Hydnum regznae Kibby, Liimat. & Niskanen

Kibby, Geoffrey & Liimatainen, Kare, 2022, Hydnum reginae newly described from Britain, Field Mycology 23 (3), pp. 77-80 : 79-80

Hydnum regznae Kibby, Liimat. & Niskanen

IF559703

Holotype: UK England, North Downs Way, White Down , Surrey , TQ113487, 13 October 2021. Under Fagus , Coll. G. Kibby, M. Tortelli & C. Soler. K-M 000265258, GenBank no: ON502618 , Kibby, G.G. & Liimatainen, K. (2002).

Nomenclatural novelties. Index Fungorum 523:1. Figs. 1, 3 , 4 & back cover

Etymology: regznae = Latin for a queen, in honour of Queen Elizabeth II’s Platinum Jubilee.

Basidiomata medium to large, growing isolated or in confluent groups. Pileus 50–150 mm diam, very irregular in outline, rounded to elongateellipsoid, fleshy, initially convex then plane to depressed and frequently with very irregular lumps and bumps, glabrous to slightly velutinous. Colour initially pure white then slowly pale cream to yellowish cream. Margin involute and remaining so, sinuous and often lobed with age (Fig. 1 & back cover). Spines decurrent, conical near the pileus margin becoming increasingly flattened near the stipe and often with two to three points per spine; 5–8 x 0.5–1 mm. Colour pale luteous at first, soon pale salmon pink ( Fig. 3 ). Stipe cylindric to slightly clavate, 20–40 ◊ 30– 40 mm, concolorous with the pileus, basal mycelium white. Context white to greyish cream in the base of the stipe. Odour ill-defined but pleasant, slightly sweet. Flavour mild, soapy then slowly slightly bitter. Macrochemical reactions: KOH + context = no reaction, Guaiac + context no reaction.

Basidiospores ovoid to broadly ellipsoid, thinwalled, hyaline, non-amyloid, (4.5-)4.9–5.4 x 3.8– 4.3 µm, av = 5.1 x 3.9 µm, Q = 1.2–1.4, av Q = 1.3 ( Fig. 4 ). Basidia 35–40 x 5–6 µm, 4- to 6-spored, sterigmata 3–4 µm. Hyphae of the apex of the spines cylindrical, thin-walled, hyaline with cylindrical to clavate ends, 3–4 µm diam. Clamp connections present.

Ecology and distribution

The English collections (holotype and paratypes) were from deciduous forest, mainly Fagus on calcareous soils in leaf litter or emerging from bare soil. So far known also from Estonia, Germany, Slovenia, Spain, and Sweden.

A collection of what appears to be the same species but awaiting sequencing has also been recorded in Wales from open calcareous grassland with Helzanthemum on the Great Orme.

The pallid fruitbodies and the small spores would place this species in subgenus Alba ( Niskanen et al., 2018) which includes H. albzdum sensu stricto and it would appear to be the only European representative of this subgenus to date. Other pallid species in Europe are usually easily distinguished by their larger and often differently shaped spores and differently coloured spines. Perhaps most similar in appearance is the white to cream-coloured H. boreorepandum Niskanen, Liimat. & Niemalä in subg. Hydnum . This is known from forests of Pzcea, Pznus and Betula in Finland and differs in its more regularly shaped fruitbodies with longer stipes, less decurrent and non-pink spines, as well as larger spores.

H. regznae appears to be genuinely rare in Britain and confined to calcareous soils. It is possible that it has been passed over as just palecoloured specimens of the common H. repandum although it is so striking in the field that this seems unlikely. The Surrey population was in a relatively small stand of Fagus on fairly steep slopes and was even observed pushing out through roadside embankments below the tree line. The possible occurrence with Helzanthemum in Wales is particularly interesting and it may be that searches on similar sites around the country will reveal more populations.

Figures

Fig. 3. Close-up of the spines of H. reginae. Photograph © Geoffrey Kibby.

Fig. 4. Spores of H. reginae, the scale bar = 10 µm. Photograph © Geoffrey Kibby.