Laboulbenia cosmodisci A. Weir, M. McHugh & W. Rossi, sp. nov.

Index Fungorum number: IF 900430;  MycoBank number: MB 900430; Facesoffungi number: FoF 14181; Fig. 1

Etymology – From Latin: referring to the name of the host beetle.

Thallus erect to sigmoidal, pale grayish brown to dark brown; total length from foot to tip of perithecium 325–375 µm. Receptacle composed of the usual arrangement of five superposed cells. Basal cell (I) brown with an orange tinge, slightly curved, and tapering towards the foot, about three times longer than broad, 60–88× 18–33 µm. Cell II grayish brown to hyaline, more elongate than cell I, becoming slightly broader distally, 78–98×25–38 µm, giving way above to cell III and the perithecial stalk cell (VI). Cell III grayish brown to brown, two to three times as long as broad, rectangular but broadening distally 55–90 × 20–43 µm, giving way distally to cell IV. Cell IV grayish brown to almost hyaline, two to three times as long as broad, 60–85×18–38 µm. Cell V gray to hyaline, small, wedge-shaped, 28–33 × 10–25 µm. Appendages formed above a thick black, flattened insertion cell that is not directly connected to the perithecium. Outer appendage basal cell hyaline, twice as long as broad, 15–20×15 µm, giving rise to another, equal, superposed cell which in turn bears distally, two long, flexuous, septate, hyaline branches. Inner appendage basal cell hyaline, only slightly longer than broad, smaller than the outer appendage basal cell, 10–13 ×8–10 µm, giving way distally to a subequal cell, which in turn bears two short and usually 1–2 celled hyaline branchlets producing paired antheridia terminally. Antheridia 5 × 8 µm, hyaline, flask-shaped, borne terminally in pairs on the inner appendage. Perithecium stalk cell (VI) brown to gray, quadrate, 25–40 ×35–40 µm. Perithecium grayish brown to dark brown, completely free, with insertion cell close to perithecial apex, 135–175 × 45–60 µm, with opaque, sub-terminal region, and hyaline, rounded, outwardly-directed lip cells. One thallus is much larger than the others reaching to 690 µm from foot to tip of perithecium. In other respects, though, this outlier thallus shares characteristics with the typical thalli as described above.

Material examined – Indonesia, Sulawesi Utara Province, Dumoga-Bone National Park, Plot A, lowland forest, el. ca. 200 m, Pitfall trap, 10–17.IV.1985, P.M. Hammond, on the elytra of Cosmodiscus sp. (BM(NH) Code No. 4.56) (Coleoptera, Carabidae, Pterostichini), K(M) 43519, holotype; AW 281 in SYR, isotype; Sulawesi Utara Province, Dumoga-Bone National Park, Hog’s Camp, el. ca. 492 m, at light, IX.1985, P.M. Hammond, on the pronotum of Cosmodiscus sp. (BM(NH) Code No. 4.56), AW 280 in SYR, paratype. Sulawesi Utara Province, Dumoga-Bone National Park, nr. Kotamubagu, Daanau Mooat, el. ca. 1200 m, Pitfall trap, 21–23.X.1985, P.M. Hammond, on the pronotum of Cosmodiscus sp. (BM(NH) Code No. 4.56), AW 282 in SYR, paratype. Sulawesi Utara Province, Dumoga-Bone National Park, Plot A, lowland forest, el. ca. 200 m, Flight interception trap, 30.X – 06.XI.1985, P.M. Hammond, on the elytra and pronotum of Cosmodiscus sp. (BM(NH) Code No. 4.56), AW 290 in SYR, paratype.

Notes – Twenty-five thalli at various stages of development have been examined on the elytra and pronotum of various specimens of a single species of Cosmodiscus. The elongate receptacular cells produce a thallus where the insertion cell is at the level of the perithecial apex, and not below the middle as in the majority of Laboulbenia species. Our collections may be compared with Laboulbenia erecta Thaxt., and differ in having a much longer basal cell of the receptacle cell (I) and the non-flattened, somewhat tapered perithecial tip with distinctly out-turned lip cells (Fig. 1). Therefore, we introduce these collections as Laboulbenia cosmodisci sp. nov.

Figure 1 – Thallus of Laboulbenia omalii (K(M) 43522, holotype). Scale bar=25 µm