Laboulbenia nilotica W. Rossi & M. Leonardi, sp. nov.
Index Fungorum number: IF 900432; MycoBank number: MB 900432; Facesoffungi number: FoF 14183; Fig. 1
Etymology – The name of the species comes from the Nile river, in whose waters were collected the host insects.
Thallus olive-gray, with darker perithecium and paler cell II, IV, V, and lower portion of cell I. Basal cell (cell I) slightly shorter than the supra basal (cell II); at the transverse septum separating these cells the receptacle is slightly inflated, then distinctly narrowed because of the concave margin of upper cell on the dorsal side. The septum dividing cell II from cell III is short and slightly oblique, while the septum between cell II and cell VI is more oblique and much longer. Cell III broadly shaped like an inverted trapeze, slightly longer than broad. Cells IV and V small, subequal, separated by a vertical septum. Insertion cell quite thin, not joined to the perithecium. Appendages broken in all the numerous examined thalli. The basal cell of the outer appendage is relatively large, divided from the outer branch by a black ring. Cell VI about twice broader than long. Perithecium ovoid, twice longer than broad, the tip not distinguished ending in a rounded apex with the hyaline ostiole distinctly turned outwards, subtended by irregular darker areas more extended on the dorsal side. Length from foot to perithecial apex 215–320 µm; perithecium 95–120×50–60 µm.
Material examined – Uganda, near Nile River, Murchison Falls National Park, 28.VII.1971, leg. N. Sanfilippo, on Orectogyrus (Trichogyrus) oscari Apetz (Coleoptera, Gyrinidae) (FI 1244a, holotype; FI WR1244b, 1244c 1245a, 1245b, 1245c, paratypes).
Notes – Our collection is quite different from all the other species of Laboulbenia associated with hosts in family Gyrinidae. It is also clearly distinct from the six species reported on insects of the genus Orectogyrus, none of which has blackened insertion cell (Thaxter 1908). Our collection has constricted basal portion of the receptacle and this character can occur in Laboulbenia strangulata Thaxt. that was described on Orectochilus sp. from Timor and India. However, Laboulbenia strangulata has a longer and distinctly concave insertion cell joined to the perithecium, very unequal and larger cells IV and V, the latter of which is extended upwards, and completely different branches of the appendages (Thaxter 1908). Our collection bears a superficial resemblance with L. pedicellata Thaxt., a common and widespread fungus occurring on ground beetles, from which is easily distinguished among other features by the different shape of the perithecial apex and the thick insertion cell joined to the perithecium (Fig. 1). Thus, we introduce our collection as Laboulbenia nilotica sp. nov.
Figure 1 – Mature thalli of Laboulbenia nilotica (FI WR1244a, holotype). Scale bars=50 µm