Podospora reunionensis Silar, 2025

Podospora reunionensis Silar , sp. nov.

( Figs 5 View FIG ; 6 View FIG ; 7 View FIG )

IF NUMBER. — 901426.

ETYMOLOGY. — Refers to the place of its discovery, La Réunion island.

HOLOTYPE. — PC0799011 ; ex-type culture: PSN1158.

HABITAT AND GEOGRAPHIC DISTRIBUTION. — PSN 1158, the only strain presently available, was isolated from dung collected in La Réunion, an island of the Indian Ocean near Madagascar, in 2022. It is available under reference BRFM 3810 at the Centre international de Ressources microbiennes-Champignons filamenteux ( CIRM-CF, Inrae, France).

ADDITIONAL FEATURES. — PSN1158 undergoes senescence on M2 but with a huge variation in longevity between the cultures and with no difference between mat1-1 and mat1-2 strains (PSN1158 mat1-1: 54 +/– 38 cm and PSN1158 mat1-2: 55 +/– 39 cm). It does not undergo Crippled Growth like the P.comata strain T ( Boucher et al. 2017; Nguyen et al. 2022). Like the other species of the P. anserina complex ( Boucher et al. 2017), it produces acellular orange-turning-to-black acellular microsclerotia-looking structures when cultivated on media with Guibourtia demeusii L. wood shavings ( Fig. 7A View FIG ). It differentiates appressorium-like structures enabling to breach cellophane when cultivated onto a layer of cellophane in the absence of glucose ( Fig.7B View FIG ). SNPs between the PSN1158 mat1-1 and mat1-2 isolates were found only in a region of about 0.9 Mb around the mating-type locus ( Fig. 7C View FIG ). Such a high level of genome-wide homozygosity indicated that the isolate was highly inbred. The differentiation around the mating-type locus showed that recombination is suppressed in this region, like in all the other species of the complex ( Hartmann et al. 2021). Finally, PSN1158 was able to exert Hyphal Interference against Penicillium chrysogenum Thom like all the other species of the complex, i.e., it was able to kill P. chrysogenum hyphae upon contacting them ( Boucher et al. 2017).

DESCRIPTION

Perithecium diameter is 370 +/– 60µm, pyriform, membranous, semitransparent, pale brown, covered with numerous hyphoid hairs. Neck of varying length and curvature depending on the lighting, blackish, coriaceous, often with a tuft of dark, rigid, agglutinated hairs, sometimes with a few scattered hairs too. Peridium with textura intricata. Asci 4-spored, clavate-lageniform. Spores spoon-shaped in the early stages. Mature spores obliquely uniseriate:spore head 35.0 +/– 1.8 × 22.7 +/– 0.8µm, ellipsoidal, flattened at the base and slightly pointed at the apex, smooth, thick-walled,with an apical central germ pore.Presence of a very long and thin primary appendage (pedicel) nearly as long as the ascospore 32.3 +/– 2.5 × 4.4 +/– 1.1µm, cylindrical, slightly tapering towards the apex. This appendage swells upon ejection so that its width reaches7.7 +/–0.8 µm.Upper secondary appendage(cauda) lash-shaped,not covering the germ pore;lower cauda solid, filiform, arising from the pedicel apex and with two (sometimes one) additional well-defined and long appendage(s) at the pedicel base 30.7 +/– 9.4 µm, near the septum.

Presence of a Cladorrhinum -like anamorph producing roundish to pear-shaped spermatia (2.6 +/– 0.4 × 2.0 +/– 0.3 µm) that did not germinate.

PSN1158 ITS sequence differs at two positions from the P. anserina reference ITS: A instead of G at position 22 and the presence of two additional Cs after position 467.