Cortinarius paraxenosma Soop & Dima, 2020

Dima, Bálint & Soop, Karl, 2020, The ‘ xenosmatoid’ group of Cortinarius (Agaricales) in New Zealand, Phytotaxa 438 (4), pp. 223-236 : 231-232

publication ID	https://doi.org/ 10.11646/phytotaxa.438.4.1
persistent identifier	https://treatment.plazi.org/id/03CA87C2-FFAD-A242-BC85-FA6C6420FD92
treatment provided by	Felipe
scientific name	Cortinarius paraxenosma Soop & Dima
status	sp. nov.

Treatment

Cortinarius paraxenosma Soop & Dima View in CoL , sp. nov.

( Figures 1C, 1E View FIGURE 1 , 2E, 2F View FIGURE 2 )

MycoBank MB833326

Holotype:— New Zealand. Taupo , Cascade Hut Track, 04 May 2003, in Fuscospora fusca forest, K. Soop CO1343 ( PDD77483 About PDD ), GenBank MT056038 ( ITS).

Etymology:—‘paraxenosma’ the Greek παρα ‘near’ referring to its resemblance to C. xenosma .

Description: — Pileus 25–50 mm diam. or more, dry, non-hygrophanous, black-brown to umber, coarsely innately fibrillose, partly coated by ochraceous grey clumps of superficial fibrils, margin with ochraceous grey tufts when young. Lamellae pale grey to brownish grey when young, adnate, close to crowded (L=74). Stipe cylindrical, robust, sometimes slightly bulbous at base, 40–70 × 7–13 mm (base to 18 mm), pale greyish yellow, mostly covered by brownish red fibrils and zones, apex white. Universal veil ochraceous, reddening, copious; partial veil white, copious. Context pale greyish yellow, reddening in stipe. Odour distinct, like raw potato; taste none. Macrochemical reactions: NaOH turns the red universal remnants on the stipe yellowish in 20 secs, no reaction elsewhere; guaiac greyish green; fluorescence in UV light absent. Basidiospores (6–)6.7–7.2–7.7(–8.2) × (4.6–)4.7–5.0–5.3(–5.7) µm, Q=1.44±0.10 (n=37), ellipsoid to ovoid, moderately verrucose ( Fig. 2F View FIGURE 2 ). Marginal elements crowded, clavate, 16–25 × 5–7 µm. Basidia 28–32 × 7–8 µm, 4-spored. Pileipellis of repent hyphae, 3–5 μm wide. Hypocutis elements irregular, ovoid, 20–32 × 17–22 μm. Clamp connections present. Partial veil hyphae 5–8.5 µm wide, mostly hyaline, some with an intracellular, more or less granular, brownish pigment, not encrusted.

Habitat:—Gregarious in Nothofagaceae forest, uncommon.

Other collections examined:— New Zealand. Taupo, Te Iringa Track, 29 April 2001, K. Soop CO1186 (PDD107519).

Comments:— Cortinarius paraxenosma is very difficult to separate macroscopically from Cortinarius xenosma . The reddening of universal veil, stipe, and context tends to be somewhat stronger in C. paraxenosma , rendering a rosy sheen overall to the basidiome. The fact that alkaline reagents discolour this red pigment, turning them yellowish on both species, may indicate that they share part of their chemistry. This trait has also been observed on a third New Zealand species, C. periclymenus Soop (2001: 122) , which is related to sect. Vibratiles Melot (1989: 99). Microscopically C. paraxenosma has slightly smaller and stronger verrucose basidiospores than C. xenosma . Genetically, however, the species are well-separated (ca. 35 nucleotide and indel differences).