Species with broader allantoid spores (2.8–3.5 µm) and less heavily encrusted cystidia than in Subulicystidium meridense Oberw.

RÉUNION. Saint-Benoît: Salazie, Hell Bourg, ca 1000 m, -21.0642, 55.5269, on dead woody branch, 23 Mar 2015, M.Striegel (L 1584a in FR; isotype in KAS).

boidinii, in honour of Jacques Boidin, a great explorer of fungi of Réunion Island, who collected this species and suggested an independent status for it.

Basidiomata annual, effused, resupinate, soft and fragile, arachnoid, thin, loosely adnate. Hymenophore smooth, finely velutinous due to numerous protruding cystidia, whitish. Margin thinning out, pruinose, adnate.

Hyphal system monomitic. All septa with clamps. Subiculum thin, with loosely interwoven richly branched hyphae 1.5–2.5 µm wide, thin-walled, hyaline and smooth. Subhymenium thin, with hyphae similar to those in subiculum but occasionally bearing slight amorphous hyaline encrustation. Cystidia subulate, rather narrow, 45–65 × 2.5–3.5 µm including encrustation, projecting up to 30 µm, without basal swelling, terminal or pleural, with thin hyaline cell wall and outer hyaline crystalline sheath covering the whole cystidia except the tapering, thin-walled, acuminate apex. Crystal protrusions on cystidium are small and clearly rectangular and arranged in longitudinal rows.

Basidia suburniform to almost clavate, 10–12 × 4–5.5 µm, thin-walled, with 4 sterigmata and a basal clamp, without or with slight amorphous hyaline encrustation at the base. Basidiospores allantoid, L=(5.7–)5.9–7.2(–7.9) µm, W=(2.6–)2.8–3.3(–3.5) μm, Q=(1.8–)2.0–2.4(–2.5), N=116/2, with minute apiculus, smooth, thin-walled, hyaline, often with two oil drops (one at each pole), negative in Melzer’s reagent.

COSTA RICA. Puntarenas: Coto Brus, Sabalito, Zona Protectora Las Tablas, Finca Cafrosa, El Tajo, 1560 m, 8.9225, -82.7956, on stem of angiosperm tree, 6 Nov 2004, K.-H.Larsson (KHL 12830 in GB). RÉUNION. Saint Pierre: Cilaos, A_Cilaos X, Forêt de la Mare-a-Joseph, kiosque au milieus des Cryptomeria D.Don, alt. 1400 m, on strongly decayed wood of Cryptomeria japonica D.Don, 20 Apr 1985, J.Boidin (LY 11247).

Boidin and Gilles (1988) in their survey of Subulicystidium from Réunion Island reported “Subulicystidium allantosporum ad interim” and referred to their specimens LY 11247 and LY 12750. We show in the current study that these two collections represent different species and only the former may be assigned to S. boidinii. We were not able to sequence LY 11247, but description and illustration (fig. 38A) provided by Boidin and Gilles (1988) and our re-measuring of basidiospores in their specimen (Supplementary files 2 and 3) agree well with our concept of S. boidinii.