Rhachomyces pilosellus (C.P.Robin) Thaxt.

Santamaria, Sergi & Pedersen, Jan, 2021, Laboulbeniomycetes (Fungi, Ascomycota) of Denmark, European Journal of Taxonomy 781, pp. 1-425 : 92

Rhachomyces pilosellus (C.P.Robin) Thaxt.

MB#192158

Fig. 18C–D

Proceedings of the American Academy of Arts and Sciences 30: 467 ( Thaxter 1895). – Basionym: Laboulbenia pilosella C.P.Robin, Traité du Microscope : 912 ( Robin 1871) [MB#566983]. –

Type: [Not designated] “ On Lathrobium from an unknown locality in France ”. [According to Santamaria et al. 1991, the type is an “ iconotype ”, i.e., the illustration given by Robin, which agrees with the ICNAFP – International Code of Nomenclature for Algae, Fungi and Plants ( Turland et al. 2018)]

Acanthomyces brevipes Thaxt. ( Thaxter 1893: 177) [MB#581132]. – Rhachomyces brevipes (Thaxt.) Saccardo ( Saccardo 1895: 454) [MB#188964]

Diagnostic features

Main axis short, consisting of 4–5 cells, continuing to a 3–4 celled lateral branch. A blackish diagonal strip is seen traversing from cell I to cell II ( Fig. 18C–D , arrows). Appendages “a” and “b” darkened, very elongated, yet coiled if undamaged ( Fig. 18C ). Type “c” appendages clustered below the perithecium. Perithecium very large, longer than main receptacle axis. [Detailed descriptions: Thaxter 1896; Majewski 1994b; De Kesel 2002]

Distribution and hosts

Grows on Lathrobium (Col. Staphylinidae Paederinae ). An uncommon species only reported from France (type), Germany ( Thaxter 1893), Poland, Ukraine ( Siemaszko & Siemaszko 1932), Belgium ( Collart 1945), Italy ( Rossi 1975), and Hungary ( Bánhegyi et al. 1985).

Collections examined from Denmark

On Lathrobium fulvipenne (Gravenhorst, 1806) (Col. Staphylinidae Paederinae )

DENMARK – Fyn (F) • Gyldenstens inddaemmede Strand ; 55°34.447′ N, 10°7.211′ E; NG75; 2 Apr. 2014; JP 687; JP det.; ZMUC C-F-123175 . – Sydsjaelland (SZ) • Østerskov ved Langebaek ; 54°59.572′ N, 12°6.715′ E; UA19; 3 Jan. 2019; JP 1300; JP det.; ZMUC C-F-123833 .

Remarks

First record from Denmark. This is one of the earliest described species of Laboulbeniales .

Figures

Fig. 18. Rhachomyces spp. A–B. R. philonthinus Thaxt. Mature thalli. In B, the lateral branch from the primary axis (a diagnostic character) is labelled (arrow). – C–D. R. pilosellus (C.P.Robin) Thaxt. Mature thalli with labelled blackened diagonal strip traversing cells I and II (arrows). –E–F. R. spinosus Santam. & Cuesta-Segura. Mature thalli. In E, primary septum (a) and spinous original spore apex (sx) are labelled. Scale bars: 50 µm. Photographs from slides ZMUC C-F-122681 (A), ZMUC C-F-122685 (B), ZMUC C-F-123833 (C–D), ZMUC C-F-123296 (E), ZMUC C-F-123062 (F).