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

Index Fungorum number: IF 559510; MycoBank number: MB 559510; Facesoffungi number: FoF13387; Fig. 1

Etymology – Named after the entomologist Paolo Magrini, who supplied us with the material utilized for the description of the new species.

Holotype – FI WR4048

Axis of the receptacle from almost straight to distinctly curved or slightly sigmoid, consisting of (14)18–29 cells; basal and suprabasal cells slender, elongate and dark brown colored, the others gradually larger and paler. Appendages occurring in the lower part of the thallus are slender, consisting of 5–6 brownish, elongate cells; these appendages are visible only on young thalli, but are broken off in very early stages of development. The upper and more lasting appendages are thicker, generally consisting of 5 relatively short, subequal cells, the series ending with a 6th cell distinctly longer and much paler, with an almost hyaline tip. Antheridial appendages consist of a single, pale brown cell bearing apically a hyaline antheridium with a tapering and distinctly curved efferent neck. Perithecium subsessile, pale grayish brown, more or less bent as to the axis of the receptacle, symmetrical or slightly asymmetrical, about three times longer than broad, slightly more inflated below, the truncate-conical and paler tip ending in a broad and blunt apex. Length from foot to perithecial apex 525–950 µm. Perithecium 135–180(200) × 45–60(70) µm. Antheridial appendages 40–45 µm. Longest sterile appendages 150 µm.

Material examined – Mexico, Querétaro, Pinal de Amoles, Ojo de Agua, 9.III.2011, G. Trezzi, on Mexaphaenops elegans Barr (Carabidae, Trechini) (FI WR4048, holotype; FI WR4049, WR4488, paratype).

Notes – The only previously described species in Rhachomyces on a cave-dwelling Trechini from Central America is R. quetzalcoatl Balazuc, occurring on Paratrechus spp. from Mexico and Guatemala. The two species of fungi share the absence of dark pigmentation on the perithecial tip and the structure of the upper appendages, but differ greatly in other characteristics, as the much shorter receptacle of R. quetzalcoatl, consisting of dozens of cells, and its more inflated perithecium (Rossi and Cesari-Rossi 1977, Fig. 2).

Figure 1 – Rhachomyces magrinii (FI WR4049, holotype). Scale bar=100 µm

Figure 2 – Rhachomyces hyperommae (FI WR2331, holotype). Scale bar=50 µm