Myxarium boreale T. Bau & X. Wang, 2023

Wang, Xia & Bau, Tolgor, 2023, A novel exidioides fungi, Myxarium boreale (Auriculariales, Basidiomycota) discovered from Northern China, Phytotaxa 618 (2), pp. 161-171 : 164-167

Myxarium boreale T. Bau & X. Wang , sp. nov. ( Figure. 2 and 3 )

MycoBank number: —849040

Diagnosis: — M. boreale is similar and close to M. cinnamomescens and M. populinum , but differs from the latters by its basidiomata larger, up 30 mm, with mineral inclusions on the surface of the hymenial; basidia 4(2)-celled, globose to subglobose; basidiospores allantoid to narrow cylindrical.

Etymology: —“boreale” refers to the species was found from boreal forest in northern China.

Type: — CHINA. Jilin Province: Changchun, back mountain of campus of Jilin Agricultural University , on fallen branches of deciduous trees, 43°81′N, 125°40′E, 235 m, 3 July 2022, T . Bau & Lisong Mu ( MHJAU67109 , holotype!) .

Description: —Basidiomata soft gelatinous when fresh; first single adpressed-orbicular, 4 mm in diam, hyaline with yellowish-white (2A2) tints when young; fusing together and making a cerebriform fructification, with grooves, shiny, semitranslucent, yellowish-white disappears, almost white (A1), up to 30 mm in widest dimension and 4–9 mm thick when mature. Hymenial surface smooth, with edges separated from the base material, irregularly, relatively blunt. The dried basidiomata is raw-umber (5F8) and appears as a thin layer or cerebriform; mineral inclusions presence. Covering with water, absorbs water and expands, slightly transparent, milk-white (1A2), light yellowish disappears.

The hymenium of the cross-section face is pale yellow, which is composed of basidia and hyphidia. Probasidia globose to subglobose, stalk up to 20–27 × 2–3 μm; mature basidia globose to subglobose, 10–11×9–10 μm, 4(2)- celled, with oil droplets; sterigmata up to 27 × 2–3 μm, cylindricus, bluntly rounded at the top. Hyphidia abundant, branched, tapering, with a forked top, up to 1.3 μm in diam. Basidiospores 11.5–13.2 × 3.4–4.4 μm, Q=3.27–3.47, allantoid to narrow cylindrical, slightly curved, hyaline, smooth, thin-walled, with varying amounts of oil droplets; produce germination tubes. Hyphal clamped, up to 3 μm in diam, hyaline, some septa swollen up to 8μm in diam.

Habitat: —Summertime growth on branches of dead deciduous trees.

Distribution: —Distributed only in Jilin Province, China, Asia.

Additional specimen examined (paratype): — CHINA. Jilin Province: Changchun, wild plantation garden of campus of Jilin Agricultural University , on fallen branches of deciduous trees, 4 July 2022, T . Bau & Siying Li ( MHJAU67110 ) .

Figures

FIGURE 2. Basidiomata of Myxarium boreale: a. fresh (HMJAU67110); b. fresh, arrow pointing yellow (HMJAU67109); c. dry (HMJAU67109); d. dry, a thin layer (HMJAU67110); e. arrow pointing towards mineral inclusions (HMJAU67110); f. covering with water (HMJAU67109). Scale bars: a=1 cm; b=0.5 cm; c,d,e,f=0.5 mm. Figures a, b and c–f were provided by Li Siying, Mu Lisong and the author, respectively.

FIGURE 3. Myxarium boreale (holotype and paratype). a. Basidiomata; b. Basidiospores; c. Hyphidia; d. Basidia. Scale bars: a=1 cm; b,d=10 μm; c=5 μm. Drawn by author.