Protoacia crispans Spirin, 2025

Spirin, Viacheslav, Malysheva, Vera, Viner, Ilya, Alvarenga, Renato Lúcio Mendes, Grebenc, Tine, Gruhn, Gérald, Savchenko, Anton, Grootmyers, Django, Ryvarden, Leif, Vlasák, Josef, Larsson, Karl-Henrik & Nilsson, R. Henrik, 2025, Additions to the taxonomy of the Auriculariales (Basidiomycota) with pedunculate basidia, MycoKeys 120, pp. 339-392 : 339-392

Protoacia crispans Spirin sp. nov.

Fig. 8 G

Holotype.

Sweden. Halland: Särö, Särö Västerskog , Pinus sylvestris (strongly decayed log with a brown rot), 12. X. 2024 Spirin 17688 * ( GB, isotype – H).

Etymology.

Crispans (Lat., present participle of ‘crispo’) – trembling, in reference to delicate consistence of basidiocarps.

Description.

Basidiocarps effused, up to 2 cm in widest dimension, semitranslucent, gelatinous, whitish, adnate; hymenophore hydnoid, spines acute, single, 0.1–0.3 mm long, 6–7 per mm; subiculum hardly visible, semitranslucent, 0.02–0.05 mm thick; margin gradually thinning-out. Hyphal structure monomitic, hyphae hyaline, clamped, frequently anastomosing; subicular hyphae thin- to slightly thick-walled, interwoven, 1–3 μm in diam., subhymenial hyphae thin-walled, quickly collapsing, interwoven, 1–3 μm in diam. Cystidia absent. Hyphidia abundant, richly branched, 1–2 μm in diam. at the apex, scattered among basidia or partly covering basidial cells. Basidia (two –) four-celled, longitudinally or obliquely septate, broadly ellipsoid to globose, pedunculate, (9.0 –) 9.2–11.9 (– 12.0) × (7.2 –) 7.3–9.1 (– 9.2) μm (n = 20 / 1), stalk distinct, up to 20 × 2–3.5 μm, sterigmata gradually tapering, rarely bifurcate, up to 15 × 2–3 μm. Basidiospores smooth, thin-walled, narrowly ellipsoid or broadly cylindrical (shorter spores) to cylindrical-subfusiform or somewhat rhomboid (longer spores), more rarely almost pyriform or lacrymoid, (5.2 –) 5.9–9.3 (– 10.2) × (3.3 –) 3.5–5.4 (– 5.8) μm (n = 30 / 1), L = 7.48, W = 4.61, Q’ = (1.3 –) 1.4–2.1 (– 2.2), Q = 1.64, with a large central oil drop.

Distribution and ecology.

Europe ( Sweden); very rotten coniferous logs ( Pinus ).

Remarks.

Protoacia crispans is morphologically highly similar to P. delicata . The two species differ mainly in basidiospore morphology, regularly broadly ellipsoid or subglobose in P. delicata and highly diverse, varying from narrowly ellipsoid or broadly cylindrical to subfusiform or lacrymoid in P. crispans . Moreover, P. crispans has shorter spines than P. delicata , which are hardly detectable by the naked eye. Phylogenetically, P. crispans is much closer to P. reliqua than to P. delicata ; their differences are listed under the latter species.

Protodontia subgelatinosa (P. Karst.) Pilát is another species that could be mistaken for P. crispans . In addition to different substrate preferences (angiosperm wood versus conifer wood), P. subgelatinosa has wider hyphidia and more regularly shaped, ellipsoid, or ovoid (very rarely cylindrical) basidiospores (see description in Spirin et al. 2019 b). Moreover, the spines of P. subgelatinosa tend to fuse in groups of three – four, and no such pattern was observed in P. crispans .

Figures

Figure 8. Basidiospores of: A. Elmericium alabastrinum (holotype); B. Hydrophana fessula (holotype); C. H. trichiesiana (holotype); D. Mycostilla chromatica (holotype); E. M. guianense (holotype); F. M. inconspicuum (holotype); G. Protoacia crispans (holotype); H. P. reliqua (holotype). Scale bar: 10 µm.