Rhizomyces tschirnhausii W.Rossi & Feijen, 2018

Rossi, Walter & Feijen, Hans R., 2018, New species of Rhizomyces (Ascomycota, Laboulbeniales) parasitic on African stalk-eyed flies (Diptera, Diopsidae), European Journal of Taxonomy 474, pp. 1-13 : 8-9

Rhizomyces tschirnhausii W.Rossi & Feijen sp. nov.

MycoBank No: MB827887 Fig. 1 D–E

Description

Basal cell hyaline, relatively small, distinctly wider than tall, with a small black foot placed laterally and flanked by a depression apparently functioning as a sucker. Suprabasal cell (cell II) much larger, yellowish gray, bearing distally the stalk cell of the perithecium (cell VI) paired with the stalk cell of the appendage (cell III). Appendage slender, flexuous, usually sigmoid, seldom exceeding the tip of the perithecium, consisting of 13–17 pale brown cells separated by conspicuous constrictions, the stalk cell subtrapezoidal or irregular, about as long as its maximum width, the others gradually longer, up to twice as long as broad, each bearing, except sometimes the lowest one, a branch arising from the upper, outer angle; these branches consist of a very small basal cell bearing 2–4 slender and relatively small antheridia with darker necks and a one-celled short, hyaline, slender and erect cell that gives rise laterally to a vertical series of slender branchlets; the latter are 2 or 3 in the lower portion of the appendage, up to 5 in the upper portion, black and variably curved, slightly enlarged at the nearly hyaline tips. Stalk-cell of the perithecium very long, erect, subhyaline, nearly uniform. Basal cell region abruptly distinguished, barrel-shaped, orange with a tinge of red, concolorous with the perithecium. The latter about three times longer than the maximum width, its wall cells spirally twisted and marked by transverse striae, the venter slightly inflated, the distal portion tapering gradually and symmetrically to the tip, which is abruptly distinguished, asymmetrical, with one of the lips much larger and hemispherical bulging outwards. Length from foot to perithecial apex 310–710 µm; from foot to the apex of the appendage 310–540 µm; perithecium 100–140 × 35–50 µm; antheridia 16–18 µm; ascospores about 28 µm.

Etymology

Named after Michael von Tschirnhaus, distinguished student of the Diptera and collector of the new species.

Types

UGANDA: Kasese distr., 17 km WNW of Kasese, near Nyakalengrja , 0.3444° N, 30.0394° E, 1630 m a.s.l., on the abdomen of a male of Diopsina africana ( Shillito, 1940) , 21 Mar. 2012, M. von Tschirnhaus leg. (holo-: FI 4091); Kabarole distr., crater landscape WNW of Fort Portal , 0.6778° N, 30.2250° E, 1555 m a.s.l., near the tip of the abdomen of a male of Diopsina africana , 13 Mar. 2012, M. von Tschirnhaus leg. (para-: FI 4090); Kasese distr., 11 km WNW of Kasese, NW above Kilembe village, 0.2217° N, 29.9900° E, 1555 m a.s.l., on the abdomen of a female of Diopsina africana, M. von Tschirnhaus leg. (para-: FI 4092).

Remarks

Because of the absence of rhizoids and the slender habitus, R. tschirnhausii sp. nov. bears a superficial resemblance with R. gracilis , from which it differs for the showy, rounded bulge at the apex of the perithecium, the color of the latter, the stockier and darker cells of the axis of the appendage, and for other minor features. It might be noted that the ascospores are quite small compared with the size of the perithecium: which is a characteristic of all the species in the genus Rhizomyces .

Figures

Fig. 1. Photomicrographs of the new species of Rhizomyces Thaxt.: A. R. forcipatus W.Rossi & Feijen sp. nov. (FI 4100a). B. Thallus of R. forcipatus sp. nov. from the wing of Teloglabrus sp. (FI 4125). C. Immature thallus of R. forcipatus sp. nov. showing the trichogyne and the basal cell holding firmly a piece of the exoskeleton of the host insect (FI 4099). D. R. tschirnhausii W.Rossi & Feijen sp. nov. (FI 4091). E. Upper portion of the perithecium of R. tschirnhausii sp. nov. (FI 4090). F. R. ramosus W.Rossi & Feijen sp. nov. (FI 4201a), amid the four mature perithecia, near the base of the stalk cells, it can be seen a fifth very immature perithecium bearing the trichogyne. G. R. ramosus sp. nov. (FI 4201a), the pyriform haustorium with remains of the host integument and cell I showing two primordia of new branches. Scale bars: 50 µm.