of 12–17 cells very different in size, shape, and color: the basal and the suprabasal
are blackened, narrow, and elongate; the following 2 or 3 are relatively small, dark and isodiametric; the others gradually broader and paler from below upwards. Appendages short, stiff, one-sided, projected obliquely upwards, consisting of 4 cells, of which the lower 3 are dark brown while the upper has a paler and curved tip. Antheridial appendages similar to the sterile ones but shorter and paler, each bearing distally a brown, elongate antheridium tapering in a curved and truncate paler tip. Perithecium broadly fusiform, with the posterior side more convex, nearly hyaline or tinged with pale yellow, brownish yellow near the base in older specimens, the hyaline and conical tip ending in a blunt apex. Length from foot to perithecial apex 280–380 µm. Perithecium, including basal cells 110–145 × 35–42 µm. Antheridia 20–25 µm. Longest appendage 90 µm.

Material examined – Autralia, NSW Border Ranges N. P., Tweed Range Rd., 4.6 km SW of Bridle Ck. Rd., alt. 580 m, 4.II–9.IV.1993, M. Gray & G. Cassis, on a femur and the abdomen of Hyperomma sp. (Staphylinidae, Paederinae, Paederini, Cryptobiina), CAMB WR2331a, holotype; FI WR2331b isotype).

Notes – The new species seems to be allied to Rhachomyces arbusculus Thaxt., described on an unidentified rovebeetle from Liberia, West Africa (Thaxter 1896). The two parasites have similar appendages and are also somewhat similar in the general habitat. However, R. abusculus is distinctly more slender and more elongate, with the cells forming the receptacle more numerous (20–25) and not strongly different from each other, and with a much narrower perithecium suffused with brown at the apex.

Figure 1 – Rhachomyces hyperommae (FI WR2331, holotype). Scale bar=50 µm