Laboulbenia divisa W. Rossi & M. Leonardi, sp. nov.
Index Fungorum number: IF 557384; MycoBank number: MB 557384; Facesoffungi number: FoF 07846; Fig. 1
Etymology – From Latin: divided, because of the lower portion of the receptacle unusually divided into many cells.
Holotype – FI WR3479a
Perithecium pale greyish brown; antheridia dark brown; appendages brown to blackish, with paler tips; the rest of the fungus is pale yellowish grey. Thallus very long and slender. Basal and suprabasal cells of the receptacle (cells I & II) replaced by a series of 6–9 gradually longer cells originated by secondary divisions. Cell III+IV stout, about one and half times, or less, longer than its maximum width, with the outer margin straight or slightly concave. Cell V relatively large, irregularly trapezoidal or wedge-shaped. Insertion cell narrow and thick, free from the base of the perithecium. Outer appendage consisting of a large, erect basal cell, blackish on the outer side and almost hyaline on the inner, from which arise outwardly five branches, each dividing dichotomously once or twice above the lower cell, which is hyaline and bordered with black on the outer side, the following cells being smaller and brownish; as whole the outer appendage appears as a dense, fan-shaped tuft of branchlets slightly exceeding in length the apex of the perithecium. Inner appendage consisting of a very small and hyaline basal cell distinctly shorter than its maximum width, from which arise two short bicellular branchlets, the lower cell of which is almost rounded, grayish brown, contrasting, separated from the smaller, paler, greyish and slenderer upper cell by a marked constriction and a thick, black septum; each of the two branchlets bear apically a tuft of (2–)3–4, elongate, bottle-shaped antheridia. Cell VI relatively small, rectangular in outline, about one and half times longer than broad. Perithecium almost entirely free, the venter slightly and evenly inflated, the wall-cells spirally twisted, describing a half turn from the base to the tip, which is rather abruptly distinguished, much darker, slightly bent inward, ending with four larges, rounded, subequal lips with hyaline margins. Length from foot to perithecial apex 880–1575 µm; perithecium 45–65×140–170 µm; antheridia 35 µm; longest appendages 225 µm.
Material examined – COSTA RICA, Prov. Cartago, Turrialba, P. N. Barbilla, Sendero el Felino, LN—217000 N 595000E, alt. 400–500 msl, 18.VII.2002, E. Rojas, upper surface of the tip of the abdomen of a female specimen of Richardia telescopica Gerdstacker (Diptera, Richardiidae) (FI WR3479a, holotype; WR3479b in InBIO, isotype). Costa Rica, Prov. Cartago, P. N. Barbilla, Dantas River, LN—218100 N 593600E, alt. 500–600 msl, Malaise trap, 9 December 1999—8 January 2000, E. Rojas, tip of the abdomen of R. telescopica (FI WR2700a and FI WR2700b, paratypes).
Notes – The division of the lower cells of the receptacle was observed so far in only two species of the large genus Laboulbenia: L. partita reported from various African and Asian countries on Chrysomelidae Alticini (Rossi and Bernardi 2018), and L. hingstonii described on a Carabidae from India (as Misgomyces hingstoni: Balazuc 1971) and known only from the type collection. Laboulbenia divisa is distinct from and not allied with these two latter species. Likely, the division of the cells of the receptacle is a rare feature arisen independently in species of Laboulbenia occurring on very different host-insects in different continents
Figure 1 – Laboulbenia divisa (FI WR3479a, holotype). a Whole thallus from the type slide. b Upper portion of an immature thallus from the type slide. Scale bars: a, b=100 µm