Stigmatomyces ferrugineus W.Rossi & M.Leonardi, 2020

Rossi, Walter & Leonardi, Marco, 2020, New Laboulbeniales from China (Ascomycota), Cryptogamie, Mycologie 20 (1), pp. 1-7 : 6

Stigmatomyces ferrugineus W.Rossi & M.Leonardi , sp. nov.

( Fig. 2F )

Thallus with a predominant rusty color, with an almost rounded perithecial venter, the axis of free appendage consisting of three slender and elongate cells bearing two antheridia each.

ETYMOLOGY. — From Latin ferrugineus which means rusty, because of the predominant color of the fungus.

MATERIAL EXAMINED. — China. Prov. Guizhou, Tongren, Fanjing Mt. , 27°56’31’’N, 108°36’55”E, 874 m, evergreen broad-leaf forests, on a Ceropegia dolichophylla Schtlr. flower, attracted by dead bee, on head and mouthparts of Desmometopa , sp. ( Diptera , Milichiidae ), 16.IX.2013, leg. A. Heiduk (holo-, FI [ FI WR3821 ]).

MYCOBANK. — MB 831082.

DESCRIPTION

Receptacle, distal portion of the free appendage and perithecial apex pale yellow; the rest of the fungus is rusty red. Receptacle long and slender, basal cell tapering gradually towards the foot, suprabasal cell slightly longer and almost rectangular. Stalk-cell of the appendage prominent, abruptly bulging out from below the insertion cell of the appendage, its outer margin distinctly concave. Free appendage slender and curving outwards, its sigmoid axis consisting of three elongate cells, each of the two lower giving rise from their upper, inner angle to a smaller cell bearing apically two large, paired and diverging antheridia, while the third, uppermost and more slender cell of the axis bears distally two superimposed antheridia, which appear non functional even in very early stages of the fungus. Stalk cell of the perithecium triangular in outline, much broader than tall; secondary stalk cell obliquely separated and about of the same size than the former; basal cells relatively small: the whole region compact. Perithecial venter large, with symmetrically rounded outline, the surface indistinctly granular, rather abruptly and almost symmetrically inflated, slightly prominent distally below the spreading base of the slender and erect neck, which is about as long as the venter, somewhat swollen at its junction with the tip; the latter ending if four lobes, three of which are small, flattened and slightly divergent, the fourth larger, rounded and more prominent. Total length 230-380 µm; perithecium 120-230 × 80-85 µm; appendage 25-45 µm; ascospores about 35 µm.

REMARKS

Stouter specimens of Stigmatomyces ferrugineus , sp. nov., bear a superficial resemblance with S. carles-tolrae Santam. & W.Rossi , which is also parasitic on a member of the Milichiidae family (i.e. Madiza glabra Fallén ); however, the latter fungus has a very different appendage with the axis composed of four cells, and much shorter receptacle and perithecial neck ( Santamaría & Rossi 1998). The third species associated with Milichiidae , i.e., S. deemingii W.Rossi & A.Weir , has a more slender perithecial venter, with the surface also coarsely granular, and a long appendage ( Rossi & Weir 2011).

Only one species of Stigmatomyces was reported from China thus far: S. ephydrae L.Mercier & R.Poisson ( Shen & Ye 2006).

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.