Catathelasma subalpinum Z. W. Ge, 2020

Ge, Zai-Wei, Wu, Jian-Yun, Hao, Yan-Jia, Zhang, Qingying, An, Yi-Feng & Ryberg, Martin, 2020, The genus Catathelasma (Catathelasmataceae, Basidiomycota) in China, MycoKeys 62, pp. 123-138 : 123

Catathelasma subalpinum Z. W. Ge sp. nov. Figs 2B , 4

Diagnosis.

Catathelasma subalpinum is distinguished from C. laorentou by having greyish-yellow to grey pilei, higher elevation (alt. 2600-3500 m) occurrence and association with Pinus densata Mast.

Type.

China. Yunnan Province: Lijiang, Ninglang, Xichuan Xiang, 14 July, 2010, J. Qin 65 (Holotype: HKAS 67751). GenBank accession numbers: - ITS, MK909099; LSU, MK909121.

Description.

Pileus 3.5-15 cm broad, hemispherical at early stage, expanding to broadly convex with age, shallowly depressed at centre, white to dirty white at first, then greyish-white (1B1) to greyish-yellow (4C4), grey (8B1) when mature, with incurved margin, viscid when wet, sometimes irregularly cracked. Lamellae slightly decurrent, crowded, whitish, thick, 8 mm in height, with 2-3 tiers of lamellulae, with smooth edge, covered by a white, well developed, thick membranous veil in early stage. Stipe 11-14 × 3-5.5 cm, fusiform, attenuated downwards, whitish to yellowish-white, firm, with double annulus in which the lower annulus is flimsy and the upper one is membranous, thick, around 2.5 cm away from the stipe apex; with white inner side and greyish-yellow outer side. Context white in pileus and stipe, not changing colour when cut, 3.5 cm thick in pileus; smell and taste farinaceous. Spore print white.

Basidiospores [43/2/2] (9) 10-12 × 5-6 μm (mean 10.7 ± 0.8 × 5.4 ± 0.5 μm), Q = (1.67) 1.80-2.20 (2.40), Qm = 1.99 ± 0.18, subcylindrical in frontal view, subcylindrical to somewhat inequilateral in side view, hyaline in KOH, amyloid, smooth, thin-walled. Basidia 35-45 × 8-9 μm, narrowly clavate, 4-spored; sterigmata up to 5 μm long. Pleurocystidia none. Cheilocystidia basidiole-like, hyalinous. Lamella trama subregular, somewhat bilateral towards lamella edge, made up of more or less parallel to interwoven hyphae. Oleiferous hyphae present in both lamella and pileus trama. Pileipellis a thick ixolattice (500-650 μm thick) of 1.5-10 μm wide hyphae which gelatinise and collapse, occasionally interspersed with oleiferous hyphae; the layer grading gradually into pileal trama. Clamp connections abundant in all tissues.

Distribution.

Known from Yunnan Province, south-western China.

Ecology.

Presumably ectomycorrhizal, in Pinus densata forests distributed at around alt. 2600-3500 m. Solitary to scattered, terrestrial.

Etymology.

The epithet " subalpinum " refers to the distribution range of the species.

Additional specimens examined.

China. Yunnan Province: Lijiang, Elephant Hill, 1 August 2011, Q. Cai 495 (HKAS 70091); Ninglang, 6 August 2011, L. P. Tang 1459 (HKAS 69920).

Discussion.

Catathelasma subalpinum is closely related to C. laorentou , which is also from south-western China. However, C. subalpinum differs by its higher elevation distribution and its association with Pinus densata , while C. laorentou has pale yellow to greyish-yellow basidiomes, associations with P. yunnanensis and Keteleeria evelyniana forests and is comparatively more common than C. subalpinum . Besides, C. subalpinum has much fewer oleiferous hyphae in the pileipellis. In addition, phylogenetic trees, reconstructed from ITS, 28S, TEF1 and concatenated ITS-LSU-TEF1, support the separation of C. subalpinum from C. laorentou .

Catathelasma subalpinum is also morphologically similar to C. ventricosum Peck) Singer in general appearance. However, C. subalpinum is found in coniferous forest dominated by Pinus densata in south-western China, while C. ventricosum is associated with hardwood trees in south-eastern North America ( Singer 1940); C. subalpinum has abundant clamp connections in all tissues and longer stipes measuring 11-14 × 3-5.5 cm (compared to the 4-5 × 4 cm for C. ventricosum ).

Catathelasma singeri from USA is morphologically somewhat similar to C. subalpinum . However, C. singeri has a slimy viscid pileus that is more similar to species within the genus Hygrophorus Fr. ( Mitchel and Smith 1978), smaller basidiomes (pileus around 6 cm, stipe 4 × 1.2 cm) compared with those of C. subalpinum (pileus up to15 cm, stipe 11-14 × 3-5.5 cm) and narrow, basidiole-like cheilocystidia.

Catathelasma evanescens , which was described from Wyoming (USA), is similar in general appearance and also has a high elevation distribution. However, C. evanescens has obvious distant lamellae, a hollow stipe, a volva-like veil around the base of the stipe and longer but narrower basidiospores measuring 14-17.5 × 3-5 μm, according to Lovejoy (1910).

Figures

Figure 2. Basidiomes of Catathelasma species in China. A Catathelasma laorentou (HKAS 92245) B Catathelasma subalpinum (HKAS 67751) C Catathelasma imperiale (HKAS 79952) D Young Catathelasma imperiale (HKAS 84299) in association with roots of Picea asperata Mast. Scale bars: 2.5 cm.

Figure 4. Microscopic features of Catathelasma subalpinum (HKAS 67751). A Basidiospores B Basidia C Pileipellis. Oleiferous hyphae are indicated by thick-walled hyphae. Scale bars: 10 μm.