Rhachomyces spiralis W.Rossi & M.Leonardi, 2020

Rossi, Walter & Leonardi, Marco, 2020, New Laboulbeniales from China (Ascomycota), Cryptogamie, Mycologie 20 (1), pp. 1-7 : 4

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

( Fig. 2B, C )

Differs from Rhachomyces longissimus Thaxt. for the very long lower appendages, for the very numerous and differently shaped upper appendages, and for the spiral twist of the thalli growing on the dorsal surface of the host.

ETYMOLOGY. — From Latin spiralis which means spiral, because of the thalli spirally twisted when growing on the dorsal surface of the host.

MATERIAL EXAMINED. — China. Guizhou, Quianxi County, Honglin Town, Luo Sai Dong , GZ/Qx/29, alt. 1445 m, on Guizhaphaenops , sp. ( Coleoptera , Carabidae ), 19.XI.2003, leg. L. Latella, S. Meggiorini & A. Bileddo (holo-, FI [FI WR3035 ]; para-, FI [FI WR3034 ]) .

MYCOBANK. — MB 831068.

DESCRIPTION

Axis of the receptacle distinctly spiral in thalli growing on the elytra and pronotum of the host insect, consisting of 19-38 cells; from slightly to distinctly curved and consisting of 12-31 cells when growing on other parts of the body. These cells are brown, usually much darker on the anterior side and along the septa, gradually enlarging from the foot to the base of the perithecium. The appendages originating from the lower cells of the axis are long, dark and stiff; those in the upper portion of the thallus are more numerous, much shorter and paler, with more slender and almost hyaline tips. Antheridial appendages very numerous, consisting of two brown cells terminated by an elongate, grayish antheridium bearing a slender and curved neck. Perithecium sessile, oblong, very slightly inflated below, light brown colored, regularly tapering to the darker, subconical tip and hyaline, blunt apex. Length of the receptacle in unstretched spiral thalli growing on elytra and pronotum: up to 790 µm; length of receptacles of thalli growing on other parts of the host 255-675 µm; perithecium 130-150 × 40-42 µm; antheridial appendages 45-50 µm.

REMARKS

The spiralized habitus of thalli growing on the hosts’ dorsal surface is unique among the species in the genus Rhachomyces and resemble tiny corkscrews emerging from (or screwed upon) the insects ( Fig. 2B ). Because of the shape of the perithecium and the length of the receptacle, R. spiralis , sp. nov., bears a superficial resemblance with R. longissimus , parasitic on Carabidae Anchomenini in Central and South America ( Proaño Castro & Rossi 2008; fig. 7). However, the sterile appendages and the antheridial appendages of the two species are very different.

Figures

FIG. 2. — A, Rhachomyces latellae, sp. nov.; B, Rhachomyces spiralis, sp.nov., immature thallus from the elytra; C, Rhachomyces spiralis, sp. nov., mature thallus from the legs; D, E, Rhachomyces toledanoi, sp. nov.; F, Stigmatomyces ferrugineus, sp. nov. Scale bars: 50 µm.