Diagnosis.

Taxon classification

Fungi

Trechisporales

Hydnodontaceae

Ordynets

Alexander

Scherf

David

Pansegrau

Felix

Denecke

Jonathan

Lysenko

Ludmila

Larsson

Karl-Henrik

Langer

Ewald

Short-spored

Subulicystidium

(

Trechisporales

Basidiomycota

): high morphological diversity and only partly clear species boundaries

MycoKeys27620182018354199

10.3897/mycokeys.35.25678

Subulicystidium

fusisporum

Ordynets & K.H.Larss.

sp. nov.

Figs 4a–c; 10e

Diagnosis.

Differs from Subulicystidium longisporum (Pat.) Parmasto by fusiform basidiospores which are ca. 10–13 µm long and 2.5–3.5 µm broad.

Type.

PUERTO RICO. Municipio Rio Grande, Luquillo Mts, El Verde Research Area, between Field Station and 16-hectare grid, 320–380 m, 18.3233, -65.8172, on fallen tree log, 9 Jun 1998, K.-H.Larsson (KHL 10360 in GB).

Etymology.

fusisporum (Lat.), having fusiform basidiospores.

Description.

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

system monomitic. All septa with clamps. Subiculum thin, with loosely interwoven richly branched hyphae 2.5–3.5 µm wide, usually thin-walled, hyaline and smooth. Subhymenium thin, with hyphae slightly broader than in subiculum, 2.7–4 µm wide, compactly arranged, often slightly thick-walled and covered with hyaline crystalline sheath. Cystidia subulate, 65–90 × 3.5–5 µm including encrustation, projecting up to 40 µm, without or occasionally with basal swelling (up to 6 µm wide), terminal, with thick hyaline cell wall and outer hyaline crystalline sheath covering the whole cystidium except the thin-walled, acuminate apex. Crystal protrusions on cystidium are small to moderately large and clearly rectangular and arranged in longitudinal rows.

Basidia suburniform, 12–14 × 4.5–6 µm, thin-walled, with 4 sterigmata and a basal clamp, often with a hyaline crystal collar at the base. Basidiospores fusiform, L=(9.7–)10.7–12.8(–13.3) µm, W=(2.1–)2.4–3.4(–3.7) µm, Q= (3.0–)3.3–4.9(–5.9), N=127/3, with minute apiculus, smooth, thin-walled, hyaline, occasionally with oil drops, negative in Melzer’s reagent. Tolerance limits for basidiospore length, width and length to width ratio in S. fusisporum based on 3 sequenced specimens are provided in the Table 2.

Table 2.

90% tolerance limits defined for the 90% probability level for the mean basidiospore length, width and length to width ratio for Subulicystidium species with at least 3 sequenced specimens. The following specimens were used to estimate tolerance limits for species: Subulicystidium fusisporum: GB:KHL 9093, 10360 and 12761; S. harpagum: GB:KHL 10733, O:F:LR 15736, KAS:L 0244 and 1726a; S. parvisporum: KAS:GEL 5032, KAS:L 0140 and 1226 and LY 12750; S. robustius: GB:KHL 10039, 10272, 10780 and 10813.

Measurement type	Estimate	Species
Measurement type	Estimate	Subulicystidium fusisporum	Subulicystidium harpagum	Subulicystidium parvisporum	Subulicystidium robustius
Spore length, µm	Sample mean	11.78	6.74	5.61	9.78
	Lower limit of 90% tolerance interval	9.64	4.34	4.78	7.81
	Upper limit of 90% tolerance interval	13.92	9.13	6.43	11.75
Spore width, µm	Sample mean	2.92	2.6	2.51	3.00
	Lower limit of 90% tolerance interval	1.65	1.62	2.06	2.44
	Upper limit of 90% tolerance interval	4.19	3.58	2.95	3.57
Spore length/width ratio	Sample mean	4.09	2.63	2.25	3.27
	Lower limit of 90% tolerance interval	1.89	0.83	1.91	2.52
	Upper limit of 90% tolerance interval	6.28	4.42	2.59	4.02

Additional specimens examined.

COSTA RICA. Puntarenas: Coto Brus, Sabalito, Zona Protectora Las Tablas, La Neblina, 8.9149, -82.7719, on stem of angiosperm tree, 5 Nov 2004, K.-H.Larsson (KHL 12761 in GB). CÔTE D’IVOIRE. Abidjan: Foret du Banco, 5.3932, -4.0525, on dead wood, 6 Jul 1974, G.Gilles (LY 7375). JAMAICA. Cornwall County: Trelawny parish, N of Crowlands, trail/road into park area, 18.2611, -77.6511, on stem of angiosperm tree, 10 Jun 1999, K.-H.Larsson (KHL 10612 in GB). PUERTO RICO. Municipio Rio Grande, Luquillo Mts, El Verde Research Area, between Field Station and 16-hectare grid, 320-380 m, 18.3233, -65.8172, on strongly decayed stem of angiosperm tree, 19 Jun 1996, K.-H.Larsson (KHL 9093 in GB), on uprooted angiosperm tree, 19 Jun 1996, K.-H.Larsson (KHL 9061 in GB).

Remarks on species.

Amongst the species considered in this study, S. fusisporum is the most probable to be confused with S. longisporum. However, careful measurement of basidiospores (length below 13 µm, see Fig. 10e vs. 10g) and rDNA sequence identity clearly point to the species of its own. The regular rectangular shape of crystal protrusion as well as their dense arrangement in longitudinal rows on cystidia in S. fusisporum is also prominent.

Figure 4.

Species of Subulicystidium with narrow fusiform basidiospores. Subulicystidium fusisporum (GB:KHL 10360, holotype): a cystidia b crystalline encrustation of hymenium c basidiospores. Subulicystidium inornatum (GB:KHL 10444, holotype): d cystidia e young hymenium with slight overall encrustation f basidiospores. Subulicystidium tedersooi (TU 110894, holotype): g cystidia, h basidiospores. All preparations done in 3% aqueous solution of potassium hydroxide (KOH) mixed with 1% aqueous solution of Phloxine. All scale bars equal 10 µm.

Figure 10.

Basidiospore shape and size in all studied species of Subulicystidium. Each species is illustrated by a single specimen and herbarium codes are indicated on the figure.