Dimorphomyces seemanii W. Rossi & M. Leonardi, sp. nov.
Index Fungorum number: IF 559784; Mycobank number: MB 559784; Facesoffungi number: FoF 12924; Fig. 1
Etymology – Named after the Australian acarologist Owen D. Seeman, who supplied us with the materials utilized for the description of this new species.
Holotype – CAMB WR2471.
Female thallus broadly fan-shaped, tinged with amber yellow. Lower portion of the basal cell (Cell I) forming a well-defined stalk. Cell II distinctly longer than broad, regularly enlarging from below upwards. Primary appendage consisting of three cells, the lower of which is quadrangular in outline, slightly to distinctly longer than broad, the following smaller, pale gray and barrel-shaped, delimited above and below by thick, dark septa, the uppermost cell hyaline rounded or slightly longer than broad; the uppermost cell is usually missing in mature thalli. Secondary receptacle usually curved, forming an almost right angle with the primary receptacle, consisting of a row of 7–10 gradually smaller cells bearing one or two perithecia or three celled appendages similar to the primary appendage. Perithecia paler than the receptacle, subfusiform, with a truncate apex. Length from foot to perithecial apex 120–175 µm; perithecium, including stalk cell 110×25 µm.
Male thallus translucent, tinged with very pale yellow. Basal cell of the receptacle slender and elongate, separated from the shorter and stockier suprabasal cell by a very oblique septum. The latter cell gives rise distally to the appendage and bears laterally the short antheridial stalkcell and a small rounded cell which protrudes outwards under the antheridium. Appendage similar to those of the female thalli. Antheridium flask-shaped, with the venter almost rounded, rather abruptly distinguished from the strongly tapering and slightly outcurved neck. Length from foot to antheridial apex 67 µm.
Material examined – Australia, SE Queensland, Lamington N. P., rainforest, 1142 m, 28.259°S, 153.162°E, 27 January 2008, leg. C. Burwell, on Micromegistus sp. (Acarina, Parantennulidae) WR3782 (holotype). NE New South Wales, Gibraltar Range, pitfall trap, 450 m, 29° 32′ S, 152° 22′ E, 1980–1981, leg. G.B. Monteith, on Micromegistus sp., WR3783.
Notes – The new species is very different from Dimorphomyces clavulifer and D. triangularis, the other two species occurring on mites. Among other differences, both the latter fungi have much longer appendages and much shorter perithecia. Dimorphomyces seemanii is easily distinguishable from all other species in the same genus for the spherical distal cell of the appendages and the rounded cell protruding under the antheridium.
Figure 1 – Dimorphomyces seemanii (FI WR3782, holotype). a mature female thallus, with broken terminal cell of the appendages. b male thallus. Scale bars: 25 µm