Diaphoromyces minutissimus W. Rossi & M. Leonardi, 2018

Rossi, Walter & Leonardi, Marco, 2018, New species and new records of Laboulbeniales (Ascomycota) from Sierra Leone, Phytotaxa 358 (2), pp. 91-116 : 96

Diaphoromyces minutissimus W. Rossi & M. Leonardi sp. nov. ( Figures 1d and 1e )

MycoBank MB 826832

Etymology:—From Latin = very small, because the new species is not only much smaller than the other species in the same genus, but it is also one of the smallest among the Laboulbeniales .

Original description:—Thallus minute, hyaline and broadly rounded in outline, abruptly enlarged above the small, stalk-like basal cell. Triseriate; median series consisting of a single, elongate and falcate cell bearing distally a small appendiculate cell; posterior series of two cells, the lower of which is irregularly pentagonal, while the upper is slender and elongate, distinctly smaller than the cell of the median series laying beside it and bearing distally a domeshaped cell subtended by a tiny flattened cell, the two forming the base of the primary appendage; anterior series of two cells, the lower broadly triangular, the upper small and flattened. Appendages two, very long and slender, usually dividing dichotomously once or twice. Perithecium broadly elliptical, tilted inward, its longer axis forming an angle of about 45° with the axis of the receptacle, its outer margin free while less than one third is free on the inner side, regularly tapering to the subconical tip and rounded apex. Length from foot to perithecial apex 45–57 μm; perithecium 26–42 × 15–28 μm; longest appendage 65 μm.

Type: — SIERRA LEONE, Western Area, Sussex beach, under the bark of a fallen tree 8°20’54.5”N, 13°13’53.8”W, 28.XI.2015, W. Rossi , on various parts of the body of Clavilispinus sp. ( Staphylinidae , Osoriinae ) (FI4066a). Additional material examined: —Same data as the type (isotype FI4066b, paratype FI4063). A total of 20 mature thalli and 8 others at various stages of development have been observed.

Comments: —The genus Diaphoromyces Thaxt. included thus far four species only, three of which previously described as members of the related genus Rickia . Two of the latter, D. marginatus (Thaxt.) Thaxt. and D. zirophori (Thaxt.) Thaxt. are large and very elongate species, reaching respectively 650 and 400 μm ( Thaxter 1931). The former is only known from the type series, occurring on Heterophaga punctulata Motschulsky ( Tenebrionidae ) in Sri Lanka ( Thaxter 1931), while the latter was reported from a few countries of Central and South America on various species of the genus Piestus ( Staphylinidae ) ( Bernardi et al. 2014). The other two species are smaller, but at least four times larger than the largest thallus of Diaphoromyces minutissimus . These are D. kuschelii A. Weir & W. Rossi , parasitic on Menimus spp. ( Tenebrionidae ) from New Zealand (Weir & Rossi 1997) and D. lispini (Thaxt.) Thaxt. occurring on Staphilinidae (see further on). The latter fungus seems to be the most closely related to the new one, from which it can be distinguished at first sight for the distinctly more elongate habitus, which is due to a much more elongate receptacle.

Figures

FIGURE 1.a: Camptomycesafricanus. b:Corethromyces golaensis. c: Corethromycessp.d:maturethallus ofDiaphoromyces minutissimus from the type slide. e: immature thallus of D. minutissimus from the type slide. f: paired male (left) and female (right) thalli of Laboulbenia buccalis from the paratype slide WR4078. Scale bars = 50 μm.