Laboulbenia omalii A. Weir, M. McHugh & W. Rossi, sp. nov.
Index Fungorum number: IF 900431; MycoBank number: MB 900413; Facesoffungi number: FoF 14182; Fig. 1
Etymology – From Latin referring to the name of the host beetle.
Thallus erect, small, completely hyaline except for portions of the perithecium, the insertion cell, and the foot. Total length from foot to tip of perithecium 163–170 µm. Receptacle cell I completely hyaline, trapezoidal, tapering slightly towards the foot, longer than wide, 18–20×13 µm. Cell II completely hyaline, rectangular, becoming more rounded near the distal septum with cells III and VI, twice as long as wide, 38–40×15–18 µm. Cell III also hyaline, rectangular or quadrate, to somewhat rounded, 23×15–18 µm, giving way distally to cell IV. Cell IV completely hyaline, rectangular, separated from cell V by a vertical septum, 20 × 13–15 µm. Cell V hyaline, small, wedge-shaped, 8–10×5–8 µm. Appendages insertion cell dark brown to black, positioned at an angle to the main axis of the thallus, relatively thick. Appendage outer basal cell much larger than inner basal cell, hyaline, with an outer distal black septum, rounded to bell-shaped, giving way to a smaller, hyaline, triangular cell from its inner face, and producing a single cell above the outer black distal septum. Cell derived from inner face can give rise to one or two superposed, flattened cells. Inner basal cell smaller, hyaline, more flattened than outer, giving way distally to a single cell that then produces two smaller cells, each of which gives rise to a broad, squat antheridium with very short neck and with nip-shaped apices. Perithecium stalk cell (VI) hyaline, curved, quadrangular, slightly wider than long, 10–12×15 µm. Perithecium short, symmetrical, slightly inflated, hyaline to smoky black, the dark suffusion particularly prevalent along the upper outer margin and sub-terminally beneath the hyaline, obtuse, lip-cells, that are subtended by a blackish area on the inner side.
Material examined – Indonesia, Sulawesi Utara Province, Dumoga-Bone National Park., Plot C, el. ca. 400 m, fallen fruit of Ficus sp., II.1985, P. M. Hammond, on the tergites of an unidentified rove beetle (BM(NH) Code No. 20.6) (Coleoptera, Staphylinidae, Omaliinae), K(M) 43522, holotype.
Notes – Only two mature and two immature thalli have been examined from the tergites of the host. Approximately, 680 species have been described in the genus Laboulbenia and only about 5% are known on hosts in family Staphylinidae. It is obvious that they do not form a monophyletic group, as even the three found on Omaliinae [L. geodromychi Baumgartner, L. omalii (described here), and L. richardii W. Rossi & Santam.] are unrelated. The presumed antheridia may be intercalary on the inner appendage in contrast to the typical external formation of these organs in this genus. The structure of the receptacle and the presence of the typical insertion cell leave no doubt as to the generic placement of this new species (Fig. 1). The structure of the appendage in our collection is distinct not only from the two species previously described on Omaliinae and from any of the more than 30 species on Staphylinidae, but also from all other known species of Laboulbenia. Therefore, we introduce this collection as Laboulbenia omalii sp. nov.
Figure 1 – Thallus of Laboulbenia omalii (K(M) 43522, holotype). Scale bar=25 µm